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Feel free to ask Myles

Posted By: myles_rose

Feel free to ask Myles - 03/12/02 05:21 AM

This is one place you can post amp questions and I will try to help.


I am putting this post up here, so if you have a question or have a comment, just post a comment here and when I see the email notification I will answer back here as quickly as I am able. If I don't get to it in a day or two, please forgive me.

I generally try to get to this in the early morning or later evening, but while we are testing and destroying tubes (which takes time while they "bake"),I try to get onto this.

Ashley Danielle is the gal in my avatar and the head of Guitar Amplifier Blueprinting Artist Relations. Ashley is also the girl biasing the Fender Deluxe Reverb in my avatar. Ashley was recently in the Slash and Billy Idol videos.


Regards,

Myles
Posted By: Wickerman_dup1

Re: Feel free to ask Myles - 03/12/02 05:57 AM

First off, thank you so much. You're a great help and I really apreciate you sharing your knowledge with us. Thank you.

Now, I use a Carvin Nomad. 50 watt, 1x12, 5 12AX7s, 4 EL84s. I love the overdrive channel, it's real crunchy and can go from a good, transparent, slight overdrive to full on metal crunch. I really enjoy the dirty channel but the clean breaks up real fast. Even on practice volume (loud, but not painful) it tends to get a little distortion. I was wondering if there were any tubes (I'm not sure if I need better preamp or power amp tubes) that stay a little cleaner but can still get some good crunch.

Stock 12AX7s - Groove Tubes GT12AX7R
Stock EL84s - Sovtek EL84/6BQ5
Posted By: Dak Lander

Re: Feel free to ask Myles - 03/12/02 06:48 AM

Hello Myles,
Jeez, this brought all kinds of things to mind...

I'll be polite.

I'm happy to have you put up a specific post to make it easier to get to your info about amps & such.

Now, can you help me play better to sound better through any amp???? \:D \:D \:D

Posted By: Boggs

Re: Feel free to ask Myles - 03/12/02 05:21 PM

Wickerman, I have heard of really good results, similar to what you describe you are looking for, by using JJs. A friend of mine on Carvin's and Keith Miller's board uses a BelAir and he loved the difference they made in it. He's primarily a blues player. Terry Hartley. If you want, I'll get you a link to him. You should hear his sound clips... He's got great tone and plays some good stuff! Boggs
Posted By: myles_rose

Re: Feel free to ask Myles - 03/12/02 07:02 PM

Quote:
Originally posted by Wickerman:
First off, thank you so much. You're a great help and I really apreciate you sharing your knowledge with us. Thank you.

Now, I use a Carvin Nomad. 50 watt, 1x12, 5 12AX7s, 4 EL84s. I love the overdrive channel, it's real crunchy and can go from a good, transparent, slight overdrive to full on metal crunch. I really enjoy the dirty channel but the clean breaks up real fast. Even on practice volume (loud, but not painful) it tends to get a little distortion. I was wondering if there were any tubes (I'm not sure if I need better preamp or power amp tubes) that stay a little cleaner but can still get some good crunch.

Stock 12AX7s - Groove Tubes GT12AX7R
Stock EL84s - Sovtek EL84/6BQ5
Wickerman;

Those amps are pretty versitile, but have a gain structure that was designed for the most part for the distortion and compression you hear.

There are a few things you can try though.

The first and easiest, would be to replace the 12AX7 in the preamp position that is closest to the input jack. This is V1. The Russian (Sovtek 12AX7WA as stock - Groove Tubes), is a pretty high output 12AX7. Try a 12AX7C (a Chinese 12AX7), as it has a little less gain.

If you want it cleaner, then in that same position try a 5751, a tube that is much the same as the 12AX7 but with about 30% less gain.

The final thing you can try, in in the last preamp position (the preamp tube the most close to the power tubes), probably V5, replace that 12AX7 with a 12AT7. This has less gain but more current drive capability and will give you more clean headroom and less output stage distortion.

If you need more ideas after those simpler ones, drop me another note here and I'll try to help further. Unfortunately, that particular amp is a pretty strong amp and when you get into that area, its a bit harder to tone them down.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 03/12/02 07:06 PM

Quote:
Originally posted by daklander:
Hello Myles,
Jeez, this brought all kinds of things to mind...

I'll be polite.

I'm happy to have you put up a specific post to make it easier to get to your info about amps & such.

Now, can you help me play better to sound better through any amp???? \:D \:D \:D

daklander;

Well, I'm not the most proficient player around for sure, but I see you are also in So Cal. Maybe we can get together ... you show me a few things, I'll show you what little I know, and maybe we'll both play a little better \:\)

I can show you a few little things to play on any amp that will show the strengths and weaknesses of a particular amp. That might help?

Regards,

Myles
Posted By: Wickerman_dup1

Re: Feel free to ask Myles - 03/12/02 09:44 PM

Thank you very much Myles. You're the best!
Posted By: rickystratcat

Re: Feel free to ask Myles - 03/13/02 01:04 AM

Hi Myles,one of the posts that got missed was mine.What I had asked was for your thoughts on substitutions for the 12AX7 other than 12AT7's or
12AU7's.I've been playing with some interesting substitutions with the 12BZ7 and 12AZ7 but I DO NOT
know enough yet to be comfortable.Can you help me understand more about tube substitution(particularly
the dangers to life and equipment)?Thanks,Ricky
Posted By: myles_rose

Re: Feel free to ask Myles - 03/13/02 03:12 AM

Quote:
Originally posted by rickystratcat:
Hi Myles,one of the posts that got missed was mine.What I had asked was for your thoughts on substitutions for the 12AX7 other than 12AT7's or
12AU7's.I've been playing with some interesting substitutions with the 12BZ7 and 12AZ7 but I DO NOT
know enough yet to be comfortable.Can you help me understand more about tube substitution(particularly
the dangers to life and equipment)?Thanks,Ricky
rickystratcat ...

Sorry I missed your post. I have written a bit on this before, so you may want to look at some of my other posts, maybe the one on the 12AX7LP.

Basically, as long as your amp is not opened up to the innards of the chassis, there is not too much exposed high voltage.

You can swap preamp tubes all around with no danger to the equipment or yourself. There is no adjustment necessary either.

A 12AT7 will give less gain than a AX7 .... and in the phase inverter postion, will yield more clean headroom before the onset of distortion.

a 12AU7 will do the same thing, but to even a greater change than the AT7.

Some folks prefer (the late SRV) 5751 tube in the first gain stage.

If you have other questions, just drop a post here, but first look around on my webpage as this is covered in a few spots.

Regards
Posted By: rickystratcat

Re: Feel free to ask Myles - 03/13/02 04:20 AM

Hi Myles,I appreciate your response.I went to your website and looked around again(I had been there before but I went back in case I missed what I was looking for).Checked out your son's site too. \:\) I think it's great.Anyway,I guess I need to re-state my
question better.I'm interested in tube substitutions
OTHER THAN the 12AT7's and 12AU7's.Specifically the 12BZ7 and the 12AZ7.I've had great results playing with those tubes in the different slots and I don't know anything about them I've searched the net high and low and I can't seem to find the information I'm looking for.Have you experimented with these tubes or can you point me in the right direction?Thanks,Ricky
Posted By: Dan South

Re: Feel free to ask Myles - 03/13/02 09:40 AM

Are you related to Floyd?

Sorry, couldn't think of a good question. \:D
Posted By: myles_rose

Re: Feel free to ask Myles - 03/13/02 08:16 PM

Quote:
Originally posted by rickystratcat:
Hi Myles,I appreciate your response.I went to your website and looked around again(I had been there before but I went back in case I missed what I was looking for).Checked out your son's site too. \:\) I think it's great.Anyway,I guess I need to re-state my
question better.I'm interested in tube substitutions
OTHER THAN the 12AT7's and 12AU7's.Specifically the 12BZ7 and the 12AZ7.I've had great results playing with those tubes in the different slots and I don't know anything about them I've searched the net high and low and I can't seem to find the information I'm looking for.Have you experimented with these tubes or can you point me in the right direction?Thanks,Ricky
rickystratcat...

Sorry, I misunderstood your question it seems.

I focus on the 12AX7, AT, AU, 12BY7A, and some of the older 6L and 6S series. They are the most common tubes in guitar and bass amps.

I think the best folks to talk to would be ...

Bob Pletka at http://www.eurotubes.com

the folks at KCA and those at Tubeworld.

Hope that helped somewhat.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 03/13/02 08:50 PM

Quote:
Originally posted by Dan South:
Are you related to Floyd?

Sorry, couldn't think of a good question. \:D
Dan South ...

Sorry ... not related. I am also not related to Pete the baseball player of the past. Come to think of it, I don't think I am related to anybody that the general pubic would know.

Myles
Posted By: peel_dup1

Re: Feel free to ask Myles - 03/13/02 08:58 PM

Hi myles
First of all thanks for your time and advice. this forum is amazing. its great to see knowledgable players help others. Polite bunch here too.

I reposted my early thread here to save you time. Here it is:

Im sure the little marshall jubilee posse would love to get your take on this amp - I tracked down the schematic for the 50w version and I wonder if you could take a look at it and advise on:

tube recommendations
getting good tube distortion (preferably high gain saturated)
whether a SS dist pedals or tube based dist pedals are better matched to this amp

..anything that you feel worth passing along.

thx in advance, peel
heres the link to the schematic:
http://home.att.net/~amptech/2550.gif
Posted By: machinex_dup1

Re: Feel free to ask Myles - 03/13/02 10:05 PM

Myles,

Im kinda new but have read alot of your posts, very informative, thanks in advance for taking the time to answer all these questions.

My question would be: what are the conditions in which to set the impedance of your amp and cabs?
Posted By: peel_dup1

Re: Feel free to ask Myles - 03/13/02 11:40 PM

Quote:
Originally posted by machinex:
Myles,

Im kinda new but have read alot of your posts, very informative, thanks in advance for taking the time to answer all these questions.

My question would be: what are the conditions in which to set the impedance of your amp and cabs?
BTW Machinex sorry about the switching problem on your jubilee. Im sure its not major. Get it fixed an crank that puppy!

Peel
Posted By: machinex_dup1

Re: Feel free to ask Myles - 03/14/02 12:51 AM

Thanks bro, its cool though I just got ahold of one of the better amp repair guys in our area so Im taking it to him tonight or tomorrow and hopefully he'll be able to take care of it ASAP, man I hope it doesnt bankrupt me, lol.
Posted By: myles_rose

Re: Feel free to ask Myles - 03/14/02 02:15 AM

Quote:
Originally posted by peel:
Hi myles
First of all thanks for your time and advice. this forum is amazing. its great to see knowledgable players help others. Polite bunch here too.

I reposted my early thread here to save you time. Here it is:

Im sure the little marshall jubilee posse would love to get your take on this amp - I tracked down the schematic for the 50w version and I wonder if you could take a look at it and advise on:

tube recommendations
getting good tube distortion (preferably high gain saturated)
whether a SS dist pedals or tube based dist pedals are better matched to this amp

..anything that you feel worth passing along.

thx in advance, peel
heres the link to the schematic:
http://home.att.net/~amptech/2550.gif
Peel;

All Marshall's have their own distinctive sound, partly because of their tone stack in the front end, but also partly because they keep a certain amount of crossover notch distortion in the output stage when they are properly adjusted.

The input is of high enough resistance that most pedals work quite well with these amps. I would play some with your bias, set it via the scope and crossover notch method rather than the current draw method on that particular amp, as you need to have the "Marshall notch" in there, but not too much ... not too little. A good Marshall guy can do this pretty easily.

Let he or she know at what settings you expect the play most often so it can be set for that particular area to be optimum, unlike the current draw method that is set at idle. Most amps like the current draw method just fine and dandy, Marshall's prefer a little different treatment to sound their best.

Keep the ECC83's in there if you want the Marshall sound, but try to find a very good one for V1 ... a NOS if you can spring for it. That is your tonal signature right there.

For V3, try to get a balanced (side A and side B of that tube should be less than .15 mA apart at 250 volts with a -2v bias). If you can get one at .1 mA or less, that is even better. Then make sure your output tubes are matched pretty closely.

If you want more clean headroom, I can help you with that, but then your Marshall won't sound as much as a Marshall.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 03/14/02 02:18 AM

Quote:
Originally posted by machinex:
Myles,

Im kinda new but have read alot of your posts, very informative, thanks in advance for taking the time to answer all these questions.

My question would be: what are the conditions in which to set the impedance of your amp and cabs?
machinex ....

Unless I don't understand the question, its pretty simple ... make them match! If you have an 8 ohm cabinet, set the amp selector to 8 ohms.

If you set it to 16 ohms, the amp will work into a heavier load, and will not sound right.

If you set it to 4 ohms, and push it hard, your will risk tube failure, tubes wearing more quickly, and output transformer failure (pretty expensive).

Regards
Posted By: Chip McDonald

Re: Feel free to ask Myles - 03/14/02 06:12 AM

Quote:
Originally posted by myles111:
So .... I am putting this post up here, so if you have a question or have a comment, just post a comment here and when I see the email notification I will answer back here as quickly as I am able.
(Taking advantage here)

What are the center frequencies and q's of the tone controls on the following amps/FX? Just out of curiousity to see it side by side in one place...

Marshall Super Lead
Fender Deluxe; Twin; Super
Boogie Dual Rect
Vox AC30/Top Boost
Gibson GA-40 (just because I have one and I'm curious if you happen to know by some weird chance (and would be very impressed if you did))
Ampeg SVT
Ibanez TS line
Boss DS-1; OD-1
Fuzz Face

Just curious...
Posted By: peel_dup1

Re: Feel free to ask Myles - 03/14/02 06:25 AM

Quote:
Originally posted by myles111:
Quote:
Originally posted by peel:
Hi myles
First of all thanks for your time and advice. this forum is amazing. its great to see knowledgable players help others. Polite bunch here too.

I reposted my early thread here to save you time. Here it is:

Im sure the little marshall jubilee posse would love to get your take on this amp - I tracked down the schematic for the 50w version and I wonder if you could take a look at it and advise on:

tube recommendations
getting good tube distortion (preferably high gain saturated)
whether a SS dist pedals or tube based dist pedals are better matched to this amp

..anything that you feel worth passing along.

thx in advance, peel
heres the link to the schematic:
http://home.att.net/~amptech/2550.gif
Peel;

All Marshall's have their own distinctive sound, partly because of their tone stack in the front end, but also partly because they keep a certain amount of crossover notch distortion in the output stage when they are properly adjusted.

The input is of high enough resistance that most pedals work quite well with these amps. I would play some with your bias, set it via the scope and crossover notch method rather than the current draw method on that particular amp, as you need to have the "Marshall notch" in there, but not too much ... not too little. A good Marshall guy can do this pretty easily.

Let he or she know at what settings you expect the play most often so it can be set for that particular area to be optimum, unlike the current draw method that is set at idle. Most amps like the current draw method just fine and dandy, Marshall's prefer a little different treatment to sound their best.

Keep the ECC83's in there if you want the Marshall sound, but try to find a very good one for V1 ... a NOS if you can spring for it. That is your tonal signature right there.

For V3, try to get a balanced (side A and side B of that tube should be less than .15 mA apart at 250 volts with a -2v bias). If you can get one at .1 mA or less, that is even better. Then make sure your output tubes are matched pretty closely.

If you want more clean headroom, I can help you with that, but then your Marshall won't sound as much as a Marshall.

Regards,

Myles
Thx Myles - much appreciated, Ill take this to my amp tech when I get my new tubes. Any particular brand of tubes that might work with this amp better than others?

Peel
Posted By: machinex_dup1

Re: Feel free to ask Myles - 03/14/02 09:21 AM

Myles,

What I meant by my question was: I know that the cab and head has to match, but I was wondering why you would set am amp to 4, 8, 16, etc ohms. whats the difference?

Thanks in advance
Posted By: myles_rose

Re: Feel free to ask Myles - 03/14/02 07:34 PM

Quote:
Originally posted by Chip McDonald:
Quote:
Originally posted by myles111:
So .... I am putting this post up here, so if you have a question or have a comment, just post a comment here and when I see the email notification I will answer back here as quickly as I am able.
(Taking advantage here)

What are the center frequencies and q's of the tone controls on the following amps/FX? Just out of curiousity to see it side by side in one place...

Marshall Super Lead
Fender Deluxe; Twin; Super
Boogie Dual Rect
Vox AC30/Top Boost
Gibson GA-40 (just because I have one and I'm curious if you happen to know by some weird chance (and would be very impressed if you did))
Ampeg SVT
Ibanez TS line
Boss DS-1; OD-1
Fuzz Face

Just curious...
Chip,

I don't keep that sort of information for the most part, and don't know of anybody that does actually.

Most amps use one of a few proven tone stacks, and on my website there are graphs for the Marshall, Fender, and Vox - so you might look there as a start.

Each amp even in the same model has differences as the tolerances were +/- 20% in many cases, so when I have an amp on the bench, I see what its doing at the particular time.

As far as effects, I don't do much with them in the design area as there are more than enough amps to keep me busy enough.

I do look at effects and their impedence though, when doing an amp blueprint. I also look at the aspects and resistance of the pickups in the particular primary guitar.

Regards
Posted By: dlb

Re: Feel free to ask Myles - 03/14/02 08:53 PM

Myles, First, thanks for the heap of helping you so kindly give. I have a newer Fender Prosonic that I dig because of it's portability but I want to sweeten the gain channel. Are you familiar with it's schematics and can you offer any assistance?
Thanks again dude.
Posted By: myles_rose

Re: Feel free to ask Myles - 03/15/02 05:51 AM

Posted By: myles_rose

Re: Feel free to ask Myles - 03/15/02 06:32 AM

Quote:
Originally posted by machinex:
Myles,

What I meant by my question was: I know that the cab and head has to match, but I was wondering why you would set am amp to 4, 8, 16, etc ohms. whats the difference?

Thanks in advance
machinex;

Speakers have a nominal resistance. Nominal means the approxmate lowest value that the speaker will have over its designed frequency range. An 8 ohm speaker may have a lower value of 8 ohms at one area of its frequency range, yet 40 ohms at another frequency. Speakers are an inductive load that is always changing, but here, we are interested in the speakers lowest value.

Tube have a high value .... say 6000-8000 ohms, and we have to make this "Match" the 8 ohm load (or 2, 2.7, 4, 8, 16) load of the speakers. Go too low, and poof .... your output transforer is history. Your transformer in a 50 watt amp is generally designed to be able to deal with 50 watts, and in some amps its even marginal at that point. So .... you have your 50 watt amp, but with a 4 ohm cabinet, and your selector is set to 16 ohms ... or 8 .... now the output section of your amp is looking at a lighter load in comparasion. Things are not matched. Your amp put out more power in the wrong way, and after a very few minutes on a lot of amps .... trouble.

If you have an amp like a Rivera, THD, or Carr, their transformers are very costly and are generally way overbuilt for the amp, so you have a lot more time before disaster when you make the mistake.

In any case, once the transformer overheats and the insulation starts to go, you may already be past the point of having a reliable amp in the future.

Basically, whether you understand it or not, just make the numbers match. .... unless you have a 100 watt amp, but are running it as a 50 watter by pulling two of the output tubes (and WHICH TWO are also very important). Then your output section needs to be matched to 1/2 the resistance of what is the normal resistance of the tubes when all 4 are installed .... so ..... with an 8 ohm cabinet and half the tubes pulled, we then set the selector to 4 ohms.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 03/15/02 06:52 AM

Quote:
Originally posted by dlb:
Myles, First, thanks for the heap of helping you so kindly give. I have a newer Fender Prosonic that I dig because of it's portability but I want to sweeten the gain channel. Are you familiar with it's schematics and can you offer any assistance?
Thanks again dude.
dlb;

I am pretty familar with the Prosonic, but need to know if its the head or the combo, as the combo has a slightly different circuit with reverb.

As far as the "gain" channel, you have the options of cascaded gain or not. Which config do you want to change?

If its the cascaded gain, that's a bit harder, as when you use one tube to drive another, that are both high gain tubes, things can get out of control very fast.

Let me know which amp, and what config you want to tone down, and I will give you a few ideas .... the first of which would be to replace the Fender/Sovtek 12AX7WA in V1 and V2, or at least have them looked at to see if they are too stong for the slots they are in. If you have 7025's in those positions, then we have a few other ideas we can go into.

Regards,
Posted By: dlb

Re: Feel free to ask Myles - 03/15/02 04:52 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by dlb:
Myles, First, thanks for the heap of helping you so kindly give. I have a newer Fender Prosonic that I dig because of it's portability but I want to sweeten the gain channel. Are you familiar with it's schematics and can you offer any assistance?
Thanks again dude.
dlb;

I am pretty familar with the Prosonic, but need to know if its the head or the combo, as the combo has a slightly different circuit with reverb.

As far as the "gain" channel, you have the options of cascaded gain or not. Which config do you want to change?

If its the cascaded gain, that's a bit harder, as when you use one tube to drive another, that are both high gain tubes, things can get out of control very fast.

Let me know which amp, and what config you want to tone down, and I will give you a few ideas .... the first of which would be to replace the Fender/Sovtek 12AX7WA in V1 and V2, or at least have them looked at to see if they are too stong for the slots they are in. If you have 7025's in those positions, then we have a few other ideas we can go into.

Regards,
Thanks for the reply, It is a 2-10 combo in the stock state except for power tubes which I've experimented with. It has the cascading gain. I deally, I would like to achieve more clean head room in channel 1 (past 3 it breaks up quick)and less of the synthetic gain sound on channel 2. I've read of mods to put master volume pots in the reverb slot and moving reverb pot to back of chassis. That interests me. It is a cool amp but hard to harness in a live situation. This little sucker runs hot as well, I have a good PC fan I am going to stick in it.
Posted By: machinex_dup1

Re: Feel free to ask Myles - 03/15/02 07:46 PM

K, that clears it up a little more for me, thanks myles
Posted By: myles_rose

Re: Feel free to ask Myles - 03/15/02 08:30 PM

Quote:
Thanks for the reply, It is a 2-10 combo in the stock state except for power tubes which I've experimented with. It has the cascading gain. I deally, I would like to achieve more clean head room in channel 1 (past 3 it breaks up quick)and less of the synthetic gain sound on channel 2. I've read of mods to put master volume pots in the reverb slot and moving reverb pot to back of chassis. That interests me. It is a cool amp but hard to harness in a live situation. This little sucker runs hot as well, I have a good PC fan I am going to stick in it.
First off, don't start doing mods to that amp or you will get a lot more noise in the higher gain states. These amps can be noisy enough unless you hand select preamp tubes.

Have your bias checked! If the amp is over or under biased, you will get all sorts of grainy nonsense down in the range you mention.... especially if the amp is overbiased and running too cool. These amps already start to breakup very quickly in the preamp stages, as that is what they were designed to do, so it is even more critical to have a good output stage after the preamp stage. I would bet, after looking at a number of these, that with your volume set to 3-4, that there is a lot of crossover notch distortion if you scope the amp.

To give you more headroom, you need to have somebody look at your first two preamp tubes to see how much above or below 1.2mA they put out with 250 volts on their plates and a -2v bias. If they are the typical Sovtek/Fender tubes, they are probably putting out more than the spec 1.2mA. The 12AX7 has a gain of about 100, so the difference between 1.2 and 1.3 is pretty dramatic.

You need to find a nice 12AX7, perhaps a 12AX7C, that has maybe 1.0mA output. The other thing you can do here is put a JAN 5751 in the V1 position.

Some good places to get either the JAN or a bit lower powered 12AX7 are Watford Valves, Tubeworld, and KCA NOS tubes. All those folks have links on my website. They are the only folks that have the equipment to measure the qualities you need AND have the tubes you'd want if you go the NOS route.

Then, you need to have your output tubes checked. If they are in a midrange, you'd want them to be at a higher range. Something like, if they are a Groove Tubes 4-5 rating, you'd want them to be a rating of 6-7.

Last, your phase inverter, let me know what is currently in there. It is the preamp tube that is closest to the power tubes. Tell me what it says on the tube, what kind it is, and as much as you can tell me about it. This is a critical tube in this amp, especially when you run the amp Class A, as if this is not balanced on the A/B sides, there will be a lot more heat generated than is already done when the amp is in Class A mode.

When you have the bias checked, find somebody uses a scope if they also use a bias probe. Many folks use a bias probe incorrectly. They might use charts or manuals that say what the correct reading for a particular amp should be, and this is often a bit off as different amps have different B+ voltages. Folks that are more technically advanced, try to figure out their real B+ voltage bu pulling one of the output tubes and taking a reading of the plate pin. This is going in the right direction, and is easier than taking the amp apart, but also gives a false reading. When one output tube is removed, the voltage changes a LOT in many amps. In one Marshall I work on, a 50 watter, it goes from about 450v to about 415v when both tubes are in the amp.

To get the proper B+, ESPECIALLY on a Prosonic, you need to pull the chassis and take the reading off the wired side of the socket with all tubes in the amp. Then you can use a bias probe more effectively.

Regards,
Posted By: Chip McDonald

Re: Feel free to ask Myles - 03/19/02 09:27 AM

Ok, here's a typically Chip off the wall angle:

Is it possible to make X-rays with a rectifier tube?

If so, is it possible to be receiving lose-doses of x-rays when near tube-rectified amps... ?
Posted By: Seegs

Re: Feel free to ask Myles - 03/21/02 11:57 AM

I just saw this after I started a thread.

Basically I want to know what does it mean when your power tubes start glowing blue?

Should I be concerned as they only have around ten hours on them? They are new GT 5881 NOS's

Seegs
Posted By: steve f

Re: Feel free to ask Myles - 03/21/02 04:53 PM

Myles, thanks for giving us the benefit of your experience.

I wanted to get your thoughts on the overall quality of Bogner amps (build quality, components used, etc), the Shiva in particular.

I recently looked at a Soldano HotRod 100+ and wasn't overly impressed compared to my Rivera M100. It sounded fine, but boy, the M100 just seems to have much more attention to detail and the quality of components seems higher. I don't won't to invest a lot of time trying to track down a Shiva if it's not going to have the quality built in like my M100.
Posted By: dlb

Re: Feel free to ask Myles - 03/21/02 07:29 PM

Quote:
Originally posted by myles111:
Quote:
Thanks for the reply, It is a 2-10 combo in the stock state except for power tubes which I've experimented with. It has the cascading gain. I deally, I would like to achieve more clean head room in channel 1 (past 3 it breaks up quick)and less of the synthetic gain sound on channel 2. I've read of mods to put master volume pots in the reverb slot and moving reverb pot to back of chassis. That interests me. It is a cool amp but hard to harness in a live situation. This little sucker runs hot as well, I have a good PC fan I am going to stick in it.
First off, don't start doing mods to that amp or you will get a lot more noise in the higher gain states. These amps can be noisy enough unless you hand select preamp tubes.

Have your bias checked! If the amp is over or under biased, you will get all sorts of grainy nonsense down in the range you mention.... especially if the amp is overbiased and running too cool. These amps already start to breakup very quickly in the preamp stages, as that is what they were designed to do, so it is even more critical to have a good output stage after the preamp stage. I would bet, after looking at a number of these, that with your volume set to 3-4, that there is a lot of crossover notch distortion if you scope the amp.

To give you more headroom, you need to have somebody look at your first two preamp tubes to see how much above or below 1.2mA they put out with 250 volts on their plates and a -2v bias. If they are the typical Sovtek/Fender tubes, they are probably putting out more than the spec 1.2mA. The 12AX7 has a gain of about 100, so the difference between 1.2 and 1.3 is pretty dramatic.

You need to find a nice 12AX7, perhaps a 12AX7C, that has maybe 1.0mA output. The other thing you can do here is put a JAN 5751 in the V1 position.

Some good places to get either the JAN or a bit lower powered 12AX7 are Watford Valves, Tubeworld, and KCA NOS tubes. All those folks have links on my website. They are the only folks that have the equipment to measure the qualities you need AND have the tubes you'd want if you go the NOS route.

Then, you need to have your output tubes checked. If they are in a midrange, you'd want them to be at a higher range. Something like, if they are a Groove Tubes 4-5 rating, you'd want them to be a rating of 6-7.

Last, your phase inverter, let me know what is currently in there. It is the preamp tube that is closest to the power tubes. Tell me what it says on the tube, what kind it is, and as much as you can tell me about it. This is a critical tube in this amp, especially when you run the amp Class A, as if this is not balanced on the A/B sides, there will be a lot more heat generated than is already done when the amp is in Class A mode.

When you have the bias checked, find somebody uses a scope if they also use a bias probe. Many folks use a bias probe incorrectly. They might use charts or manuals that say what the correct reading for a particular amp should be, and this is often a bit off as different amps have different B+ voltages. Folks that are more technically advanced, try to figure out their real B+ voltage bu pulling one of the output tubes and taking a reading of the plate pin. This is going in the right direction, and is easier than taking the amp apart, but also gives a false reading. When one output tube is removed, the voltage changes a LOT in many amps. In one Marshall I work on, a 50 watter, it goes from about 450v to about 415v when both tubes are in the amp.

To get the proper B+, ESPECIALLY on a Prosonic, you need to pull the chassis and take the reading off the wired side of the socket with all tubes in the amp. Then you can use a bias probe more effectively.

Regards,

Ok, I finally got around to this. The rectifier tube is a Chinese 5AR4 GZ34 (Fender on it).It has sovtek 12ax7wa's throughout with exception of the reverb tube. It came with sovtek 5881WXT 6L6 power tubes. I have more recently installed Audio Classic 6L6WGB matched set at a 10 rating. It made a bit of clarity difference but took away some warmth. What do you think my next steps should be?
Thanks again!
Posted By: dlb

Re: Feel free to ask Myles - 03/22/02 01:22 AM

Quote:
Originally posted by steve f:
Myles, thanks for giving us the benefit of your experience.

I wanted to get your thoughts on the overall quality of Bogner amps (build quality, components used, etc), the Shiva in particular.

I recently looked at a Soldano HotRod 100+ and wasn't overly impressed compared to my Rivera M100. It sounded fine, but boy, the M100 just seems to have much more attention to detail and the quality of components seems higher. I don't won't to invest a lot of time trying to track down a Shiva if it's not going to have the quality built in like my M100.
Myles is certainly the more reliable source for your inquiry but I thought I would lend you my oppinion being a Shiva ownwer. I've had mine for about 8 months now and I feel it has re-inspired my aspirations to be a player. It is very consistant and full of character. It does have the dreaded circuit board plunk dab in the middle of all those quality tubes and transformers but I will add that it too is robust and loaded with industrial quality parts.
As far as the chassis, it is like any good amp. You can only go so far before you create a boat anchor. The cabinet is like most as far as joints and material thickness. It is heavy but worth every carry.
I have other good amps and still use them so my oppinion is not Bogner skewed.
Hope this encourages you.
Posted By: myles_rose

Re: Feel free to ask Myles - 03/22/02 01:46 AM

Quote:
Originally posted by Seegs:
I just saw this after I started a thread.

Basically I want to know what does it mean when your power tubes start glowing blue?

Should I be concerned as they only have around ten hours on them? They are new GT 5881 NOS's

Seegs
Seegs....

No concern, enjoy it!

Some tubes with an open plate construction, or more open than most, let you see the "blue glow" when the B+ is on (amp off standby and ready to play). 6L6B tubes are really great for that.

6L6GE's or 6V6's have so much of the structure encased, that you don't see the blue glow.

I usually turn off the lights where I have amps where you can see the tubes, as I like the blue glow. If it starts to get all red outside the plate structure, then you have problems.

You're just fine. If you peek inside and look at the blue off the plates, you can tell a little bit about the purity of the innards of the tube. Solid blue is great, and some red spots in the blue are impurities. Look in some new tubes and there are a lot more red spots these days. Just an issue of quality.

Regards
Posted By: myles_rose

Re: Feel free to ask Myles - 03/22/02 02:04 AM

Quote:
Originally posted by steve f:
Myles, thanks for giving us the benefit of your experience.

I wanted to get your thoughts on the overall quality of Bogner amps (build quality, components used, etc), the Shiva in particular.

I recently looked at a Soldano HotRod 100+ and wasn't overly impressed compared to my Rivera M100. It sounded fine, but boy, the M100 just seems to have much more attention to detail and the quality of components seems higher. I don't won't to invest a lot of time trying to track down a Shiva if it's not going to have the quality built in like my M100.
steve f -

The Bogner's are very well constructed amps. Look at the solder work, PC boards, and other aspects. There is no reason that their amps won't be around for your grandkids to play as the vintage amps of tomorrow.

Rivera amps are a slightly different story, in a manner of speaking, and your M-100 should not be compared to most other amps. Paul Rivera is something of an anal personality. He does not care if his amps are around for the next 50 years, he wants them to be around for the next ice age or something. If you look at his threaded inserts with machine screws for just the cabinet, it only goes to say that the rest of the amp is built to be a piece of gear in some military battle or something. I guess if you say that Bogner and Demeter are "A" construction, and a Fender amp of the past is a C- (yet they stand the test of time), then a Rivera amps has to be given some weird sort of different classification, such as what we used to use when I was in the marine industry .... Lloyds A1 +++ Most amps output transformers are good up to the amps wattage rating, but in the case of Rivera amps, they are at least double of that. I cannot think of ever seeing a transformer failure on a Rivera product.

Soldano is a bit of a different breed. They use a more minimal approach to construction. They are fine amps, but use more of a Mesa approach to build, with a bit of Crate thrown in on the side (such as output tube sockets mounted with pop rivets). At the last NAMM show, I was told the reason for the pop rivets rather than screws and nuts, were that the pop rivets had a lower profile so oversized tube bases would seat all the way. This makes a degree of sense, but even 6550's and KT-66's are now available with tapered bases which fit normally mounted tube sockets.

Tube sockets can fail at times, and I don't like getting out a power drill to fix an amp.

Just as comparason, Mesa uses self tapping sheet metal screws to mount the tube sockets. My Mk I also has self tapping sheet metal screws to mount the transformers. From time to time I go into the amp and tighten up everything when I start to get a buzz here and there, which for me is no big thing. In the case of the Bogner and Rivera amps, you don't have this little added exercise.

I hope I answered this. In closing though, don't compare other amps to your M-100. Its something like comparing a Bentley Turbo R to a Lincoln. Both nice cars, but different attention to the build of the product.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 03/22/02 02:53 AM

Posted By: myles_rose

Re: Feel free to ask Myles - 03/22/02 03:14 AM

Quote:
Originally posted by dlb:
Quote:
Originally posted by steve f:
Myles, thanks for giving us the benefit of your experience.

I wanted to get your thoughts on the overall quality of Bogner amps (build quality, components used, etc), the Shiva in particular.

I recently looked at a Soldano HotRod 100+ and wasn't overly impressed compared to my Rivera M100. It sounded fine, but boy, the M100 just seems to have much more attention to detail and the quality of components seems higher. I don't won't to invest a lot of time trying to track down a Shiva if it's not going to have the quality built in like my M100.


Myles is certainly the more reliable source for your inquiry but I thought I would lend you my oppinion being a Shiva ownwer. I've had mine for about 8 months now and I feel it has re-inspired my aspirations to be a player. It is very consistant and full of character. It does have the dreaded circuit board plunk dab in the middle of all those quality tubes and transformers but I will add that it too is robust and loaded with industrial quality parts.
As far as the chassis, it is like any good amp. You can only go so far before you create a boat anchor. The cabinet is like most as far as joints and material thickness. It is heavy but worth every carry.
I have other good amps and still use them so my oppinion is not Bogner skewed.
Hope this encourages you.
dlb -

In case I gave a misleading impression, let me try to be a little more specific.

The Riveras are great amps. The Bogners are great amps. I feel they are built with designs and mechanical engineering that will take either amp into the 22nd century.

As far as the "dreaded circuit board" ... with modern composit materials used in PCB's there is no moisture absorbtion as in older tag boards used in amps of the past (they did not have fiberglass). The wiring traces and runs are optimized for the best response and least noise with a PCB. Some people say it is harder to change parts on a PCB, and this to me is nonsense. I guess I use the correct wattage soldering iron. The consistancy of PCBs is always there, while with point to point wiring, you better hope somebody took the time to really check what they were doing, otherwise there are stray grounding noises and inconsistancy.

A well designed and built amp is just that, regardless of a lot of other factors.

The Bogner Shiva is a wonderful piece of work. It is not as complicated as oen of the other models, which may be an issue to some, and a feature to others. The bottom line with the Shiva is, it is a terrific amp that sounds wonderful and is very versitile, and you can actually carry it and a 2x12 cabinet somewhere, or use the combo version, and not kill yourself.

The Rivera M-100 like I said, is something of a unique amp, and you also have to remember, that they did not make a lot of them, and Paul Sr. probably looked at every one of them.

I think it comes down to personal preference for the sound and features. Either of the amps from Bogner or Rivera will bring you a LOT of trouble free sound with great tone, for decades and decades.

Regards,
Posted By: dale661

Re: Feel free to ask Myles - 03/22/02 08:05 AM

Myles, this is dale661 from the harmony-central forum as well. I've asked you a few questions here and there and you've always given me some pretty good advice. So here goes another question for ya man. Could I put some KT66's in my Mesa Boogie Triple Rectifier 3 channel head? What I'm asking you is would you think there would be enough space? Also, would it be all right for them to be in my amp if they could fit? I read somewhere or another that KT66's draw a lot more heater current or something another like that and it could mess some amps up that weren't designed to handle those loads I guess you could say. Also, if all of that is all right...what kind of tonal differences would these KT66's have from say some JJ 6L6GC's. I'm just curious about all of that. I am probably fixing to hop in the bed. Could you please e-mail me @ GibsonMarshall21@aol.com ? I'd appreciate it Myles. Thanks

Dale
Posted By: zero interrupt

Re: Feel free to ask Myles - 03/22/02 07:59 PM

Myles,
You responded to a post I had earlier about my Rivera Knucklehead 100. I'm writing to now to troubleshoot. I bought the amp used, so I probably need to change the tubes anyway. I've had the amp for about 2 years and so did the previous owner.
I need a sweet jazz tone and a very tight crunch. I'm not really familiar with changing tubes(although I read thru your site) and I also don't have a manual for the amp head. What preliminary steps do you reccomend I take? Or can you reccomend someone who does blueprinting in the NY Metro area? Thanks. I appreciate any help.

Max
Posted By: myles_rose

Re: Feel free to ask Myles - 03/22/02 09:03 PM

Quote:
Originally posted by dale661:
Myles, this is dale661 from the harmony-central forum as well. I've asked you a few questions here and there and you've always given me some pretty good advice. So here goes another question for ya man. Could I put some KT66's in my Mesa Boogie Triple Rectifier 3 channel head? What I'm asking you is would you think there would be enough space? Also, would it be all right for them to be in my amp if they could fit? I read somewhere or another that KT66's draw a lot more heater current or something another like that and it could mess some amps up that weren't designed to handle those loads I guess you could say. Also, if all of that is all right...what kind of tonal differences would these KT66's have from say some JJ 6L6GC's. I'm just curious about all of that. I am probably fixing to hop in the bed. Could you please e-mail me @ GibsonMarshall21@aol.com ? I'd appreciate it Myles. Thanks

Dale
dale661 ....

Its hard to jump back and forth in email, so in the future if you want an email response, just send me the question in email format.

The KT-66 has more low end and low mids than other 6L6 family tubes in most amps. Its a great tube, and as far as space, I don't know if they will fit in your amp as I have never tried that. I believe they are 4 5/8" tall, but may be off on that, as that is from memory. On some amps where the fit is tight, you may have to pull the chassis from the cabinet to get enough room to plug them in and out.

The heater current is more with the KT-66. It is 1.27 amps. On a conventional 6L6 it is .9, and on an EL-34 it is 1.5.

Your Mesa has enough reserve that the heater current will not be an issue.

The issue is, will they fit .... and also, with the Mesa's fixed bias, you will need to be sure KT-66's are biased differently, as they are generally a stronger tube than 6L6's, and generally need a bias adjustment. Mesa also does not offer these tubes, so you'd want to be able to experiment with various ranges to try to get your bias in the ballpark. These tubes like current more than voltage, so shoot for an idle dissapation of no more than 55% if using a bias probe type device, or if adjusting with a scope, I like the crossover notch to just be there a touch when the amp is turned up about 60% of the way, rather than the usual 70% or so.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 03/22/02 10:00 PM

Quote:
Originally posted by zero interrupt:
Myles,
You responded to a post I had earlier about my Rivera Knucklehead 100. I'm writing to now to troubleshoot. I bought the amp used, so I probably need to change the tubes anyway. I've had the amp for about 2 years and so did the previous owner.
I need a sweet jazz tone and a very tight crunch. I'm not really familiar with changing tubes(although I read thru your site) and I also don't have a manual for the amp head. What preliminary steps do you reccomend I take? Or can you reccomend someone who does blueprinting in the NY Metro area? Thanks. I appreciate any help.

Max
Max,

Your amp has pretty easy tube access.

Are the output tubes the originals as supplied by Rivera? If they are, there should be a sticker on the base, blue and silver, with a number. Le me know the number.

At that point, I can tell you what range of other folks tubes you could use, or you can just call Rivera at 818-833-7066 and they can send you a replacement set. If you get tubes in the same range,
then you would not need to rebias your amp.

If they are not the stock tubes, then let me know what they are. Also, if not original tubes, you should probably have the bias checked just to be sure.

As far as preamp tubes, they are interchangable for the most part without any adjustment required. You may want to check on the Rivera website (www.rivera.com) and go to the ROG (Rivera Owners Group) and look for some of their posts. A lot of folks there have great comments and ideas in regard to preamp tubes.

I'd try a 12AX7C (new Chinese 12AX7) in V1, the first preamp tube position, and see how that sounds.

On the Rivera website, there may also be a user's manual available.

I don't know of anybody in your area that does amp blueprinting. I think I am one of the first that do this outside of some high end amp makers that do this for specific customers, such as Dumble on specific amps. There are a lot of great amp techs in NYC though, check with some of the better vintage music stores.

Regards
Posted By: zero interrupt

Re: Feel free to ask Myles - 03/22/02 10:16 PM

Quote:
Originally posted by myles111:
Quote:


Are the output tubes the originals as supplied by Rivera? If they are, there should be a sticker on the base, blue and silver, with a number. Le me know the number.

If they are not the stock tubes, then let me know what they are. Also, if not original tubes, you should probably have the bias checked just to be sure.

They don't seem to be the original tubes. No blue sticker. This is what is printed on the side of the tube: SVETLANA ELECTRON DEVICES INC
EL34
MADE IN RUSSIA
9804
There is also a stamp to the right of that: OTH55

I'm not sure if the preamp tubes are stock either:
MARSHALL ECC83 is printed on them.

Thanks

Max
Posted By: myles_rose

Re: Feel free to ask Myles - 03/23/02 02:44 AM

Quote:
Originally posted by zero interrupt:
Quote:
Originally posted by myles111:
Quote:


Are the output tubes the originals as supplied by Rivera? If they are, there should be a sticker on the base, blue and silver, with a number. Le me know the number.

If they are not the stock tubes, then let me know what they are. Also, if not original tubes, you should probably have the bias checked just to be sure.

They don't seem to be the original tubes. No blue sticker. This is what is printed on the side of the tube: SVETLANA ELECTRON DEVICES INC
EL34
MADE IN RUSSIA
9804
There is also a stamp to the right of that: OTH55

I'm not sure if the preamp tubes are stock either:
MARSHALL ECC83 is printed on them.

Thanks

Max
Max,

The Svetlana's are the way to go on that amp in most cases. Those are the tubes Rivera uses in these amps as standard issue.

The preamp tubes are a different story. The ECC83 may make the amp sound too dark, and it will have less gain then the tubes the amp is supplied with.

I would try some inexpensive Sovtek 12AX7WA tubes for a start in the V1 and V2 position if there are ECC83's in there now. If you have the money, replace all the ECC83's with the Sovteks for now. The front end of this amp was set up to use tubes with this sort of gain structure.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 03/28/02 04:01 AM

Just bumping this for those that missed it.
Posted By: semperfi666

Re: Feel free to ask Myles - 03/28/02 02:18 PM

Hi Myles!
My rig at the moment:
Digitech 2120, Marshall el34 50/50 and 2 marshall 1960A cabs...
I play mostly metal and my trouble is that I can't get rid of that annoying "ooomph" in the bottom! I have tried to changed the preamp section, messed around with the EQ and dynamics but the bottom is not tight at all.(I do want bass in the sound, but it seem to "crack" up when I crank up the volume...)
I havent tried to changed the tubes in the 2120(out of the box...Vostek I think)
Can someone please help me to get a relly tight sound? You know what I want Limp B, Metallica and that kind of music.
I don't have the cash for a Mesa right now, but I belive I got the hardware to do some of the job...Or?hehe
What tubes should I consider?
I know this sound newbie, but hey- thats what I am
Thanks in advance!
Regards
--------------------------------------------------------------------------------
Posted By: myles_rose

Re: Feel free to ask Myles - 03/28/02 09:08 PM

Quote:
Originally posted by semperfi666:
Hi Myles!
My rig at the moment:
Digitech 2120, Marshall el34 50/50 and 2 marshall 1960A cabs...
I play mostly metal and my trouble is that I can't get rid of that annoying "ooomph" in the bottom! I have tried to changed the preamp section, messed around with the EQ and dynamics but the bottom is not tight at all.(I do want bass in the sound, but it seem to "crack" up when I crank up the volume...)
I havent tried to changed the tubes in the 2120(out of the box...Vostek I think)
Can someone please help me to get a relly tight sound? You know what I want Limp B, Metallica and that kind of music.
I don't have the cash for a Mesa right now, but I belive I got the hardware to do some of the job...Or?hehe
What tubes should I consider?
I know this sound newbie, but hey- thats what I am
Thanks in advance!
Regards
--------------------------------------------------------------------------------
semperfi666 ...

Because of the Digitech, you have a tough issue, as
that is nowhere close to a Marshall preamp front
end.

This is one of the issues that face folks using rack
setups of a sort, when they want to get a sound that
was from a conventional head and cabinets, or a
combo amp.

Changing tubes in the Digitech won't help all that
much either, as the tubes are used more for a bit
of compression, and have only a very small part in
the tone shaping. The tone shaping is done in the
digital realm with lots of little silicon devices
which have a different character.

I'm sorry that I cannot help you here, but your
rig has a specific color of tone that is the product
of what it was intended to do.

Its something like when a Marshall owner tells me
he wants more low mids and lows, and a cleaner sound.
I tell him to go buy a Fender Twin Reverb. Then you
have more sonic bases and colors covered.

Sorry and good luck.

Myles
Posted By: evets

Re: Feel free to ask Myles - 03/29/02 07:08 PM

Myles, thanks for offering your time. I have Marshall JCM2000 (DSL50) head which I intend to use to drive a stereo power amp. I'll be taking the output from the preamp out thus disconnecting the output stage. Since the output stage won't be driven, should I worry about loading it, should I remove the tubes, or should I use a dummy load?
Thanks,
Steve
Posted By: myles_rose

Re: Feel free to ask Myles - 03/29/02 08:58 PM

Quote:
Originally posted by evets:
Myles, thanks for offering your time. I have Marshall JCM2000 (DSL50) head which I intend to use to drive a stereo power amp. I'll be taking the output from the preamp out thus disconnecting the output stage. Since the output stage won't be driven, should I worry about loading it, should I remove the tubes, or should I use a dummy load?
Thanks,
Steve
Steve,

Some amps like Rivera amps, turn off the B+ and effectively turn off the power amp section by the use of shorting jacks for the speakers. When there is nothing in the jack, the power amp is off. This is more expensive to do, so most folks don't do this.

In your amp, you need to keep a load on the output section unless shorting jacks are used (which I do not know without looking at prints at the moment) or not.

I would use a load such as a THD Hotplate, which is probably the best unit out there at this time, much better than the Marshall Power Brake from the past that was normally what was used for your sort of application, and a lot less expensive. You could even come off of the THD and then also get the true color of the driven output section, which is a lot nicer than just using the preamp section. You also have the benefit of additional EQ and some other features. Then you come off your preamp out, or effects send, or line out to your rig, and off the THD to a monitor cabinet if you'd like, where you can adjust the level from the THD Hotplate.

Regards,
Posted By: evets

Re: Feel free to ask Myles - 03/29/02 09:41 PM

Thank you for the reply, Myles. I have an old Power Soak (Tom Schloz) which I know is a resistive load, rather than inductive as in the Power Brake. (I'm not familiar with the Hot Plate) Do you discourage the use of a resistive load? (Maybe I just need to invest in a Hot PLate!) Thanks again for your time, and have a great weekend!

Steve
Posted By: myles_rose

Re: Feel free to ask Myles - 03/30/02 02:45 AM

Quote:
Originally posted by evets:
Thank you for the reply, Myles. I have an old Power Soak (Tom Schloz) which I know is a resistive load, rather than inductive as in the Power Brake. (I'm not familiar with the Hot Plate) Do you discourage the use of a resistive load? (Maybe I just need to invest in a Hot PLate!) Thanks again for your time, and have a great weekend!

Steve
Steve,

That will work just fine. Eight ohm speakers, as an example have a nominal value of eight ohms at certain frequencies, but will have higher resistance at other frequencies. As long as the amp is working into a load, rather reactive or inductive, it will make no difference, as all you need to do is keep the amp working into a load.

So, if you are not trying to play quietly with your amp running full bore, then the Hot Plate is not needed as what you have will work fine for your application.

Regards
Posted By: JamesPeters

Re: Feel free to ask Myles - 03/31/02 01:50 PM

Hey Myles. I just finished my first "production" (non-prototype, professional looking) amp a few days ago. Just figured I'd stop by here to let you know you can check out pics on my site if you like. Later!
Posted By: Lance-a-not

Re: Feel free to ask Myles - 03/31/02 06:28 PM

That looks sweet James, now when can we hear it ?? Very nice!!

Lance
Posted By: myles_rose

Re: Feel free to ask Myles - 03/31/02 08:51 PM

Quote:
Originally posted by JamesPeters:
Hey Myles. I just finished my first "production" (non-prototype, professional looking) amp a few days ago. Just figured I'd stop by here to let you know you can check out pics on my site if you like. Later!
James....

It looks very nice.

What sort of voltage are you running on the B+?

What output tube is the output transformer optimized for?

The only suggestion I have, is tack down some of the wiring with high temp silicone after you figure the best routing for the minimum noise. That way when the amp travels, it will stay quieter when it gets to its destination.

I know point to point wiring is in vogue, but this amp would be a good candidate for a mil-spec circuit board. The trace routing could be developed on computer circuit simulation software which is used by the PCB houses, and you'll end up with a quieter amp that also is consitant from amp to amp once you go into larger scale production. Heavy mil-spec traces which are available from a lot of PCB folks are so thick that they carry more current than most of the wire used today in botique amps.

In any case, it is a very pretty package, and when you look how backordered amps such as the THD items are, there is sure a market for lower powered great sounding amps!

Keep me in the loop, and if you want to send me an email and some text info, I'd be more than happy to put you on my website, as your product is not "middle of the road", is nicely done, and is right in line with the sort of things I like personally.

Once again .... very nicely done.

Now ... what about pricing?

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 03/31/02 09:03 PM

Quote:
Originally posted by JamesPeters:
Hey Myles. I just finished my first "production" (non-prototype, professional looking) amp a few days ago. Just figured I'd stop by here to let you know you can check out pics on my site if you like. Later!
James ...

One more thing here.

I looked at your webite at the FAQ's.

There is a point you might want to make, when folks ask about gain with only two preamp tubes. Most amps like a Marshall, have only two stages of gain in reality.

V1 is split into two parts, the A and B side. Same with a Fender amp. Side A is used for one of the inputs, and Side B for the other. It is one stage of gain.

In Fender, V2 is used for the vibrato channel, one side of the tube for each input.

Now, if you run one side of a preamp tube into the other side, what you have is cascaded gain, like a Mesa Boogie Mk. 1 as the originator of that idea. Then you multiply the gain by over 100 depending on the circuit.

Modern amps don't use that same form of gain cascading, it is more of changing the plate voltage from the older Fenderish values of 150v-180v, to higher plate voltages and different bias voltages.

In essence here, the bottom line, is even if your amp only had one preamp tube, depending on the design, you could have more front end gain than any current Mesa Rectifier, Marshall whatever, or most other things.

and .... I still think you are on a great track here, keep up the good work!

Myles
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/01/02 01:04 AM

Thanks Myles! Yeah about the preamp tube thing--I just wanted to clear up a basic misconception that was going around, that my amp (in the pictures) couldn't possibly be getting that amount of pregain. I'm going to avoid a more technical explanation, for the sake of not hurting people's brains! \:\)

So, silicone the wires down, you say? Got lots of silicone, no problem there!

As for the board--I don't have any problem leaving it as-is. As it is, the layout is pretty high gain and low-noise (higher gain and lower noise than I had before), and a fair number of components are wired right to the sockets to help keep the noise down. The board itself doesn't take me that long to make; more of the time is spent wiring things to and from it to be honest. Thanks for the suggestion though, because if I ever do get into any kind of steady production I may have to look into that (everything that can save me time will be helpful). I'm also trying not to incur any additional costs at this point, since I have very few orders at this point and I'm dead broke from buying parts (and other things happening in my life right now). With any luck that'll change soon enough; I'm optimistic. \:D

The 3CP1 I'm selling for $480 USD (plus shipping of course), and that's without tubes though. Being that I've had tubes break in shipping before, I'd rather not ship them with the amp. That, and I get no deals whatsoever on tubes, and truth be told it seems that most places in the US seem to sell them for cheaper than here in Canada anyway.

That price, I'm trying to keep that low for the first while anyway. I can forsee the price increasing somewhat (especially if I let a distributor carry it, then I'll have to raise prices to allow their "cut"). I'm going to try to do all the sales myself though, through the Internet or word of mouth...or advertising etc.--I'd really like to be able to offer an amp like this at a very reasonable price.

The output section is honestly optimized for all three tube types--EL34, 6L6/5881, and 6V6. Since I'm using the Hammond 125DSE, I can run 2500 or 5000 ohms on the primary depending on the tap and the secondary load, which works out perfectly for designing the amp around tube data sheet "typical operating conditions" examples. So, with the EL34 or 6L6/5881, I'm using 2500 on the primary, and with 6V6 I'm using 5000 on the primary. The 6L6/5881 also works right within "typical operating conditions" at 5000 ohms on the primary as it turns out, making it the "wild card" tube in this design--it'll work at 4, 8 or 16 ohms whereas the EL34 is only 4/8 ohms, and the 6V6 is only 8/16 ohms. The 6L6 is actually starting to become my favorite tube in this amp.

The bias points for the power tubes are dead-on what's considered to be the "normal operating conditions" for single-ended class A at the B+ the amp runs at (which is 250V), right from tube data sheet examples. The plate voltages are slightly lower when using a 6L6 or EL34 (like maybe 240 or so), and with a 6V6 it runs at an even 250V. I messed around with cathode resistor values to hear what it would sound like biased hotter or colder, and honestly it sounds best for all three tubes right where it is now anyway.

If I run the 6550 in there, it would be really biased cold, but it would run with only a marginal mismatch of the primary impedance compared to "typical operating conditions" mentioned in the datasheet examples (2500 ohms primary instead of the 1500 ohms recommended for that B+). The bias current would be really low, but I know a guy using an AX84 high octane (which I helped him build) who says his is running fine, not drawing more than 65mA plate current (well within spec of the 125DSE), and sounds really neat. I plan to try that out soon too.

Hey, feel free to ask any more questions if you like, or email me directly. I'll get to you later on in the next day or two with stuff for a link from your site--thanks for the offer! I'll link you back too. ;\)
Posted By: myles_rose

Re: Feel free to ask Myles - 04/01/02 02:13 AM

Quote:
Originally posted by JamesPeters:
Thanks Myles! Yeah about the preamp tube thing--I just wanted to clear up a basic misconception that was going around, that my amp (in the pictures) couldn't possibly be getting that amount of pregain. I'm going to avoid a more technical explanation, for the sake of not hurting people's brains! \:\)

So, silicone the wires down, you say? Got lots of silicone, no problem there!

As for the board--I don't have any problem leaving it as-is. As it is, the layout is pretty high gain and low-noise (higher gain and lower noise than I had before), and a fair number of components are wired right to the sockets to help keep the noise down. The board itself doesn't take me that long to make; more of the time is spent wiring things to and from it to be honest. Thanks for the suggestion though, because if I ever do get into any kind of steady production I may have to look into that (everything that can save me time will be helpful). I'm also trying not to incur any additional costs at this point, since I have very few orders at this point and I'm dead broke from buying parts (and other things happening in my life right now). With any luck that'll change soon enough; I'm optimistic. \:D

The 3CP1 I'm selling for $480 USD (plus shipping of course), and that's without tubes though. Being that I've had tubes break in shipping before, I'd rather not ship them with the amp. That, and I get no deals whatsoever on tubes, and truth be told it seems that most places in the US seem to sell them for cheaper than here in Canada anyway.

That price, I'm trying to keep that low for the first while anyway. I can forsee the price increasing somewhat (especially if I let a distributor carry it, then I'll have to raise prices to allow their "cut"). I'm going to try to do all the sales myself though, through the Internet or word of mouth...or advertising etc.--I'd really like to be able to offer an amp like this at a very reasonable price.

The output section is honestly optimized for all three tube types--EL34, 6L6/5881, and 6V6. Since I'm using the Hammond 125DSE, I can run 2500 or 5000 ohms on the primary depending on the tap and the secondary load, which works out perfectly for designing the amp around tube data sheet "typical operating conditions" examples. So, with the EL34 or 6L6/5881, I'm using 2500 on the primary, and with 6V6 I'm using 5000 on the primary. The 6L6/5881 also works right within "typical operating conditions" at 5000 ohms on the primary as it turns out, making it the "wild card" tube in this design--it'll work at 4, 8 or 16 ohms whereas the EL34 is only 4/8 ohms, and the 6V6 is only 8/16 ohms. The 6L6 is actually starting to become my favorite tube in this amp.

The bias points for the power tubes are dead-on what's considered to be the "normal operating conditions" for single-ended class A at the B+ the amp runs at (which is 250V), right from tube data sheet examples. The plate voltages are slightly lower when using a 6L6 or EL34 (like maybe 240 or so), and with a 6V6 it runs at an even 250V. I messed around with cathode resistor values to hear what it would sound like biased hotter or colder, and honestly it sounds best for all three tubes right where it is now anyway.

If I run the 6550 in there, it would be really biased cold, but it would run with only a marginal mismatch of the primary impedance compared to "typical operating conditions" mentioned in the datasheet examples (2500 ohms primary instead of the 1500 ohms recommended for that B+). The bias current would be really low, but I know a guy using an AX84 high octane (which I helped him build) who says his is running fine, not drawing more than 65mA plate current (well within spec of the 125DSE), and sounds really neat. I plan to try that out soon too.

Hey, feel free to ask any more questions if you like, or email me directly. I'll get to you later on in the next day or two with stuff for a link from your site--thanks for the offer! I'll link you back too. ;\)
James....

I think this is turning into one of the longer posts, but its a great subject!

First of all, you are on the right track!

On the silicone issue, its just a fast and effective way of keeping some of the longer runs in place.

On the board .... in a smaller production environment, you'll do fine, but if your amp gets the same sort of attention as I think it might, you might want to think of the circuit board idea down the road in the background.

Your price is right on target, considering a store would mark it up 40% or so, and there are offerings that are similar that are in the $995 range.

As far as not shipping with tubes, in an amp like this, there are so many personal choices that can be made, even in one family such as the 6L6 family, that I think that idea is fine. What Steve Carr does on his EL-34 Hammerhead, is ship the tubes in bubble wrap, not installed in the amp.

As far as you getting no deals on tubes, you should. You are an amp manufacturer. There are a few great amp builders who are very limited production such as Kendrick (Trainwreck) and others, that use Groove Tubes as standard equipment. I would think that the folks at Groove Tubes would be willing to give you manufacturing status. I am not sure, but would sure ask them about it. Considering they carry all the various 6L6, 5881, 6550's, EL-34's and 6V6's, as well as all flavors and makers of preamp tubes, they would be a great source. The way they package their tubes is also a lot better than most vendors, if not all of them. Their packaging holds up in tour use for my clients, so for tubes that move around the country, I always use their stuff.

Maybe on Monday, give them a call at 818-361-4500, and ask to talk to Rick Bensen. Tell him we have been talking and I suggested that as an amp maker, I gave you his number and suggested you call him to see if you could get manufacturer prices. Let me know if you need any help with this, as I'd be happy to call him too.

Your output section .... in a word .... or a few .... very very well done !!!

Too many folks go for high plate voltages. Tubes are devices that like current more than voltage. 250 volts is the standard test reference for the folks that make the tubes, and so many amps sound so much nicer when you get that 400-500 volts back down to half of that, and the current goes up instead.

Your impedience matching is right on the money too, and the Hammond is a great transformer, very pretty and musical.

On 6550's, I prefer the Chinese ones, the 6550C, as they have less power than the 6550A, and you can get them to distort easier. They have a softer vacuum than the USA ones. Running them at low plate voltages makes them really sweet. I like a 6550C in a Univalve on its low voltage setting a lot. I also, by the way prefer 6L6's to most other tubes most of the time ... or 6V6's. Maybe its my blues preferences, or when you want massive thick distortion, the 6L6 has more body then the EL-34, while the EL-34 has better articulation and attack at those sorts of levels.

In any case, keep up the good work, give Rick a call, and I'll talk to you soon.

Regards,

Myles
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/01/02 02:42 AM

Thanks for the tip Myles, and for the props! \:\) I'll have to ask about any discounts I can get for tubes...but somehow I doubt I'm going to get any special treatment just yet. Noone really knows me yet, so it's not like I'm some really famous amp guru that they'd already know about. I'll still ask them though--hopefully those discounts won't involve having to buy in large quantities (because I still can't afford to do that, at least not yet).

Yeah, once I heard the amp at 250V B+ I knew that was part of the sound. The higher powered one coming soon (3CP2) will stick to 250V B+, which made my transformer choices a little narrower...but I'm not going any higher in B+ if I can avoid it. I'll do 1500 on the primary parallel class A, which will do: 2 x EL34, 2 x 6L6, or 1 x 6550.

Another bonus of sticking with that low a B+ is that all my components, wires, etc. are much higher rated than what they need to be--part of my concern with the amps was to keep the design "bulletproof", and this helps a lot.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/01/02 08:53 PM

Quote:
Originally posted by JamesPeters:
Thanks for the tip Myles, and for the props! \:\) I'll have to ask about any discounts I can get for tubes...but somehow I doubt I'm going to get any special treatment just yet. Noone really knows me yet, so it's not like I'm some really famous amp guru....
JamesPeters...

There are a lot of folks out there that just built a few amps a year (Dumble), or make amazing amps on a very limited scale where their names are not household names (Kendrick) .... so I think you'd still be able to meet their (Groove Tubes) criteria as a manufacturer. I'd give it a try.

Myles
Posted By: peel_dup1

Re: Feel free to ask Myles - 04/01/02 09:38 PM

Myles,

Sorry if this is repetitive, Im curious to know how much swapping a 12ax7 tube in my Rocktron Voodu valve rack preamp would affect tone? The voodu runs into a Mesa 50/50

Thanks Peel
Posted By: myles_rose

Re: Feel free to ask Myles - 04/02/02 03:13 AM

Quote:
Originally posted by peel:
Myles,

Sorry if this is repetitive, Im curious to know how much swapping a 12ax7 tube in my Rocktron Voodu valve rack preamp would affect tone? The voodu runs into a Mesa 50/50

Thanks Peel
Peel,

Better quality tubes make any amp sound better.

The issue with rack mount components though, makes the differences a little harder to quantify. In most rack mount preamps, there is all sorts of other circuitry, and at times for the EQ, a lot of solid state items in the mix. This is one of the reasons that rack systems fell out of favor somewhat, compared to the era back in the 80's .... people did not know how to match the preamp and the amp, or would use a nice preamp with a solid state amp, etc.

Its easy enough to try though, and pretty cheap too. You can buy a nice NOS RCA or Sylvania tube from folks like KCA or Tube World, for less than $25 in most cases. Thats nearly as cheap as a retail "new" tube. Pop it in, and listen. If the note does not seem to have a lot more "life", then there are other factors that need to be addressed.

Hope this helped at least a little....

Regards,
Posted By: Lance-a-not

Re: Feel free to ask Myles - 04/02/02 05:41 AM

Quote:
Originally posted by JamesPeters:
Hey Myles. I just finished my first "production" (non-prototype, professional looking) amp a few days ago. Just figured I'd stop by here to let you know you can check out pics on my site if you like. Later!
James,

Whoops, I was ill this weekend... I missed that there were clips. While I don't have Myles' expertice, my ears wanted me to let you know you got a real winner there, VERY, VERY NICE! I am thinking my univalve may be needing a friend.

Would the amp be able to run a KT66 ?

Lance
Posted By: sgguitarzz

Re: Feel free to ask Myles - 04/02/02 07:13 AM

Myles I hope you can help.
My Mark IIB has a 60/100 switch. I use it in the 60 watt position. According to the Boogie manual when used this way only the 2 outside tubes are being used. I believe the 2 inside tubes are kind of in standby. When in 100 watt mode all 4 6L6's are being used. Is this correct? I have just put some Yellowjackets in (2) so I put them in the two outside slots and left the 2 inside as they were (2 JJ 6L6GC's) but the THD guide says in a 4 power tube amp to put them inside when using 2 YJ.

Dennis
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/02/02 07:47 AM

Quote:
Originally posted by Lance-a-not:
James,

Whoops, I was ill this weekend... I missed that there were clips. While I don't have Myles' expertice, my ears wanted me to let you know you got a real winner there, VERY, VERY NICE! I am thinking my univalve may be needing a friend.

Would the amp be able to run a KT66 ?

Lance
Thanks Lance! KT66 you say...ok I just looked at some data sheets and I think it's a go. I'll have to actually get my hands on one to test, to make sure it doesn't draw too much current--but I honestly think it'll be fine. (Now, where can I get a KT66... \:\) )

I'll see if I can scrounge one somewhere in town. If you like, I can email you when I find out--it might be up to a week depending on if they're any KT66 tubes in stock or not.
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/02/02 09:03 AM

Oh hey I just realised--that's a honkin' tall tube! I may have to change the dimensions of the amp to allow it to fit. What's your KT66 measure--both seated depth (not including the pins, after the bottom of the base) and overall length?
Posted By: fantasticsound

Re: Feel free to ask Myles - 04/02/02 01:53 PM

Hi Myles,

My question was missed, as well. I had difficulty getting internet access on the rest of our Middle East tour, so I had few chances to bump the thread. Here it is.

Neil\'s tube question regarding a Peavey Delta Blues 2 - 10" combo.

Thanks for any assistance you can provide.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/02/02 07:48 PM

Quote:
Originally posted by sgguitarzz:
Myles I hope you can help.
My Mark IIB has a 60/100 switch. I use it in the 60 watt position. According to the Boogie manual when used this way only the 2 outside tubes are being used. I believe the 2 inside tubes are kind of in standby. When in 100 watt mode all 4 6L6's are being used. Is this correct? I have just put some Yellowjackets in (2) so I put them in the two outside slots and left the 2 inside as they were (2 JJ 6L6GC's) but the THD guide says in a 4 power tube amp to put them inside when using 2 YJ.

Dennis
sgguitarzz ...

You are correct.

On the Mark IIB, when you flip the 60/100 watt switch to the 60 watt position, the -52 volts that is normally supplied in the 100 watt position to the center two tubes is shut off. This effectively shuts down these tubes, yet leaves them in the circuit, so the impedience in teh output section stays the same.

In a 100 watt older Marshall amp for example, that does not have a switch, if you want to cut the power in half, you actually have to remove two of the tubes, but also you need to remember to change your output impedience switch to compensate for the loss of two tubes. In the Mesa, you do not have to adjust anything.

So, go ahead and put the yellow jackets in the outer two positions and flip to the 60 watt position, and you will be in business. I think you will like how it sounds, sort of a Vox AC-15 with more power and more effective tone controls.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/02/02 07:57 PM

Quote:
Originally posted by JamesPeters:
Oh hey I just realised--that's a honkin' tall tube! I may have to change the dimensions of the amp to allow it to fit. What's your KT66 measure--both seated depth (not including the pins, after the bottom of the base) and overall length?
James ...

Just jumping in here even though you were talking to somebody else....

There are now a few KT-66's. The ones that are pretty tall are the copies of the old GEC or Genelux tube from the U.K. The are from China for the most part. They are a hard fit to say the least, but there is also a Sovtek version with a shorter base, that is more of a 6550 style base, with the metal ring. It is a shorter tube, and fits a little easier in more places.

The KT-66 in original form is a big tube. Its a great tube, putting out about 90+ mA at test settings, compared to the 72 mA of a standard 6L6GC. It does require a slightly different bias most of the time.

It will also not fit, unfortunately, in the reissue of the Marshall model 1962 bluesbreaker amp. For some reason when they made this amp, the dropped the cabinet depth from about a foot to about 9 1/2 inches, so how the KT-66, which was the original tube used back then, won't fit. I guess that's no big deal, because with 25% or more less cabinet volume, it already sounds different for other reasons. Thankfully the KT-66 will fit in their JTM-45 reissue.

Regards,
Posted By: retroguitarist

Re: Feel free to ask Myles - 04/02/02 08:01 PM

hey miles, i got a question for you



or

which one should i buy for you?
Posted By: myles_rose

Re: Feel free to ask Myles - 04/02/02 08:14 PM

Quote:
Originally posted by fantasticsound:
Hi Myles,

My question was missed, as well. I had difficulty getting internet access on the rest of our Middle East tour, so I had few chances to bump the thread. Here it is.

Neil\'s tube question regarding a Peavey Delta Blues 2 - 10" combo.

Thanks for any assistance you can provide.
fantasticsound...

Answered that over in the link you had here....

Regards,
Posted By: sgguitarzz

Re: Feel free to ask Myles - 04/02/02 08:22 PM

Myles -

Thank you very much for your quick response. It is much appreciated. You are providing a valuable service for all of us out here.

Dennis
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/02/02 10:43 PM

Thanks Myles. I did find a few KT66's locally...apparently they're the larger ones--I'm going to pick them up in a couple days anyway and try them.

Fortunately for me, to make them work in my amps all I have to do is change enclosure measurements slightly, before the enclosure is made...if I need to that is. \:\)
Posted By: fantasticsound

Re: Feel free to ask Myles - 04/02/02 11:23 PM

Just to clarify, Myles...

The tube that actually glowed was not installed during travel. It was a replacement one of the guitarists had brought. I take it from your answer that we should NOT expect the tubes in this amp to glow? Under all conditions, or should we expect the tubes to warm up over an hour and a half or two hour set? The stock tubes never glowed. I'm a novice when talking tube amps, but I thought most amp tubes glow after the initial warm up time. Is this correct? Am I missing something in your reply?

Thanks.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/03/02 01:06 AM

Quote:
Originally posted by retroguitarist:
hey miles, i got a question for you

which one should i buy for you?
retroguitarist ...

Probably the lower ....

If I was going for the upper one, I'd want to go back to Amsterdam and take the brewery tour, if they still have it. I went on those tours almost every day during part of 1970. They probably don't even have the tours anymore.

Thanks,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 04/03/02 01:10 AM

Quote:
Originally posted by sgguitarzz:
Myles -

Thank you very much for your quick response. It is much appreciated. You are providing a valuable service for all of us out here.

Dennis
Dennis,

You are more than welcome. Some days responses are faster than others. If I am out working away, its sometimes faster, as there is more free time waiting around for folks to show up for sound checks or whatever, as long as there is a phone line handy.

When I am here, I take the emails in between work or waiting for tubes to cool or whatever.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/03/02 01:43 AM

Quote:
Originally posted by JamesPeters:
Thanks Myles. I did find a few KT66's locally...apparently they're the larger ones--I'm going to pick them up in a couple days anyway and try them.

Fortunately for me, to make them work in my amps all I have to do is change enclosure measurements slightly, before the enclosure is made...if I need to that is. \:\)
JamesPeters,

Don't feel bad, the KT-66 won't fit in the THD Univalve either. Andy was thinking of making the cover taller, but thought it made the amp look less pretty, then he considered sort of a dome on the top of the cover, but so far as passed on that idea too.

When I use a KT-66, I just leave the cover off, as it looks like a high end audio amp, the KT-66 is a pretty tube when all lit up, and it also reminds me of the MC-60 and other McIntosh amps of the past, with their exposed tube compliment.

I think your amp looks pretty the way it is. I would not change it. Maybe try the Sovtek KT-66 which is shorter.

Regards,
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/03/02 02:11 AM

Quote:
Originally posted by myles111:
I think your amp looks pretty the way it is. I would not change it. Maybe try the Sovtek KT-66 which is shorter.
Oh, the Sovteks are shorter? Right on; those are the ones in stock at the music store anyway.

In any case, if I did have to change the height it would've been more than I wanted to--I'd have to leave at least an inch from the top of the tube to the underside of the top of the enclosure (so the tubes don't smack against the enclosure when you're removing them!) I had looked up the tallest tube that I had planned to use with the amp, the 6CA7 (EL34 equivalent), and based the measurement on its longest overall length plus one inch or so for clearance. I'd almost forgotten about that... \:\)

But I'm still going to try the KT88 and 6550 in it soon. And, if that Sovtek KT66 fits, then for sure I'm giving it a test.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/03/02 03:05 AM

Quote:
Originally posted by fantasticsound:
Just to clarify, Myles...

The tube that actually glowed was not installed during travel. It was a replacement one of the guitarists had brought. I take it from your answer that we should NOT expect the tubes in this amp to glow? Under all conditions, or should we expect the tubes to warm up over an hour and a half or two hour set? The stock tubes never glowed. I'm a novice when talking tube amps, but I thought most amp tubes glow after the initial warm up time. Is this correct? Am I missing something in your reply?

Thanks.
fantasticsound,

If you mean, on an output tube, the outside of the plate structure is glowing, that is bad.

The tube may be faulty, or of a different heat range than what the bias is set for.

If you are talking about inside the tube, some tubes have construction that lends a better look see into the tube and the plate structure on the other side.

Were they the same tubes, the glowing and the non glowing?

Also, if the tube traveled, who knows what may have transpired. Only a good high voltage tube tester or a vacuum tube curve tracer could tell you that.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/03/02 03:22 AM

Quote:
Originally posted by JamesPeters:
Quote:
Originally posted by myles111:
I think your amp looks pretty the way it is. I would not change it. Maybe try the Sovtek KT-66 which is shorter.
Oh, the Sovteks are shorter? Right on; those are the ones in stock at the music store anyway.

In any case, if I did have to change the height it would've been more than I wanted to--I'd have to leave at least an inch from the top of the tube to the underside of the top of the enclosure (so the tubes don't smack against the enclosure when you're removing them!) I had looked up the tallest tube that I had planned to use with the amp, the 6CA7 (EL34 equivalent), and based the measurement on its longest overall length plus one inch or so for clearance. I'd almost forgotten about that... \:\)

But I'm still going to try the KT88 and 6550 in it soon. And, if that Sovtek KT66 fits, then for sure I'm giving it a test.
JamesPeters,

Well, whatever you do, keep me informed. You're doing some great work here.

Myles
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/03/02 04:03 AM

Ok, but you're beginning to make me blush! \:D
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/03/02 09:53 AM

Ok, just tested the 6550 in it (Svetlana 6550C, and 6550B--that I got from the guy who's making my enclosures...leftovers from his Ampeg SVT when he switched to KT88s as it were).

The current draw slightly exceeds the spec for both the power tranny and the output tranny, but just by a hair. 72mA plate current--2mA "extra" for the 70mA rated OT (Hammond 125DSE), and 7mA "extra" for the Hammond 269EX PT (rated at 65mA, so that's not much extra anyway). Given that these Hammond trannies have been known to withstand considerably worse abuse, I'd say it's a go for the 6550. (The trannies didn't even get warm, and I was actually using a 125CSE OT rated for 60mA max. for the test, just to know for sure if the 125DSE would be safe--call me paranoid! \:\) ) Oh yeah, and the heater current draw is still 300mA below what the filament supply is rated for (2.2A instead of 2.5A), so that's a gimme.

The 6550 has a fairly nice sound in this amp, all things considered, which being biased this cold I found surprising (72mA, for a tube which "normally" should see about 140-150mA at this plate voltage--222V B+). It's total heavy metal at this point--really high headroom so the preamp gain "crackle" comes through a lot. It's more forceful and not as bouncy as the 5881, so the envelope is more "square" and abrupt. Not exactly what I had intended the amp to be used for, but hey I'll take it! \:\) Actually, since the plate voltage is browned out that extra amount, it still has a nice warmth to it. I like the woody overtones of 6550s usually--I'll have to check it out my amp cranked with a less overdriven preamp sound, to hear if I can really take advantage of that or not at this bias point/B+. (Hmm, I wonder what triode mode will sound like...)

Talk to you later!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/03/02 08:24 PM

Quote:
Originally posted by JamesPeters:
Ok, just tested the 6550 in it (Svetlana 6550C, and 6550B--that I got from the guy who's making my enclosures...leftovers from his Ampeg SVT when he switched to KT88s as it were).

The current draw slightly exceeds the spec for both the power tranny and the output tranny, but just by a hair. 72mA plate current--2mA "extra" for the 70mA rated OT (Hammond 125DSE), and 7mA "extra" for the Hammond 269EX PT (rated at 65mA, so that's not much extra anyway). Given that these Hammond trannies have been known to withstand considerably worse abuse, I'd say it's a go for the 6550. (The trannies didn't even get warm, and I was actually using a 125CSE OT rated for 60mA max. for the test, just to know for sure if the 125DSE would be safe--call me paranoid! \:\) ) Oh yeah, and the heater current draw is still 300mA below what the filament supply is rated for (2.2A instead of 2.5A), so that's a gimme.

The 6550 has a fairly nice sound in this amp, all things considered, which being biased this cold I found surprising (72mA, for a tube which "normally" should see about 140-150mA at this plate voltage--222V B+). It's total heavy metal at this point--really high headroom so the preamp gain "crackle" comes through a lot. It's more forceful and not as bouncy as the 5881, so the envelope is more "square" and abrupt. Not exactly what I had intended the amp to be used for, but hey I'll take it! \:\) Actually, since the plate voltage is browned out that extra amount, it still has a nice warmth to it. I like the woody overtones of 6550s usually--I'll have to check it out my amp cranked with a less overdriven preamp sound, to hear if I can really take advantage of that or not at this bias point/B+. (Hmm, I wonder what triode mode will sound like...)

Talk to you later!
James,

One thing that might work a bit in your favor, is that on small amps, people tend to drive them at max a lot more often than larger amps.

Most folks think that class A amps draw the same amount of plate current at idle, as they do at full output, but this is not 100% true .... at full output they actually drop a few percentage points (very slight), than at idle.

You will probably be safe, but in the case of output transformers, you don't have much safety margin there. Mos folks in the past put transformers rated at 50 watts in an amp designed to develop 50 watts, and this is the reason for more output transformer failures than one might expect. Today's amps are driven harder than those in the past, musical styles have changed. We also have the issue of things like tubes that fail more easily, and an output tube failure can take out an output transformer at times too. There are also folks that improperly set the output impedience selectors, and with a narrow margin on the transformer, it means a lot less time before there is failure.

A lot of folks now use transformers with a much higher rating than the amp would require from a strict engineering sense, such as Rivera and THD. Maybe talk to the folks at THD, as they may be able to be a great transformer supplier for you.

Regards,

Myles
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/03/02 09:01 PM

Thanks again for the tips, Myles. I do think that the 6550 drawing 72mA instead of 70, through the 125DSE, is plenty fine though. To be honest, it's not a "wonderful" sound in the amp anyway--I think the EL34 is nicest, and the 6L6s/5881s have nice definition and are more than adequate for "metal" music. The 6550 is more abrupt and unforgiving with dynamics in the higher gain settings--kinda like solid-state that way (but not really, you know what I mean).

I'm going to sell the amp with the 125DSE by default, and if someone absolutely wants reliability with a 6550 then I'll just put in a 15W 125ESE--they're the same price anyway! \:\)

Talk to you later.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/04/02 01:59 AM

Quote:
Originally posted by JamesPeters:
Thanks again for the tips, Myles. I do think that the 6550 drawing 72mA instead of 70, through the 125DSE, is plenty fine though. To be honest, it's not a "wonderful" sound in the amp anyway--I think the EL34 is nicest, and the 6L6s/5881s have nice definition and are more than adequate for "metal" music. The 6550 is more abrupt and unforgiving with dynamics in the higher gain settings--kinda like solid-state that way (but not really, you know what I mean).

I'm going to sell the amp with the 125DSE by default, and if someone absolutely wants reliability with a 6550 then I'll just put in a 15W 125ESE--they're the same price anyway! \:\)

Talk to you later.
JamesPeters,

Try a 6550C, a Chinese version of the 6550. They have about 20% less output, and a softer vacuum, so they distort a bit more like 6L6's. They also like lower plate voltages, so these may be quite nice in your amp.

If you order some from anybody, tell them you want something that is about the same as a Groove Tubes #2 or #3 rating, as these will draw a bit less current, and also distort a little easier and quicker.

Regards,
Posted By: Eddie123579

Re: Feel free to ask Myles - 04/04/02 02:37 AM

Myles - I'm a refuge from the HC amp forum and figured I'd check out your new digs. I have two tube related questions for you.

Background. I have a Rivera K100 head. As backups to the stock preamp tubes which were:

V1 Sovtek 12AX7WB
V2 Sovtek 12ax7wb
v3 Sovtek 12ax7LP
v4 Sovtek 12ax7wb
v5 Sovtek 12ax7lp

I purchased 5 JJ ECC83S.

Because the Sovtek WBs have a pretty crappy reputation, I figured I'd try the JJs in all slots. There was no major improvement to be heard. I love the sound of the amp but I wonder if I'm using it to its full potential.

Question #1. Without putting in expensive NOS preamp tubes, do you have any reccomendations for my amp using the tubes I already have or maybe some other manufacturers such as EH?

Question #2. The stock power tubes are Svetlana EL34's and Rivera has a stamped #7 on the tubes. I was going to purchase some JJ's as backups. Can I purchase tubes from other manufacturers (since I know the rating that rivera uses)that are rated similarly and not have to worry about adjusting the bias on the amp?

Thanks in advance for your advice.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/04/02 04:07 AM

Quote:
Originally posted by Eddie123579:
Myles - I'm a refuge from the HC amp forum and figured I'd check out your new digs. I have two tube related questions for you.

Background. I have a Rivera K100 head. As backups to the stock preamp tubes which were:

V1 Sovtek 12AX7WB
V2 Sovtek 12ax7wb
v3 Sovtek 12ax7LP
v4 Sovtek 12ax7wb
v5 Sovtek 12ax7lp

I purchased 5 JJ ECC83S.

Because the Sovtek WBs have a pretty crappy reputation, I figured I'd try the JJs in all slots. There was no major improvement to be heard. I love the sound of the amp but I wonder if I'm using it to its full potential.

Question #1. Without putting in expensive NOS preamp tubes, do you have any reccomendations for my amp using the tubes I already have or maybe some other manufacturers such as EH?

Question #2. The stock power tubes are Svetlana EL34's and Rivera has a stamped #7 on the tubes. I was going to purchase some JJ's as backups. Can I purchase tubes from other manufacturers (since I know the rating that rivera uses)that are rated similarly and not have to worry about adjusting the bias on the amp?

Thanks in advance for your advice.
Eddie,

Paul Rivera optimizes his amps for the WB's and in most cases these work really well in his amps. The ECC83's may be a bit of a different sound, so that is all personal preference.

I have a lot of his products, and have swapped things all over the place, but generally come back to his selections.

The most important factor on the preamp tubes, is knowing what is in there, as far as the characteristics of the tube, so you can get about the same gain structure as what you had in there before.

It all comes down to personal preference on the preamp tubes.

On Paul's Svetlana's ... a #7 is, I believe, in his lower range, with something like a #13 at the top. You may want to give them a call and ask, but Paul does do a bit of extra screening on his tubes, so if you amortize the cost over at least a year, it may be the best way to go. If you do get Svetlana's in the same range, then you would not need to re-bias.

My only caution here, would be to stay clear of The Tube Store, as their rating system leaves much to be desired.

Sorry, as this sounds like I have been of absolutely no help.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 04/07/02 09:39 PM

Bumping for new folks that may have missed this
Posted By: hechtdavid

Re: Feel free to ask Myles - 04/09/02 05:33 AM

Hi Myles,

I just started experimenting with changing pre-amp tubes on my 1999 Evil Twin. Got a few JJ's from Bob at Eurotubes and so far so good... I especially like the improved reverb. The overdrive sounds are nice and crunchy, but the new ECC83s in V1 doesn't sound much different than the stock 7025 that it replaced. Here's my question. Since the fx loop never gets used, do I essentially have new tubes in V4 and V7 (the fx send and return)? I'll be doing a few swaps in V1 between the JJ's and the 7025's that came with the amp, so I thought I could swap out the tube in V7 and put it in V1. OK with you? BTW, the old 7025's still sound pretty darn good. Seems to me that they have a lot of life left in them. How often do you change your pre-amp tubes?
Posted By: myles_rose

Re: Feel free to ask Myles - 04/09/02 06:58 PM

Quote:
Originally posted by hechtdavid:
Hi Myles,

I just started experimenting with changing pre-amp tubes on my 1999 Evil Twin. Got a few JJ's from Bob at Eurotubes and so far so good... I especially like the improved reverb. The overdrive sounds are nice and crunchy, but the new ECC83s in V1 doesn't sound much different than the stock 7025 that it replaced. Here's my question. Since the fx loop never gets used, do I essentially have new tubes in V4 and V7 (the fx send and return)? I'll be doing a few swaps in V1 between the JJ's and the 7025's that came with the amp, so I thought I could swap out the tube in V7 and put it in V1. OK with you? BTW, the old 7025's still sound pretty darn good. Seems to me that they have a lot of life left in them. How often do you change your pre-amp tubes?
hechtdavid,

On most amps, depending on if the loop is a series or parallel loop, and a few other factors, you may be able to remove the tubes altogether. This may also allow your amps power supply to be able to provide a bit more plate voltage to the other preamp tubes. This is an old Fender trick, where people either pull V1 or V2 when they only use one of the channels.

So .... yes, feel free to swap.

Preamp tubes last for years, with the exception of the phase inverter or driver tube, which some believe should be changed when output tubes are changed.

Regards,
Posted By: hechtdavid

Re: Feel free to ask Myles - 04/09/02 07:12 PM

Thanks Myles, And speaking of fx loops... Is it worth it to use them for a few stompboxes? I usually run pretty clean - direct into the amp, but occasionally I use a crybaby wah, MXR phase 90 and boss digital delay/reverb pedal all in line to the amp. Should I be using the loop?
Posted By: PeachPhan

Re: Feel free to ask Myles - 04/09/02 07:37 PM

I have a question for you...
I have a Phillips 5751 in the V2 (phase inverter/driver) slot of my Ghia - both sides are within 4 points of each other per Bob Pletka whom I bought the tube from... Is this close enough to use in the pi/driver slot? Would a closer match be even better?
I'm asking because I've noticed that the "A" note on the 14th fret of the "G" string and the 10th fret of the "B" string doesn't seem to want to sing like the rest of the notes... Is there some reason that could be happening? (it's doesn't "sing" much less, but I do notice it)
Posted By: myles_rose

Re: Feel free to ask Myles - 04/09/02 07:39 PM

Quote:
Originally posted by hechtdavid:
Thanks Myles, And speaking of fx loops... Is it worth it to use them for a few stompboxes? I usually run pretty clean - direct into the amp, but occasionally I use a crybaby wah, MXR phase 90 and boss digital delay/reverb pedal all in line to the amp. Should I be using the loop?
hechtdavid,

Using an effects loop in most cases is preferable to plugging the box(es) into the amp input, as when you do that, you loose highs, and mess up a few other things, as most amps front ends are looking to see the loading of a guitar. On cheap effects (that sometimes sound great because they are cheap and cheesy), they can really mess up the front end, tonewise.

Wah and Volume pedals work better in the front end, and not in the effects loop.

Regards,
Posted By: dlb

Re: Feel free to ask Myles - 04/09/02 07:49 PM

Myles,
Before I ask another off the wall question, I feel like I owe a bit of gratitude to your generousity. Knowing you are probably too humble to accept any form of barter, do you have a favorite institution or charity I could donate to on your behalf? (struggling musicians pipe down!)

Here goes....
I have an old Allied, Microphone-Instrument amplifier I picked up with great hopes of making a guitar amp out of it. It is probably 50's vintage.
I recognized that it was loaded with a pair Mullard EL34's and 4-5 12a??'s. It has reverb as well. It has a master and 4 input channels all with volume and tone. The transformers are identicle in size to most guitar amps.
Fooling around I plugged my guitar into it and connected a 8ohm 12" cab to it. It was obvious the tubes were old but it breaks up to a tone heaven.

Do you know of anyone that would take on a challenge like this? Or do you think I'm on crack?
I would do the cabinet work but I would need an expert to re-configure the electronics. I was thinking Voodoo may be interested.??

Best Regards,

dlb
Posted By: myles_rose

Re: Feel free to ask Myles - 04/09/02 07:58 PM

Quote:
Originally posted by PeachPhan:
I have a question for you...
I have a Phillips 5751 in the V2 (phase inverter/driver) slot of my Ghia - both sides are within 4 points of each other per Bob Pletka whom I bought the tube from... Is this close enough to use in the pi/driver slot? Would a closer match be even better?
I'm asking because I've noticed that the "A" note on the 14th fret of the "G" string and the 10th fret of the "B" string doesn't seem to want to sing like the rest of the notes... Is there some reason that could be happening? (it's doesn't "sing" much less, but I do notice it)
PeachPhan,

Ghia's, and all Dr. Z amps, really shine with matched output sections... they are loose something when its not matched. This is even more noticible in these amps than in AC-30's and AC-15's.

I am not sure what Bob's "4 points" are, but I like to have the same mA on each side of the driver, so something like 1.2 and 1.2, with a transconductance if at 1.2 mA, of 1600 on each side, though a range in TC from 1520 - 1680 or so works fine for me in these amps. Again, the closer the better.

If you want to loose a touch of the shrill that you can get at times in some volume settings that are very high, and get a bit more headroom before extreme distortion, then go for something in the 1.0mA range, which is about 83% of what a standard tube would test out at.

The symptoms you mention are the precise result of a mismatched output section.

Also, make sure your output tubes are really closely matched. A standard EL-84 at industry test settings will be a 48mA tube. In these amps, I like a 2% match, which does not give you that much room to play ( 47mA on the low side and 49mA on the high side, as an example, from industry standard. ) If Bob has some healthy examples, say, 51 mA, that's great too, just make sure they are within 2% of each other.

While this might seem pretty intense, as most folks match within 10% at times, and 5% is considered terrific, Bob over at Eurotubes generally matches within 1 mA, so in the above case, within 2% on this tube, and even close on a tube like a 6L6 which would have a 72mA rating, so his 1mA would be a 1.3% match, which is pretty fantastic.

Bob Pletka is one of my favorite tube guys. He is very sharp, has some pretty extensive knowledge, but also supplies great products at some pretty insane prices. Just as an example, my "COST" on a JJ 12AX7 from most of my sources is $7.85 to $8.55. Bob's cost I believe is $7.50, though I may have made a mistake, and that is the cost that Bob sells them to anybody for, not just people in the business.

A great quad of matched (and I mean MATCHED ... not the sort of matching that some folks do) EL-84's will normally run $40.00 to $50.00. From Bob I think they are $30.00. On top of that, he is small enough that he can still take time to tailor tubes for a specific amp and will talk to the customer.

Regards,
Posted By: PeachPhan

Re: Feel free to ask Myles - 04/09/02 08:33 PM

Thanks Myles!
Here's a bit more...
I think the EL-84's I got from Bob were both at 36 ma... a perfect match, but lower ma than you had mentioned (I think you mentioned 47 ma)... What would be the difference?
I believe the "4 points" I mentioned regarding the 5751 were 4 ma (i.e. both sides were within 4 ma of each other)... so around 2%... That works for the pi/driver slot right?
PeachPhan
Posted By: myles_rose

Re: Feel free to ask Myles - 04/09/02 10:36 PM

Quote:
Originally posted by dlb:
Myles,
Before I ask another off the wall question, I feel like I owe a bit of gratitude to your generousity. Knowing you are probably too humble to accept any form of barter, do you have a favorite institution or charity I could donate to on your behalf? (struggling musicians pipe down!)

Here goes....
I have an old Allied, Microphone-Instrument amplifier I picked up with great hopes of making a guitar amp out of it. It is probably 50's vintage.
I recognized that it was loaded with a pair Mullard EL34's and 4-5 12a??'s. It has reverb as well. It has a master and 4 input channels all with volume and tone. The transformers are identicle in size to most guitar amps.
Fooling around I plugged my guitar into it and connected a 8ohm 12" cab to it. It was obvious the tubes were old but it breaks up to a tone heaven.

Do you know of anyone that would take on a challenge like this? Or do you think I'm on crack?
I would do the cabinet work but I would need an expert to re-configure the electronics. I was thinking Voodoo may be interested.??

Best Regards,

dlb
dlb,

You are more than welcome.

I don't have any favorite charity (that's a pretty bad reflection on me I guess, but my wife takes care of that).

I guess all I can ask in return, is try to help somebody starting out in music, no matter what their chosen instrument. If you can give some words of advice or encourgement, that's pretty fantastic payment to me. I like the folks I meet here, and this is a nice break between soldering iron sessions and tube testing.

On mic and PA amps, they have a lot of great possibilities. The main drawback, is they are EQ'd for full range, and for some guitar uses, that is not what we are used to hearing. BUT, they make fantastic amps for jazz guitar or acoustic guitar, when the acoustic guitar is set up with a pickup.

Your preamp tubes are probably AT7's, AY7's or AU7's as they were more popular in the 50's, but they are ALL interchagable with themselves and with 12AX7's, with no adjustment necessary and no modification of any sort.

I would love to know what the plate voltage was on the EL-34's, just for curiosity sake.

It may not be an issue of having tubes that are too old. You may just be overloading the input with a guitar, or there is a big impedience mismatch, as a guitar pickup is 5k to 12k and a mic is 600 ohms.

The first thing I would try, is get a matching transformer (at any good music store), and that will get your impedience to match your amp.

Your 8 ohm cabinet, may or may not be correct. Is there any indication on the back of the amp as to what sort of speaker load it was designed for? Worse comes to worse, you can always have a tech measure the output taps of the output transformer.

You may not have as big of a challenge on your hands as you think. I'd first try the matching transformer, and you may find you have a real gem on your hands.

If you want to go beyond that, then we need to look at the circuit, which can be done even without prints, but that can be time consuming. You can then change some of the pots, caps, and resistors to make either a Fender, Vox, or Marshall tone stack on the front end.

Frankly if you did that, you would just end up with sort of a Marshall 45-50 clone in a way. Your amp was probably a lot more costly than the original Marshall amps of the 60s, and in the 50's, electronics were made even nicer than in the 60's in some cases.

I'd keep it as is, and use it for jazz, rhythm, or acoustic. Play a Rickenbacker 12 string through it. With the wide frequency response, it might sound just amazing.

I guess you can talk to Trace at Voodoo and get his take on what I have said here, as he might have some other feelings. He's a sharp fellow, and his advice would be worth listening to.

Regards,
Posted By: telewhacker

Re: Feel free to ask Myles - 04/09/02 11:17 PM

hi Myles, i have a question about the Ashdown Peacemaker 40 combo:
so you have worked on a few of those? were the problems
minor/major/maint?
i have been seriously mulling over the 40W combo... do you know if they are
hand-wired like the heads, or have schematics around to do a comparison
possibly? you have to submit a reason for wanting their schematics on their
website, and they have never replied with the secret code or whatever it
takes to get in.
If I buy one of these amps, it will have to shipped to me directly from CA
, so it will be a pig in a poke, and i sure could use some enlightened
advice or critiques.
i have heard that they rival the chimey tones of Vox/Matchless, and have
more bottom-end to them, which would be right up my alley, but i am getting
this from a sales-rep, so who knows?
tell me what you think man!
thanks!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/10/02 02:50 AM

Quote:
Originally posted by PeachPhan:
Thanks Myles!
Here's a bit more...
I think the EL-84's I got from Bob were both at 36 ma... a perfect match, but lower ma than you had mentioned (I think you mentioned 47 ma)... What would be the difference?
I believe the "4 points" I mentioned regarding the 5751 were 4 ma (i.e. both sides were within 4 ma of each other)... so around 2%... That works for the pi/driver slot right?
PeachPhan
PeachPhan,

Bob tests at a different plate voltage than I do, so I draw more current at a lower voltage, and draws less current at a higher voltage. Since Ohms law is always equal, either result is fine.

So, since you have two 36mA tubes, you are in great shape.

As far as the 5751's four point could not be 4mA, as the tube at reference voltage is 1.2mA as standard, so we'd be about 300% off! Even .4mA would be way too much. If Bob is using something like a Hickock or B&K, they have their own scale. On one of my machines, it is a 4000 point scale, so in that case, four points is a really slim number.

I trust Bob a lot, so if he says 4 points on his scale is considered in his realm to be matched, I'd be just fine going along with this, as I know how picky he is. He also has a really great grasp of Dr. Z amps, Matchless, and Vox.

Happy playing \:\)

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/10/02 03:37 AM

Quote:
Originally posted by telewhacker:
hi Myles, i have a question about the Ashdown Peacemaker 40 combo:
so you have worked on a few of those? were the problems
minor/major/maint?
i have been seriously mulling over the 40W combo... do you know if they are
hand-wired like the heads, or have schematics around to do a comparison
possibly? you have to submit a reason for wanting their schematics on their
website, and they have never replied with the secret code or whatever it
takes to get in.
If I buy one of these amps, it will have to shipped to me directly from CA
, so it will be a pig in a poke, and i sure could use some enlightened
advice or critiques.
i have heard that they rival the chimey tones of Vox/Matchless, and have
more bottom-end to them, which would be right up my alley, but i am getting
this from a sales-rep, so who knows?
tell me what you think man!
thanks!
telewhacker,

I am sorry, but the only Ashdown amps I have worked on, or heard for that matter, are the Peacemaker 50 and 100 watt Class A/B heads.

I have not heard any of their Class A combos, although I did hear some in the background maybe at the last NAMM show a few months back.

I don't know if they are built the same as the heads,
and did not have a chance to look inside any of their 20, 40, or 60 watt models.

In fact, I do not even know their tube compliment. I will assume (and maybe incorrectly), that the 20 watter is a 2 x EL-84 amp, with a bit more plate voltage and a Vox AC-15 ... I have been able to get 22 watts out of a AC-15. On the 40 watt version, I will assume (again, maybe off base here), that it is a 4 x EL-84 amp, with a bit more plate voltage than an AC-30 or a Matchless DC-30.

On the 60 watter, I have NO IDEA! Maybe its four EL-34's, or something as two of them in Class A could be 22 or so watts, but maybe these are at high voltages to .... or .... 6 EL-84's? That may be interesting. I just have no idea.

Maybe ask the sales rep?

Sorry.
Posted By: Rai168

Re: Feel free to ask Myles - 04/10/02 05:02 AM

Hi Myles - thank you for answering all my questions - here goes - it's from a 3 part email so I apologize for the length -

Hi Myles,
>
>An Updated question for you - which tube psotion is
>the phase inverter? In a previous email you stated -
>
>... the most important aspect of your phase inverter
>tube is making sure the two sides match within 0.2 mA.
>Then also be sure your output set is closely matched
>
>I have a chance to buy a matched pair of RFT ECC83's.
>I'm planning on using it in the V1 position and
>possibly the phase inverter position. My set up would
>be V1 RFT v2 Phillips 12ax7 (If I'm correct the V4 is
>the phase inverter - not sure though) v3 Phillips and
>v4 RFT
>
>Again in my power amp Section I have 2 preamp tubes to
>help w clipping. Right now it goes v1 Phillips 12ax7
>WA and Sovtek 12At7. Would replacing the Sovtek 12At7
>in the pwoer amp section w a 12ax7 cause me to lose
>clarity but more gain? Just curious - I'm working on
>getting a Phillips, or GE 12at7 for that position.
>
>Finally is it important for all the preamp tubes to
>match or mainly the phase inverter tube? Thanks again
>Myles - Hope all is well...
>
>Rai
>
P.S. Would these be good to replace the 12AT7 (not
>sure if an ECC82 is the same as a 12AT7) Here are the
>specs - Would I be better w a 12at7 or 12ax7 for the
>P.I.? How would thee be for the 12At7 in the power amp
>section?
>
>I have 2 pieces of used ECC-82 tubes.
>Made by RFT(Germany).
>Packing:OEM.
>
>15-20 years ago the electron tubes have become
>needless because of modernization
>of a Microwave Laboratory of Technological Institute
>of Budapest.
>
>The tubes have been checked by a calibrated Hickok
>539B tube tester.
>By the operating manual of the tester the typical
>value
>of the MC(Mutual Conductance) of the ECC-82 tube
>is:1950
>This is taken as 100%.
>(Given for each tube System 1 and System 2 [in
>Micromhos]).
>On each tube I placed a little white sticker with the
>measurement results.
>
>MUTUAL CONDUCTANCE TEST: here we can get exact
>numerical value in micromhos.
>The condition of TUT (Tube Under Test) can be
>expressed in percent.
>For example:in case of ECC-82 the listed typical
>value of mutual conductance is 1950 micromhos.
>If the TUT has 2300, the percental condition is
>(2300/1950)x100%=118%.
>
>Result of the mutual conductance test, as follows:
>
>-Nr.001.tube
>triode No.1.=2700/1950x100=(139%),
>triode No.2.=2800/1950x100=(144%).
>
>-Nr.002.tube
>triode No.1.=1800/1950x100=(92%),
>triode No.2.=1900/1950x100=(97%).
>
>
>Thanks Myles...
>
>Rai
>
Well I got my eye on a matchedpair of RFT 12ax7's
>(aside from the ones I sent you specs on) He states
>they are matched to each other but the triodeas are w
>in close spec - here is what he replied.
>
>The pairs are closely matched to within 0.50 db, where
>you will not get
>any skweing of the sound image.
>
>
>Is that close enough? Again they are 12ax7's so I'm
>not sure if that would be decent for the PI position.
>$26 for both so I think I may go for it if you say
>they are decent. I'll probably put them in the front
>section as opposed to the PI if they aren;t close
>enough for the PI.
>
>I talked to Mike at VHT - he broke down what each
>position does in my amp and about the PI section
>
>V-1 Intial stage - important - first gain stage but he
>said V2 and V3 are more of the tone changers as far as
>distortion characteristics - seems a lil weird but
>I'll buy it. v4 is the last gain stage - I guess the
>clean channel goes from v-1 and bypasses 2 and 3 and
>goes to v4 - I'm assuming I'd want a cleaner tube
>there if I want my clean to shine. Anything you could
>recommend for a Fender type direction clean?
>
>As for the PI section get this - the 2 preamp tubes by
>the pwoer section he says are for the PI. 1 12ax7 and
>1 12at7. Right now I have a phillips 12ax7was back
>there w the stock sovtek 12at7. How would i go about
>matching the PI section here? Would I jsut get 2
>matched Inverter tubes (both sides of the triode)?
>
>Thanks for all your patience -you seem to be the one w
>the msot knowledge so I hope I am not bothering you
>too badly...
>
>thank you -
>
>Rai
http://www.CalyxinRuin.com
Posted By: Ian-UK

Re: Feel free to ask Myles - 04/10/02 05:01 PM

Hi again Myles. I just got some preamp tubes (RFT ECC83) for my Cornford and I was just wondering which tube you would use where. Reason I ask this is because the outputs are 255/252, 258/257 and 250/252 I'm tempted to put the 258/257 one in the v1 position as the output is higher but it is also a better match and so probably the best suited for the phaze splitter? Just wondering if it will make much of a difference as they all seem pretty well matched anyway.

Cheers,

Ian............
Posted By: myles_rose

Re: Feel free to ask Myles - 04/10/02 07:19 PM

Quote:
Originally posted by Rai168:
Hi Myles - thank you for answering all my questions - here goes - it's from a 3 part email so I apologize for the length -

Hi Myles,
>
>An Updated question for you - which tube psotion is
>the phase inverter? In a previous email you stated -
>
>... the most important aspect of your phase inverter
>tube is making sure the two sides match within 0.2 mA.
>Then also be sure your output set is closely matched
>
>I have a chance to buy a matched pair of RFT ECC83's.
>I'm planning on using it in the V1 position and
>possibly the phase inverter position. My set up would
>be V1 RFT v2 Phillips 12ax7 (If I'm correct the V4 is
>the phase inverter - not sure though) v3 Phillips and
>v4 RFT
>
>Again in my power amp Section I have 2 preamp tubes to
>help w clipping. Right now it goes v1 Phillips 12ax7
>WA and Sovtek 12At7. Would replacing the Sovtek 12At7
>in the pwoer amp section w a 12ax7 cause me to lose
>clarity but more gain? Just curious - I'm working on
>getting a Phillips, or GE 12at7 for that position.
>
>Finally is it important for all the preamp tubes to
>match or mainly the phase inverter tube? Thanks again
>Myles - Hope all is well...
>
>Rai
>
P.S. Would these be good to replace the 12AT7 (not
>sure if an ECC82 is the same as a 12AT7) Here are the
>specs - Would I be better w a 12at7 or 12ax7 for the
>P.I.? How would thee be for the 12At7 in the power amp
>section?
>
>I have 2 pieces of used ECC-82 tubes.
>Made by RFT(Germany).
>Packing:OEM.
>
>15-20 years ago the electron tubes have become
>needless because of modernization
>of a Microwave Laboratory of Technological Institute
>of Budapest.
>
>The tubes have been checked by a calibrated Hickok
>539B tube tester.
>By the operating manual of the tester the typical
>value
>of the MC(Mutual Conductance) of the ECC-82 tube
>is:1950
>This is taken as 100%.
>(Given for each tube System 1 and System 2 [in
>Micromhos]).
>On each tube I placed a little white sticker with the
>measurement results.
>
>MUTUAL CONDUCTANCE TEST: here we can get exact
>numerical value in micromhos.
>The condition of TUT (Tube Under Test) can be
>expressed in percent.
>For example:in case of ECC-82 the listed typical
>value of mutual conductance is 1950 micromhos.
>If the TUT has 2300, the percental condition is
>(2300/1950)x100%=118%.
>
>Result of the mutual conductance test, as follows:
>
>-Nr.001.tube
>triode No.1.=2700/1950x100=(139%),
>triode No.2.=2800/1950x100=(144%).
>
>-Nr.002.tube
>triode No.1.=1800/1950x100=(92%),
>triode No.2.=1900/1950x100=(97%).
>
>
>Thanks Myles...
>
>Rai
>
Well I got my eye on a matchedpair of RFT 12ax7's
>(aside from the ones I sent you specs on) He states
>they are matched to each other but the triodeas are w
>in close spec - here is what he replied.
>
>The pairs are closely matched to within 0.50 db, where
>you will not get
>any skweing of the sound image.
>
>
>Is that close enough? Again they are 12ax7's so I'm
>not sure if that would be decent for the PI position.
>$26 for both so I think I may go for it if you say
>they are decent. I'll probably put them in the front
>section as opposed to the PI if they aren;t close
>enough for the PI.
>
>I talked to Mike at VHT - he broke down what each
>position does in my amp and about the PI section
>
>V-1 Intial stage - important - first gain stage but he
>said V2 and V3 are more of the tone changers as far as
>distortion characteristics - seems a lil weird but
>I'll buy it. v4 is the last gain stage - I guess the
>clean channel goes from v-1 and bypasses 2 and 3 and
>goes to v4 - I'm assuming I'd want a cleaner tube
>there if I want my clean to shine. Anything you could
>recommend for a Fender type direction clean?
>
>As for the PI section get this - the 2 preamp tubes by
>the pwoer section he says are for the PI. 1 12ax7 and
>1 12at7. Right now I have a phillips 12ax7was back
>there w the stock sovtek 12at7. How would i go about
>matching the PI section here? Would I jsut get 2
>matched Inverter tubes (both sides of the triode)?
>
>Thanks for all your patience -you seem to be the one w
>the msot knowledge so I hope I am not bothering you
>too badly...
>
>thank you -
>
>Rai
http://www.CalyxinRuin.com
Rai,

I'll try to get through this, but may miss a bit due to the length.

It may be best in the future, to ask a few specific questions in a given post.

Using a 12AT7 in the place of a 12AX7 in V1 will reduce your gain.

It is NOT important for all the preamp tubes to match one another. The only critical tube is the phase inverter, as far as matching of the A and B sides.

It is however, very advantageous to know what those other tubes are doing, especially the tube in the first gain stage. This is where a vendor such as Watford Valves has an advantage over most of the other vendors, they have a rating system.

On your MC data, you are on the right track, but
there are a few other factors that I look at, such
as raw gain, transconductance, and then the actual
curve characteristics.

That 0.50db spec is something that I don't understand. Looking at how and where a tube is used, and its basic amplification factor, I don't know if that db is a converted number of some sort, or an end value based on a mic in front of a speaker at the old dbSpl @ 1 meter on axix reading, or what.

If you talk to Mike again at VHT, if he is the same Mike that worked at Rivera for many years, please say hello from me. If its the Mike I think it is, you can go with what he tells you with confidence.

For a Fender sort of clean, you need a Fender sort of tone stack. That's pretty much the bottom line here. There are too many Marshall folks that I talk to that want more of a Fender sound. I tell them to buy a older Bassman head or Bandmaster head, and an A/B switch and use their Marshall and the Fender.

I hope I covered most of your questions. If I missed things, which I am sure I did, just post them, sort of in question format, with a question or two per post maybe.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/10/02 07:33 PM

Quote:
Originally posted by Ian-UK:
Hi again Myles. I just got some preamp tubes (RFT ECC83) for my Cornford and I was just wondering which tube you would use where. Reason I ask this is because the outputs are 255/252, 258/257 and 250/252 I'm tempted to put the 258/257 one in the v1 position as the output is higher but it is also a better match and so probably the best suited for the phaze splitter? Just wondering if it will make much of a difference as they all seem pretty well matched anyway.

Cheers,

Ian............
Ian,

Derek's scale over at Watford is very precise, and really breaks things down to a precise value, so a few points difference on his scale is still so much closer than one can imagine, its scary.

I don't remember what his point spread is on what he considers a "balanced" valve, but the closer is always better.

I would probably use the 250/252 in the phase inverter position, as here we are generally looking for current drive more than voltage gain, and frankly, a 99.2% match is pretty darn close!

All these tubes (valves) are so close, that moving them around, even in V1, or the first gain stage, is probably not going to be a perceived difference. If you want to try something different down the road, then perhaps try in V1 one of his valves in the 190 or so range. That will drop gain in the front end a lot and give you a lot more headroom, if you have a need for a clean sound for a particular situation.

The "problem" with Watford Valves, is you do get, and you do know, what you have in your hands, so at times its can be more tempting to buy two or three tubes from them when you initially only wanted to replace a single bad one \:\)

Regards,
Posted By: Mike6112

Re: Feel free to ask Myles - 04/10/02 07:36 PM

I am new to this forum, so thanks for having something like this to bounce questions and such.

I am looking for a decent acoustic amp and, of course, on a budget. Can you help?

To make it worse, I would like to be able to get an electric amp that would work well for my acoustic.

Anything like that out there.

Thanks again!
Posted By: Ian-UK

Re: Feel free to ask Myles - 04/10/02 07:52 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by Ian-UK:
Hi again Myles. I just got some preamp tubes (RFT ECC83) for my Cornford and I was just wondering which tube you would use where. Reason I ask this is because the outputs are 255/252, 258/257 and 250/252 I'm tempted to put the 258/257 one in the v1 position as the output is higher but it is also a better match and so probably the best suited for the phaze splitter? Just wondering if it will make much of a difference as they all seem pretty well matched anyway.

Cheers,

Ian............
Ian,

Derek's scale over at Watford is very precise, and really breaks things down to a precise value, so a few points difference on his scale is still so much closer than one can imagine, its scary.

I don't remember what his point spread is on what he considers a "balanced" valve, but the closer is always better.

I would probably use the 250/252 in the phase inverter position, as here we are generally looking for current drive more than voltage gain, and frankly, a 99.2% match is pretty darn close!

All these tubes (valves) are so close, that moving them around, even in V1, or the first gain stage, is probably not going to be a perceived difference. If you want to try something different down the road, then perhaps try in V1 one of his valves in the 190 or so range. That will drop gain in the front end a lot and give you a lot more headroom, if you have a need for a clean sound for a particular situation.

The "problem" with Watford Valves, is you do get, and you do know, what you have in your hands, so at times its can be more tempting to buy two or three tubes from them when you initially only wanted to replace a single bad one \:\)

Regards,
Thaks Myles, always informative \:\)
Posted By: myles_rose

Re: Feel free to ask Myles - 04/11/02 12:47 AM

Quote:
Originally posted by Mike6112:
I am new to this forum, so thanks for having something like this to bounce questions and such.

I am looking for a decent acoustic amp and, of course, on a budget. Can you help?

To make it worse, I would like to be able to get an electric amp that would work well for my acoustic.

Anything like that out there.

Thanks again!
Mike,

There are a lot of products out there, but its all personal preference.

This may be a great question to post on its own to all the folks here. There are a lot of issues to consider.

There are a lot of what I call, "converted" guitar amps that use a speaker cabinet that was originally optimized for electric guitar. Some even use the same circuit with a bit of EQ changes.

With acoustic guitar, in my opinion, one is looking to make the guitar louder, and keep as much of the original instruments sound as possible, with as little coloration as possible.

One amp I like a lot is a solid state amp made by a German company called AER. ( http://www.aer-amps.de/ )

They have a pretty wide product line, but start at amp $1000 retail and go up a lot from there.

There are amps by Trace Elliott and Fender that you can look at, and quite a few from other folks too.

I think the best idea would be to ask folks here.

Sorry I could not help very much

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/11/02 12:55 AM

Quote:
Originally posted by Ian-UK:
[QUOTE]Originally posted by myles111:
[qb] [QUOTE]Originally posted by Ian-UK:
[qb]Hi again Myles. I just got some preamp tubes (RFT ECC83) for my Cornford and I was just wondering which tube you would.....
Ian,

No problem and you are welcome ....

Regards,
Posted By: jivey311

Re: Feel free to ask Myles - 04/11/02 08:44 PM

I have a JCM900 50Watt head, and the tubes are about a year old. When I first bought it used, it was pretty loud in a band setting on like 5-6. But that was up against a SS crate head. Now I'm up against a 5150, and I have to turn my amp up to 11. And the clean is barely there anymore. Is that just the tubes that need changing? Will a retubed JCM900 be able to compete in volume with the 5150? I have a LP Gothic, and my guitarist has a Custom 22 PRS. I also have a SD Custom custom in the bridge.

My main question is, do I need a more wattage to cut through in the band? or will my JCM900 50 watt head, work?
Posted By: myles_rose

Re: Feel free to ask Myles - 04/12/02 12:25 AM

Quote:
Originally posted by jivey311:
I have a JCM900 50Watt head, and the tubes are about a year old. When I first bought it used, it was pretty loud in a band setting on like 5-6. But that was up against a SS crate head. Now I'm up against a 5150, and I have to turn my amp up to 11. And the clean is barely there anymore. Is that just the tubes that need changing? Will a retubed JCM900 be able to compete in volume with the 5150? I have a LP Gothic, and my guitarist has a Custom 22 PRS. I also have a SD Custom custom in the bridge.

My main question is, do I need a more wattage to cut through in the band? or will my JCM900 50 watt head, work?
jivey311,

Piece of cake ....

First off, 100 watts is only 3db louder than 50 watts.

What speaker config are you using.

To increase your sound level by a factor of four, you double your speaker area. That means, if you are using a 4x12, you then use 2 4x12 cabinets.

That's one way.

Another, if you are using a 4x12, get a more efficient cabinet with a larger sound dispersion area. Go listen to a THD 2x12 ported cabinet with your head at a THD dealer. You'll be surprise.

Another way ....

Have your amp made correct and optimized. Most amps are far from being set up correctly.

The process here is something of a subset of what I call blueprinting, which is explained a bit on my website.

I can typically get over 70 watts out of a Marshall 50 watt head without any modification with 25 watt EL-34 output tubes.

I's first look at your V1 preamp tube. It is very likely that is may be down up to 40% in gain as compared to what a stock ECC83 is supposed to put out. Most I find are in the 0.9 mA range instead of the 1.2 mA spec. You'd first want to get a good tube in here, something in a range even above 1.2 mA. There are not too many people that do this. I do this for my clients, but do not sell tubes. I would suggest you contact Watford Valves (look at http://www.watfordvalves.com ) and get what they call a "driver" tube from them, and ECC83, with a rating of about 260-270. That right there, will bring your gain up considerably.

Now, if you want to take it a bit further, and have more "balls" over the entire spectrum, you contact Bob Pletka at http://www.eurotubes.com and get a JJ EL-34L or S, not sure of his designation these days, but in any case, not the normal EL-34. The L or S tubes have a different plate structure, and are 30 watt tubes, not the 25 watt type that is normal for an EL-34. These are the tubes used by Joe Walsh, Joe Perry, and Billy Gibbons from ZZ top.

Tell Bob to pick you out some healthy ones, at the high end of his scale.

Then your amp needs to be re-biased for these tubes, no matter what their scale.

If you have a tech or know your B+ voltage (with the old tubes IN THE CIRCUIT) ... not one pulled to measure the B+, but measure it from the wire side of the socket, then let me know, and I can get your tech in the ballpark for idle dissapation.

Part of a Marshall's sound comes from a part of the crossover notch distorion still in the output waveform, so you should not have the bias set with a simple device such as a bias probe. These work great on a lot of amps, but not Marshalls. For the Marshall, your tech will need a signal generator and a scope.

With normal 25 watt tubes like Svetlana's, I can get about 65-70 watts out of your head if its B+ voltage is up to factory spec. With the L or S EL-34's, I can usually get 75-80 watts pretty easily with those 30 watt tubes.

I'd also have Watford send you a V2 tube (also ECC83) with a rating of 250 or higher, and a matched "balanced valve" as they call it. This will assure a matched output section, also explained on my website.

There is no reason that your 800 cannot be just as loud, or even a bit louder with its pushed midrange, as a 5150, playing though the same cabinets.

Regards,
Posted By: mmenard79

Re: Feel free to ask Myles - 04/12/02 02:58 AM

I bought an old blackface bassman that had old sylvania power tubes. I played it one day with no problem. A couple of days later, i fired it up and get nothing but barely audible preamp saturation. I swaped the power tubes and it worked fine. The sylvania don't ligh at all. What i would like to know is does this sound like the normal death of tubes or is there something wrong with the amp that caused the tubes to fail?
thanks
matt
Posted By: myles_rose

Re: Feel free to ask Myles - 04/12/02 04:02 AM

Quote:
Originally posted by mmenard79:
I bought an old blackface bassman that had old sylvania power tubes. I played it one day with no problem. A couple of days later, i fired it up and get nothing but barely audible preamp saturation. I swaped the power tubes and it worked fine. The sylvania don't ligh at all. What i would like to know is does this sound like the normal death of tubes or is there something wrong with the amp that caused the tubes to fail?
thanks
matt
Matt,

Blackface Bassmans are pretty sturdy amps. If the tubes did not light at all, even the heaters, then I would say your 6.3 volt heater supply failed, but this would have also caused the preamp tubes to not work either. On some 6L6's it hard to see the heater, so perhaps it was just tube failure.

Since replacing the output tubes (I hope you replaced both at the same time), fixed the problem, it seems that your power transformer, and output transformer are fine.

To be on the safe side, you may want to replace the preamp tube that is the most close to the output tubes, as that is the phase inverter than drives your output section. If its old, it may be suspect, and perhaps changing to new output tubes loaded the phase inverter differently, so it worked fairly well again.

I'd have your bias checked, since you replaced the output tubes, as Fender amps can sound good or great, depending a lot on the bias setting. This also has a lot to do with tube life.

I don't know if you are in my area, Los Angeles, but if you are, I'd be happy to check your bias for you at our upcoming amp clinic. There is no charge for the clinic, so its a nice way to avoid a $40-$60 bench charge, and learn a lot more about your amp and its other areas at the same time.

Regards,

Myles
Posted By: deke1000

Re: Feel free to ask Myles - 04/12/02 07:20 AM

Last summer, I purchased a 1979-80 Hiwatt DR504 (the "Custom 50" fifty watt, 2 input model from the Joyce era). Unfortunately, since then I've had issues with it. The main one being that after 15 or 20 minutes of moderate playing, the sound "dissipates" to a feeble that you can talk comfortably over.

Sometimes this is temporary -- and the amp will "catch its breath" and suddenly rejuvenate back to Hiwatt roar. Other times it won't, but will go back to normal after about 30 seconds of a rest on stand-by.

Right away, I took it in to a trusted local tech who specializes in British amps (Acme Guitars in St. Louis, MO), and he suggested it was the filter caps. So, we replaced all of the filter caps -- and I put some THD Yellowjackets in there as well, as the old EL34s were mismatched and ready for retirement.

This seemed to solve the problem, but within a few weeks, the problem of sound dissipation came back. At first it was minimal, but now it is chronic to the point where I can't play the amp for any longer than 15 minutes without all of my volume and tone going down the toilet.

I've perhaps found perhaps another tech to take it to -- but my options seem rather limited in this area, especially for this sort of amp and this sort of problem. So before I do, I'm wondering given your experience you might have an idea of what this amp needs. I know it's hard to diagnose an amp by e-mail without hearing it, but perhaps you have an idea of what could be causing this; and, if it is easily fixable; or if I should give up and get another amp?

Know that it seems that in the amps lifetime, someone tried a lot of Frankenstein mods to it: adding an effects loop; and rigging the normal "channel" of the amp to behave like a gain stage for the bright channel...most of these have been removed, but remnants of them still remain.

Anyway, I appreciate any thoughts you might have on this matter. My band is rather serious and I need a road-worthy, no-hassle amp that will excel at mostly Byrdsy sort of jangle with a touch of some spacey rock stuff... so maybe the Hiwatt is not the ticket for this application after all.

I hope to hear from you soon.
Posted By: boanerges

Re: Feel free to ask Myles - 04/12/02 09:27 AM

I recently retubed my CAE se3+ - it used to have Chinese tubes, but I replaced them (due to microphonics) with Sovtek 12ax7wb's. I believe that some of the harsh, compressed upper midrange and poor tone comes from these tubes. What's your recommendation - which tubes will be optimal for this preamp?

Also, where is the driver tube located in these amps - there's no schematics available...

Thanks!

Boanerges
Posted By: Mr. Dan Licks

Re: Feel free to ask Myles - 04/12/02 02:15 PM

Hi Myles,
We have just purchased, (based in part on your recommendation!), a second hand .50+ for my son. His first "real" amp and it really hits the spot! At the moment it has what seem to be the original tubes in it: STR 12AX7-A, STR SPAX7-A, STR 12AX7-A, STR 12AT7, and a STR 12AX7-A on the end of the line. Power is 6L6 STR 420. All marked Mesa. For the time being he will keep these going, but we would like to know what other options are and if they would make the amp sound still better. What would you suggest?
I have a lead on half a dozen SIEMENS CV492 / ECC83. Do you know these. Are they worth perusing for this amp? They have been tested on a FUNKE W19 and are good. Or is it better to play it safe and go straight to Watford?
Many thanks! How do you find the time to be so helpful?
Dan
Posted By: myles_rose

Re: Feel free to ask Myles - 04/12/02 09:41 PM

Quote:
Originally posted by deke1000:
Last summer, I purchased a 1979-80 Hiwatt DR504 (the "Custom 50" fifty watt, 2 input model from the Joyce era). Unfortunately, since then I've had issues with it. The main one being that after 15 or 20 minutes of moderate playing, the sound "dissipates" to a feeble that you can talk comfortably over.

Sometimes this is temporary -- and the amp will "catch its breath" and suddenly rejuvenate back to Hiwatt roar. Other times it won't, but will go back to normal after about 30 seconds of a rest on stand-by.

Right away, I took it in to a trusted local tech who specializes in British amps (Acme Guitars in St. Louis, MO), and he suggested it was the filter caps. So, we replaced all of the filter caps -- and I put some THD Yellowjackets in there as well, as the old EL34s were mismatched and ready for retirement.

This seemed to solve the problem, but within a few weeks, the problem of sound dissipation came back. At first it was minimal, but now it is chronic to the point where I can't play the amp for any longer than 15 minutes without all of my volume and tone going down the toilet.

I've perhaps found perhaps another tech to take it to -- but my options seem rather limited in this area, especially for this sort of amp and this sort of problem. So before I do, I'm wondering given your experience you might have an idea of what this amp needs. I know it's hard to diagnose an amp by e-mail without hearing it, but perhaps you have an idea of what could be causing this; and, if it is easily fixable; or if I should give up and get another amp?

Know that it seems that in the amps lifetime, someone tried a lot of Frankenstein mods to it: adding an effects loop; and rigging the normal "channel" of the amp to behave like a gain stage for the bright channel...most of these have been removed, but remnants of them still remain.

Anyway, I appreciate any thoughts you might have on this matter. My band is rather serious and I need a road-worthy, no-hassle amp that will excel at mostly Byrdsy sort of jangle with a touch of some spacey rock stuff... so maybe the Hiwatt is not the ticket for this application after all.

I hope to hear from you soon.
Deke,

Has anybody looked at the output tubes and the power supply output? Having the amp work fine for 20 minutes and then die to a whisper, sounds like a bad output tube, a bad phase inverter, or a power supply issue.

I don't think this would be filter caps, as when a cap is bad, it is pretty much bad. Also, with a bad filter cap on the power supply, you would hear 60 cycle hum all the time, or you would have strange harmonics that would be heard off the note you were playing.

The installation of Yellow Jackets would have no impact on the amp, other than if you had bad output tubes, then the YJ's with their fresh EL-84's would eliminate that problem.

I would have asked the tech to look at your B+ voltage, and make sure it was within range of spec, and also to look at how much ripple there was on the high voltage, before replacing the filter caps.

I would also want to know the B+ voltage when the problem showed up, just by keeping the amp chassis open and a lead clipped to pin 3 of the output tube socket with the amp running, and seeing the voltage there when it died.

I would also have the bias checked.

I think any decent tech can check the things above.

This should be a pretty easily (and cheaply) rectified problem. If its a heat sensitive diode in the bridge rectifier, that is a cheap fix too. The only time it may get expensive, is if the output transformer is bad, but there would be signs pointing to something like that.

I think this problem should be able to be found without resorting to the shotgun approach of replacing parts such as caps. This should be able to be found for a normal minimum bench charge of a hour, as a lot of folks have, which should range from maybe $45 to $75 for a basic checkout. In my case, when an amp has a heat sensitive possible problem, I just leave it hooked up to a load, and go work on something else, leaving a meter or scope on it, so I can look around once in a while. That way the clock stops for the customer.

The issue gets complicated with mods, unless there were prints and doumentation supplied when you bought the amp. I typically stay away from modded amps, unless I can see it was a good job. I will work on modded amps if it was done by somebody like Voodoo or Torres Engineering.

I would try to get rid of any parts of the old mods, especially since the mods are not all intact.

If you do Byrds sorts of things, Rickenbacker stuff, then a Hiwatt is great, as they are clean amps. The best amps to reproduce the Byrds from the mid 60's era is probably the Fender Twin Reverb, or a Showman, which was also used by them and the Jefferson Airplane before Grace Slick came into the picture.

In that sort of music, a cleaner amp is the ticket, and a Hiwatt was a clean amp. The tone stack though, is a Marshall tone stack, which is a lot different than a Fender tone stack, so you may want to try a Twin Reverb reissue. With a few tube changes and a few adjustments, they are right in the ballpark with the originals.

You may also be able to find a Silver Face twin reverb, with can really do very nicely, and are not all that expensive.

Hope this helped a little at least.

Regards,
Posted By: papamaverick

Re: Feel free to ask Myles - 04/12/02 10:11 PM

Hey Myles

I emailed you but you mentioned it would be easier to get ahold of you on one of the forums, so here goes.

Love your articles…really neat stuff. I recently upgraded to JJ tubes at your recommendation and am very pleased. Anyhow, I have a quick question for you, since you're one of the people I KNOW has a good ear for sound. My rig is built around a Les Paul with Seymour Duncan Alnico II Pro (bridge) and '59 (neck) pickups and a Mesa Boogie Maverick. Both the guitar and amp produce nice, warm, vintage-y tones. The Maverick is similar in design to the Vox AC30 in regards to tubes…I'm using 6x JJ ecc83s and 4x JJ el84s; the Maverick I have is a 4x10 combo with Jensen P10R alnico speakers. It also has two channels—one cleaner and one that pushes the gain. However, I do not have much opportunity to play my amp to its fullest potential—normally, I'll end up w/ the master about way up. I've done my best to find a workable setting between the master and gain; but because of volume limitations (I'm pushing it as it is) I have to have the gain up around 5-6 to get a good crunch.

Let me explain what I am looking for: I want to be able to use this one amp (as I cannot afford another one) and get some el84-sounding distortion as well as a nice clean sound. I am buying a hotplate this summer, so I will be able to get it up to levels right before the el84s begin breaking up, but I'm still stuck using the preamp distortion (which is good, but just not power amp sounding). I've included a few hundred dollars in my summer budget to buy some distortion/overdrive/boost pedals; what should I get in order to have a nice distortion sound that's as close as I can get to el84 breakup without going all the way? At this point, I'm looking primarily at the Menatone Top Boost in a Can, the Vox V810 Valve Tone, and the Vox V830 Distortion Booster.

I play Brit pop / alternative music (heavy influences are U2, Radiohead, Pink Floyd, Oasis, etc. along with some more American-sounding bands such as Third Eye Blind and Goo Goo Dolls along w/ all the classic stuff-Hendrix, Zeppelin, Beatles, etc). Any help would be GREATLY appreciated.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/12/02 10:12 PM

Quote:
Originally posted by boanerges:
I recently retubed my CAE se3+ - it used to have Chinese tubes, but I replaced them (due to microphonics) with Sovtek 12ax7wb's. I believe that some of the harsh, compressed upper midrange and poor tone comes from these tubes. What's your recommendation - which tubes will be optimal for this preamp?

Also, where is the driver tube located in these amps - there's no schematics available...

Thanks!

Boanerges
Boanerges,

I'd get a generic JAN NOS 12AX7WA as a start for your V1 position. That is the preamp tube the closest to the input jack. If you want more treble and brighness, then try a 7025 in that same position. If you want a "different" sort of sound from the 12AX7 that is hard to quantify, try an ECC83.

If in those tubes, you want more or less gain, then you need to talk to the following folks....

For more gain, go to Watford Valves for the 12AX7's and ask for something around "250-270".

For your ECC83, go to Bob Pletka at Eurotubes and ask him for a tube with higher gain than average.

Watford can also help with a 7025.

Most of my clients have all three on hand, as they are all a different sound.

As far as the phase inverter, it is the preamp tube that is physically the closest to the output tubes. In this position you can use a 12AX7 for the normal sound, or get more clean headroom by using a 12AT7. In either case, here you need a tube that has the A and B sides closely matched, much more so than current production tubes are that are generally found. With tubes off the shelf, this is a crap shoot, and the odds are against you. I have said before, on a good day 1 in 20 tubes are matched, and on an average day its more like 1 in 50.

Either Watford Valves or Eurotubes can supply a matched phase inverter tube. In the case of Watford Valves in the U.K. they call this a "balanced" valve, rather than a phase inverter/driver tube as we say here in the U.S. Just because it is termed "balanced", you still need to tell them you'd want this to me "matched on the A and B sides".

Bob Pletka at Eurotubes can also supply matched phase inverters.

There may be other folks that can do this when it comes to new tubes, but these two folks are the only ones that have shown over time to us that they do this flawlessly.

I hope this helped.

Regards,
Posted By: paranoid

Re: Feel free to ask Myles - 04/12/02 10:29 PM

What can you sey me about the new Laney 3 channels tt heads?
Thanks
Posted By: myles_rose

Re: Feel free to ask Myles - 04/12/02 10:38 PM

Quote:
Originally posted by Mr. Dan Licks:
Hi Myles,
We have just purchased, (based in part on your recommendation!), a second hand .50+ for my son. His first "real" amp and it really hits the spot! At the moment it has what seem to be the original tubes in it: STR 12AX7-A, STR SPAX7-A, STR 12AX7-A, STR 12AT7, and a STR 12AX7-A on the end of the line. Power is 6L6 STR 420. All marked Mesa. For the time being he will keep these going, but we would like to know what other options are and if they would make the amp sound still better. What would you suggest?
I have a lead on half a dozen SIEMENS CV492 / ECC83. Do you know these. Are they worth perusing for this amp? They have been tested on a FUNKE W19 and are good. Or is it better to play it safe and go straight to Watford?
Many thanks! How do you find the time to be so helpful?
Dan
Dan,

I am sure you son will be happy with the amp. Its a lot nicer than what I had when I was his age.

The original Mesa tubes (which are generally Sovtek or at times Chinese) in the preamp section are probably fine for now. They are selected to be pretty free from microphonics, and are good enough tubes.

In the case of the power tubes, the STR-420's there are too issues that might have you consider replacement of those. One, they are Chinese. The sound quite awful, really holding back the sound that amp is capable of producing. If you like the amp now, you will like it a lot more without the Chinese power tubes. The other problem, Chinese or not, with Mesa tubes in their narrow range to match their fixed bias, the tubes are overbiased, so the amp runs on the cool side, and has a bit more of a grainy nature than you really want.

What I would suggest is that you go to a Svetlana 6L6, as this tube has a nice broad tone spectrum. You can also go to a JJ 6L6, but the Svetlana is a little more neutral.

These are both available from Watford and Groove Tubes. In the case of a JJ tube, you can get those from Watford, Eurotubes, Groove Tubes, and a lot of other folks.

The issue here, is that you want a tube that is a bit outside of the Mesa range. What you'd want to tell folks if you order a set of these, is that you want something that would be about the same as a Groove Tubes #7 rating.

In the case of Watford Valves, if you tell them what your amp is, they know all of this, and just tell them you want tubes in a range that are better suited for a Mesa amp than the Mesa colder tubes.

The Siemens tubes you have would be better suited for use in a Marshall amp, as the Mesa front end would not make as much of an advantage here. The Mesa's front end is engineered for a neutral or generic 12AX7. It would sound better in some ways, and more articulate, but in the Mesa, there is a lot of other signal processing going on that will mask some of the nice features of a Siemens tube. If you get them for cheap, then by all means, throw one into the first preamp position (V1) and listen to see if you like it more than a 12AX7. That all boils down to personal taste. V1 and V2 are the only positions in this amp that will make a tone change, so you do not have to go and change a lot of things. V1 is actually the primary first gain stage here too, so it is more important, in a manner of speaking, than V2.

How I find time ... sometimes its pretty easy, as I just have up a PC when I am working, and waiting for things to heat up, cool down, or bake.

Regards,
Posted By: Mr. Dan Licks

Re: Feel free to ask Myles - 04/12/02 10:43 PM

Myles, you are a peach! What a man! Thanks again...and again...and again....
Dan
Posted By: deke1000

Re: Feel free to ask Myles - 04/13/02 01:13 AM

Thanks so much Myles! I am giving your suggestions to my tech this weekend... hopefully it will be a cheap easy fix and I'll be back in business. Meanwhile, I'll be borrowing a buddy's Twin while the amp is in the shop -- we'll see how we gel. Thanks again for the tips!
Posted By: hechtdavid

Re: Feel free to ask Myles - 04/13/02 01:28 AM

Hi Myles, I've got a Music Man 110-RD Fifty for smaller gigs and rehearsing. As you probably know, its got a solid state front end and 2 6L6's for power. This model has one 12AX7 for the drive (limiter) channel. I tried a few different 12ax7's in there and the sound didn't seem to change much, so I ended up putting the original Sylvania back in there. I've got some NOS Phillips 7581A's for power and there is no bias adjustment (no standby switch either). Anything special I should know about caring for this little gem? Since MM is no longer in the amp biz and parts are probably scarce, I want her to be as healthy as possible. I've only replaced tubes with Svet 6L6GC's and the 7581a's so far. Any words of wisdom?

Thanks again and again,

David
Posted By: Rai168

Re: Feel free to ask Myles - 04/13/02 01:44 AM

Hi Myles - sorry about hte confusing last post but it was comprised of 3 emails I had written. Anyhow - long story short, I got the RFT's and I'm pretty excited to hear em. Heard a lot of great things from other VHT owners who use them. Anyhow my 1 question is this -

On the VHT's (after speaking w Mike) I learned that 2 pre amp tubes by the power tubes in the back (Most of the tone chain is in front) are actually the phase inverter section. There are 2 tubes that do the Inverting. How would the theory of matched tubes in the PI section relate to this? One is a 12ax7 and the other a 12aT7? Would both tubes, both triode's for each tube - have to match w/in themselves?

Thanks Myles and sorry for the earlier confusion.

Best wishes -

Rai
http://www.CalyxinRuin.com
Posted By: myles_rose

Re: Feel free to ask Myles - 04/13/02 02:37 AM

Quote:
Originally posted by papamaverick:
Hey Myles

I emailed you but you mentioned it would be easier to get ahold of you on one of the forums, so here goes.

Love your articles…really neat stuff. I recently upgraded to JJ tubes at your recommendation and am very pleased. Anyhow, I have a quick question for you, since you're one of the people I KNOW has a good ear for sound. My rig is built around a Les Paul with Seymour Duncan Alnico II Pro (bridge) and '59 (neck) pickups and a Mesa Boogie Maverick. Both the guitar and amp produce nice, warm, vintage-y tones. The Maverick is similar in design to the Vox AC30 in regards to tubes…I'm using 6x JJ ecc83s and 4x JJ el84s; the Maverick I have is a 4x10 combo with Jensen P10R alnico speakers. It also has two channels—one cleaner and one that pushes the gain. However, I do not have much opportunity to play my amp to its fullest potential—normally, I'll end up w/ the master about way up. I've done my best to find a workable setting between the master and gain; but because of volume limitations (I'm pushing it as it is) I have to have the gain up around 5-6 to get a good crunch.

Let me explain what I am looking for: I want to be able to use this one amp (as I cannot afford another one) and get some el84-sounding distortion as well as a nice clean sound. I am buying a hotplate this summer, so I will be able to get it up to levels right before the el84s begin breaking up, but I'm still stuck using the preamp distortion (which is good, but just not power amp sounding). I've included a few hundred dollars in my summer budget to buy some distortion/overdrive/boost pedals; what should I get in order to have a nice distortion sound that's as close as I can get to el84 breakup without going all the way? At this point, I'm looking primarily at the Menatone Top Boost in a Can, the Vox V810 Valve Tone, and the Vox V830 Distortion Booster.

I play Brit pop / alternative music (heavy influences are U2, Radiohead, Pink Floyd, Oasis, etc. along with some more American-sounding bands such as Third Eye Blind and Goo Goo Dolls along w/ all the classic stuff-Hendrix, Zeppelin, Beatles, etc). Any help would be GREATLY appreciated.
papamaverick,

Thanks for sending your email over here. That way more folks get the possible benefit.

Thanks for the compliment on my ear. I wish I could also have a better ability to play \:\) I guess I was always trying to find how and what was used to make this or that recording over the years, so over time I turned into something of what is usually a vast storehouse of useless information!

Your rig sounds great. The SD Alnico's are great pickups and in a LP, a great combination that has both output but also articulate and defined highs, which are lost too often these days.

As far as your amp, the world's biggest secret it seems, are Mesa Class A amps. Everybody talks the Single, Dual, and Triple rectifiers and forgets amps like yours and the Blue Angel. If you want the Class A Vox/Matcheless sort of sound, these are a lot less expensive, and in the case of an AC-30, a lot more reliable and a lot easier to work on!

The ECC-83's are just the ticket for the Brit sound. The have a different plate structure than a 12AX7, especially different from the long plate Sovteks such as the LP and LPS. The short plate structure of the ECC83 also makes them less prone to microphonics, which really helps in some combo amps.

4x10's are the best option in that amp. The speaker cones are lighter than 12's, so there is faster transient response on the mid highs and highs. 4 10's also have more bass than 2 12"'s. My only complaint about a 4x10 combo is the weight!

Try the master ALL the way up sometime, as then it is effectively out of the circuit, and then drop your gain and use clean channel. Its pure blues, and makes a lot of AC-30's sound thin if their output transformers are getting old.

The THD hotplate is a great idea. It allows you to get the level of distortion you want, and with your amp, the more output tube distortion and less preamp tube distortion you can get, the better it sounds. Remember, the Vox AC-30 did not have all that much front end gain... its sound came from the output tubes being driven, not the front end. As far as the top boost variant, Brian May from Queen did not use a top boost, even he preferred the AC-30/4 rather than the TB AC-30/6.

With the hotplate, you can get the distortion you want and then set it to the overall level that you or others can stand.

As far as getting the output to break and distort at a more rational level (I know the Maverick is not supposed to be a 80+ watt amp, but 30 watts of Class A can be as loud as about 85 watts of class A/B ... just put a Matchless DC-30 next to a Fender Twin Reverb and compare) .... all you have to do is drop down to a lower output EL-84. You can go to Eurotubes and ask Bob Pletka for a softer set, something in a Groove Tubes #2 or #3 rating, or get Groove Tubes EL-34S (make sure they are the "S" tubes, as the other two they sell are Sovteks) in a #2 or #3 rating.

If I was in your area, I'd help you find a output set that ran about 38-40mA @ 250 volts with a -7.3 volt bias. The "normal" average tube at this setting would be about 48mA.

When you start to plug in pedals and effects, try to do so in the effects loop. If you plug into the amp input and you seem to see your high end and sparkle drop off, then replace V1 with a 7025. This is also an old Marshall trick. Remember though, it was the output distortion that makes these amps sound super, less of the preamp distortion.

I think with some of the above, you will be pretty happy. If some notes seem to have more sustain than others, go get a matched driver/phase inverter from Eurotubes or Watford Valves. They make a bigger difference than even in class A/B amps, and in A/B amps it can be pretty dramatic.

Hope this was of some value.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/13/02 02:45 AM

Quote:
Originally posted by paranoid:
What can you sey me about the new Laney 3 channels tt heads?
Thanks
paranoid,

I am sorry, but I know absoulutely nothing about them. I have not seen one myself. I don't have any clients using them currently.

Maybe check over on Harmony Central in the amp reviews section. Usually there is something there on just about any amp.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/13/02 03:06 AM

Quote:
Originally posted by Mr. Dan Licks:
Myles, you are a peach! What a man! Thanks again...and again...and again....
Dan
Dan,

You're welcome

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 04/13/02 03:43 AM

Quote:
Originally posted by deke1000:
Thanks so much Myles! I am giving your suggestions to my tech this weekend... hopefully it will be a cheap easy fix and I'll be back in business. Meanwhile, I'll be borrowing a buddy's Twin while the amp is in the shop -- we'll see how we gel. Thanks again for the tips!
deke1000,

You are welcome.

Feel free to have your tech drop me a line. I have an amp clinic this weekend, but can be reached at that store ( 818-789-8884 ) at California Vintage Guitar and Amp. I will be there from 11am to 4pm California time. He can also email me if he or she would like that better.

I'll be happy to try to help point them in the right direction so it will take less time, and hopefully cost you less money. If you were a pro, backed by Warner Reprise or somebody, then I'd let your record company suffer \:\) but for "real players" on a budget, I try to support them a bit more.

Regards,
Posted By: Griffinator

Re: Feel free to ask Myles - 04/13/02 03:52 AM

OK, Myles - I'll throw one at you.

I'm looking at replacing the speakers and power tubes (4x6L6) in my Peavey Deuce VT. Someone suggested Celestion Vintage 30's, which I'm leaning towards, for speaker replacements. If you have a different opinion, I'm all ears. More importantly, though, what brand and spec 6L6 should I use?

Thanks in advance!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/13/02 04:03 AM

Quote:
Originally posted by Rai168:
Hi Myles - sorry about hte confusing last post but it was comprised of 3 emails I had written. Anyhow - long story short, I got the RFT's and I'm pretty excited to hear em. Heard a lot of great things from other VHT owners who use them. Anyhow my 1 question is this -

On the VHT's (after speaking w Mike) I learned that 2 pre amp tubes by the power tubes in the back (Most of the tone chain is in front) are actually the phase inverter section. There are 2 tubes that do the Inverting. How would the theory of matched tubes in the PI section relate to this? One is a 12ax7 and the other a 12aT7? Would both tubes, both triode's for each tube - have to match w/in themselves?

Thanks Myles and sorry for the earlier confusion.

Best wishes -

Rai
http://www.CalyxinRuin.com
Rai168...

Each of the tubes in the phase inverter section should be matched. In stereo amp applications, there are also often 2 phase inverters/drivers.

Say hello to Mike from me if he is the Mike that used to be at Rivera.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/13/02 05:01 AM

Quote:
Originally posted by hechtdavid:
Hi Myles, I've got a Music Man 110-RD Fifty for smaller gigs and rehearsing. As you probably know, its got a solid state front end and 2 6L6's for power. This model has one 12AX7 for the drive (limiter) channel. I tried a few different 12ax7's in there and the sound didn't seem to change much, so I ended up putting the original Sylvania back in there. I've got some NOS Phillips 7581A's for power and there is no bias adjustment (no standby switch either). Anything special I should know about caring for this little gem? Since MM is no longer in the amp biz and parts are probably scarce, I want her to be as healthy as possible. I've only replaced tubes with Svet 6L6GC's and the 7581a's so far. Any words of wisdom?

Thanks again and again,

David
David,

These amps are pretty sturdy, so you probably don't have to worry all that much.

The reason you do not hear all that much of a difference when you change the preamp tube, is that a lot of the signal processing is done with a solid state front end, as is a lot of the gain and tone shaping. The tube is there mostly for compression.

On the output section, stick to good 6L6's. Svetlana's are a good bet in this amp and NO Chinese tubes should ever be used. These amps have some extremely high B+ voltages. I have seen some Music Man amps with 700 volts on the plates, and that is very very very high. The next highest I have seen is a 600 volt Marshall model 1959, which had a lot of power, but Marshall's seem to sound better at about 450 volts of B+ to most folks.

Make sure your amp is biased, and even though fixed bias, this can be checked, and if off, adjusted in other ways. If you stick to mid-range tubes, such as a Groove Tubes value of H5, you will be fine. This amp also likes all the tubes in the Mesa range, any of their color codes. Just only use their STR-454 (Svetlanas).

Keep the pots clean by using the amp a lot. Use the amp at least a few hours a month, and that will keep the caps in good shape.

Parts for these amps are not really hard to get, and are not all that expensive. Its harder to find some vintage amp parts for some of the more obscure amps, or tubes for some of the Ampeg's as as example.

These are great sounding amps, and unfortunately at times, VERY loud. You can get more output section distortion at lower volumes, and cool off the amp due to decreased current draw by using a Groove Tubes rating of #3 or #4, or a Mesa supplied tubes that are color coded RED or YELLOW. The REDs are cooler than Mesa's YELLOWs. These are both the same as a Groove Tubes #4 rating.

Stay clear of the 7581's in this amp as they have a 450 volt max grid #2 rating, while the 6L6GC has a rating of 500 volts. With the B+ your amp develops, that 50 volt margin is nice to have, as there is a lot of voltage on your plates and grid in its pentode configuration.

Your amp was one of only about three models they made with a tube in the preamp. The rest were all solid state. Your amp is considered the best sounding along with the "sixty-five" and the "one-thirty", and both of them used 6CA7 output tubes, a heavy duty USA version of an EL-34 that can handle 800 volts on the plates but still 500 volts on the grid.

Most of the amps I have measured like yours have about 585 volts of B+, but like I said, some have read much higher.

Your diode bridge is made up from 1N4003's rather than 1N4007's and they seem to last forever.

The only spot in the amp that might be considered a weak link in the chain, are transistors Q3 and Q4 that drive some of the output circuit. These are JE1692 parts, quite easy to find, not expensive, and that is about the only part I have seen fail. It failed when coffee went into the amp, so I guess I cannot call it a "weak link".

For some reason, even though they are somewhat complicated amps inside, with a lot of parts, they ship really well, and hold up on tours and bad handling. I don't know why exactly, but they are used by a lot of folks as backup amps when the more trendy boutique amps with all their point to point wiring fail or start making noise as the carefully laid point to point wiring moves around if not strain relieved properly. By the way, Carr amps, use proper strain relieving and are not subject to that last comment.

So, all in all, I guess all I can say, is stick some Svetlana's in there, and play your heart out, and if you feel free to do so, get some casters on your amp and ride it down the stage loading ramp. It does not seem to hurt them.

Its also nice, that they are not "vintage" or "boutique" amps with a high value, as they can still be found at good prices, and folks steal other amps first at a gig.

When somebody has something to say against solid state amps, these amps with a mostly, or totally solid state front end, can open a few eyes. They also show how important output tubes are in a hybrid design.

Happy playing \:\)

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/13/02 05:14 AM

Quote:
Originally posted by Griffinator:
OK, Myles - I'll throw one at you.

I'm looking at replacing the speakers and power tubes (4x6L6) in my Peavey Deuce VT. Someone suggested Celestion Vintage 30's, which I'm leaning towards, for speaker replacements. If you have a different opinion, I'm all ears. More importantly, though, what brand and spec 6L6 should I use?

Thanks in advance!
Griffinator,

That's a hard one, as it is all personal taste. The Vintage 30's are great speakers. They have the same magnet structure at the "100" series, and can handle 60 watts with ease, so I was never sure why they called them "30"'s. They are also more efficient than a lot of other Celestions, at 100db at 1 meter with 1 watt.

I like Celetions for rock from the 80's and on, and Jensen P-12R's for rock from the 60's and 70's, or blues, but again, that is personal preference.

As far as output tubes, I'd go over to my website and look at the 6L6 reviews that were done by Watford Valves, and read their feelings, and stay clear of my technical mumbo jumbo for the most part.

When it comes down to personal taste, I have copied something I said once before in a forum response, when somebody asked me which of two amps was better. I think it applies here too, so here it is again:

This was in response to a forum question where somebody was asking which of two amps was "better"

Hmmmmm....

Bogner or Soldano? Which is better?

Can I ask a question to help answer the question ....

You are walking down the street on a nice day. You are a single male, open to a night out with female company if the situation presents itself. As you walk down the street, coming right toward you are two girls.

One is 5'8", blonde hair, green eyes, and drop dead gorgeous.

The other is 5'4" brunette, blue eyes, and equally as much of a knockout.

As they both approach and get close enough to speak, one of them gives you a big smile and starts the opening of conversation, and starts to flirt with you in a nice way.

Do you really care at this point which one of them it was?

Just like girls .... or guys (if you're female) ... or actually girls and girls or guys and guys or .... Its a matter of what you are open to at the time and what appeals to you. Both the girls in this case are terrific, and I think both your amp examples are terrific too... its a matter of taste and timing .... how much cash do you have in your pocket when you walk into the store and one of those amps is on the floor.

Regards and sorry if this was no help at all \:\(
Posted By: Griffinator

Re: Feel free to ask Myles - 04/13/02 05:38 AM

Well, there's two things I wanted to accomplish by asking these questions.

1) Get a clearer picture of what to absolutely avoid in brands.

2) Gain a better understanding of how a given spec tube will affect the sound of the amp - especially in the power stage.

I like the sound of this amp through a couple of cabs I've plugged it into - one was a Carvin 4x12, the other a late 60's Ampeg bass cab loaded with Celestion Greenbacks. Obviously, with the power tubes shot to heck, the longer it was on, the less I liked it. \:\)

I really want to recapture the vintage Deuce sound, but I've little faith in Black Widow speakers or SovTek tubes...
Posted By: myles_rose

Re: Feel free to ask Myles - 04/14/02 04:18 AM

Quote:
Originally posted by Griffinator:
Well, there's two things I wanted to accomplish by asking these questions.

1) Get a clearer picture of what to absolutely avoid in brands.

2) Gain a better understanding of how a given spec tube will affect the sound of the amp - especially in the power stage.

I like the sound of this amp through a couple of cabs I've plugged it into - one was a Carvin 4x12, the other a late 60's Ampeg bass cab loaded with Celestion Greenbacks. Obviously, with the power tubes shot to heck, the longer it was on, the less I liked it. \:\)

I really want to recapture the vintage Deuce sound, but I've little faith in Black Widow speakers or SovTek tubes...
Griffinator,

In your amp, my personal choice would be Svetlana 6L6's for more rock, or NOS 5881's for a bit less power but more articulation and definition.

With 5881's I'd also use a JAN 5751 tube in your first gain stage.

For speakers, I'd use Weber's or my standby Jensen's with Alnico magnets.

Regards,
Posted By: Griffinator

Re: Feel free to ask Myles - 04/14/02 07:03 AM

Thanks - I'll experiment a bit with some of those combinations, and let you know how it goes \:\)
Posted By: Rai168

Re: Feel free to ask Myles - 04/14/02 10:31 AM

Thank you very much Myles for your patience and answer. I will pass on the hello - take care and again Thank you.

Rai
http://www.CalyxinRuin.com

Quote:
Originally posted by myles111:
Quote:
Originally posted by Rai168:
Hi Myles - sorry about hte confusing last post but it was comprised of 3 emails I had written. Anyhow - long story short, I got the RFT's and I'm pretty excited to hear em. Heard a lot of great things from other VHT owners who use them. Anyhow my 1 question is this -

On the VHT's (after speaking w Mike) I learned that 2 pre amp tubes by the power tubes in the back (Most of the tone chain is in front) are actually the phase inverter section. There are 2 tubes that do the Inverting. How would the theory of matched tubes in the PI section relate to this? One is a 12ax7 and the other a 12aT7? Would both tubes, both triode's for each tube - have to match w/in themselves?

Thanks Myles and sorry for the earlier confusion.

Best wishes -

Rai
http://www.CalyxinRuin.com
Rai168...

Each of the tubes in the phase inverter section should be matched. In stereo amp applications, there are also often 2 phase inverters/drivers.

Say hello to Mike from me if he is the Mike that used to be at Rivera.

Regards,
Posted By: jivey311

Re: Feel free to ask Myles - 04/14/02 10:05 PM

What's the difference between 6L6's and EL34's? In my JCM900 50 watt head, I have 6L6's, can I change those to EL34's? The 30 watt ones?
Posted By: HBK

Re: Feel free to ask Myles - 04/15/02 12:49 AM

Hi Myles,

I'm thinking about buying the Marshall AVT20 amp. I play mostly rock/hard rock and punk (Oasis - Nirvana). The amp will be for bedroom use mainly, I'm concerned the amp won't give me the distortion/tone I need at low volumes. Have you heard this amp in action at these kind of volumes ? I've been phoning local music shops to try it out but none seem to have them in stock at the moment. Any help would be great,

Thanks.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/15/02 01:00 AM

Quote:
Originally posted by jivey311:
What's the difference between 6L6's and EL34's? In my JCM900 50 watt head, I have 6L6's, can I change those to EL34's? The 30 watt ones?
jivey311,

They are very different tubes. I have made a number of posts in this forum on that subject. There is also a lot of info on that on my website.

Basically, you should not have 6L6's in a stock Marshall JCM 900, as its output transformer was set for the impedience of EL-34's, which is a bit different than 6L6's. This won't hurt anything, and a lot of folks do this sort of thing.

In any case, you can use any of the EL-34's in your amp, just make sure to have the bias checked. These are the original tubes in your Marshall and will make it sound like what folks think Marshalls generally sound like.

I hope when the 6L6's we installed, the bias was changed. If not, your amp is not sounding anywhere as nice as it could, even with the 6L6's.

Your preamp tubes in that amp, for the typical Marshall sound and the way it came from the factory, should be ECC83's by the way.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/15/02 01:06 AM

Quote:
Originally posted by HBK:
Hi Myles,

I'm thinking about buying the Marshall AVT20 amp. I play mostly rock/hard rock and punk (Oasis - Nirvana). The amp will be for bedroom use mainly, I'm concerned the amp won't give me the distortion/tone I need at low volumes. Have you heard this amp in action at these kind of volumes ? I've been phoning local music shops to try it out but none seem to have them in stock at the moment. Any help would be great,

Thanks.
HBK,

The folks you mention and the style of music they play and you like, uses a lot more front end distortion than output section distortion. That means you are in luck in a few ways.

Just about any of the AVT series can have the volume/gain cranked a bit on the high side, then the master set low, and still get a lot of drive and distortion at lower levels.

I'd go to the Harmony Cental forums, look in the amp reviews by their users, and it will probably tell you all you might need to know and more.

Regards,
Posted By: GTO

Re: Feel free to ask Myles - 04/15/02 02:13 AM

Myles, great info! I hope you're still around.
Could you go over the basics of using the "Standby" switch, or point us to a link. I believe this is a much overlooked issue with tube amps and improper use can cause tubes to wear out prematurely. Also, I'm sure that I'll learn something too, as I'm certainly no expert.

Thanks.
Posted By: not coaster MODERATOR

Re: Feel free to ask Myles - 04/15/02 06:48 AM

Myles- I think you memtioned that you know the gent who puts together the JT Pedals for Mesa Boogie. I own the Valveboy and Can't begin to describe what an upgrade it is from the Visual Sound J&H, which I had thought was a pretty decent Plexi Tone. Have you gotten a chance to try it out?

I've not talked to anyone else with one either. Just wanted to say it's in a league of its own and see what you thunk.

Cereal
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/15/02 08:00 AM

Hey GTO, mind if I butt in? \:D

The standby switch is used to break the connection of the high voltage in the amp. That would leave only the filament heater supply of the tubes powered when the power is on (and the standby is off). The whole deal with that is to let the tubes heat enough to be able to handle their operation. It takes between 30-90 seconds (depending on the tube) to fully heat the tube's filaments to a normal operating temperature.

If the tubes filaments aren't hot enough, what can happen is that if signal hits the grid of the tube it starts going about doing its thing...and electrons get stripped off the cathode ("cathode stripping"), resulting in premature tube wear. Keeping standby off for the first couple minutes the amp is on, then turning standby on, will help keep your tubes healthy longer. If your amp doesn't have a standby, then it's advisable to not play your guitar until the amp has been on a couple minutes. If the amp has a tube rectifier, those take a while to get the high voltage up to proper range, so in reality standby may not be needed on any amp with a tube rectifier. I'd still use the standby though if it's on the amp, since you're not "rushing" to start playing before the tubes are good and ready.

Powering down, it might probably be just as good to shut the standby off first until signal is gone...although I'm not sure if this matters or not since if you powered down while signal is on, it takes the tubes' filaments a while to cool.

The issue of shutting off with/without standby gets thrown around a lot, but nothing significant has come of the discussions as far as I know. One guy I know said he puts it on standby for a few minutes before shutting off, to let the tubes cool...but the logic in this seems flawed--if the tubes get that much hotter from the high voltage being on the plates, then how significant a difference is it if you remove the plate voltage first, then remove the filament supply later. I mean, do your tubes really cool more evenly by doing this? It seems unlikely.

Oh well. That's all I got! \:D
Posted By: Gabriel E.

Re: Feel free to ask Myles - 04/15/02 05:59 PM

Myles,

Ok. Here's a question that's been bugging me:

I have a Fender 5F4 Super Amp that someone cut into a head. It puts out about 28 watts into 4 ohms. I have 2 - 8ohm speaker cabs that I run it through (an open back with Celestion Vintage 30s and a closed back with Celestion G12M75s). While both cabs together sound good, I like the more compressed sound and lower volume of the amp running into a single 8 ohm cab.

So: Can I run the amp into an ABY box and switch between the two cabs while the amp is running (the open back for clean, the closed back for dirty)? Can I switch between one cab on to BOTH cabs on while the amp is running?

Thanks,

Gabriel
Posted By: papamaverick

Re: Feel free to ask Myles - 04/15/02 06:49 PM

Hey Myles

Your last answer helped a lot. I'm pretty sure I know what I need to do now.

One last question...for my Mesa Maverick, would buying a NOS 5ar4/GZ34 rectifier tube (I'd probably go for the Mullar) make any difference in comparison to the stock tube (Chinese)?

Dave
Posted By: myles_rose

Re: Feel free to ask Myles - 04/15/02 07:34 PM

Quote:
Originally posted by GTO:
Myles, great info! I hope you're still around.
Could you go over the basics of using the "Standby" switch, or point us to a link. I believe this is a much overlooked issue with tube amps and improper use can cause tubes to wear out prematurely. Also, I'm sure that I'll learn something too, as I'm certainly no expert.

Thanks.
GTO ...

I am still around ....

The standby switch generally has a fairly simple purpose.

There are a number of voltages in an amplifier.

There is the "heater" voltages, generally either 6.3 volts or 12.6 volts. When the amp is on and the standby ON or OFF, this voltage is still applied to the tubes. It is the glow you see in all the tubes, and the preamp tubes.

The preamp tubes also have plate voltages, and these are also on as soon as the amp power switch is on.

In the case of the power tubes, with the standby switch OFF, there is heater voltage (so the tubes light up), but the PLATE voltage, also called B+ voltage is off. These are high voltages, from 300 volts to over 600 volts in some amps.

When you first turn on your amp, wait about 30 seconds at the least, to give the tubes time to come up to operating temperature, before you flip the standby switch to operating position. This will help get the most tube life from your output set. I also like to leave the amp in standby mode for about five minutes after playing hard, to let the tubes cool down more slowly in most amps.

Hope this helped.

If you want to more in depth about tubes, on my website is a sort of reddish box with a link in there.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/15/02 07:56 PM

Quote:
Originally posted by Cereal:
Myles- I think you memtioned that you know the gent who puts together the JT Pedals for Mesa Boogie. I own the Valveboy and Can't begin to describe what an upgrade it is from the Visual Sound J&H, which I had thought was a pretty decent Plexi Tone. Have you gotten a chance to try it out?

I've not talked to anyone else with one either. Just wanted to say it's in a league of its own and see what you thunk.

Cereal
Cereal,

Those pedals were done by John. I have played with them a bit, and I have to agree, they are great.

What you have to think about though, is that they were designed by a guy that has been a crack amp tech for Mesa for years (and also a great amp guy on other amps too), and he's also a great player that performs. This is a little different from somebody like me, and actually a lot of the other techs I know ... most of us are "okay" or "fair" players, and don't perform all that much, if it all.

In the case of a lot of techs and engineers, we think we "know" what folks want. I think that is why whenever I do amp work, folks just cannot drop of the amp and come back a week later. I need them to be there when the amp work is being done. That way its not a case of me thinking I know what they want, but them telling me yes or no as work progresses.

In the case of John at Mesa, he knows what he wants, and he knows how it will be used in a real performance situation. Andy Marshall from THD is another of those fellows that is also a "player", and that's why so many of his designs work out so well. Being tech types, these folks also know how and why things fail, so there is also a reliability component in their designs that is not there at times when some "engineer" makes a design from a parts catalogue.

I'm sure you'll be happy for a lot of years, and your grandkids will probably end up with some sort of classic vintage piece of gear \:\)

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/15/02 08:27 PM

Quote:
Originally posted by JamesPeters:
Hey GTO, mind if I butt in? \:D

The standby switch is used to break the connection of the high voltage in the amp. That would leave only the filament heater supply of the tubes powered when the power is on (and the standby is off). The whole deal with that is to let the tubes heat enough to be able to handle their operation. It takes between 30-90 seconds (depending on the tube) to fully heat the tube's filaments to a normal operating temperature.

If the tubes filaments aren't hot enough, what can happen is that if signal hits the grid of the tube it starts going about doing its thing...and electrons get stripped off the cathode ("cathode stripping"), resulting in premature tube wear. Keeping standby off for the first couple minutes the amp is on, then turning standby on, will help keep your tubes healthy longer. If your amp doesn't have a standby, then it's advisable to not play your guitar until the amp has been on a couple minutes. If the amp has a tube rectifier, those take a while to get the high voltage up to proper range, so in reality standby may not be needed on any amp with a tube rectifier. I'd still use the standby though if it's on the amp, since you're not "rushing" to start playing before the tubes are good and ready.

Powering down, it might probably be just as good to shut the standby off first until signal is gone...although I'm not sure if this matters or not since if you powered down while signal is on, it takes the tubes' filaments a while to cool.

The issue of shutting off with/without standby gets thrown around a lot, but nothing significant has come of the discussions as far as I know. One guy I know said he puts it on standby for a few minutes before shutting off, to let the tubes cool...but the logic in this seems flawed--if the tubes get that much hotter from the high voltage being on the plates, then how significant a difference is it if you remove the plate voltage first, then remove the filament supply later. I mean, do your tubes really cool more evenly by doing this? It seems unlikely.

Oh well. That's all I got! \:D
James....

I saw the post on this question, and replied to it before I saw your answer to his question. If I would have saw your answer first, I would have just pointed to your answer!

The last paragraph of your answer is confusing to me a little, I think its the nomenclature of standby ON vs OFF at times.

I think moving the standby swith to the position where the amp will NOT play, meaning the B+ is turned off, is what I like to do for a few minutes before shutting down an amp, especially a Class A amp, that with the B+ on, runs just as hot as it would when run full bore. The tubes would have a lower bulb temerature after a few minutes with the heater on and the B+ off, than with the heater on and the B+ on. I think this is what you were also saying, but the ON and OFF, vs STANDBY and OPERATE, or something like that, sometimes can get confusing.

By the way, how is your latest amp coming along?

An interesting side issue on your amp on this subject in a way ... on a single ended class A chatode biased amp, there is a fun little phenomonon (I probably trashed the spelling on that word), that happens in these amps. At idle, they draw max current, but at full load, they actually develop a tiny bit less current draw, in the 1/10ths of percentage points mostly, but still a micro bit less. Nothing really worth ever considering, but interesting for some like me that don't have better things to think about at times \:\)

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/15/02 09:58 PM

Quote:
Originally posted by Gabriel E.:
Myles,

Ok. Here's a question that's been bugging me:

I have a Fender 5F4 Super Amp that someone cut into a head. It puts out about 28 watts into 4 ohms. I have 2 - 8ohm speaker cabs that I run it through (an open back with Celestion Vintage 30s and a closed back with Celestion G12M75s). While both cabs together sound good, I like the more compressed sound and lower volume of the amp running into a single 8 ohm cab.

So: Can I run the amp into an ABY box and switch between the two cabs while the amp is running (the open back for clean, the closed back for dirty)? Can I switch between one cab on to BOTH cabs on while the amp is running?

Thanks,

Gabriel
Gabriel,

The 5F4 Super used two speakers as stock.

As long as your impedience does not drop below four ohms, you will be okay.

With two eight ohm cabinets in parallel, you would still be safe.

You need a good switch though, that with switch in a clean way without any spikes. Something like what stereo stores use when the demo speakers, switching from one to another using the same amp.

It sounds like with your 2 eight ohm cabinets, that the the 2x12's is probably two 16 ohm speakers wired in parallel, so this is fine.

The mix of the V30's and 75's is a nice combination. The speakers are very close in efficiency, within 2db or so, but have different resonant frequecies. This really opens up a sound image. Folks today are getting wise to this by putting two different speakers in the same combo amp or cabinet. For years I have used 1x12 ported cabinets with different Celections in each. It makes more of a stereo sort of image, than a bigger mono sort of image.

The Super's even at 28 watts, are loud amps. I can see where using two cabinets could be too loud at times. When you double your speaker radiating area, you just about quadruple your sound levels.

Just have a good switch, and this will work very nicely. Running one cab at 8 ohms will drop your power a bit, but remember, when a speaker is marked as being 8 ohms, that is 8 ohms nominal ... i.e., its lowest value at a given frequency. At other frequencies, it can be 75 ohms, 92 ohms, 18 ohms, or whatever. Its the lowest value we are concerned about, and in your case, you are safe.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/15/02 10:14 PM

Quote:
Originally posted by papamaverick:
Hey Myles

Your last answer helped a lot. I'm pretty sure I know what I need to do now.

One last question...for my Mesa Maverick, would buying a NOS 5ar4/GZ34 rectifier tube (I'd probably go for the Mullar) make any difference in comparison to the stock tube (Chinese)?

Dave
Dave,

The Mullard will be much more reliable, but then again, the Chinese ones, when they fail, usually fail in the first hours of use, so you are pretty safe at this point.

The Mullard will give you more B+ voltage, but Mesa amps seem to sound prettier to me at least, as their voltages are not extreme, and they are closer to the sweet spot that tubes prefer. If you want more B+ voltage and a tighter and brighter sound, just flip the switch to your solid state rectifier. Sort of the best of both worlds.

These amps are really terrific. For now, I'd just spend time playing and enjoying the amp. If you have more than a few hours on your stock GZ34, it should be fine, and I'd pass on the extra money. I have the stock rectifier in a Blue Angel, and its been just fine and dandy for years. If I plug in a NOS rectifier in the Blue Angel, I personally notice no difference in that particular amp or circuit, but have measured about a 25 volt change in B+. So at least in my amp, 25 volts does not make a change to my ears or to a few others I have shown this to also.

It does make a difference in some older amps, like tweed Fenders, whose power transformers are getting weak, and saggy, and having a good strong rectifier is pretty important if you want more of the original sound from these amps. The again, lot of folks like the "aged" sound some of these amps produce.

In the case of your amp, Mesa amps in general, have very nice power sections, and your amp will develop its intended voltages in the power supply section long enough that when your grandkids play their old grand dad's "vintage" amp from the 20th century, it will still be working great.

I tend to get wordy .... always .... so bottom line ..... You have a great amp. Save your money and take the $75 or maybe even more for a Mullard GZ-34, and go out to dinner with your wife or girlfriend or significant other, or even somebody you pick up somewhere if you are still young enough or good looking enough to do that sort of thing \:\)

Regards;
Posted By: Gabriel E.

Re: Feel free to ask Myles - 04/15/02 10:23 PM

Quote:
You need a good switch though, that with switch in a clean way without any spikes. Something like what stereo stores use when the demo speakers, switching from one to another using the same amp.
Thanks for the quick reply Myles. Just to be safe - the jump from 4 ohms to 8 ohms doesn't qualify as a spike?

I have a Morley ABY switch. Probably not quiet enough huh?

Thanks again,

Gabriel
Posted By: GTO

Re: Feel free to ask Myles - 04/16/02 12:28 AM

Quote:
Originally posted by JamesPeters:
Hey GTO, mind if I butt in? \:D

The standby switch is used to break the connection of the high voltage in the amp. That would leave only the filament heater supply of the tubes powered when the power is on (and the standby is off). The whole deal with that is to let the tubes heat enough to be able to handle their operation. It takes between 30-90 seconds (depending on the tube) to fully heat the tube's filaments to a normal operating temperature.

If the tubes filaments aren't hot enough, what can happen is that if signal hits the grid of the tube it starts going about doing its thing...and electrons get stripped off the cathode ("cathode stripping"), resulting in premature tube wear. Keeping standby off for the first couple minutes the amp is on, then turning standby on, will help keep your tubes healthy longer. If your amp doesn't have a standby, then it's advisable to not play your guitar until the amp has been on a couple minutes. If the amp has a tube rectifier, those take a while to get the high voltage up to proper range, so in reality standby may not be needed on any amp with a tube rectifier. I'd still use the standby though if it's on the amp, since you're not "rushing" to start playing before the tubes are good and ready.

Powering down, it might probably be just as good to shut the standby off first until signal is gone...although I'm not sure if this matters or not since if you powered down while signal is on, it takes the tubes' filaments a while to cool.

The issue of shutting off with/without standby gets thrown around a lot, but nothing significant has come of the discussions as far as I know. One guy I know said he puts it on standby for a few minutes before shutting off, to let the tubes cool...but the logic in this seems flawed--if the tubes get that much hotter from the high voltage being on the plates, then how significant a difference is it if you remove the plate voltage first, then remove the filament supply later. I mean, do your tubes really cool more evenly by doing this? It seems unlikely.

Oh well. That's all I got! \:D
James,
Please butt in any time. Great info, you cleared up the issue that I was most concerned about, when to switch to standby at power-on.

Thanks!
Posted By: GTO

Re: Feel free to ask Myles - 04/16/02 12:32 AM

Thanks for the reply Myles. The "still around" comment was an inadvertant leftover paste from the HC forum, please don't be offended. Thanks for the info James and Myles, both of you hit the nail on the head.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/16/02 01:44 AM

Quote:
Originally posted by Gabriel E.:
Quote:
You need a good switch though, that with switch in a clean way without any spikes. Something like what stereo stores use when the demo speakers, switching from one to another using the same amp.
Thanks for the quick reply Myles. Just to be safe - the jump from 4 ohms to 8 ohms doesn't qualify as a spike?

I have a Morley ABY switch. Probably not quiet enough huh?

Thanks again,

Gabriel
Gabriel ...

You can try it, but first make sure it is capable of handling 50 watts at least. Most A/B switches are made to switch voltages of less a volt, and very low current. I'd also recommend a capacity of at least an amp in capacity.

You might want to first try it on some low powered effects or something, and when you switch it, see if you can hear a thump or loud click.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/16/02 02:05 AM

Quote:
Originally posted by GTO:
Thanks for the reply Myles. The "still around" comment was an inadvertant leftover paste from the HC forum, please don't be offended. Thanks for the info James and Myles, both of you hit the nail on the head.
GTO ....

You are more than welcome.

Regards,

Myles
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/16/02 08:05 AM

Hey Myles, how goes? Yeah, I tend to ramble sometimes...the typing almost gets ahead of my train of thought! Good thing to clear up the "standby on / standby off"--I remember being confused by the standby switch a few years back. "Turn standby on", someone would say, and I'd be like, "Umm, you mean use 'standby', so that the amp doesn't make any noise?"

A little like saying the phrase "Close the lights" (a french-canadian thing you might hear sometimes)--the first thing I think of is "closing the circuit", which means turning the lights on. \:D

The amp is doing very well--that's part of the reason I've delayed launching petersamps.com for the last week. I got tweaking again--there goes the week! \:\) But I found a touch more subtlety while getting more gain yet...then in the end had to back off the gain somewhat because on its loudest settings it would get feedback. I know that's not the end of the world or anything, but part of the idea behind this amp was that no matter what setting I used on the dials/switches, I'd always find it "useable". I'm glad I spent the time, because I like the amp a lot more now than I did even a couple weeks ago.

Some people can't quite put their finger on what's different if I don't crank the gain, but some people on the other hand consider it a drastic improvement.

Now, I just have to MP3 the new clips (I have maybe a couple hours before bed tonight yet--long days at work!), paste the updated text, and get a couple pics pages going.

Work work work! \:\) Talk to you later!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/16/02 07:07 PM

Quote:
Originally posted by JamesPeters:
Hey Myles, how goes? Yeah, I tend to ramble sometimes...the typing almost gets ahead of my train of thought! Good thing to clear up the "standby on / standby off"--I remember being confused by the standby switch a few years back. "Turn standby on", someone would say, and I'd be like, "Umm, you mean use 'standby', so that the amp doesn't make any noise?"

A little like saying the phrase "Close the lights" (a french-canadian thing you might hear sometimes)--the first thing I think of is "closing the circuit", which means turning the lights on. \:D

The amp is doing very well--that's part of the reason I've delayed launching petersamps.com for the last week. I got tweaking again--there goes the week! \:\) But I found a touch more subtlety while getting more gain yet...then in the end had to back off the gain somewhat because on its loudest settings it would get feedback. I know that's not the end of the world or anything, but part of the idea behind this amp was that no matter what setting I used on the dials/switches, I'd always find it "useable". I'm glad I spent the time, because I like the amp a lot more now than I did even a couple weeks ago.

Some people can't quite put their finger on what's different if I don't crank the gain, but some people on the other hand consider it a drastic improvement.

Now, I just have to MP3 the new clips (I have maybe a couple hours before bed tonight yet--long days at work!), paste the updated text, and get a couple pics pages going.

Work work work! \:\) Talk to you later!
James,

Its going pretty nicely. The amp clinic I held last weekend was a lot of fun and it was pretty busy, but I still had enough time to talk to folks a bit.

So, you think you ramble on too much? Look at my posts \:\)

"Close the lights" .... French / Canadian? Funny... my wife and her family use that all the time, and my wife was born in Burbank CA., and her mom was born in Italy.

On the feedback issue, try a few different tubes in V1 and perhaps change a cap value on its socket. Some combinations of preamp and driver can be sensitive to that issue. Maybe don't go for all that much gain as stock, as to me anyway, at a certain point it all turns to fuzz tone sounds. You can get LOTS of vain cascading side A and B of V1, and then for clean just use one side of V1.

Keep up the great work. I am looking forward to your release!

Regards,
Posted By: dlb

Re: Feel free to ask Myles - 04/16/02 08:27 PM

Hello Myles,
I posted about tube configuration for my Fender Prosonic Combo. Per your recommendation, I bought a jan GE 5751 and I also had a few GT 12AT7's then I got a pair of Svetlana 6L6GC's. After a few hours of swaping V1,V2,V3 around I think I have a combination that satisfies me. It took a combination of AX,AT,5751 to get there but it's there.
My last question on this amp is, is there a big bias difference going from 5881's to 6L6GC's?

Thanks a million again!....(Bows low only looking at the kings feet and retreats backwards)
Posted By: Mr. Dan Licks

Re: Feel free to ask Myles - 04/16/02 09:51 PM

"Close the lights" .... French / Canadian? Funny... my wife and her family use that all the time, and my wife was born in Burbank CA., and her mom was born in Italy.
Deffinitly a French and Italian thing. In the old days when I was living in Paris I was studying with Nadia Boulenger. She would always tell us about something she heard on the radio.."This morning I opened the radio and heard a most beautiful emmision...."
;\)

Myles,
Ever hear power tubes start to sing all by them selves? Our 6L6 420s do now and again, until I give them a friendly tap. OUT OF TUNE AT THAT! Sort of a flat b flat. Sucks if you are playing a blues in A. \:D
Dan
Posted By: myles_rose

Re: Feel free to ask Myles - 04/17/02 01:22 AM

Quote:
Originally posted by dlb:
Hello Myles,
I posted about tube configuration for my Fender Prosonic Combo. Per your recommendation, I bought a jan GE 5751 and I also had a few GT 12AT7's then I got a pair of Svetlana 6L6GC's. After a few hours of swaping V1,V2,V3 around I think I have a combination that satisfies me. It took a combination of AX,AT,5751 to get there but it's there.
My last question on this amp is, is there a big bias difference going from 5881's to 6L6GC's?

Thanks a million again!....(Bows low only looking at the kings feet and retreats backwards)
dlb,

Prosonics are tricky amps to get set up right. Without test equipment to measure the tubes so you know what you have, the only way left is to do what you did .... trial and error.

The Prosonic has a LOT of gain. It has more gain than my Mesa Mk. 1, by quite a bit. They are pretty terrific amps. Their basic problem, is in cascaded gain mode, they have so much gain possible, that using both volumes at over 3 or 4, makes so much gain that the sound becomes fuzzed out. With the 5751's and 12AT7's you are dropping the gain, where you can now get to about 5-6 on at least one of the volume controls, and then the amp also has more articulation, and they really sing.

The bias on 5881's and 6L6GC's is pretty close. Some 5881's are 26 watt tubes, rather than 30 watters as the 6L6GC, and some 5881's generally spec out higher than their 26 watt rating. Both the tubes vary a lot, but Fender typically sets their bias to run the amps pretty hot, but still with a lot of range to slip tubes in and out with some amps. With others, such as the Pro Reverb, the bias is set to draw about 30mA which is really a bit cool at the plate voltage these amps develop. The Prosonic is somewhere in the mid point, and it has a LOT of leeway, as the tube rectifier really drops the plate voltage compared to the solid state rectifier section.

Bottom line here, the short answer .... you can use 5881's or 6L6GC's in your amp, and if they are something like Groove Tubes, you can pretty much use anything from a #3 to a #7, and your bias will be pretty fine. If its any of the Fender/GT color coded tubes, these are all pretty close to a #5 range, something like the Mesa color code that translates to GT ratings of 4-6.

You're probably just fine, but even if you are running hot, these amps do great even running hot. If the plates are not glowing, you're fine.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/17/02 01:26 AM

Quote:
Originally posted by Mr. Dan Licks:
"Close the lights" .... French / Canadian? Funny... my wife and her family use that all the time, and my wife was born in Burbank CA., and her mom was born in Italy.
Deffinitly a French and Italian thing. In the old days when I was living in Paris I was studying with Nadia Boulenger. She would always tell us about something she heard on the radio.."This morning I opened the radio and heard a most beautiful emmision...."
;\)

Myles,
Ever hear power tubes start to sing all by them selves? Our 6L6 420s do now and again, until I give them a friendly tap. OUT OF TUNE AT THAT! Sort of a flat b flat. Sucks if you are playing a blues in A. \:D
Dan
Dan,

Yes. If they are Mesa STR-420's, they are Chinese tubes and not too reliable. If they are the Mesa Chinese, then try to replace them as soon as you get the chance.

Regards,
Posted By: Biz Markie

Re: Feel free to ask Myles - 04/17/02 04:41 AM

Hey Myles! I originally started a new thread with this one, but this is probably a better place for my question. I have a JCM 600 all tube head and cab. It has 2 Svetlana EL34s in the power amp section and 4 ECC83s (12AX7) in the pre-amp stage. It has clean and overdrive channels. I have to replace the power amp tubes as one of them has died. I'm wondering if the power tube section of the amp really plays a crucial role in the tone and if I could change the tone in this area? Also, I've read the some stuff on a link you posted about how the pre-amp tubes can change the tone of an amp. I'm wondering if there are any tubes out there that can make the overdrive channel have more distortion and bite. Or if not, is there a mod that can be made to the amp do this. I'm not fond of the overdrive I'm getting now (well not now as the amp is dead, but when it was working). It sounds too smooth with hardly any bit and the distortion is kinda tame. I usually use the clean channel at just about full volume with a Tube Screamer and a Boss EQ in front. I'd like to have a more dynamic sound as I don't have a "clean" channel as such. Just curious if theres something like a "JCM 600 to JCM 800 mod" sorta like the familiar TS-9/TS-808 mod. Thanks.
Posted By: JamesPeters

Re: Feel free to ask Myles - 04/17/02 11:53 AM

Quote:
Originally posted by Mr. Dan Licks:
"This morning I opened the radio and heard a most beautiful emmision...." ;\)
Oh man, I could only imagine someone saying that to me--I think I'd split my sides! \:\)

Ok, I got a few clips up...I have a couple more hours of stupid noodling to go through before I put the rest up, but I had to get something up--too many people were asking for clips for me to leave it until "I had the time" (which the way it's going this week, may never happen, lol!)

Catch you later!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/17/02 07:15 PM

Quote:
Originally posted by Biz Markie:
Hey Myles! I originally started a new thread with this one, but this is probably a better place for my question. I have a JCM 600 all tube head and cab. It has 2 Svetlana EL34s in the power amp section and 4 ECC83s (12AX7) in the pre-amp stage. It has clean and overdrive channels. I have to replace the power amp tubes as one of them has died. I'm wondering if the power tube section of the amp really plays a crucial role in the tone and if I could change the tone in this area? Also, I've read the some stuff on a link you posted about how the pre-amp tubes can change the tone of an amp. I'm wondering if there are any tubes out there that can make the overdrive channel have more distortion and bite. Or if not, is there a mod that can be made to the amp do this. I'm not fond of the overdrive I'm getting now (well not now as the amp is dead, but when it was working). It sounds too smooth with hardly any bit and the distortion is kinda tame. I usually use the clean channel at just about full volume with a Tube Screamer and a Boss EQ in front. I'd like to have a more dynamic sound as I don't have a "clean" channel as such. Just curious if theres something like a "JCM 600 to JCM 800 mod" sorta like the familiar TS-9/TS-808 mod. Thanks.
Markie,

The output section can have a big change on your sound too.

Adjusting the bias make an amp run cooler or hotter, distorts quicker or later, makes it smoother or more coarse.

Outside of bias, the type of tubes you use has an effect too. Svetlana's are full bodied and very well rounded, Mullards are very linear, Siemens are smooth and predictible, and JJ's are very strong in the upper mid and above range, while still as strong in the low end as a Svetlana.

This is part of the reason behind what I call "blueprinting", that is, changing tubes and settings for a particular player's tastes and requirements.

You can make your output section cleaner or distort quicker by tube selection, even within a specific tube type and maker. This is why folks like Groove Tubes have a range of 1-10 for their tubes.

Changing the phase inverter (V4 on your amp) can make the preamp distortion more of a factor if you go in one direction, or the poweramp have more of it's character if you go in the other direction.

As far as mods, one of the best folks in the business is Trace over at voodoo amps.

Hope this helped.

Regards,
Posted By: jazzcaster

Re: Feel free to ask Myles - 04/17/02 10:12 PM

A quick question for Myles! I have a new Fender Pro Reverb (Pro Tube Series). I love it. I want to experiment with some tube swaps. My question is....which tubes (ie. function, like tremolo, reverb etc.)correspond to which location on the chassis (ie. V1, V2, V3 etc.). I have the schematic that came with the amp, but I don't know how to read it....it's almost all Greek to me!).

Thanks Myles (or anyone else who can help).
Posted By: Mr. Dan Licks

Re: Feel free to ask Myles - 04/17/02 11:32 PM

Hi Myles,
Man, how do you manage to keep your cool? I was just over at HC to see what was going on on the amp forum and fought my way through all the adolescent rantings of squigglewhatshisname. Some nice cats over there, but I like it better here.
You suggested Svets of a Groove Tube #7 rating for our 50 Cal+. I saw somewhere that the Mesa color scale runs from red (warm sound) to blue(cold, hard sound). Is this correct? Now, by putting hotter tubes in a Boogie do we in effect change the bias of the amp? Would the result be more or less the same as setting the bias hotter and using a colder tube? (No, I am NOT planning to put a trim pot on the bias) Just wondering.
What do you think of this setup on the pre tubes? (Suggested by an Aussie on HC who played a 50 Cal for 10 years)
V1-GT 12ax7R2, V2-Mesa 12ax7C, V3-Mesa 12ax7C,V4-(12AT7), V5-Sovtek 12ax7LPS + the 6L6GC Svets you suggested.
Many thanks,
Dan

This thread seem to be more of a forum within a forum. Deffinitly cool.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/18/02 12:15 AM

Quote:
Originally posted by jazzcaster:
A quick question for Myles! I have a new Fender Pro Reverb (Pro Tube Series). I love it. I want to experiment with some tube swaps. My question is....which tubes (ie. function, like tremolo, reverb etc.)correspond to which location on the chassis (ie. V1, V2, V3 etc.). I have the schematic that came with the amp, but I don't know how to read it....it's almost all Greek to me!).

Thanks Myles (or anyone else who can help).
jazzcaster,

I cannot help yet ... I am waiting for the prints from Fender on one of them I am working on currently.

I have had the amp for a week from a client. I do know that V1 and V2 are the normal first gain stages, and if you look, you will probably find these two tubes have a small o-ring at the bottom of their heat sheilds (unlike the others), and these two tubes are also wrapped in shrinkwrap to cut down on microphonics. (This is an old trick ... sometimes a rubber band on a first gain stage helps reduce microphonics in an emergency when you don't have other tubes at a gig).

In any case, I have been going through the amp, making my own conclusions as I move along.

So far this is what I have learned.

1. These amps use fairly high B+ voltage ... on the order of 465 volts. VERY nice power supply section.

2. The amp is a bit overbiased and cool at its suggested 30mA, but is not at all grainy, and if you raise the bias, you may find the amp even louder than it already is.

3. The clean channel is LOUD and CLEAN and if you want the sound and power of a Twin Reverb, this amp has it in spades.

4. The gain channel is just plain crazy. This amp is capable of more first gain stage gain than just about anything I have ever seen. Fender seems to have met the clean and ultra gain issue with a very high degree of success.

5. V1 and V2 were too hot, and by going to some selected 12AX7's with a bit less output, it allowed the gain and volume on the gain channel to be able to be turned to more than 3 and 3. Prior to that, the gain was more extreme than my Mesa amps.

6. The Jensen 12" speaker in there is the definitive speaker choice for this amp ... you can get the classic 60's and 70's sound of the Jefferson Airplane or Quicksilver Messenger Service ... the Byrds or any of the San Francisco rock groups of that era on the clean channel. DO NOT change this speaker.... it is perfect.

7. The amp on the gain channel has more articulation and definition of individual notes within a chord than my Mesa amps, my Mesa preamp, or the SLO-100 or Marshalls.

As I learn more, I will post it, or drop me an email and we can keep in touch.

This amp is something of a change for Fender. Their Prosonic was their first venture into very high gain with a cascaded gain circuit, and they learned a lot with that amp it seems, as its a nice amp with a lot of features such as the rectification, etc.

This particular amp is going to be one of their classics in the future, I'd bet on it. There is a LOT of room to work as the chassis is very deep, and the box itself is quite a bit deeper than a Twin Reverb, so even with a single 12", the sound is immense, something like the Single Showman of the past.

The amp is built VERY VERY VERY well. Its transformers are really terrific. Its a pretty heavy sucker, but maybe not as bad as a Twin Reverb, and a bit easier to get into a car trunk.

The stock Sovtek 6L6's are pretty fair, but soon I will be trying some Svetlana's, until I can get a duet of the new 6L6GE's from Groove Tubes, as I am out of those or they are in other amps for testing.

Bottom line here .... this is one of the most versitile amps I have seen in a very long time. Its just a matter of time until Fender looks at their pricing, as it is more than a Super Reverb as far as useage, and thank goodness it has a 1/4 power setting of 12 1/2 watts .... but then again, even at settings of 1 1/2 on the volumes, it still makes a Rickenbacker 12 string crack and bark on the chords on the chean channel, and will sing forever on the gain channel with the gain at 3 and the volume on 4.

You have one of the first great unknown (so far) amps of modern day ... with the blackface flair of the past.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/18/02 01:38 AM

Quote:
Originally posted by Mr. Dan Licks:
Hi Myles,
Man, how do you manage to keep your cool? I was just over at HC to see what was going on on the amp forum and fought my way through all the adolescent rantings of squigglewhatshisname. Some nice cats over there, but I like it better here.
You suggested Svets of a Groove Tube #7 rating for our 50 Cal+. I saw somewhere that the Mesa color scale runs from red (warm sound) to blue(cold, hard sound). Is this correct? Now, by putting hotter tubes in a Boogie do we in effect change the bias of the amp? Would the result be more or less the same as setting the bias hotter and using a colder tube? (No, I am NOT planning to put a trim pot on the bias) Just wondering.
What do you think of this setup on the pre tubes? (Suggested by an Aussie on HC who played a 50 Cal for 10 years)
V1-GT 12ax7R2, V2-Mesa 12ax7C, V3-Mesa 12ax7C,V4-(12AT7), V5-Sovtek 12ax7LPS + the 6L6GC Svets you suggested.
Many thanks,
Dan

This thread seem to be more of a forum within a forum. Deffinitly cool.
Dan,

How do I keep my cool? Just realize that some folks speak without thinking, and just let it pass most of the time.

I like it more over here too, as it seems at times that I can spend more time as there is less traffic to deal with from some of the folks like the fellow you mentioned earlier. There are great folks on both forums, but I give this forum my first priority.

As far as the Mesa scale .... here it is, compared to the Groove Tubes scale:

Mesa vs Groove Tubes scale
Red 4
Yellow 4
Green 5
Gray 5
Blue 6
White 6

Mesa keeps their tubes in a narrow range. On my Mesa amps, the amps are still a little cold even with the Mesa "white" tubes.

Basically, as an example, if your amp is at, lets say, a 38% idle dissapation with a Mesa "green" set of 6L6's, and you go to a "blue", you may go to about 40%-42% on your bias idle dissapation, without adjusting anything.

I find Groove Tubes #7 ratings work best in my own Mesa amps, which is a bit outside of the Mesa range, but still just a hair about 50% ID, which is still lower than some folks prefer. This 50% range gives good overall performance and very long tube life.

I would pass on the bias control pot, as there are tubes from folks like Watford Valves and Eurotubes, that can pick tubes dialed right in to your particular amp, without having to adjust anything.

On the Aussie fellow that have his ideas, I have to agree with him technically, its really a matter of taste. His picks are right on the money, the only issue that plagues some Mesa amps is microphonics in V1 and V2. His choice for V1 is typically a tube that is pretty good in the microphonic rejection department, and this is the weak spot in most any amp, Mesa or non-Mesa.

Mesa amps have a high gain structure, so the are more prone to microphonics. Your Caliber 50 has a bit of advantage over a Mark series though, it is physically larger than a Mark, so there is a bit more room between V1 and the back of the speaker. Sometimes its a matter of 1/2 and inch, or in your neck of the woods, 1cm or so, or a slightly different position of the tube in relation to the speaker position. The Caliber and Nomad series from Mesa are a lot nicer in this aspect than the Mark series, until you get to the Mk IV if you opt for the wide chassis.

I'd go along with your Aussie friend's post, he's right on the money, and NOS tubes in a modern amp like yours might sound pretty or nicer to some folks, might sound worse to others, but in the end, your amp will sound pretty darn great they way it is. The WEAK area in Mesa amps that use 6L6's is when they are supplied with the Mesa STR-420 tubes, which are Chinese. Any other designation from Mesa is a vast improvement. Their STR-454's are Svetlana tubes, and Mesa sells those for less than a lot of other folks sell Svetlana tubes.

Regards,

Myles
Posted By: jazzcaster

Re: Feel free to ask Myles - 04/18/02 05:39 AM

Myles,

Thanks so much for your great info on the new Pro Reverb. I will keep in touch and hope to hear more after you've had a chance to delve further into the amp you have. As a note (hey...I can actually offer "you" some info!), I swapped out the stock Sovtek 6L6 Groove tubes (I had no real problem with them, I'm just a tinkerer at heart) and replaced them with som Svetlana's. WOW! Did I say Wow?! I've heard many good things about this 6L6, and now I know why. My clean channel sounds....well....cleaner, if thats possible. I guess "more sparkle" is how to describe it in cliche terms. But the real treat is the overdrive. It is buttery smooth compared to the stock Groove Tubes. (I play a Strat with Van Zandt Blues pups). I adjusted the bias to the Fender spec of 30mv. I had also adjusted the bias on the stock tubes when I first got the amp (they were slightly "cold", if thats the term (26mv). Once I figure out the pre-amp tubes, I'll start a bit of swapping to feed my curiosity. My God this amp has me jazzed!!!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/18/02 06:03 AM

Quote:
Originally posted by jazzcaster:
Myles,

Thanks so much for your great info on the new Pro Reverb. I will keep in touch and hope to hear more after you've had a chance to delve further into the amp you have. As a note (hey...I can actually offer "you" some info!), I swapped out the stock Sovtek 6L6 Groove tubes (I had no real problem with them, I'm just a tinkerer at heart) and replaced them with som Svetlana's. WOW! Did I say Wow?! I've heard many good things about this 6L6, and now I know why. My clean channel sounds....well....cleaner, if thats possible. I guess "more sparkle" is how to describe it in cliche terms. But the real treat is the overdrive. It is buttery smooth compared to the stock Groove Tubes. (I play a Strat with Van Zandt Blues pups). I adjusted the bias to the Fender spec of 30mv. I had also adjusted the bias on the stock tubes when I first got the amp (they were slightly "cold", if thats the term (26mv). Once I figure out the pre-amp tubes, I'll start a bit of swapping to feed my curiosity. My God this amp has me jazzed!!!
jazzcaster,

The amp I am in the process of still doing on and off had the stock tubes in V1 and V2 changed right at the start too.

I am trying to get a duet of the new GE tubes to put in there (I have a post on them in here somewhere), and then we will proceed.

I have a lot of the Svets around, and generally prefer them for just about anything, but still want to try the new GE's, as in a Vibroverb they made than amp come to life even more than with the Svets that were in there.

Regards,
Posted By: Rai168

Re: Feel free to ask Myles - 04/18/02 06:17 AM

Hi Myles. I am running GE6550A's in my VHT Ultralead. I know these are a high output tube. What's a good bias to run it at? I think my tech may have them a lil cold...I was originally running the Sovtek KT88's and he had to turn the bias down for the GE6550A's. Just looking for a recommendation as I play hi-gain stuff. Thanks -

Rai
http://www.CalyxinRuin.com
Posted By: Mr. Dan Licks

Re: Feel free to ask Myles - 04/18/02 08:40 AM

Myles,
Well, things are beginning to make some sense to me, thanks to you old pros out there!
One short follow-up:
Just in principal, if you go from a #5 to a #7, what would be the general, overall change in the sound? In other words, cold tubes = ?????, hot tubes =?????.
Yesterday my son went to practice with his friends and his teacher and "had to" play through a Marshall. When he came home, first thing he said was, "I like my Boogie better!" \:D Can't wait to trash the 420s....
Dan
Posted By: aeon

Re: Feel free to ask Myles - 04/18/02 06:17 PM

Myles:

I have a couple of questions about that Fender Pro Reverb you are working on. With the fairly high B+ voltage it uses, it is able to derive ~50 watts from a duet of 6L6 valves. How does the Pro Reverb make the switch to 12.5 watts? Does it only use one of the 6L6s and also drop the B+ voltage, or does it continue to use both valves with a more severe drop of the B+ voltage?

A pair of THD Yellowjackets will usually drop a 50 watt amp to 20 watts as it moves from 6L6 to EL84. Do you think the Pro Reverb quarter-power mode would still function with EL84s, giving an output of ~5 watts?

The Pro Reverb had already caught my attention, but your praise of it has heightened my interest further. Thanks in advance!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/18/02 07:16 PM

Quote:
Originally posted by Rai168:
Hi Myles. I am running GE6550A's in my VHT Ultralead. I know these are a high output tube. What's a good bias to run it at? I think my tech may have them a lil cold...I was originally running the Sovtek KT88's and he had to turn the bias down for the GE6550A's. Just looking for a recommendation as I play hi-gain stuff. Thanks -

Rai
http://www.CalyxinRuin.com
Rai168,

The bias for a KT-88 and 6550A is different, but I would not be able to give you a figure until I know your B+ voltage.

That would get us in the ballpark, but to really dial it in, would involve some knowledge of your playing style, and I'd possibly fine tune the bias using a scope so I could set it more closely to where you keep your volume and master controls set to give you some playing dynamics which is tricky with 6550A's, as they are so clean

Get back to me with your B+ voltage and we'll continue.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/18/02 08:08 PM

Quote:
Originally posted by Mr. Dan Licks:
Myles,
Well, things are beginning to make some sense to me, thanks to you old pros out there!
One short follow-up:
Just in principal, if you go from a #5 to a #7, what would be the general, overall change in the sound? In other words, cold tubes = ?????, hot tubes =?????.
Yesterday my son went to practice with his friends and his teacher and "had to" play through a Marshall. When he came home, first thing he said was, "I like my Boogie better!" \:D Can't wait to trash the 420s....
Dan
Dan,

As a simple example, but still pretty complete actually .... if you had a set of #5's in an amp and you saw that when you turned the volume control to say, "5" and your guitar to "10", that when you played heavy, you got output tube distortion, and then changed to a #7 set of tubes, you would then see the amp would be cleaner at the same settings, and you'd maybe have to turn the amp to a higher setting to get back that same amount of distortion.

With the 7's, the amp would be cleaner at a given setting, and a bit louder too at the same setting as with the 5's.

Most players like mid range tubes, as they are plenty loud enough when clean, and then when they play harder, it distorts more as your playing attack is harder. So in essence, you keep the guitar and amp settings in a range so you have a lot of feel and dynamics ... play more on the lighter side and its clean, and dig in harder and it gets dirty.

As far as your son prefering his amp to a Marshall, that is not too much of a surprise. Marshall amps have a particular sound, and they have a lot more midrange boost as designed in their design when compared to a Fender amp. I have a section on my webpage on this subject with graphs of the response curves of both of these amps. What Marshalls do, they do great, and there are two kinds of Marshall owners/users .... those which live by the Marshall sound alone and would not play anything else ... and those that have a Marshall in their "inventory" to use when they want the Marshall sound.

There are a lot of amps that imply they can sound like a Marshall, and the word of attention here is "LIKE", .... which is not the SAME. Marshall amps have a simple circuit with very little in the signal path. The four input and early Marshalls have no reverb, or effects loops, so there is little to alter the signal path. Marshall amps also have crossover notch distortion in their design as part of their sound. This is one reason that these amps do not sound their best when biased using the current draw method. They also have the feedback loop coming off the 16 ohm tap of their output transformer, rather than off the 2 ohm tap as on a tweed Fender Bassman, which some folks think are the same circuit. Where the tone controls are in a Marshall vs. a Fender, post gain / pre gain, is yet another difference.

Your son's Mesa is an amp a lot more versitile than a Marshall, so unless he fell in love with the Marshall sound, I could see his viewpoint.

Also, Marshall amps have their magic come into play when turned up near or at their max. This is why folks like Jeff Beck use 50 watt heads rather than 100 watt heads. They get to their max at a more rational level.

Regards,
Posted By: Mr. Dan Licks

Re: Feel free to ask Myles - 04/18/02 08:22 PM

Gotcha.
So it boils down to finding a balance between pre tube distortion and power tube distortion. We find that with the volume knob set at 4, the sound has plenty of distortion, any highter and it is too much. Now, how can you tell the difference between what is being distorted in the pre section, and what is being distorted in the power section. There must be a significant difference.
Thanks, Dan
Posted By: myles_rose

Re: Feel free to ask Myles - 04/18/02 08:37 PM

Quote:
Originally posted by aeon:
Myles:

I have a couple of questions about that Fender Pro Reverb you are working on. With the fairly high B+ voltage it uses, it is able to derive ~50 watts from a duet of 6L6 valves. How does the Pro Reverb make the switch to 12.5 watts? Does it only use one of the 6L6s and also drop the B+ voltage, or does it continue to use both valves with a more severe drop of the B+ voltage?

A pair of THD Yellowjackets will usually drop a 50 watt amp to 20 watts as it moves from 6L6 to EL84. Do you think the Pro Reverb quarter-power mode would still function with EL84s, giving an output of ~5 watts?

The Pro Reverb had already caught my attention, but your praise of it has heightened my interest further. Thanks in advance!
aeon,

Getting 50 watts from a pair of 6L6's is pretty easy with 465 volts on the plates. A few years back, Fender had an amp called the "75" that pulled 75 watts from a pair with over 500 volts on the plates. Most of the black face 60's Bassman heads I work on produce more than 50 watts, and in some cases, up to 70.

How it gets down to its 1/4 power rating, is by lowering the voltage on the B+ as well as a few other places in the circuit, such as bias voltage changes, etc.

The Yellow Jackets will work fine at the 1/4 power setting, but the issue with EL-84's is that they tend to get into distortion fairly quickly and have a smooth distortion character. That's why a lot of folks like them a lot.

Go play one of them at a Sam Ashe or Guitar Center or any Fender dealer. Compare their clean sound to a Twin Reverb, and then switch to the drive channel. Its a pretty unique and versitile amp. It can sort of go from Jazz/Rhythm/Country/Pedal Steel to the strongest and most sustaining lead tones that would open the eyes of the most die hard Metal/Thrash/Speed players. About the only complaint you might hear, is folks wanting something in the middle, and I think we found that with a few changes here and there, and then turning the gain channel's volume to a higher setting and setting the gain control low, down to about "2", for a nice crunch where chords are still very refined.

It seems to do what amps at three times the money do, and at times, a bit more.

I'd get one myself, but family finances etc. are one issue, regardless of the cost, and dealing with my wife and "why do you need another amp", is an even more difficult proposal \:\)

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/18/02 08:42 PM

Quote:
Originally posted by Mr. Dan Licks:
Gotcha.
So it boils down to finding a balance between pre tube distortion and power tube distortion. We find that with the volume knob set at 4, the sound has plenty of distortion, any highter and it is too much. Now, how can you tell the difference between what is being distorted in the pre section, and what is being distorted in the power section. There must be a significant difference.
Thanks, Dan
Dan,

If you want more preamp or front end distortion, turn the master low and the volume/gain high.

If you want a blues sound, and nice output distortion, turn the master all the way up, to effectively get it out of the circuit and turn the amp into something of a "non-master-volume" amp, and then use your volume/gain at the very low settings for output tube distortion and less preamp overdrive.

Regards,
Posted By: Mr. Dan Licks

Re: Feel free to ask Myles - 04/18/02 08:48 PM

Right. So the front end type is more for the screaming leads, and the back end for a warmer, gentler kind. That is the impression we have gotten when we have done just that.
Thanks again for taking the time to answer these "stupid" questions. I hope that the information is also helpful to others. Even though a lot of it is still over my head, I get a lot out of your posts to others.
Dan
Posted By: myles_rose

Re: Feel free to ask Myles - 04/18/02 11:52 PM

Quote:
Originally posted by Mr. Dan Licks:
Right. So the front end type is more for the screaming leads, and the back end for a warmer, gentler kind. That is the impression we have gotten when we have done just that.
Thanks again for taking the time to answer these "stupid" questions. I hope that the information is also helpful to others. Even though a lot of it is still over my head, I get a lot out of your posts to others.
Dan
Dan,

You are right on track. Metal and speed players and hard rock folks take the scraming lead route, and blues players take the output crunch road most of the time.

Don't worry about whether a question seems "smart" or "stupid", as there are a lot of folks that would like to ask a lot of things, but its people like you that surface the question for the benefit of a lot of people. The less you know on a subject, the more detail is needed in the explanation, and that turns out to be a good thing, as it fills in a lot of blanks for some folks where they may know the answer, but not the reason "why" behind the answer.

By the way .... when you get to the states, I'd be happy to trade some graded tubes for some pastry!

Regards,
Posted By: Mr. Dan Licks

Re: Feel free to ask Myles - 04/18/02 11:57 PM

Mmmmmmmm, sounds good, but pastery doesn't travel well and it is VERY hard for me to resist temptation! ;\)
Posted By: myles_rose

Re: Feel free to ask Myles - 04/19/02 12:21 AM

Quote:
Originally posted by Mr. Dan Licks:
Mmmmmmmm, sounds good, but pastery doesn't travel well and it is VERY hard for me to resist temptation! ;\)
Dan...

Darn it! Its my weakness too.

Myles
Posted By: not coaster MODERATOR

Re: Feel free to ask Myles - 04/19/02 03:03 AM

Myles

I have a friend with a nylon acoustic. He's an average player and it's an average guitar. What will it take to put a pickup in that thing?
Posted By: myles_rose

Re: Feel free to ask Myles - 04/19/02 04:07 AM

Quote:
Originally posted by Cereal:
Myles

I have a friend with a nylon acoustic. He's an average player and it's an average guitar. What will it take to put a pickup in that thing?
Cereal,

There are pickups in all ranges. For a classical or nylon strung guitar, there are some nice contact pickups that work fairly well. Then you can go right on up the scale with a piezo bridge and buffered preamps etc.

The best fellow to talk to is either:

David Neely at 323-850-7043

or

"the amazing Nick" at 818-344-8300 who is the fellow that takes care of all the guitars over at Norman's Rare Guitars.

or

In Westwood, call Pat at Westwood Music at 310-378-4251. Pat was at Coruthers (I butchered the spelling there I'm sure) for about a decade before coming to westwood.

Those are my favorite guitar folks, but there are a lot of nice ones around, so somebody here may also have a suggestion.

Regards,
Posted By: not coaster MODERATOR

Re: Feel free to ask Myles - 04/19/02 04:31 AM

Thanks Myles. I'll pass all 3 numbers along.
Posted By: MesaUser

Re: Feel free to ask Myles - 04/19/02 04:37 AM

Myles, I have a 3 chan. Mesa Rectifier that I pull 2 tubes....which of course leaves me using 2. I have the Ohmage and everything matched. My question is...will this hurt my amp in anyway by runnin it like this for long periods of time. By the way...Im using Mesa labled Svet el34's. Thanks!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/19/02 07:47 PM

Quote:
Originally posted by MesaUser:
Myles, I have a 3 chan. Mesa Rectifier that I pull 2 tubes....which of course leaves me using 2. I have the Ohmage and everything matched. My question is...will this hurt my amp in anyway by runnin it like this for long periods of time. By the way...Im using Mesa labled Svet el34's. Thanks!
MesaUser,

If you are using a 100 watt Mesa, which I think is what you are saying here, you can pull two of the tubes to make this into a 50 watt amp with no problems.

There are a few things to remember though ....

1. If you are using a 16 ohm cabinet, plug it into the 8 ohm speaker jack. If you are using an 8 ohm cabinet, plug it into the 4 ohm jack. Your output tubes have impedience too, and you need to keep this matched.

2. Swap the tubes you use with the ones you pulled every once in a while so they do not end up as one pair with a lot of wear, and the other unused pair stronger.

By doing this 50 watt setup, the heater current needs are dropped on your amp and your power transformer is under less strain too, as well as not having to drive the other pair of tubes, so it gives your amp a little rest in a manner of speaking. Keep in mind also, that you still have a beefy power supply that was designed for a 100 watt amp, so don't expect some of the sound associated with a 50 watt amp when its power supply is taxed. This is one of the reasons some folks like Jeff Beck prefer 50 watt amps rather than just pulling tubes out of 100 watters, but you will get your amp to get into that nice range of output distortion at more rational levels, and it will sound pretty nice.

Regards,
Posted By: OldManMetal

Re: Feel free to ask Myles - 04/19/02 08:48 PM

Myles, I have a couple of questions I hope you can help me with. Both deal with tubes.

1. What tubes do you recommend for a Peavey Delta Blues 210 combo, used for everything from clean tones to rockin' blues tones?

2. What tubes do you recommend for a Mesa Boogie .50 Caliber + head used for mainly heavier tones?

Thanks for you help
Posted By: Cornforduser

Re: Feel free to ask Myles - 04/19/02 08:58 PM

Myles,
How great to know about the new GE 6L6!!!!
BTW, What would you do in my amp ?
Mullard ECC83 + GE 5751 + Mullard ECC83 (driver)
Mullard ECC83 + Mullard ECC83 + GE 5751 (driver)
What would be the effect of each ???
Posted By: myles_rose

Re: Feel free to ask Myles - 04/20/02 05:40 AM

Quote:
Originally posted by jazzcaster:
A quick question for Myles! I have a new Fender Pro Reverb (Pro Tube Series). I love it. I want to experiment with some tube swaps. My question is....which tubes (ie. function, like tremolo, reverb etc.)correspond to which location on the chassis (ie. V1, V2, V3 etc.). I have the schematic that came with the amp, but I don't know how to read it....it's almost all Greek to me!).

Thanks Myles (or anyone else who can help).
jazzcaster,

Here is a later answer as I get deeper into these amps.

First off, you are going to have to follow the tube chart inside the amp, as these puppies are laid out a bit differently than most amps. The phase inverter is still the closest to the output tubes, but being that the output tubes are about in the center of the amp, it makes for some unique thinking.

In any case, here is sort of what happens in this amp:

The input jack feeds V1A. This also feeds the gain control on the gain channel. It also feeds the normal channels tone circuit, and the normal channels volume control, which feeds V1B, for the normal channel's next gain stage. This feeds V3B, and that feeds V8A (the effects send) and then comes back in with V8B, the effects return.

V5B is used to supply the preamp out jack on the back panel to send a signal to a board, another amp, or house system. Reverb is present in this signal.

V5A is the reverb return

V7A and V7B are the reverb send drivers, and are in parallel, so there is a lot of current capable here. This is a 12AT7 tube.

On the high gain channel, the signal from V1A above hits V2A for another stage of gain, and then its off to V2B, for yet another stage of gain again.

Just like most amps, V1 and V2 are your primary gain and tone generation components.

After V2B comes V3A to drive the tone circuit, and this is sent off to the volume control for this side of the amp, the gain side. Remember, we had a stage of gain from V1A on the other circuit which fed the gain control on this side of the amp.

V6A and V6B are the vibrato send and return.

V4A and V4B is the phase inverter. This is the tube you'd notmally like to be matched. Its in its "proper place", close to the output tubes, but due to the amps layout, it is not the "highest V number" preamp tube as is the usual or most common case with most amps.

With the tube chart in the amp, you should be able to find all these 8 preamp tubes without too much trouble.

Regards,
Posted By: jazzcaster

Re: Feel free to ask Myles - 04/20/02 03:58 PM

Hi Myles,

I am indebted for life for your help with the Pro Reverb tube section ID. I muddled through the schematic and managed to identify the reverb and vibrato, but was lost on the rest. I'm off to the races now. My only concern with this amp is that the vibrato channel has a lot of hiss, very audible. And the vibrato is not really audible at the 1/4 power setting. Is there a tube change I can make to quiet it down (and increase the "audibility on the 1/4 power setting?), or is this the nature of the beast? Does the Pro Reverb you are working on exhibit this problem? The hiss does not change with guitars (ie. it's not noisy single coils that are the culprit) and there is no problem on any of the other channels. My Peavey Delta Bluse 115 tremolo(vibrato) is much, much quieter, and thats what I'm using as my benchmark.

Thanks so much again Myles for your help. (I'm learning more on your forum page in the past few days than from any other source, ever).
Posted By: myles_rose

Re: Feel free to ask Myles - 04/20/02 06:04 PM

Quote:
Originally posted by OldManMetal:
Myles, I have a couple of questions I hope you can help me with. Both deal with tubes.

1. What tubes do you recommend for a Peavey Delta Blues 210 combo, used for everything from clean tones to rockin' blues tones?

2. What tubes do you recommend for a Mesa Boogie .50 Caliber + head used for mainly heavier tones?

Thanks for you help
OldManMetal,

I really cannot recommend a particular tube, as that is strictly personal taste. It also gets into a match of rise times and preamp tubes with power tubes, but rise times and the like depend on your playing style, attack, pick or no pick, heavy pick vs. light pick, and a ton of other factors.

I'd maybe have you start out by going to my website and reading some of the tube reviews and reports over there. That will get you in a ballpark or on some direction.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/20/02 06:16 PM

Quote:
Originally posted by Cornforduser:
Myles,
How great to know about the new GE 6L6!!!!
BTW, What would you do in my amp ?
Mullard ECC83 + GE 5751 + Mullard ECC83 (driver)
Mullard ECC83 + Mullard ECC83 + GE 5751 (driver)
What would be the effect of each ???
Cornforduser,

You amp .... hard question, as I do not know the individual characteristics of each of the tubes as far as rise times, output, etc. I'd need to look at each of these on a tracer as I do for my blueprinting comments.

Assuming all these are at the average factory spec though:

5751 in V1 will give you less front end gain and let the output stage play a larger part in your sound.

Tubes in V2 will have much less effect than those in V1, as V1 is your first gain stage.

In V3, a 5751 will give you a bit more clean headroom, but I'd prefer a 12AT7 in that position in your amp, as that is more of the characteristic sound of the Bassman circuit.

The Mullards in V1 and V2 will generally give you more detailed and complex sound, as these are very articulate tubes.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/20/02 07:18 PM

Quote:
Originally posted by jazzcaster:
Hi Myles,

I am indebted for life for your help with the Pro Reverb tube section ID. I muddled through the schematic and managed to identify the reverb and vibrato, but was lost on the rest. I'm off to the races now. My only concern with this amp is that the vibrato channel has a lot of hiss, very audible. And the vibrato is not really audible at the 1/4 power setting. Is there a tube change I can make to quiet it down (and increase the "audibility on the 1/4 power setting?), or is this the nature of the beast? Does the Pro Reverb you are working on exhibit this problem? The hiss does not change with guitars (ie. it's not noisy single coils that are the culprit) and there is no problem on any of the other channels. My Peavey Delta Bluse 115 tremolo(vibrato) is much, much quieter, and thats what I'm using as my benchmark.

Thanks so much again Myles for your help. (I'm learning more on your forum page in the past few days than from any other source, ever).
jazzcaster,

You're welcome for any help I gave.

Ah ... the vibrato culprit ....

These amps have a LOT of gain and a lot of high voltages running all over the place. With some of the interconnects, there is sometimes more hiss and hum than in some other amps. This is one of the reasons that preamp tubes in the Fender DeVille series have microphonic problems with one tube, while the same tube in a Black Face reissue will be fine as an example.

In your amp, V6 might be replaced with a better tube than the Russian Sovtek WA that it came with from the factory. I'd put a JAN NOS 12AX7A in there from somebody like KCA tubes. They are probably about $15.00. If you want to go with a new tube, try a Sovtek 12AX7LPS, as this may also help, or hit a Mesa Boogie store if there is one in your area and get one of their 12AX7's which are now the Electro Harmonix 12AX7EH, but they sell them for $10 retail, so its a pretty decent price. This is a driver position, so you don't need to go to the expense of any NOS or boutique high priced tubes.

Keep me informed and I'll try to step you through this. There is also a little cap trick that can be done to the socket for this tube, but for now, lets keep it stock.

These amps are not as quiet as some others, but that is due to the capability of very high gain and there is a lot going on inside of them. They are as quiet as most of today's high gain offerings, but most of today's high gain amps do not have the ability to get the clean sound of a Twin Reverb like your amp can get in addition to the gain it can get.

Regards,
Posted By: glzebub

Re: Feel free to ask Myles - 04/20/02 07:33 PM

hello there myles.
could you spare just a sec for my problem,

i bought a few months ago after saving for a year a trace elliot C50 (owned by Gibson now btw), the manual says that four of the five ECC83's are used on clean and on overdrive, however when the overdrive boost (channel 3) is kicked on, a fifth preamp tube comes into the fray, another ECC 83 i believe, would it be possible to change this fifth tube to some sort of high gain tube so as to really emphasise the gain addition, cos it's a bit tame. something harder edged like a modern marshsall, it's still a bit vintage sounding just like the od without the boost, very little difference. i do love the normal drive channel but i would just love more of a change between theese two modes
one final thing, the output tubes are two Svetlana EL-34's, are these any good (i know nothing of this brand), would changing them improve the tone?
thank you very much.
Posted By: jazzcaster

Re: Feel free to ask Myles - 04/21/02 01:07 AM

Thank-you for the suggestions on the Vibrato issue Myles. I'll try this and give you some feedback on it afterwards.

Cheers!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/21/02 01:21 AM

Quote:
Originally posted by glzebub:
hello there myles.
could you spare just a sec for my problem,

i bought a few months ago after saving for a year a trace elliot C50 (owned by Gibson now btw), the manual says that four of the five ECC83's are used on clean and on overdrive, however when the overdrive boost (channel 3) is kicked on, a fifth preamp tube comes into the fray, another ECC 83 i believe, would it be possible to change this fifth tube to some sort of high gain tube so as to really emphasise the gain addition, cos it's a bit tame. something harder edged like a modern marshsall, it's still a bit vintage sounding just like the od without the boost, very little difference. i do love the normal drive channel but i would just love more of a change between theese two modes
one final thing, the output tubes are two Svetlana EL-34's, are these any good (i know nothing of this brand), would changing them improve the tone?
thank you very much.
glzebub,

The "fifth" tube is not what kicks on for extra gain. Only your first two preamp tubes are used for gain. Its more a matter of changing some voltages more than anything else after the first two gain stages, and a single ECC83 can provide two stages of gain depending on how the circuit is set up.

Your last preamp tube is generally you phase inverter and this is not a part of the gain structure.

ECC83's these days are made by Ei in some cases and by JJ in other cases. These tubes vary from 50% below spec to 40% above, and its all chance unless you have a way to measure and grade the preamp tubes.

If you want more gain, what you need to do is replace V1, as it feeds everything else, with an ECC83 (if you want to keep the same tonal characteristics and not make the amp darker or brighter). You have two options:

1. Call Bob at Eurotubes and have him hand pick you and ECC83 and tell him you want a really strong one.

2. Go to the Watford Valves website, and order an ECC83 from them, but tell them you want something in the 270-280 range. That will give you a LOT of gain.

Both these folks are on my website with their links.

On your Svetlana's .... some folks think these are some of the best EL-34's around. The are much better than the Sovteks which in turn are much better than any of the Chinese offerings.

If you want more mids, then you can go for a JJ E34L tube, which is an even stronger tube. These are also available as the E34LS tube from Groove Tubes with a slight difference.

For now, and to save some money, I'd just go for the preamp tube, as your Svetlana's are very strong and very nice tubes.

Hope this helped.

Regards,
Posted By: Griffinator

Re: Feel free to ask Myles - 04/21/02 01:47 AM

Hey - one more question for you:

I've got a Fender Lead I that I just replaced hardware on - but I've discovered that the stock pickup is either too worn out or just not hot enough for my purposes.

Any recommendations on a pickup with more output, but still functions well in the coiltap/split 'bucker configuration? I love having that flexibility to go into "Strat" mode - and I want a pickup that will sound good split.

Cheers!

Griff
Posted By: hechtdavid

Re: Feel free to ask Myles - 04/21/02 10:04 PM

Hi Myles,

I'm still looking for that perfect preamp tube set-up for my 1999 "Evil" Twin. I got a few JJ's (thanks Bob) and they really did the trick cleaning up the reverb and added some crunch (along with some grainy-ness) to the drive channel, but I'm still not happy with the clean sound. I've got 2 Groove Tube 7025's (Serbian origin) on the way. Where would you put 'em? V1(ch1), V2 (ch1 drive) or V3 (ch2) ? BTW, do you ever tour to the heartland? Would love to attend one of your amp clinics, but from Wisconsin to LA with a Twin is quite a haul. (Hell, even across town is a haul with this beast!)

Thanks - You're the BEST!
Posted By: Cornforduser

Re: Feel free to ask Myles - 04/22/02 11:12 AM

Myles,
If the original Bassman preamp layout was :
12AY7 + 12AX7 + 12AX7 (driver) why people claim that a 12AT7 in the driver will make it more Bassman-ish???
Thanks.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/22/02 07:17 PM

Quote:
Originally posted by Griffinator:
Hey - one more question for you:

I've got a Fender Lead I that I just replaced hardware on - but I've discovered that the stock pickup is either too worn out or just not hot enough for my purposes.

Any recommendations on a pickup with more output, but still functions well in the coiltap/split 'bucker configuration? I love having that flexibility to go into "Strat" mode - and I want a pickup that will sound good split.

Cheers!

Griff
Griffinator,

There are so many pickups out there that this is one of those questions where you may want to talk directly to the folks over at a play like Seymour Duncan.

This is all personal taste.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/22/02 07:52 PM

Quote:
Originally posted by hechtdavid:
Hi Myles,

I'm still looking for that perfect preamp tube set-up for my 1999 "Evil" Twin. I got a few JJ's (thanks Bob) and they really did the trick cleaning up the reverb and added some crunch (along with some grainy-ness) to the drive channel, but I'm still not happy with the clean sound. I've got 2 Groove Tube 7025's (Serbian origin) on the way. Where would you put 'em? V1(ch1), V2 (ch1 drive) or V3 (ch2) ? BTW, do you ever tour to the heartland? Would love to attend one of your amp clinics, but from Wisconsin to LA with a Twin is quite a haul. (Hell, even across town is a haul with this beast!)

Thanks - You're the BEST!
David,

The 7025's may be too bright for some tastes. I'd first try one of these in V2. If that does not do the trick, then put the tube back in V2 that was there, and try the 7025 in V1.

Your grainy nature may come from the output section now being driven in a different way than before if you have more or less gain going to the phase inverter.

Is your bias adjusted properly?

The 7025's are the "Fender sound", but newer Fender designs went to the 12AX7's rather than the 7025's.

I generally like a 12AX7 in V1 and V2 of these amps, rather than a JJ version, I'd prefer a JAN version of a USA tube (mostly still under $20), either GE's, Philips, or RCA.

The next choice on my list for these are the Sovtek 12AX7LPS or the 12AX7EH (Electro Harmonix) tubes, but be sure you know their output, as a tube that is too hot will add all sorts of noise and coarseness to the sound.

The best and safest bet on this attack, is to save time and get what you really want. What you want are tubes for V1 and V2, both 12AX7's, from Watford Valves, with a rating of 215 or so for V1 and 240 or so for V2 using their scale.

(For my clients, this would be a rating of 92 for the V1 tube and 108 for V2).

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/22/02 08:13 PM

Quote:
Originally posted by Cornforduser:
Myles,
If the original Bassman preamp layout was :
12AY7 + 12AX7 + 12AX7 (driver) why people claim that a 12AT7 in the driver will make it more Bassman-ish???
Thanks.
Cornforduser,

I think some of the reason for folks saying this is a lack of understanding the various stages of change in the circuits and the change in tubes.

In the 6G6 circuit, a 7025 was used, but this was a USA tube that was a slightly lower output tube, that was stronger in construction, than the 12AX7's of the day back then. Today's non-US 7025's are quite a bit different than those of the past. Today, the gain characteristics of a 12AT7 are close to the 7025 in the past, and somebody probably used this, the rumor started, and everybody jumped on the bandwagon perhaps.

The 5E6-A used two 12AY7's in the first two positions and 6L6G's which are only about 19 watt tubes, less than later 26 watt 5881's and those are less than today's 6L6GC's, so this is really a very different citcuit.

The 5F6 is at times considered the "classic" Bassman circuit. This was the config you mentioned at the start of your writing. This did use the 12AX7 in the phase inverter position, but this amp also used a rectifier called an "83", which put out 450-0-450, and was very different than the later GZ34/5AR4 with its 550-0-550 output, so by using the modern rectifier, and then using a 12AT7 in the driver position, you can reduce the delta in the phase inverter portion of the circuit perhaps, or maybe some folks think it compensates in some way to make thing sound different, or .... maybe its just that folks are used to Fender using 12AT7 drivers a lot.

In the 5F6A circuit, Fender went to the GZ34 rectifier, which was perhaps the major change to some ways of thinking.

I would use what sounds the best to your own ears, as these tubes are all able to be changed to your heart's content. I like 12AY7's in V1 on these amps a lot, but a 12AX7 from somebody like Watford Valves with a rating of about 170, works really nicely too.

Regards,
Posted By: Ricksar

Re: Feel free to ask Myles - 04/22/02 08:49 PM

Myles

I enjoy reading your thoughtful advice on various websites. Perhaps you can help me. I have a 1994 Gibson Les Paul Standard with Ernie Ball Super Slinky strings. I am looking for an amp (and effects?) which would give me some of the following amp tones: 1) Jimmy Page on "Led Zepplin 2", 2) Martin Barre on Jethro Tull's "Aqualung", 3) Leslie West on any old Mountain album, 4) Tony Iommi on the first "Black Sabbath" album, and/or 5) Jeff Healey.

Having traded in a Marshall Valvestate 8040 with which I was dissatisfied, I am left with a POD and a 1968 Fender Princeton Reverb.

If the process of finding the right tone becomes too time-consuming (I am a self-employed mid-40's-something, living in suburban Connecticut, 35 miles from NYC, who works long hours and plays so infrequently that I no longer have callouses on my fingers), I will probably buy a modeling amp (e.g., Vox Valvetronix or Line 6 Flextone?) just to have "something".

Can you provide me with any guidance before I take this "desperate" step (which is seemingly inconsistant with the pattern of your advice)? I just don't have the time to try lots of amps and the digital solution is beginning to look like an acceptable one. (Though the range of sounds that I am looking for is fairly narrow. I want that fat humbucking tone which makes it sound as though the pick is plucking against the pickup and causing the note to "wail"). Or might it be my guitar? Many thanks!
Posted By: glzebub

Re: Feel free to ask Myles - 04/22/02 08:55 PM

thanks for the help myles, new valve on it's way.
very much appreciated.
Posted By: hechtdavid

Re: Feel free to ask Myles - 04/22/02 10:40 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by hechtdavid:
Hi Myles,

I'm still looking for that perfect preamp tube set-up for my 1999 "Evil" Twin. I got a few JJ's (thanks Bob) and they really did the trick cleaning up the reverb and added some crunch (along with some grainy-ness) to the drive channel, but I'm still not happy with the clean sound. I've got 2 Groove Tube 7025's (Serbian origin) on the way. Where would you put 'em? V1(ch1), V2 (ch1 drive) or V3 (ch2) ? BTW, do you ever tour to the heartland? Would love to attend one of your amp clinics, but from Wisconsin to LA with a Twin is quite a haul. (Hell, even across town is a haul with this beast!)

Thanks - You're the BEST!
David,

The 7025's may be too bright for some tastes. I'd first try one of these in V2. If that does not do the trick, then put the tube back in V2 that was there, and try the 7025 in V1.

Your grainy nature may come from the output section now being driven in a different way than before if you have more or less gain going to the phase inverter.

Is your bias adjusted properly?

The 7025's are the "Fender sound", but newer Fender designs went to the 12AX7's rather than the 7025's.

I generally like a 12AX7 in V1 and V2 of these amps, rather than a JJ version, I'd prefer a JAN version of a USA tube (mostly still under $20), either GE's, Philips, or RCA.

The next choice on my list for these are the Sovtek 12AX7LPS or the 12AX7EH (Electro Harmonix) tubes, but be sure you know their output, as a tube that is too hot will add all sorts of noise and coarseness to the sound.

The best and safest bet on this attack, is to save time and get what you really want. What you want are tubes for V1 and V2, both 12AX7's, from Watford Valves, with a rating of 215 or so for V1 and 240 or so for V2 using their scale.

(For my clients, this would be a rating of 92 for the V1 tube and 108 for V2).

Regards,
Hi Myles,

Is there anyplace in the US that will "rate" these tubes? For your clients, what do the numbers 92 and 108 refer to? I'm hoping to get something domestically..

Thanks again,

David
Posted By: myles_rose

Re: Feel free to ask Myles - 04/22/02 10:56 PM

Quote:
Originally posted by Ricksar:
Myles

I enjoy reading your thoughtful advice on various websites. Perhaps you can help me. I have a 1994 Gibson Les Paul Standard with Ernie Ball Super Slinky strings. I am looking for an amp (and effects?) which would give me some of the following amp tones: 1) Jimmy Page on "Led Zepplin 2", 2) Martin Barre on Jethro Tull's "Aqualung", 3) Leslie West on any old Mountain album, 4) Tony Iommi on the first "Black Sabbath" album, and/or 5) Jeff Healey.

Having traded in a Marshall Valvestate 8040 with which I was dissatisfied, I am left with a POD and a 1968 Fender Princeton Reverb.

If the process of finding the right tone becomes too time-consuming (I am a self-employed mid-40's-something, living in suburban Connecticut, 35 miles from NYC, who works long hours and plays so infrequently that I no longer have callouses on my fingers), I will probably buy a modeling amp (e.g., Vox Valvetronix or Line 6 Flextone?) just to have "something".

Can you provide me with any guidance before I take this "desperate" step (which is seemingly inconsistant with the pattern of your advice)? I just don't have the time to try lots of amps and the digital solution is beginning to look like an acceptable one. (Though the range of sounds that I am looking for is fairly narrow. I want that fat humbucking tone which makes it sound as though the pick is plucking against the pickup and causing the note to "wail"). Or might it be my guitar? Many thanks!
Ricksar,

If you are going to play in your house and just want to fool around a bit, then any of the modeling amps are fine. Its mostly a matter of features and price in respect to them.

If you are ever going to play in a live situation, then for the Mountain sound, there is really only one choice, and that is to find a mid 60's vintage Sunn amps, as what lined the stages at Woodstock, along with the Fender's, Marshalls, and Acoustic 360's.

A four input Marshall will get you most of the other sounds associated with what you mention, but these were driven very hard.

When you say you are "left with" the 68 Princeton Reverb, consider yourself fortunate. This is a great amp, and if you get a real tube type distortion pedal and front end that amp using input #2, which will give the front end of the Fender more headroom by about 6db, you will be in business with a great sound at rational levels.

Make sure your Fender amp is properly biased, and has the proper tube compliment. If they are original tubes, they are probably long overdue for a change, and this will make a very big difference.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/22/02 11:13 PM

Posted By: hechtdavid

Re: Feel free to ask Myles - 04/22/02 11:26 PM

Posted By: Guitarzan

Re: Feel free to ask Myles - 04/24/02 03:47 PM

hi Myles, i am the guy with the digitech rp14d looking to replace the tube, i can get these tubes:
12ax7a jan-philips ecg usa
12ax7 canadian marconi cmc
usa ecg philips ..with blue silk screened lettering , marked 12ax7,ecc83,7025 on the box and the tube
these are all N.O.S tubes
how do you rate these for tone and gain as well as microphonics? in a multieffect unit is microphonics an issue?
Posted By: MesaUser

Re: Feel free to ask Myles - 04/24/02 08:22 PM

Hello Myles, How hard is it to blow a tranny? My recto(3 channel) has went through a few accidents, as in having the cab unplugged while its on, plugging the cab into the wrong spkr jack. I remember someone sayin that newer amps have a built in load type thing, and I remember the recto manual didnt say anything about damaging the tranny. So does my amp have something to protect from this. It still sounds fine to me.
Posted By: MesaUser

Re: Feel free to ask Myles - 04/24/02 08:27 PM

I accidentally pressed refresh or back on my browser...Sorry Myles.
Posted By: myles_rose

Re: Feel free to ask Myles - 04/25/02 03:16 AM

Quote:
Originally posted by MesaUser:
Hello Myles, How hard is it to blow a tranny? My recto(3 channel) has went through a few accidents, as in having the cab unplugged while its on, plugging the cab into the wrong spkr jack. I remember someone sayin that newer amps have a built in load type thing, and I remember the recto manual didnt say anything about damaging the tranny. So does my amp have something to protect from this. It still sounds fine to me.
MesaUser,

If you amp is working fine, and you did not smell smoke, you are probably okay.

Some of today's amps have a shorting jack in the speaker output from the amp, so when nothing is inserted, there is no B+ to the power section. This was always a cool feature of Rivera amps, but not in a lot of Mesa amps, or others.

Even with a shorting jack, running an amp at the wrong load, will in time (sometimes a very short time), cause tube failure or output transformer failure.

It sounds though, that you are fine.

Amps with older transformers that have seen years of abuse can die in a flash, so its best, even with new amps, to be a bit careful.

Regards,
Posted By: jazzcaster

Re: Feel free to ask Myles - 04/25/02 06:06 AM

Hi Myles,

Just a short update on my Pro Reverb vibrato problem (Lots of noise, not audible at 1/4 power setting). It was, in fact, a defective tube (V6). I replaced the stock Sovtek with a Jan GE 12AX7WA and its fine....quiet, and works great at 1/4 power setting. I didn't really suspect a bad tube because the amp was brand new. Live and learn.....thank-you for your help. How are you making out with your customers Pro Reverb that you've been working on?

Best regards!
Posted By: myles_rose

Re: Feel free to ask Myles - 04/25/02 08:23 PM

Quote:
Originally posted by guitarzan:
hi Myles, i am the guy with the digitech rp14d looking to replace the tube, i can get these tubes:
12ax7a jan-philips ecg usa
12ax7 canadian marconi cmc
usa ecg philips ..with blue silk screened lettering , marked 12ax7,ecc83,7025 on the box and the tube
these are all N.O.S tubes
how do you rate these for tone and gain as well as microphonics? in a multieffect unit is microphonics an issue?
guitarzan,

Microphonics are not as much of an issue in effects, pedals, or even heads as they are in a combo amp.

High gain circuits, even effects, do prefer tubes without a lot of noise though.

I cannot rate those for gain, as gain is all over the scale. You need to look at each of those tubes individually.

Basically from a tone standpoint, a 12AX7 will be a bit darker than an ECC83, and a 7025 will be brighter than the other two.

Gain on a 12AX7 can range from .06mA to over 1.7mA, with the industry standard from the 40's and 50's being 1.2mA. This will make a very big difference in any sort of effect or gain pedal.

The only way to be sure, it to classify and measure your tubes, or purchase them from somebody who can do this such as Eurotubes or Watford Valves. There may be others, but these are the folks I know and currently use.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/25/02 08:53 PM

Quote:
Originally posted by jazzcaster:
Hi Myles,

Just a short update on my Pro Reverb vibrato problem (Lots of noise, not audible at 1/4 power setting). It was, in fact, a defective tube (V6). I replaced the stock Sovtek with a Jan GE 12AX7WA and its fine....quiet, and works great at 1/4 power setting. I didn't really suspect a bad tube because the amp was brand new. Live and learn.....thank-you for your help. How are you making out with your customers Pro Reverb that you've been working on?

Best regards!
jazzcaster,

The first thing I do with any amp, especially a NEW amp, is pull all the tubes and check them out.

In a loud factory environment, they just make sure the amp makes sound, the reverb and vibrato turn off and on, and thats about it.

New bad tubes are VERY common. More are bad than are good from the tube factories.

The work is done on the one I was working on, and all I can say, is hang onto yours, I think you will see it go up in value over the years.

The Fender Pro Tube series is like the original Blackface series in concept and build. They use a tube reverb and vibrato as the old amps did, and the signal chain is all tube.

Their Hot Rod series are tube amps, but the reverb and vibrato are driven with solid state devices, so they are a bit of a hybrid in some respects, but still super amps for the money asked.

Then they have their Custom Shop series with all the point to point wiring etc.

Its nice they have such an extensive line with products that are usable in the real world, and in a performance venue or live venue, rather than the offerings of some other folks.

Regards,
Posted By: Guitarzan

Re: Feel free to ask Myles - 04/26/02 02:51 AM

thanks again, Myles. i will probably go with the jan-philips.it should be an improvement over the sovtek 12ax7wa.i am not familiar with the canadian marconi 12ax7. i need some tone and am looking for a tight bottom and a and a friendly high end.
Posted By: jazzcaster

Re: Feel free to ask Myles - 04/26/02 04:15 AM

Hi Myles,
Bias, bias, bias.....yet another question...

How much "lee-way, free board, etc." is there when setting the bias (before you damage something, that is). And how much of a change in bias is really significant? Fender gives a bias spec of 30ma for the new Pro Reverb. I am reading through Dan Torres's "Inside Tube Amps" book and his chart gives a bias setting of 25.7ma (voltage of 465, class A/B, 6L6 tube). The lower the ma, the colder the bias, correct? Is 5ma or so either way going to make any difference I can hear? (or damage the tubes/amp?). Dan suggests setting the bias "by ear", that is, set the bias, play through it for a few minutes, then reset/adjust til it sounds right. This makes sense to me, but I don't know the min/max I can go with the adjustment before something is damaged. I have Svetlana 6L6's in now, an upgrade from the stock Sovteks (I noticed an improvement right away).

Thanks Myles,

best regards.
Posted By: Saint Frank

Re: Feel free to ask Myles - 04/26/02 09:29 PM

Hey Miles, being new to tube-dom, I have a coupla questions (well, more like 20,000 but most will have to wait).
I just got a Peavey Rockmaster. Pretty nice unit, especially once I get a power amp that I can have some master control over (I'm using the power amp out of my Laney and have no master volume). Anywho, I want to replace the stock Peavey 12AX7s and am looking to get a more Vox-ish sound on the clean and crunch, and a Marshall-y/ Laney sound out of the Ultra channel. My understanding of the gain stages is that they are cascading with the first tube being used by all, then adding tubes up to four in the Ultra channel. I'm thinking ECC83s in the first two sockets, a 12AX7 in the third and a 7025 or another 12AX7 in the last. Thoughts?

------------------
http://www.saintfrank.com
Posted By: myles_rose

Re: Feel free to ask Myles - 04/27/02 12:04 AM

Quote:
Originally posted by jazzcaster:
Hi Myles,
Bias, bias, bias.....yet another question...

How much "lee-way, free board, etc." is there when setting the bias (before you damage something, that is). And how much of a change in bias is really significant? Fender gives a bias spec of 30ma for the new Pro Reverb. I am reading through Dan Torres's "Inside Tube Amps" book and his chart gives a bias setting of 25.7ma (voltage of 465, class A/B, 6L6 tube). The lower the ma, the colder the bias, correct? Is 5ma or so either way going to make any difference I can hear? (or damage the tubes/amp?). Dan suggests setting the bias "by ear", that is, set the bias, play through it for a few minutes, then reset/adjust til it sounds right. This makes sense to me, but I don't know the min/max I can go with the adjustment before something is damaged. I have Svetlana 6L6's in now, an upgrade from the stock Sovteks (I noticed an improvement right away).

Thanks Myles,

best regards.
jazzcaster,

The bias of 30mA that Fender suggests is nice value for the most part. Its still a bit on the cool side, but should sound fine enough for most tastes.

Using Torres figure, I would need to know if it figures a 6L6GC or a 6L6B etc. The 6L6 family ranged from 19 watts to 30 watt tubes. If Torres is saying that at 465 plate volts with a 30 watt 6L6GC, should be set at 25.7mA, then I would have a different feeling on this, but this would be a figure that would surely give you long tube life.

I know a lot of folks that set bias by ear, and since audio memory is very subjective, and the room acoustics and playing style can really effect settings, I generally pass on this method.

Remember, a race car engines runs it best, the few seconds before it blows up, and this is true of a lot of amps too.

Your amp has a nice easy way to set bias, and I'd stick to that, maybe go as high as 38mA without damage but with much faster tube wear. I think the Fender figure of 30mA is a nice figure, and at this setting, your Svets will have a nice long life and sound very good. If you want to see if you can hear a difference, try going to 32mA. Look for things like increased clarity on the clean channel, that is, how high you can turn up the volume and still have a clean sound. If it does not change things, then just be happy the way it is.

Regards,
Posted By: daddyelmis

Re: Feel free to ask Myles - 04/27/02 12:05 AM

Myles:

here's a question I can't seem to get an answer to. I've got a Marshall DSL201 with NOS Jan/Phillips 12AX7WA's in the preamp and JJ's for the EL84's.

I'm running a Digitech 2101 on the front end (also with the JAN/Phillips 12AX7WA) for analog & digital effects (not through the loop). In the clean channel, everything sounds great. In the distortion channel, the digital effects (delays, flange, etc.) are greatly more pronounced, to the point where it is very noticeable and sound like a different patch.

To keep the analog effects (compression, distortion, eq) on the front end of the amp, I'm constrained to run the digital effects that way (essentially using the 2101 like an elaborate stomp box).

My question is why are the effects so pronounced in the distortion channel? I run that channel at about 3-4 on gain and 5-6 on volume, using it to get the "marshall" overdrive. I drive the power amp at about 7 (nice thing about the low wattage amp, power tube effect at volume that doesn't kill people).

BTW, I've replaced all 4 stock 12AX7's with the JAN/Phillips, and the clean channel breaks up nicely with gain at 5-6 and guitar volume cranked, and cleans up well rolling off the guitar. Any observations on using all 12AX7A's in the preamp?

Thanks,

Greg
Posted By: daddyelmis

Re: Feel free to ask Myles - 04/27/02 12:13 AM

Myles:

One follow up I forgot . . . what can you tell me about biasing this amp? I can't seem to find any info about bias on this amp. I had to do a semi-emergency power tube change when I put the JJ's in, and did not adjust bias. The amp sound and behaves fine (sounding better than before). But, of course, I'm worried that I'm ruining something.

thoughts?
Posted By: myles_rose

Re: Feel free to ask Myles - 04/27/02 12:17 AM

Quote:
Originally posted by Saint Frank:
Hey Miles, being new to tube-dom, I have a coupla questions (well, more like 20,000 but most will have to wait).
I just got a Peavey Rockmaster. Pretty nice unit, especially once I get a power amp that I can have some master control over (I'm using the power amp out of my Laney and have no master volume). Anywho, I want to replace the stock Peavey 12AX7s and am looking to get a more Vox-ish sound on the clean and crunch, and a Marshall-y/ Laney sound out of the Ultra channel. My understanding of the gain stages is that they are cascading with the first tube being used by all, then adding tubes up to four in the Ultra channel. I'm thinking ECC83s in the first two sockets, a 12AX7 in the third and a 7025 or another 12AX7 in the last. Thoughts?

------------------
http://www.saintfrank.com
Saint Frank,

I think I answered this earlier at some point?

In any case, only your first two preamp tubes are used in the gain stage, and 90% of that is in the first 12AX7.

Your tone shaping is nothing at all like that of a Marshall or a Vox, so if you are looking to sound more like either of those amps, but never both, that is pretty tough without a mod to your tone stack and some other areas.

All I can say, is try an ECC83 in V1, and see if that gets you closer to what you desire.

Good luck,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/27/02 12:21 AM

Quote:
Originally posted by daddyelmis:
Myles:

One follow up I forgot . . . what can you tell me about biasing this amp? I can't seem to find any info about bias on this amp. I had to do a semi-emergency power tube change when I put the JJ's in, and did not adjust bias. The amp sound and behaves fine (sounding better than before). But, of course, I'm worried that I'm ruining something.

thoughts?
daddyelmis,

Are they JJ EL-34 tubes or E34L tubes? If they are the E34L tubes, I'd have the bias checked.

Regards,
Posted By: daddyelmis

Re: Feel free to ask Myles - 04/27/02 02:38 AM

Are they JJ EL-34 tubes or E34L tubes? If they are the E34L tubes, I'd have the bias checked.

Regards,[/QB][/QUOTE]

They are JJ EL-84's (20 watt amp).
Posted By: AgentOrange

Re: Feel free to ask Myles - 04/27/02 09:03 PM

I have a Mk1 Mesa Rectoverb 50W combo and i love it but it has certain problems that i belive are due to old or defective valves. Im sure it should be louder than it is, having tried others that seemed to be, which leads me to believe there is a power tube failure, both are glowing orange but i still believe this to be the case. At a recent band practice, the other guitarist had to use an old 40 watt practice amp (Peavey Envoy 110) which worryingly kept up with me, even with the master and ouput volumes at 12 oclock (after this point, the sound turns to mud and there is neglegable increase in volume, another problem possibly caused by bad valves). Also, it now seems to have developed a low rumble/hum which doesnt get louder by increasing the output volume, leading me to believe that this is a power amp problem and once again, probably (and hopefully) due to a valve failure. Do you think i am right in thinking that the lack of volume isnt just an inherant design floor but a valve problem (seeing as i am unable to get a useable sound past 12 oclock on both volume controls)?

Its main application is high gain rhythm and lead playing, tho i do regularly enjoy the fantastic clean channel, it has two channel over all and two modes per channel. I was wondering what pre/poweramp valves would suit it best. I would like a more defined gain response from it and also, if possible, a better treble reponse. It has 7 valves in total, 5x 12AX7s and 2x 6L6s (50watts).

The rectoverb is a fixed bias amp, so, would it be possible to replace all the valves my self, or would i be advised to seek out an amp tech (the dealer i bought it from is 2 hours drive away). If no, then how much do you tihnk it would cost. I have been told that most Mesas come biased cold and that by having this set correctly, tone can be vastly improved. Would this be an expensive operation if done at the same time as the valve replacement, assuming this is required.

Additional technical information, taken from manual, though i was unsure how to interpret it since it seems to describe 6 Preamp valves when there are onyl 5 (it discriminates between 5 and 6 not 5A and 5B):-

Description of Valve Functions

V1A-Input Stage
V1B-2nd Stage (Rhythm & Lead)
V2A-3rd Stage Rhythm
V2B-3rd Stage Lead
V3A-4th Stage Lead
V3B-5th Stage Lead
V4A-FX Send
V4B-FX Return
V5 + V6 - Phase Inverter

In summary, how much do you think it would cost, from the information given, to aleviate my amp problems, including the price of new valves and any labour required? A quick reply would be greatly appreciated. Also, i live in the UK, so Watfor Valves are onyl aphone call away to order any valves you can recommend.

cheers
Posted By: dave251

Re: Feel free to ask Myles - 04/28/02 03:26 PM

An update on the acoustic/electric/300B amp project....

The buzz is gone; we added a 12AX7 to the to front end, rather than using the first stage of the 6SN7. Since Brett feels like we will have enough gain from the first stage of the 12AX7, we will try using the second half for the 300B driver...keeping our tube complement to a minimum. Most of the 300B experts claim the 6SN7 is necessary as the impedance match with the 300B is about right.

Do you have any recommendations for a currently manufactured 12AX7? None of this NOS stuff, we need to be able to use these in a production environment.

So, the current tube complement is: 12AX7 to 6SN7 to 300B; still using the 5U4 as rectifier.

Brett will have the amp out on the first live job next Friday. Basically an "acoustic" situation with the addition of electric bass and pedal steel. He says it won't quite match the volume of his BF Deluxe yet...but it's real close.
Posted By: fairock

Re: Feel free to ask Myles - 04/28/02 08:49 PM

Hi Myles,
I am new to the tube amp. Seems like everyone's asking you questions on Harmony and musicplayer. So I thought, hey why not my turn. Thank you
in advance.
I would like to know what would be good preamp and power tubes for a Mesa Boogie Rectoverb 50 watts combo?
People seem to put 12AT7 at Phase inverter. What exactly is Phase inverter? Does V5 with 12AT7 affect the gain of power tubes?
V1= input
V2= Channel 1( clean)
V3= Channel 2( lead )
V4= FX Loop
V5= Phase inverter

Thanks
Posted By: GTO

Re: Feel free to ask Myles - 04/29/02 03:11 AM

Hey Myles!
When you get a chance, I'm noticing a buzzing noise through my amp when I'm not touching the strings on my guitar. It's actually not that loud but it is noticeable. What could this be? It's happening with all of my guitars, single coil(s) and humbucker(s). Also, what could be a jangly noise coming from the back of the amp that only is audible as certain notes are played at about half volume?

Thanks for your time and the info
Posted By: myles_rose

Re: Feel free to ask Myles - 04/29/02 11:59 PM

Quote:
Originally posted by daddyelmis:
Are they JJ EL-34 tubes or E34L tubes? If they are the E34L tubes, I'd have the bias checked.

Regards,
They are JJ EL-84's (20 watt amp).[/QB][/QUOTE]

daddyelmis,

I think I got confused....

You will not need a bias check with the EL-84's as they really do operate very well over a very wide range and operate at lower plate voltages.

Just play and enjoy!

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/30/02 12:24 AM

Quote:
Originally posted by AgentOrange:
I have a Mk1 Mesa Rectoverb 50W combo and i love it but it has certain problems that i belive are due to old or defective valves. Im sure it should be louder than it is, having tried others that seemed to be, which leads me to believe there is a power tube failure, both are glowing orange but i still believe this to be the case. At a recent band practice, the other guitarist had to use an old 40 watt practice amp (Peavey Envoy 110) which worryingly kept up with me, even with the master and ouput volumes at 12 oclock (after this point, the sound turns to mud and there is neglegable increase in volume, another problem possibly caused by bad valves). Also, it now seems to have developed a low rumble/hum which doesnt get louder by increasing the output volume, leading me to believe that this is a power amp problem and once again, probably (and hopefully) due to a valve failure. Do you think i am right in thinking that the lack of volume isnt just an inherant design floor but a valve problem (seeing as i am unable to get a useable sound past 12 oclock on both volume controls)?

Its main application is high gain rhythm and lead playing, tho i do regularly enjoy the fantastic clean channel, it has two channel over all and two modes per channel. I was wondering what pre/poweramp valves would suit it best. I would like a more defined gain response from it and also, if possible, a better treble reponse. It has 7 valves in total, 5x 12AX7s and 2x 6L6s (50watts).

The rectoverb is a fixed bias amp, so, would it be possible to replace all the valves my self, or would i be advised to seek out an amp tech (the dealer i bought it from is 2 hours drive away). If no, then how much do you tihnk it would cost. I have been told that most Mesas come biased cold and that by having this set correctly, tone can be vastly improved. Would this be an expensive operation if done at the same time as the valve replacement, assuming this is required.

Additional technical information, taken from manual, though i was unsure how to interpret it since it seems to describe 6 Preamp valves when there are onyl 5 (it discriminates between 5 and 6 not 5A and 5B):-

Description of Valve Functions

V1A-Input Stage
V1B-2nd Stage (Rhythm & Lead)
V2A-3rd Stage Rhythm
V2B-3rd Stage Lead
V3A-4th Stage Lead
V3B-5th Stage Lead
V4A-FX Send
V4B-FX Return
V5 + V6 - Phase Inverter

In summary, how much do you think it would cost, from the information given, to aleviate my amp problems, including the price of new valves and any labour required? A quick reply would be greatly appreciated. Also, i live in the UK, so Watfor Valves are onyl aphone call away to order any valves you can recommend.

cheers
AgentOrange,

The first problem is that your tubes, as you are putting it, are glowing orange. If you mean the normal red glow of the heaters, that is one thing, but if the plate structure is glowing, this is another issue, and a bad one.

I need to assume, and correct me if I am wrong, that the tubes in this amp are not MESA tubes, but were replaced at some time in the past. If they were Mesa tubes, this would not generally happen.

If your amp is so underbiased that the tubes are glowing, this indeed would trash your tubes, and really make the amp sound very poorly.

You should first get those 6L6's replaced. You can order Mesa tubes directly, and if you do, I'd go with their STR-454's which are Svetlana tubes, and better than the Sovtek or Chinese tubes they also sell.

Mesa amps are overbiased, which makes them run on the cold side, so you are correct in what you have been told.

You do not need to have a tech look at the amp unless there are other problems. I would first change the output tubes.

V5 is the phase inverter, but it does use both sides of this triode for that function.

Since you are in the UK, that would be an even better bet than Mesa. Just tell them the tubes are for a Mesa amp, and they will pick tubes for you that are mid-range tubes that will work fine in your amp.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/30/02 12:46 AM

Quote:
Originally posted by dave251:
An update on the acoustic/electric/300B amp project....

The buzz is gone; we added a 12AX7 to the to front end, rather than using the first stage of the 6SN7. Since Brett feels like we will have enough gain from the first stage of the 12AX7, we will try using the second half for the 300B driver...keeping our tube complement to a minimum. Most of the 300B experts claim the 6SN7 is necessary as the impedance match with the 300B is about right.

Do you have any recommendations for a currently manufactured 12AX7? None of this NOS stuff, we need to be able to use these in a production environment.

So, the current tube complement is: 12AX7 to 6SN7 to 300B; still using the 5U4 as rectifier.

Brett will have the amp out on the first live job next Friday. Basically an "acoustic" situation with the addition of electric bass and pedal steel. He says it won't quite match the volume of his BF Deluxe yet...but it's real close.
Dave,

These are tubes that are similar in some aspects and very different in other aspects.

What you may want to do, is leave the socket for the 6SN7 and supply the amp with an adaptor, that will make the correction and allow the use of a 12AX7.

The impedience of the 12AX7 ranges from about 62,500 ohms using 250 plate volts and a -2v bias, to 80,000 ohms at 100 volts with a -1 volt bias.

The 6SN7 is about 7700 ohms ( or about ten times less ), at 250 volts with a -8 volt bias, and at 90 plate volts with a 0 volt bias, is down to about 6700 ohms.

The 12AX7 can dissapate about a watt, and the other tube about 5 times that, or about 5 watts.

With either tube though, generally, the lower you can get your plate voltage, the wider your bandwidth and frequency response, so it becomes a matter of compromise ... to get the drive and gain you want and yet keep the bandwidth you like.

Let me take a look at the prints again, and keep me informed.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 04/30/02 12:53 AM

Quote:
Originally posted by fairock:
Hi Myles,
I am new to the tube amp. Seems like everyone's asking you questions on Harmony and musicplayer. So I thought, hey why not my turn. Thank you
in advance.
I would like to know what would be good preamp and power tubes for a Mesa Boogie Rectoverb 50 watts combo?
People seem to put 12AT7 at Phase inverter. What exactly is Phase inverter? Does V5 with 12AT7 affect the gain of power tubes?
V1= input
V2= Channel 1( clean)
V3= Channel 2( lead )
V4= FX Loop
V5= Phase inverter

Thanks
fairock,

As far as rcommending tubes, that is really user taste and preference.

I would steer clear of Chinese output tubes in most cases, but there are some nice Chinese preamp tubes if you want to tame some of the brighness in some amps.

As far as the phase inverter, a 12AT7 will give you more clean headroom, but most Mesa owners are looking for gain, which this would contraindicate.

As far as tubes, maybe read some of the reviews and writeups on my website. This will also explain a bit about a phase inverter.

Regards,
Posted By: Nollykin

Re: Feel free to ask Myles - 05/01/02 01:12 AM

Myles: I have a formal complaint about the member JTK.

He has been posting spam on these boards a good many times, and we have already confronted him and asked him to stop. When I asked you to perhaps warn him, in his post, "www.live1on1guitarlessons.com", I was followed up by a private message from him in which I was abused in the following way:

"Here is the message sent by jtk:

Subject: Talk to me...
--------------------------------------------------

Hey, I don't understand what your problem is? Mind your fucking business! I am a vaid instructor and trying to bring my site to attention. You have way too much free time to police shit dude! FUCK OFF and don't write back!"

Now, I am all for fairness, and stuff, and I'm not saying "get rid of him"... but a formal warning would be nice...

Ta, myles - hope you can sort this out, moderator.

Nolly
Posted By: myles_rose

Re: Feel free to ask Myles - 05/01/02 01:44 AM

Quote:
Originally posted by GTO:
Hey Myles!
When you get a chance, I'm noticing a buzzing noise through my amp when I'm not touching the strings on my guitar. It's actually not that loud but it is noticeable. What could this be? It's happening with all of my guitars, single coil(s) and humbucker(s). Also, what could be a jangly noise coming from the back of the amp that only is audible as certain notes are played at about half volume?

Thanks for your time and the info
GTO,

I need to know a bit more.

The type of amp you have?

How old is the amp?

It sounds like it could be a few things as you have different symptoms.

On the noise all the time - could be a preamp tube - does this happen if you lift the ground with a lift? Does it happen the same in all places, as you may have bad AC?

The noise from the back of the amp is some sort of vibration of a component or microphonics in possibly an output tube. These would both happen at certain frequencies.

In combo amps this is more of a common occurance. If you have a Mesa product, this is quite common as they use self tapping sheet metal screws to hold everything, even heavy items such as transformers, and these amps need to be "torqued down" at least a few times a year with regular use.

Regards,
Posted By: GTO

Re: Feel free to ask Myles - 05/01/02 02:31 AM

Quote:
Originally posted by myles111:
Quote:
Originally posted by GTO:
Hey Myles!
When you get a chance, I'm noticing a buzzing noise through my amp when I'm not touching the strings on my guitar. It's actually not that loud but it is noticeable. What could this be? It's happening with all of my guitars, single coil(s) and humbucker(s). Also, what could be a jangly noise coming from the back of the amp that only is audible as certain notes are played at about half volume?

Thanks for your time and the info
GTO,

I need to know a bit more.

The type of amp you have?

How old is the amp?

It sounds like it could be a few things as you have different symptoms.

On the noise all the time - could be a preamp tube - does this happen if you lift the ground with a lift? Does it happen the same in all places, as you may have bad AC?

The noise from the back of the amp is some sort of vibration of a component or microphonics in possibly an output tube. These would both happen at certain frequencies.

In combo amps this is more of a common occurance. If you have a Mesa product, this is quite common as they use self tapping sheet metal screws to hold everything, even heavy items such as transformers, and these amps need to be "torqued down" at least a few times a year with regular use.

Regards,
It's a Traynor YCV80 (2x12). I haven't had it for very long, just a few months. If it's the preamp or power amp tubes, what should I look for? How should the tubes be seated? I'm a little in the dark here. I bought the amp mail order after I heard a friend's YCV40 and have been very pleased with the tone. Unfortunately, these problems have popped up recently. I've been in contact with Yorkville and they said to send it to them. I hate to tell ya but it's gonna be expensive just to send the thing to and fro and I'm concerned that it'll come back with a note saying that they couldn't find anything wrong with it. I was wondering if there's something that I could do to rectify the situation myself or locally, I live in the Cincinnati,OH area. I'm a novice at amps but have worked with electronics for a while now. Any suggestions?
Thanks for responding BTW.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/01/02 03:30 AM

Quote:
Originally posted by Nollykin:
Myles: I have a formal complaint about the member JTK.

He has been posting spam on these boards a good many times, and we have already confronted him and asked him to stop. When I asked you to perhaps warn him, in his post, "www.live1on1guitarlessons.com", I was followed up by a private message from him in which I was abused in the following way:

"Here is the message sent by jtk:

Subject: Talk to me...
--------------------------------------------------

Hey, I don't understand what your problem is? Mind your fucking business! I am a vaid instructor and trying to bring my site to attention. You have way too much free time to police shit dude! FUCK OFF and don't write back!"

Now, I am all for fairness, and stuff, and I'm not saying "get rid of him"... but a formal warning would be nice...

Ta, myles - hope you can sort this out, moderator.

Nolly
Nollykin,

I have just received a private message from him today in regard to his lessons. I will speak to him and ask, rather than send messages to individuals in an unsolicited way from this forum, if he could use some other method.

If his lessons and website are good for a lot of folks, I will be happy to add his info to my own website, and in that way, if people want, they can click and go to his website, and if they are not interested, they can ignore it.

Oen of the aspects of this website that is nice, is that folks generally do not send out unsolicited stuff to people and keep things on a more informative and helpful level.

I guess a lot of us slip up from time to time ... even today on a post I mentioned that during an amplifier clinic a "special deal", but at least forks can ignore it, as I do not send things to specific folks.

I will try to follow up.

Regards
Posted By: myles_rose

Re: Feel free to ask Myles - 05/01/02 03:37 AM

Posted By: overcomer

Re: Feel free to ask Myles - 05/01/02 06:18 AM

hi myles,i, as others, appreciate all the time you spend giving out your help. i have a 69 super reverb with rca tubes, sounds very nice, i like it loud and clean, BUT, i have heard of all the cool mods that can be done with certain 6L6s to cause a very early breakup, and also know about 5751s and 12ay7s and 12au7s,,, but, when i take it to a good tech i know for an adjustment, what tubes should i go with to get this tone out of it? i know it has to do with the right v2 preamp tube and the right 6L6s. what would the best tube compliment be along with the right "running hot" bias? thanks james in kansas,,,
Posted By: halcyon

Re: Feel free to ask Myles - 05/01/02 08:44 AM

hey myles i got a rectoverb head and im thinking of getting all jj's. will they be too dark? Will they work well with my rectoverb? also what number powertubes(6L6) should i get to get me out of crossover dist. also could i put 10's in there without hurting the amp or tubes?
Posted By: dave251

Re: Feel free to ask Myles - 05/01/02 06:45 PM

Myles- What would be the audible difference between AC heated filaments and DC heated filaments? We're getting ready to start on the second amp and this question came up....

Thanks,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/01/02 09:19 PM

Quote:
Originally posted by overcomer:
hi myles,i, as others, appreciate all the time you spend giving out your help. i have a 69 super reverb with rca tubes, sounds very nice, i like it loud and clean, BUT, i have heard of all the cool mods that can be done with certain 6L6s to cause a very early breakup, and also know about 5751s and 12ay7s and 12au7s,,, but, when i take it to a good tech i know for an adjustment, what tubes should i go with to get this tone out of it? i know it has to do with the right v2 preamp tube and the right 6L6s. what would the best tube compliment be along with the right "running hot" bias? thanks james in kansas,,,
James,

That might seem like an easy question(s), but its really one of the hard ones.

First of all, the biggest problem is your amp. The Super Reverb is a tough character, as it is very versitle. This may seem like a good point, but in fact, it lends to the confusion.

Some amps do one thing well, and one thing only. A Twin Reverb is a clean amp all the time, and when its driven into distortion, its not as nice of a compressed distortion as some other amps. On top of that, it has a lot of headroom and dynamic range, so a player's touch on the amp does not have as much impact as on some other amps.

Then on the other side of the scale, there are amps like the Vox AC-30, which has its own sound, and things like a Deluxe Reverb, which has a great wide range of dynamics and touch, but is a bit small for some folks in a larger venue. Last, there are amps like my Marshall JTM-45 ... This is an amp with ONE sound, and really ownly sounds right at one setting!

Your Super Reverb can be clean, compressed, blusey, can fill a big room, and has much more touch dynamics than the 85-100 watt Fender amps.

What I do with these amps, is use a set of Tung-Sol 5881's in the output section. These are NOS tubes, but there are a lot of them around, and even Groove Tubes sells them for about the same cost as the Svetlana 6L6's or the JJ 6L6's.

I get these with a rating of mid range, about #5, or else the amp can still be a bit too loud. If you want more clean headroom, then go to a #7 set.

On the gain stage, the V1 and V2 tubes, your amp has more voltage on the plates than a Twin Reverb. Your amp has about 270 volts on the plates, which is pretty healthy. A Twin Reverb AB763 circuit has about 20-30 volts less on the plates of V2 (the vibrato channel preamp). On the AA769 circuit, it is about 210 volts, even lower than the AB763 circuit.

If you want to tame the front end gain, then try a 5751 in V1 if you plug into the normal channel, or V2 if you use the vibrato channel.

If you want the original Fender sound, then make sure you use 7025's in V1 and V2, as these are a brighter tube than a 12AX7.

If you want a darker amp, more for jazz and blues, then go to a 12AX7C (Chinese, but get a new Chinese not an old one).

Most of my Fender clients keep at least these three tubes and swap them depending on the sound they want at the time. Think of it as the first generation of "modeling amp" \:\)

It is VERY important to have a matched phase inverter in these amps. The amp will be much more articulate and the sustain at even lower levels will improve dramatically. You can get matched 12AT7's from a few folks such as Eurotubes and Watford Valves. Just ask for a tube where the A and B sides are matched.

Preamp tubes also vary widely in specs, so try to get your tubes from a vendor than can tell you what the tubes are doing, and then they can also get you a replacement with the same characteristics. Too many times, somebody replaces a preamp tube with a "new" one, and their gain and tone goes down the toilet, as the new tube had 30% less output then the "old" tube that was in the amp.

On output tubes, there are the 5881's which I mentioned above, but after testing for the last few months the new GE 6L6 tube from Groove Tubes, these are what we have been using in 40-50 watt Fender amps. They make the Vibro King amazing.

For bias as a starting point:

For 5881's, have your bias set to 31mA.

For the new 6L6GE's set bias to 29mA

For Svetlana, 6L6GC Sylvania's or JJ's, set the bias to 34-36mA.

These are good starting points, and this assumes your B+ voltage is about 460 volts, which seems to be the most common voltage on these amps.

Make sure your filter caps are in good condition. If they are going bad, but not yet all dried out of have not failed, the will limit the sustain as your power supply will not have the reserve it can have. A good tech will have a capacitor tester, but a good tech with a scope can look at the noise and ripple on the power and if he has a keen eye, can measure the noise floor of the amp to check the caps. These caps are not all that expensive and are not hard to change, so if you need new caps and your tech wants $150 or so, then find a new tech. This is a job that is under an hour.

So, try a few different preamp tubes, and get your bias checked, and let me know if you need more specific help, just maybe phrase your post in here with specific questions, and I will get to them one at a time.

Hope this was at least of some help.

Regards,
Posted By: overcomer

Re: Feel free to ask Myles - 05/02/02 12:10 AM

oh yeah, that is a tremendous help, i had thought ( while i was waiting for your reply) about getting a pair of the new groove tube 6L6 ge's. and the info you have given is really quite extensive. too bad i live so far away, i would definitely give you some business. now all i have to do is advise my sometime tech, who is very capable, of your insight and go from there... thanks again.
Posted By: mikey_dup1

Re: Feel free to ask Myles - 05/02/02 12:17 AM

Thanks Miles for all the great info. I am still working with my Fender Deville I picked up last week. Would I be disappointed by using a 12AT7 in the rectifier spot? Also what's better Svets 6L6 or Groove Tubes?
Posted By: myles_rose

Re: Feel free to ask Myles - 05/02/02 01:09 AM

Quote:
Originally posted by halcyon:
hey myles i got a rectoverb head and im thinking of getting all jj's. will they be too dark? Will they work well with my rectoverb? also what number powertubes(6L6) should i get to get me out of crossover dist. also could i put 10's in there without hurting the amp or tubes?
halcyon,

The JJ's are actually a little brighter in your amp than Svetlana's. They work really nicely in any of the Mesa Rectifier series that use 6L6's as an output tube.

You will never get totally out of crossover notch distortion with a class A/B amp. Its more of a matter in how high you can crank up the amp before this is a part of the picture. In some amps, like Marshall amps, you NEED crossover distorion at a certain level or they do not sound like Marshall amps.

Normally, you want to see some crossover notch at about 70% of the amps max drive level. If you bias so cold that the distortion does not come until way later, or never comes at all, then the cold bias makes the output run so hot, that tube life suffers, the amp has no dynamic range, and it does not sound right.

For your amp, I like tubes with a Groove Tubes range of 7-8. This gets the notch off of "4" and puts it closer to the desired "7", really cleans up the amp, makes it smoother (especially at lower settings), gives you much more in the area of touch dynamics, and will give the amp more output overall with a wider frequency response range.

In the case of JJ's, Bob Pletka is sort of a master at picking the right range tubes for Mesa's fixed bias. He's got this down pat.

JJ's are very strong tubes physically as well, which is a nice attribute if the amp does a lot of travelling. They seem to hold up well in an airfreight situation.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/02/02 02:11 AM

Quote:
Originally posted by dave251:
Myles- What would be the audible difference between AC heated filaments and DC heated filaments? We're getting ready to start on the second amp and this question came up....

Thanks,
dave251,

There is not a difference in program material sonic quality, but there can be a difference in background noise sonic quality.

With DC heaters, the amp may have less 60 cycle hum on the preamp tube which depending on the rest of the circuit may make a difference.

DC heaters are a bit more expensive, but are worth it in the long run, especially in an amp that you may want to be as quiet as possible. It is also a sign of a good design when somebody turns on an amp and it is not noisy.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/02/02 04:05 AM

Quote:
Originally posted by overcomer:
oh yeah, that is a tremendous help, i had thought ( while i was waiting for your reply) about getting a pair of the new groove tube 6L6 ge's. and the info you have given is really quite extensive. too bad i live so far away, i would definitely give you some business. now all i have to do is advise my sometime tech, who is very capable, of your insight and go from there... thanks again.
overcomer,

I'd love your business, but I do not sell tubes. When I work on amps, I have clients bring their own tubes, and then I test and classify them. I do keep preamp tubes for my clients, but these are not for sale, they are in reserve for their use.

As far as the GT 6L6GE's, these would be magic in your amp. There was a great article that was done by Harmony Central on this tube on 4/29, a few days ago. I copied this article and posted it in the Groove Tubes area of my website, so there is now even more information on this tube. Its at http://www.guitaramplifierblueprinting.com/groovetubes.html

In any case, good luck, and you are welcome.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/02/02 04:18 AM

Quote:
Originally posted by mikey:
Thanks Miles for all the great info. I am still working with my Fender Deville I picked up last week. Would I be disappointed by using a 12AT7 in the rectifier spot? Also what's better Svets 6L6 or Groove Tubes?
mikey,

If you mean using a 12AT7 in the phase inverter position, it will give you more clean headroom in teh output section. Just give it a try, its a matter of taste. Turn your master all the way up and then set the volume to the point, when your guitar is all the way up, that you just get the onset of output tube distortion.

Then, with the same settings, try the same thing with the 12AT7 in place of a 12AX7, and you will see you have a cleaner sound. This assumes that the 12AX7 you have in there now is about where one is supposed to be, spec wise, which is something of a crap shoot, and the 12AT7 is also close to mid spec. The only way to know for sure is to measure your tubes, but for the cost of a 12AT7, its a cheap experiment where you might love the results.

As far as Groove Tubes vs. the Svets, the Groove Tubes 6L6R2 is a Svetlana tube. The difference on this tube is how it is matched. This is why GT tubes last about 20% longer than most tubes from the "same" maker, and turn out to generate a more symmetrical output waveform. In the case of some GT tubes, GT gets involved with the tube factory and makes some subtle changes specifically for them. If you look at a JJ E34L and an GT E34Ls, which are supposed to be the "same tube", you will see a different plate structure on the outside of the assembly.

The GT 6L6R2 is a great tube, and the Svetlana 6L6 is a great tube, and if properly matched, they are both terrific. I prefer them to the JJ's, but then I am an old coot, and more into blues than speed metal. In the case of EL-34 amps though, I prefer the E34L JJ tube or GT E34Ls over the Svetlana EL-34. Then again, its personal preference. Actually, if I had a choice and could afford them, for EL-34 amps I'd always pick a KT-77 GEC as second choice and a good USA 6CA7 as first choice if I could afford them.

Regards
Posted By: overcomer

Re: Feel free to ask Myles - 05/02/02 04:43 AM

well, what i meant to day and didnt was that the term conscientious used to be known only in the term "conscientious objecter", in the days of the draft, which dates me, my number was high in 1970. i am glad you are putting this info out, it is a great resource. it seems the tube world, and also the UPS, USPS, and fedex "gods" of this realm are taking their due of our dollar, but i dont fault the tube world really, with modeling amps and things coming in, tubes are really taking a beating. my amp tech, the one i will take my super to, does not use tubes that are over 40 bucks a pair, he is a super "rebuilder" from tulsa named rick potter, and quite good and really, i am glad that new tubes are available. it would be a shame to have amps with no tube tone. one fellow came into the music store i visit and was talking about how he was looking for a solid state amp because his peavy classic 30 fell off the back of the seat of his car and it messed up a tube. his idea of amps is, if it has the least bit of problem it is no good. i have a 100 watt harry joyce head with 4 el34s and 4 ei 12ax7s, but i cant find a rectifier tube on it, it must have a solid state in there. i am through amp searching, but thought it would be a good idea to find a way to lower the head room on this super, use it in conjunction with the joyce, which is mammoth clean and also overdriven. it is a beast like no other i have ever played, harry joyce is dead now, but i am glad i got one of them. it is great for huge stage clean, but then again, so is evans, hah, but tubes have the warmth. well, i have rambled, and again, this is a great resource...i meant to say that it is very cool that you are conscientious, as many are not, it is a gift. sorry for the multiple posts...
Posted By: Gearasameanstoamusicalend

Re: Feel free to ask Myles - 05/02/02 03:15 PM

Quote:
Originally posted by myles111:
[QB] . . . if you have a question or have a comment, just post a comment here and when I see the email notification I will answer back here as quickly as I am able . . . /QB]
Dear Myles, Have enjoyed reading your posts and have learned from them. Thank you. My questions regard an older solid state amp. I purchased a Polytone Mini-Brute amplifier. However, this is an older model, head only, no speakers. I think that it is a PA application. However, it has instrument inputs only, and no XLR. It has three channels and one line out. I bought this at an auction very cheap, sound unheard. It is one of the black velour models, pre vinyl tolex. My questions follow: Is the line out an instrument line, or a speaker line, meaning what kind of cable would I use to connect to a speaker? What ohm rating would be the proper match in a speaker cabinet? Does it matter whether it is 4 or 8 ohms? Thanks for having this post. Best regards!
Posted By: sgguitarzz

Re: Feel free to ask Myles - 05/02/02 08:39 PM

Hey Miles. I am hoping you can help me. I was hoping you can give me some tube advice for my Boogie Mark IIB. It sounds okay but we are all always looking for better. It has the 60/100 option which I always use on 60 which is still too loud anyway. I use it with two Reverend Alltone 1250's (one internal and one external). I really like these speakers. Great versatile and warm sound. It also has reverb and equalizer. I was using 4 JJ 6L6GC's for the power tubes but switched out the outer two and replaced them with THD Yellowjackets. My preamp tube setup is as follows:

V1 - Telefunken ECC83
V2 - Mullard CV4004
V3 - Brimar CV4004
V4 - Telefunken ECC83
V5 - RCA 5751

Any comments or suggestions would be appreciated. I play classic rock so I need to cover a lot of sounds and I cannot go too far in any one direction. Also, my main guitar is a 69 Gibson SG backed up with a newly aquired PRS Santana SE which I like. Finally, I use a pedalboard with various effects such as wah (Teese RMC1), overdrive/distortion (Visual Sound J&H), chorus/echo (Visual SOund H20), EQ (Dano Fish & Chips), Flanger (Ibanez FL9), Phaser (Akai Intelliphase) and booster (MXR micro amp).
Sorry for the long post. Thanks.

Dennis
Posted By: myles_rose

Re: Feel free to ask Myles - 05/03/02 02:14 AM

Quote:
Originally posted by overcomer:
well, what i meant to day and didnt was that the term conscientious used to be known only in the term "conscientious objecter", in the days of the draft, which dates me, my number was high in 1970. i am glad you are putting this info out, it is a great resource. it seems the tube world, and also the UPS, USPS, and fedex "gods" of this realm are taking their due of our dollar, but i dont fault the tube world really, with modeling amps and things coming in, tubes are really taking a beating. my amp tech, the one i will take my super to, does not use tubes that are over 40 bucks a pair, he is a super "rebuilder" from tulsa named rick potter, and quite good and really, i am glad that new tubes are available. it would be a shame to have amps with no tube tone. one fellow came into the music store i visit and was talking about how he was looking for a solid state amp because his peavy classic 30 fell off the back of the seat of his car and it messed up a tube. his idea of amps is, if it has the least bit of problem it is no good. i have a 100 watt harry joyce head with 4 el34s and 4 ei 12ax7s, but i cant find a rectifier tube on it, it must have a solid state in there. i am through amp searching, but thought it would be a good idea to find a way to lower the head room on this super, use it in conjunction with the joyce, which is mammoth clean and also overdriven. it is a beast like no other i have ever played, harry joyce is dead now, but i am glad i got one of them. it is great for huge stage clean, but then again, so is evans, hah, but tubes have the warmth. well, i have rambled, and again, this is a great resource...i meant to say that it is very cool that you are conscientious, as many are not, it is a gift. sorry for the multiple posts...
Your "number" dates you? I have you beat there. When I got out of high school, they did not even have the lottery yet! We had limited options ... enlist, get drafted, go to Canada, go to prison after burning your draft card, or hold down 16 1/2 units in college. The last choice was not an option for a screw up like me, so I enlisted.

Modeling amps have their place in the studio or for composition, but I have yet personally heard one that I feel can stand on its own without any effects and have the dynamics of a tube amp. Perhaps someday.

I think having a price of less than $40 for a set of tubes is somewhat limiting, but if your tech can make your amp sound good to you with tubes like that, then that is super. I wonder how it would sound with some closely matched great ones though? It would be fun to do something of a blind test where your amp had its output tubes pulled and something else tried, to see what you felt about the difference. I will say, I have heard some great Fender amps with the least expensive Sovtek's in there, but that were set up properly, and they sounded a LOT better than the same amp model with expensive NOS tubes that were not matched and had the bias improperly set for the amp. A good tech can make a good amp sound great.

Your Joyce head has a solid state rectifier, and solid state rectifiers are pretty much the only choice in a 100 watt amp, as a GZ34 is doing about its best with a 50 watt amp. These amps are monsters and a nice tight regulation circuit is just what these amps need. When was the last time you saw a tube rectifier after 1965 in a 100 watt head like a Marshall or Hiwatt? Never, with the exception of the Mesa Rectifiers, and they use one for each 50 watt section.

As far as the multiple posts .... nobody is counting (and of they are, maybe they need something better to do).

Regards,
Posted By: freddynl

Re: Feel free to ask Myles - 05/03/02 02:14 AM

Hello Miles,
I could not find the answer with the search so I guess the question was not asked yet.
It looks like I will start with some gigging after 20 years of absence..
Now I undusted an old fender concert amp (1983 black faced- 60 watts rms) I still had in a corner.
It probably needs some new tubes.
So my question is what tubes would you recommand for this amp, to get as clean as possible!
(I will use it for jazz so I don't want dirty output \:\) )

Thanks for advice,

Fred
Posted By: myles_rose

Re: Feel free to ask Myles - 05/03/02 02:49 AM

Quote:
Originally posted by Gearasameanstoamusicalend:
Quote:
Originally posted by myles111:
[QB] . . . if you have a question or have a comment, just post a comment here and when I see the email notification I will answer back here as quickly as I am able . . . /QB]
Dear Myles, Have enjoyed reading your posts and have learned from them. Thank you. My questions regard an older solid state amp. I purchased a Polytone Mini-Brute amplifier. However, this is an older model, head only, no speakers. I think that it is a PA application. However, it has instrument inputs only, and no XLR. It has three channels and one line out. I bought this at an auction very cheap, sound unheard. It is one of the black velour models, pre vinyl tolex. My questions follow: Is the line out an instrument line, or a speaker line, meaning what kind of cable would I use to connect to a speaker? What ohm rating would be the proper match in a speaker cabinet? Does it matter whether it is 4 or 8 ohms? Thanks for having this post. Best regards!
Gearasameanstoamusicalend,

All the Polytone amps I have ever seen had about 110 or so watts of output.

They are considered by a lot of folks to be one of the finest amps for Jazz and acoustic guitars around.

The line out is is to run to a board, with a line level output. It is not a speaker driving output.

The amps I have all seen have a speaker output, and these are solid state output sections that work very nicely at any impedience, as long as it is not less than 2 ohms.

I hope this was of some help. I am not aware of any of these amps that were just preamps without a speaker output.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/03/02 04:17 AM

Quote:
Originally posted by sgguitarzz:
Hey Miles. I am hoping you can help me. I was hoping you can give me some tube advice for my Boogie Mark IIB. It sounds okay but we are all always looking for better. It has the 60/100 option which I always use on 60 which is still too loud anyway. I use it with two Reverend Alltone 1250's (one internal and one external). I really like these speakers. Great versatile and warm sound. It also has reverb and equalizer. I was using 4 JJ 6L6GC's for the power tubes but switched out the outer two and replaced them with THD Yellowjackets. My preamp tube setup is as follows:

V1 - Telefunken ECC83
V2 - Mullard CV4004
V3 - Brimar CV4004
V4 - Telefunken ECC83
V5 - RCA 5751

Any comments or suggestions would be appreciated. I play classic rock so I need to cover a lot of sounds and I cannot go too far in any one direction. Also, my main guitar is a 69 Gibson SG backed up with a newly aquired PRS Santana SE which I like. Finally, I use a pedalboard with various effects such as wah (Teese RMC1), overdrive/distortion (Visual Sound J&H), chorus/echo (Visual SOund H20), EQ (Dano Fish & Chips), Flanger (Ibanez FL9), Phaser (Akai Intelliphase) and booster (MXR micro amp).
Sorry for the long post. Thanks.

Dennis
Dennis,

First off its mYles .... not related to Miles Davis \:\)

Second ..... don't worry about the length of your post, nobody is charging by the line here \:\)

I like specific posts like this.

Okay .... lets take a crack at this.

The Mesa Mk IIB is a terrific amp, and a workhorse. It can withstand a ton of abuse and toleraltes impedience mismatches better than a lot of others. The bad aspect of these amps are twofold:

1. Way too loud
2. Way too heavy when you get fooled by their size!

Even in the 60 watt setting, you are only dropping the volume by about 2 1/2db, so that is not too much help in making them quiet. I know a lot of folks these days that use the THD Hotplate with Mk. series amps.

Your Reverend speakers make the problem worse, as these are really articulate speakers and they have a really broad sound dispersion, and are efficient to boot. Your amp in the 60 watt setting with only one of these is about 5-7db louder than a Marshall 100 watt #1959 full stack, so again, you are in sonic db violation territory with most local enforcement laws.

The JJ's continue to make things worse in this aspect. JJ's are VERY strong tubes, and at least with Mesa tubes, they are in a range where the amp runs cool, and is down at least 20 watts from what you are probably putting out. If when you bought the tubes you told them they were for a Mesa amp, a smart cookie would have given you tubes to get the amp into a warmer range, and the drawback of that in your case, is even more power. A Mk III that I looked at recently at a clinic was putting out over 145 watts with JJ's in it.

The yellow jackets will help over the amp in its full on config, but you still have to contend with the fact that your 60 watt section is probably putting out over 75 or close to 80 watts. Be sure to swap these JJ's with the other two that are removed, so they wear evenly ever once in a while.

V1 - Telefunken ECC83
This is always a great choice, but they can be microphonic in these amps. If yours is quiet, then it probably has a bit less gain than some others in the same family, which will help. The ECC83 to me is a bit bright in your amp. You may want to try a 12AX7C, which will tone down the brighness, and keep that nice tube in a drawer or for special occasions.

V2 - Mullard CV4004
This is also a great tube, but with the gain cascade circuit, if its a strong example, you may find that with your volume 1 at 3 and your volume 2 at 4-5, you are already getting so much drive, that the articulation and sparkle starts to go away and you need to raise your presence. I would like to be able to test each of these tubes, and I'd take the one with the lower gain and slower rise time, put it in V2, and a 12AX7C in V1 with about a 90 rating (a way I grade tubes for my clients). On your V1 I would want a rating no higher than 80. That gives a nice usable gain over a wider range, say up to 6 on volume 1 and 6 on volume 2.

V3 - Brimar CV4004
This is fine, but this is not really in the tone generation stage, so a nice tube like this can be replaced with a less expensive tube.

V4 - Telefunken ECC83
I'd also remove this and use a 12AX7 or 12AX7C for the same reason as V3.

V5 - RCA 5751
This is a step in a good direction. The 5751 typically has about 70% of the gain of some 12AX7's but does not have the current drive of a 12AT7. You may want to try a 12AT7 here, which will give you the basic gain structure of the 5751 but give you more headroom in the process.

Perhaps try this 5751 in V1 and then V2 and see how that sounds to you.

One very important aspect of V5, is that you want the A and B sides to be equal in spec. Mesa's really sing with a matched output section, and die almost as badly as some class A amps when this is not a close match. You can get matched phase inverters from Watford Valves in the U.K., but for now, they are one of the few folks that do this. Do not rely on folks that say they can match on a common tester, as these testers work on a static voltage and static bias, and that is NOT how guitar amps work. It may look matched at the static setting, but in real life, the curves will not be the same. This is also the same sort of problem I see all the time with output tubes that were matched in a static state. They work very very well, but when you listen to those amps that ring, sing, and sustain at all levels all over the fretboard, these are the ones I end up finding have a very balanced output section.

The above starting points will let you cover a wider sonic ground, but in the classic rock area, you will have more articulation and definition.

The 69 SG could not be a better match for this amp. These amps like 10k and up pickups plugged into their input jack! With single coil pickups, I do things a little different on the V1 tube to try to compensate for single coil pickups.

Your Santana is also a cool match, but your amp likes the Dragon II PRS pickups a bit better for some styles, but the SE pickups to my ear are better than the ones in the PRS 24 series guitars. In any case, any humbucker or PRS pickup sounds great in this amp.

If you are getting any hum that is bothersome, drop me another post, as there is something we can do about that too.

If you find you are loosing highs from your pedal board .... (try the guitar alone, then plug it in with effects and see if you miss highs), let me know that too, as there is something we might be able to do about that too, but with those JJ's, you probably are not lacking in the treble department!

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/03/02 04:41 AM

Quote:
Originally posted by freddynl:
Hello Miles,
I could not find the answer with the search so I guess the question was not asked yet.
It looks like I will start with some gigging after 20 years of absence..
Now I undusted an old fender concert amp (1983 black faced- 60 watts rms) I still had in a corner.
It probably needs some new tubes.
So my question is what tubes would you recommand for this amp, to get as clean as possible!
(I will use it for jazz so I don't want dirty output \:\) )

Thanks for advice,

Fred
Fred,

If your amp has sat unused for a few years, the filter caps in the power supply need to be checked as they probably dried out.

A good tech can check this pretty quickly for you with a capacitor checker. They should also be inspected visually to see if the weep hole has stuff coming out of it, as this is what is supposed to happen when they go bad.

If they are on their way out, this can be checked by having a tech check the noise floor on your amp using a scope. This is pretty easy, it is something we do at the amp clinics as part of our normal routine.

Your tubes may be just fine and dandy. Can you write back at some point and tell me what they are?

If they do need replacement, the tubes that sound the most like Fender in the days of Fender in these amps and the earlier 60's blackface amps to most of my clients are the Tung-Sol 5881 NOS tubes. You can get these from Groove Tubes in the USA and Watford Valves in the UK. To keep the amp clean, you want something with a rating the same as about a Groove Tubes #7 rating.

If your old tubes are good or if you stick in new ones, be sure to have your bias checked and adjusted if necessary. Your Concert is one of the amps designed by Paul Rivera, and is a pretty strong amp. The best place to start with bias is at about -50 volts.

Make sure if you change the output tubes, you also put in a fresh 12AT7 in the phase inverter position. If there is a 12AX7 in there now, somebody changed it, and get rid of it. Make sure to get a balanced or matched phase inverter. This tube is V7 on your tube chart.

V1 and V2 should be 7025's and not 12AX7's.

These amps can have up to 500 volts on the plates (B+ voltage) so should not be looked at by a tech in the same way as a Concert with the earlier AB763 circuit, as they had abot 40 volts less on the plates.

Spray in all the pots with a good tuner cleaner/lube, not just contact cleaner, or the pots may stick and freeze up.

Let me know if you need any more help. Let me know how it turned out.

If you are in the Los Angeles area, I would be happy to check your amp and the caps for free at the upcoming amp clinic on May 11th. Details are on my website.

Regards,
Posted By: jetboy

Re: Feel free to ask Myles - 05/03/02 10:56 AM

Myles,

you are amazing, I'm just getting back into all this after some time off for kids, I'm finding all kinds of info both here and at harmony-central. Can't imagine how you keep up.

Anyway, like I said, just getting back at this. Traded some old gear that I didn't need/want and bought a new rig. A Badcat Cub Reverb, a 15watt class A. 2 EL84's, 2 12AX7's in the preamp, a 5AR4 rectifier and a 12AX7 phase inverter. I like the amp and to me it sounds pretty darn good as is, however in reading some reviews about it, other users are replacing the OEMs with NOS tubes and they claim major improvement. Well I'm all for that but not so sure where to put the $.

Badcat supposedly uses a Chinese 5AR4 and ruby tubes for the power section, not sure about the preamp section.

After reading/lurking most of the amp section at HC seems like some NOS tubes would give an improvement but where should I start?

The rectifier seems like a logical choice since there seems to be agreement that the Chinese tube is less than stellar and maybe a NOS tube in V1.

Any thoughts on this? Seems like I could spend another $200+ and retube the Cub with all NOS but that seems like overkill at least for what I do/want.

Am I just experiencing major GAS from reading all this stuff about amps again?

thanks so much for all the time you spend on the boards giving out so much info to the uniformed.

Mark
Posted By: myles_rose

Re: Feel free to ask Myles - 05/03/02 08:24 PM

Quote:
Originally posted by jetboy:
Myles,

you are amazing, I'm just getting back into all this after some time off for kids, I'm finding all kinds of info both here and at harmony-central. Can't imagine how you keep up.

Anyway, like I said, just getting back at this. Traded some old gear that I didn't need/want and bought a new rig. A Badcat Cub Reverb, a 15watt class A. 2 EL84's, 2 12AX7's in the preamp, a 5AR4 rectifier and a 12AX7 phase inverter. I like the amp and to me it sounds pretty darn good as is, however in reading some reviews about it, other users are replacing the OEMs with NOS tubes and they claim major improvement. Well I'm all for that but not so sure where to put the $.

Badcat supposedly uses a Chinese 5AR4 and ruby tubes for the power section, not sure about the preamp section.

After reading/lurking most of the amp section at HC seems like some NOS tubes would give an improvement but where should I start?

The rectifier seems like a logical choice since there seems to be agreement that the Chinese tube is less than stellar and maybe a NOS tube in V1.

Any thoughts on this? Seems like I could spend another $200+ and retube the Cub with all NOS but that seems like overkill at least for what I do/want.

Am I just experiencing major GAS from reading all this stuff about amps again?

thanks so much for all the time you spend on the boards giving out so much info to the uniformed.

Mark
Mark,

For being out of this for a long time, I have to say that when you got back into it, you sure did it right!

I am very familar with the Bad Cat line, and I have talked to Mark Samson now and then about the Bad Cat line he developed as their designer. In the area of Bad Cat, there are a few differences from the Matchless in the DC-30 type amp, that are slight and subtle, but I don't see how these two companies compete, as they are all Mark Sampson amps any way you look at it.

In any case, your particular amp is perhaps my favorite of the entire line. I like it a bit more than the Matchless version mostly because of the addition of reverb over the older Matchless.

Your amp sounds pretty great the way it is. There is not a lot to do to them.

In the case of the Chinese rectifier, these have over a 50% failure rate, but the failures are usually in the first hours of use. If you have more than a week or so on your amp, you are probably fine. The Russian Sovtek rectifier is a more sturdy part, but if you are not having problems, I would just leave it as it is.

On your output EL-84's .... look at them, and if they are the Sovtek's and not the JJ's, you may want to get a set of the JJ's. They are much better tubes, and in this amp, you want them to be closely matched. The best place for these is Eurotubes. They are at http://www.eurotubes.com and you may want to call there and ask to speak to Bob Pletka. He is the owner, and sells these tubes for what is probably less than anybody I can think of, $15.00 for a pair. He will match them really closely, much closer than most folks.

You can also ask him if the new JJ GZ34 rectifier is available, and if it is, that might be a nice consideration for a spare or replacement, as it will raise your plate voltages a bit and give you even more output.

In V1, there are so many choices, it all boils down to personal preference. There are a lot of NOS tubes that are rationally priced, such as the RCAs, GEs and others at times.

In these amps, a nice ECC83 is always super for the VOX sound, and then have a 12AX7C to smooth things out for more blues if you like.

There are lots of things one can do to improve most amps, but in the case of yours, there is not much left to do. It was done right from the get-go. Mark Sampson used to hand pick tubes for his Matchless amps, but stopped doing that when he had Matchless because people would get the amps home and start to swap things all around.

So, at this point you are into the changes for $15.00 for a possible new set of output tubes, and probably less than $20 for a rectifier. I guess at about $35 we are below your $200 limit \:\)

Remember, on this amp, you can plug a 5Y3 in the rectifier to drop the voltages and you will also have a different feel to the amp as the rise time for voltage on the 5Y3 is really long compared to the 5AR4. The 5AR4 hits it max voltage in about .12 seconds while a 5Y3 takes almost .5 seconds (a full half a second) to recover to max voltage from 0 volts. It takes about .25 seconds to recover from 200 volts to 300 volts. This makes the amp feel and play a lot differently. You can also use a 5U4 in there, which is sort of a split between the other two.

These amps are great in clubs and bars, but they are also a lot louder than their false 15 watt rating. These amps typically put out more than their claimed 15 watts, and remember, these are "class A watts", which technically are the same as class A/B watts, because a watt is a watt, but for various reasons, they seem like "louder" watts. If you ever hear a 30 watt Vox AC-30 compared to an 85 watt Fender Twin Reverb, you will see what I mean. They are both LOUD amps.

These are also great in the studio, and much more like the Vox AC-15's that Brits used in the studios so much more often than the AC-30.

If your amp is too loud, there are ways to tame that too, just drop me a line.

Happy playing, and nice choice.

Sorry I could not spend more of your money. next time buy a $300 amp and we'll take it from there \:\) and triple its original price with ease .... speakers, transformers, tubes, and hours of replacing parts to middle spec rather than spec at the edge of the envelope, and then adjustments and more adjustments to things like bias (in a class A/B amp) and resistor changes to the preamp tubes to get the proper factory plate voltages, etc., etc., etc.

You actually saved yourself a lot with this type of amp, and chances are your grandkids will play it someday as a "vintage" amp from the 20th century, or the turn of the 21st century.

Regards,
Posted By: sgguitarzz

Re: Feel free to ask Myles - 05/03/02 08:39 PM

Thank you Myles (got it right this time). I appreciate your very detailed response. You make reference though to my use of the JJ tubes but actually I am really not using the JJ's 6L6's. I replaced the two outer tubes with the Yellowjackets (which are using JJ EL-84's) and the two JJ's on the inside are not really used in the 60 watt position (I believe they are kind of in standby) so I do not think they have any influence on the sound.
I will try your suggestions on moving the 5751 to the V1 or V2 spot. I mostly use the clean channel anyway so I guess V1 would be more appropriate. I will also look into getting a matched 12AT7 for the phase inverter from Watford Valves. Any suggestions for which one? I have one or two 12AT7's around to replace it with for now. Also, any suggestions for the 12AX7C's? How do these differe from the 12AX7?
As you said these guitars do sound nice with this amp. I will probably upgrade the pickups in the Santana with something stronger. You mentioned the PRS Dragon II's. I was thinking of a set of Rio Grandes (Texas for the neck and BBQ for the bridge). What do you think about this?
The amp is very quiet. The only time I had a hum was in the reverb circuit once which turned out to be a bad tube.
I do love these Reverend speakers but they are very efficient. What would be a better match and would the difference be worthwhile?
I know I have asked a lot of questions. I do appreciate your time and expertise.

Dennis
Posted By: TurboDog

Re: Feel free to ask Myles - 05/03/02 10:00 PM

Heya Myles,

I had a chance to get an old Martin amp from a local music shop. It was only $150, but I passed. My friend who works there snatched it up and still has it.

Do you know anything about the old Martin amps? I can find no info whatsoever. I remember hearing that they were made for Martin by somebody else.

It's a small amp, with maybe an 8" or 10" speaker. It was very simple. I played it, and remember it having a sweet tone. I have no clue what tubes it used or anything.

I may could get thios amp off my friend, but he's been offered some decent money for it.

Any info?

Oh, and thanks for the EL34 test results. I'l be retubing my Rivera 30-12 soon and will take all your results into account. I can get EH's pretty cheap, so I think I'll try them.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/03/02 11:54 PM

Quote:
Originally posted by sgguitarzz:
Thank you Myles (got it right this time). I appreciate your very detailed response. You make reference though to my use of the JJ tubes but actually I am really not using the JJ's 6L6's. I replaced the two outer tubes with the Yellowjackets (which are using JJ EL-84's) and the two JJ's on the inside are not really used in the 60 watt position (I believe they are kind of in standby) so I do not think they have any influence on the sound.
I will try your suggestions on moving the 5751 to the V1 or V2 spot. I mostly use the clean channel anyway so I guess V1 would be more appropriate. I will also look into getting a matched 12AT7 for the phase inverter from Watford Valves. Any suggestions for which one? I have one or two 12AT7's around to replace it with for now. Also, any suggestions for the 12AX7C's? How do these differe from the 12AX7?
As you said these guitars do sound nice with this amp. I will probably upgrade the pickups in the Santana with something stronger. You mentioned the PRS Dragon II's. I was thinking of a set of Rio Grandes (Texas for the neck and BBQ for the bridge). What do you think about this?
The amp is very quiet. The only time I had a hum was in the reverb circuit once which turned out to be a bad tube.
I do love these Reverend speakers but they are very efficient. What would be a better match and would the difference be worthwhile?
I know I have asked a lot of questions. I do appreciate your time and expertise.

Dennis
Dennis,

I messed up here. I thought you were using the yellow jackets with the other tubes.

What you are saying is that the yellow jackets are your source and with the amp in 60 watt mode the other pair are effectively off (actually the B+ is off on these in that setting.

Got it.

In that case your amp can probably be played without the police making a house call.

If you use the clean channel, then you are correct and experiment with V1.

Watford carries a number of 12AT7's, but my favorite ones of theirs are the PHILPS and the G.E 12AT7/ECC81 tubes. I think the Philips is less expensive, I do not remember their pricing, but each of these is offered in what they call a "balanced valve" which really makes a nice difference in the phase inverter position.

12AX7C's need to be off the new tooling. How you tell this is by looking inside the tube at the top of the tube just under the silver getter flash. If you see a little square or rectangle, than avoid it. If you see a little round halo, then its a better bet. These tubes are darker than non-Chinese 12AX7's, and blues players, slide players, and jazz folks prefer them a lot of the time.

One problem with them though, is sometimes their rise time is very fast, too fast for some folks, and that can make them sound almost solid state in nature. This is due to inconsistancy where some of their characteristics are not in a range where they should be in relation to their gain. This is where things get a bit tricky unless you have access to a curve tracer. Maybe when you contact Watford you can ask if you can specify something with a transconductance less than 1650, as this will help.

I have not heard the Rio Grande's in the Santana. Maybe somebody that has more experience with them can say something here.

Good - your amp is quiet!

On your speakers, you could always stick in some inefficient speakers, but these amps sound best with speakers like yours or EV's. They are loud, but they were designed to be. One thing you can do is refrain from using your second speaker. When you double your radiating area, you get a LOT more sound and air moving out there. Save the second speaker for the big arena or something.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/04/02 12:08 AM

Quote:
Originally posted by TurboDog:
Heya Myles,

I had a chance to get an old Martin amp from a local music shop. It was only $150, but I passed. My friend who works there snatched it up and still has it.

Do you know anything about the old Martin amps? I can find no info whatsoever. I remember hearing that they were made for Martin by somebody else.

It's a small amp, with maybe an 8" or 10" speaker. It was very simple. I played it, and remember it having a sweet tone. I have no clue what tubes it used or anything.

I may could get thios amp off my friend, but he's been offered some decent money for it.

Any info?

Oh, and thanks for the EL34 test results. I'l be retubing my Rivera 30-12 soon and will take all your results into account. I can get EH's pretty cheap, so I think I'll try them.
TurboDog,

Valco, Supro, Premier, and Gretsch amps were at times made under the same roof, and perhaps that is where the Martin amps came from too. I don't know.

Sometimes I am a vast storehouse of useless information, but there are a LOT of times that I am stumped. This is one of them.

You may want to look up Trace from Voodoo Labs, as he's a lot smarter than I am, or talk to Dan Torres over at Torres Engineering.

The EH tubes are a nice match in that amp and will make that Rivera a pretty versitile amp. If the price is right, that is always nice too!

Regards,
Posted By: TurboDog

Re: Feel free to ask Myles - 05/04/02 12:25 AM

Woohoo!!

I stumped Myles! Do I get some kind of prize for that? \:D
Posted By: myles_rose

Re: Feel free to ask Myles - 05/04/02 01:45 AM

This is a reply I wrote for a fellow over on Harmony Central. Generally I tell people to come over here, as that way it benefits folks here and forms something of a FAQ list, but I did answer this over there and felt it would be of benefit to Marshall folks over here.

He initially let me know he had an older Marshall that he wanted to start playing again that had been dormant for a long time.

Here it is:

quote:
--------------------------------------------------------------------------------
Originally posted by soundelixir:
Agghrrrr....... 3 things I don't have...... So, my Bias Rite Bias King is worthless then? I guess I'll just have to get my tech to install them from now on. Also, he and I have been discussing possible filter cap changes (my amp is 31 years old), and he told me that they are responsible in a large part for the "tone" of the amp. Is this so? So, would there be a cap combination that would more of an "Eddie" tone or an "AC/DC" tone? Well, anyways, it sounds like the JJ's might be right up my alley; I'll probably try them out soon. I'd love to bring my amp to you, but I'm on the east coast and probably won't get to Cali for a while. I really appreciate the offer though!
--------------------------------------------------------------------------------

soundelixir,

Don't fret! (no pun intended).

You can use your bias king, it just takes a few steps to get it right. If you bias out too much of the crossover notch, then the amp sounds too clean and looses the characteristic Marshall crunch.

Here is the drill:

1. First, measure your B+ voltage. To get an accurate reading, you need to have the tubes in place, because if one is pulled the B+ will rise.

2. Once you know your B+, if you are using normal EL-34 tubes, you want to divide 25 by your bias voltage. If you are using E34L or E34Ls tubes, then use a value of 30.

3. Lets say we have 450 plate volts off pin 3 of the tube socket as an example. 25/450 = .0555

4. Multiply that .0555 by 1000

5. That gives us 55.5, which is the maximum idle dissapation of that particular tube in your amp at that B+ voltage for a 25 watt tube.

6. Write down your B+ voltage for future reference, as this will not change unless there is some problem, and the more to steer clear of those voltages, the better it is for your health depending on your luck.

7. Now we take 50% of the 55.5 as a starting point. That gives us about 28mA. With your volume all the way down, tone controls set to 5, and no input signal, adjust your bias probe to 28.

8. Now play the amp with it turned to "7". You can leave the bias probe in place. You will see some big numbers as you play, but ignore all of these.

9. If your amp is too clean, then drop down to say 27, 26.5, 26, 25.5 etc., to get the crunch you want.

10. If the amp is too dirty, raise it in the same way as above, but go no higher than 36mA or your amp will be running very hot.

You may get lucky right off the bat, but your bias king or bias probe can be used, it just takes a bit of time. The benefit is that you get to hear how things change as you make the changes. You may find you prefer a setting that may not be the same setting as you get with a scope anyway. Whenever I adjust bias, I always make folks play, and we rarely end up at our starting point anyway.

Filter caps in Marshalls are VERY important. The caps in the tone circuit are also important as they are right in the signal path. Its the bit caps that dry out though, and your tech is right on the money.

Now as far as those caps, we are all used to seeing the big blue LCR caps that are about as big as the tubes themselves. There is a new cap around that has the same base and mounting, but they are much shorter, newer, last much longer, and cost less. They are made by the JJ factory, the same folks that make the tubes. In a power supply, 50mf @ 500v is pretty much 50mf @ 500volts, so you have an option here. Talk to your tech about them. Eurotubes sells them, and so does Antique Electric Supply at tubesandmore.com

The retail cost on the 50mf caps is $10.95 each and on 100mf caps its $12.95 each from AES. Eurotubes may be cheaper. The LCR's are about $20 each retail. They have a pretty big markup as a lot of folks pay more to have the "blue" caps in their amp as original, but keep in mind the orignal caps can go away in as little as 5 years in a Marshall. The newer caps last much longer.

My cost on LCR's is $7.95
My cost on JJ 50mf is $6.55 (if I buy 10 its $5.79)
My cost on JJ 100mf is $8.85 (if I buy 10 its $7.87)

Those prices are for each one.

Now you have a general idea of markup on cost vs. retail, so you can check what you are being charged when you have work done.

Hope this was of some benefit.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/04/02 02:53 AM

Quote:
Originally posted by TurboDog:
Woohoo!!

I stumped Myles! Do I get some kind of prize for that? \:D
TurboDog,

Yes.....

Free amp checkout at one of our free amp clinics? But there is also free candy there, AND I will buy you a beer or a coke at the bar next door also.

Myles
Posted By: jetboy

Re: Feel free to ask Myles - 05/04/02 03:43 AM

Quote:
Originally posted by myles111:
[QUOTE]Originally posted by jetboy:
[qb]Myles,

For being out of this for a long time, I have to say that when you got back into it, you sure did it right!

I am very familar with the Bad Cat line, and I have talked to Mark Samson now and then about the Bad Cat line he developed as their designer. In the area of Bad Cat, there are a few differences from the Matchless in the DC-30 type amp, that are slight and subtle, but I don't see how these two companies compete, as they are all Mark Sampson amps any way you look at it.

In any case, your particular amp is perhaps my favorite of the entire line. I like it a bit more than the Matchless version mostly because of the addition of reverb over the older Matchless.

Your amp sounds pretty great the way it is. There is not a lot to do to them.

In the case of the Chinese rectifier, these have over a 50% failure rate, but the failures are usually in the first hours of use. If you have more than a week or so on your amp, you are probably fine. The Russian Sovtek rectifier is a more sturdy part, but if you are not having problems, I would just leave it as it is.

On your output EL-84's .... look at them, and if they are the Sovtek's and not the JJ's, you may want to get a set of the JJ's. They are much better tubes, and in this amp, you want them to be closely matched. The best place for these is Eurotubes. They are at http://www.eurotubes.com and you may want to call there and ask to speak to Bob Pletka. He is the owner, and sells these tubes for what is probably less than anybody I can think of, $15.00 for a pair. He will match them really closely, much closer than most folks.

You can also ask him if the new JJ GZ34 rectifier is available, and if it is, that might be a nice consideration for a spare or replacement, as it will raise your plate voltages a bit and give you even more output.

In V1, there are so many choices, it all boils down to personal preference. There are a lot of NOS tubes that are rationally priced, such as the RCAs, GEs and others at times.

In these amps, a nice ECC83 is always super for the VOX sound, and then have a 12AX7C to smooth things out for more blues if you like.

There are lots of things one can do to improve most amps, but in the case of yours, there is not much left to do. It was done right from the get-go. Mark Sampson used to hand pick tubes for his Matchless amps, but stopped doing that when he had Matchless because people would get the amps home and start to swap things all around.

So, at this point you are into the changes for $15.00 for a possible new set of output tubes, and probably less than $20 for a rectifier. I guess at about $35 we are below your $200 limit \:\)

Remember, on this amp, you can plug a 5Y3 in the rectifier to drop the voltages and you will also have a different feel to the amp as the rise time for voltage on the 5Y3 is really long compared to the 5AR4. The 5AR4 hits it max voltage in about .12 seconds while a 5Y3 takes almost .5 seconds (a full half a second) to recover to max voltage from 0 volts. It takes about .25 seconds to recover from 200 volts to 300 volts. This makes the amp feel and play a lot differently. You can also use a 5U4 in there, which is sort of a split between the other two.

These amps are great in clubs and bars, but they are also a lot louder than their false 15 watt rating. These amps typically put out more than their claimed 15 watts, and remember, these are "class A watts", which technically are the same as class A/B watts, because a watt is a watt, but for various reasons, they seem like "louder" watts. If you ever hear a 30 watt Vox AC-30 compared to an 85 watt Fender Twin Reverb, you will see what I mean. They are both LOUD amps.

These are also great in the studio, and much more like the Vox AC-15's that Brits used in the studios so much more often than the AC-30.

If your amp is too loud, there are ways to tame that too, just drop me a line.

Happy playing, and nice choice.

Sorry I could not spend more of your money. next time buy a $300 amp and we'll take it from there \:\) and triple its original price with ease .... speakers, transformers, tubes, and hours of replacing parts to middle spec rather than spec at the edge of the envelope, and then adjustments and more adjustments to things like bias (in a class A/B amp) and resistor changes to the preamp tubes to get the proper factory plate voltages, etc., etc., etc.

You actually saved yourself a lot with this type of amp, and chances are your grandkids will play it someday as a "vintage" amp from the 20th century, or the turn of the 21st century.

Regards,
Myles,

thanks for the incredible reply, from reading the posts here and at HC I'd say i'm getting advice I should be payin' for so thanks for your dedication to making amps sound better.

As for the last part of your post, funny i already did that the year before. I knew I wanted the real deal (TUBES!!!!) and I'd been searching for that full out sound of my former Super Reverb but with a lot less volume. I ended up building a Torres Tiny Tone ($400 + $120 for a small cab and a weber 10) which was fun and it did give me pretty good tone at speaking volume but the versatility wasn't there, no clean tones to speak of and no reverb. Ended up playing it as an effect into my Super (with all the clicks and pops and still too much volume).

Bought a pod ($300)and that was better, more versatility and a fake reverb and stopped using with the Super. Still not quite right but closer.

Then I had my latest bout of what could only be called male menopause ( I will be 50 this month) I finally decided it was worth the effort and $$. I bought a custom built JET guitar (hence the Jetboy moniker) and traded my '67 SG, which I never really liked as much as I thought I would, for the Bad Cat and sold my '68 Super.

Now here's what ever wisdom I can impart to those in NEED of that tone. You can do it the long way or just break out your wallet ;-)

So much for the rambling....

I pulled the tubes from the Cub and they are all sovteks, and the rectifier is a Ruby. I'm going to order some JJ's and give'm a try. Also after going to your web site and reading the tube tests I decided to go for broke (literally) and order a combination of a NOS mullard 4004 and a NOS ge jan 12ax7 and a set of NOS ge el84's from KCnostubes. I guess I'll find out whether there is real or just poseur (me) tones in this rig, after this it certainly won't be the amps fault.wAN8qE

I know there will be some that will moan about dumping the Super, and it was a real nice amp but way too loud for me (the Cub is still too loud but not as bad) and the Super needed some real overhauling, caps and tubes etc.

again thanks so much for the help on this and i hope someone is paying you for all the time you spend here and at HC.

Like you said, 20 years from now my daughters boy friends will be playing the Cub wondering who will inherit it.

Mark
Posted By: TurboDog

Re: Feel free to ask Myles - 05/04/02 04:55 AM

Ah Myles,

I'm closer to Atlanta, so I'll have to take a raincheck. Sooner or later you'll get to our neck of the woods and me and Chip and a few others will pay a visit.

Actually with all of your advice, I will be buying you a few beers.

Hey, how safe would it be for me to turn the bias down a hair and just drop some new EH's in there? I know there are some amp techs areound, but I don't know any and I'm afraid I'd be ampless for a few days.
Posted By: sgguitarzz

Re: Feel free to ask Myles - 05/04/02 06:11 AM

Hey Myles. Thanks for the tips. I was able to pick up two of the GT 12AX7C's at Sam Ash ($14 each). I checked and the both have the round halo thing under the silver getter flash. I was amazed SA had them. I will try putting the 5751 in V1, 12AX7C in V2 & V4, and put a 12AT7 in V5 (I have an Amperex Bugle Boy and a JJ to choose from). I will switch out the V3 Brimar and replace it with a JJ 12AX7 I have. I guess we will see what happens.
As far as using one speaker the problem is the Alltones can only handle 50 watts and the Boogie is on the 60 watts setting. That is why I always used the two speakers.
I have a gig Saturday night so it will be a good test.

Dennis
Posted By: freddynl

Re: Feel free to ask Myles - 05/04/02 04:00 PM

Many thanks for your advice Myles, I am pretty sure I could not have these advices easily in
netherlands, in fact I would not know where to find a capable technician for these amps.

Quote:
Originally posted by myles111:

If your amp has sat unused for a few years, the filter caps in the power supply need to be checked as they probably dried out.

----
Initially when I switched the amp on, there were a lot of crackles, which made me turn it off and send my post to you.
Now I did switch it on again today and only a few crackles, which were gone within a few minutes.
They did not come back.
Crackles came back as soon as I plugged a guitar, and after some moving a bit of the inputjack to get some possible corrosion off hence crackles gone as well.. \:\)
The sound is as clear,warm and dynamic as I could remember.
In fact I played last night on a practice with the other guitarists amp, a line6 modular whatever it is, I could not get it sound like I wanted. just cold/metallic sound.
I really thought that I had it wrong (nobody complained, anyway about the sound) but when I am now listening to the concert amp..I can tell you these modular amps don't come even close... \:\)

So it looks like it just needs some cleaning of pots and cleaning of input contacts like you said

-------------
A good tech can check this pretty quickly for you with a capacitor checker. They should also be inspected visually to see if the weep hole has stuff coming out of it, as this is what is supposed to happen when they go bad.
----
wright this is something to cheque on

-----
If they are on their way out, this can be checked by having a tech check the noise floor on your amp using a scope. This is pretty easy, it is something we do at the amp clinics as part of our normal routine.

Your tubes may be just fine and dandy. Can you write back at some point and tell me what they are?

----
I think by now they are in great condition.
This is what's written on the tubes by the way;
Fender special design
023556 (30,11,23) ACS
-----

If they do need replacement, the tubes that sound the most like Fender in the days of Fender in these amps and the earlier 60's blackface amps to most of my clients are the Tung-Sol 5881 NOS tubes. You can get these from Groove Tubes in the USA and Watford Valves in the UK. To keep the amp clean, you want something with a rating the same as about a Groove Tubes #7 rating.

If your old tubes are good or if you stick in new ones, be sure to have your bias checked and adjusted if necessary. Your Concert is one of the amps designed by Paul Rivera, and is a pretty strong amp. The best place to start with bias is at about -50 volts.

Make sure if you change the output tubes, you also put in a fresh 12AT7 in the phase inverter position. If there is a 12AX7 in there now, somebody changed it, and get rid of it. Make sure to get a balanced or matched phase inverter. This tube is V7 on your tube chart.
there's no tube with 12ax7.
In fact I bought this amp new myselve in 1983 and I never replaced any tube, so it is in original state. (even the control cheque card before it leaves the factory was in it.)

V1 and V2 should be 7025's and not 12AX7's.

----
there is 7025 on most of the preamp tubes. (7x)
I could not read four of them, And I did not
want to pull them out as the amp is fine so far and I could not pull them out without using heavy force, which I like to avoid if not needed.

-------
Spray in all the pots with a good tuner cleaner/lube, not just contact cleaner, or the pots may stick and freeze up.

----
wright,,, mmm. this means I have to unmount the amp to get there..
as soons as it start's crackling will do that..
thanks.
----
Let me know if you need any more help. Let me know how it turned out.

----
If you are in the Los Angeles area, I would be happy to check your amp and the caps for free at the upcoming amp clinic on May 11th. Details are on my website.

I whish I was, but there's a long distance between netherlands and L.A. \:\)

Regards,[/QB]
Thank's again
Fred
Posted By: myles_rose

Re: Feel free to ask Myles - 05/04/02 07:17 PM

Posted By: myles_rose

Re: Feel free to ask Myles - 05/04/02 07:45 PM

Quote:
Originally posted by TurboDog:
Ah Myles,

I'm closer to Atlanta, so I'll have to take a raincheck. Sooner or later you'll get to our neck of the woods and me and Chip and a few others will pay a visit.

Actually with all of your advice, I will be buying you a few beers.

Hey, how safe would it be for me to turn the bias down a hair and just drop some new EH's in there? I know there are some amp techs areound, but I don't know any and I'm afraid I'd be ampless for a few days.
TurboDog,

You can be pretty safe in the bias area. There is normally a pretty wide range where tubes will run safely.

With the amp off, find the max and min ranges of your bias pot, set it in the middle, and then after a few minutes of tuning on and running, just make sure the outer plate structure is not glowing red or orange. If the amp sounds fine enough, you may not be where is best for sound, but it will get you by. You may even like it just fine and want to leave it there.

As far as Atlanta, that is a possibility this summer along with D.C./Virginia, Orlando, and New Orleans.

Regards,
Posted By: sgguitarzz

Re: Feel free to ask Myles - 05/04/02 09:03 PM

Just a suggestion - come to NYC. We could use you here also. I will be first in line \:\) .

Dennis
Posted By: myles_rose

Re: Feel free to ask Myles - 05/05/02 01:29 AM

Quote:
Originally posted by sgguitarzz:
Just a suggestion - come to NYC. We could use you here also. I will be first in line \:\) .

Dennis
Dennis,

Well, unless it was in the line of work already there or a vacation, you'd have to talk to some store about paying my travel and expenses out there \:\)

Besides, on the East Coast you guys have Trace over at Voodoo!

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/05/02 01:42 AM

Quote:
Originally posted by freddynl:
Many thanks for your advice Myles, I am pretty sure I could not have these advices easily in
netherlands, in fact I would not know where to find a capable technician for these amps.

.... cutting by Myles for brevity ....

I whish I was, but there's a long distance between netherlands and L.A. \:\)

Regards,
Thank's again
Fred[/QB][/QUOTE]

Fred,

You are on the right track. As far as the codes on the tubes, they are usually batch codes and date codes, but the best way to tell what they really are is to look at them.

Just clean those pots and jacks when you get the time, and the tube sockets too.

By the way, from September 1969 to November of 1970 I live in Holland ... in Amsterdam, on the canal (Singel) at 27 Singel. It was great. If the Paradiso is still there, drop in for me \:\)

Regards,
Posted By: jetboy

Re: Feel free to ask Myles - 05/05/02 06:25 AM

Hi Myles,

after reading everything I could find, I went crazy (must be the old age) ordered the NOS tubes including a mullard 4004 and a NOS GE 12ax7 and el84's and THEN ordered some JJ's from Bob at Eurotubes. The JJ's are a balanced ecc83 for the phase inverter and a variety of graded ecc83's with a set of lower value el84's to reduce some volume on the Bad Cat. Man I'll have enough tubes to last a lifetime, at least my lifetime.

Too much info!!!! I guess the analysis part of all this got to me, I'm just gonna try'em all and see what I like.

I figure ultimately it will be cheaper now then later and I'll pretty much know the limits of the Bad Cat and will be able to decide for myself whether all this NOS stuff is for real or just for people (like me I guess) with too much time on their hands.

Harkens back to my youth where I spent way too much time thinking about hifi gear ;-) or my (current) other hobby/job Mac computers.

talk about anal..... I'm starting to think like the posters at HC, looking for the holy grail. good thing I still have some $ left over from selling my Super. My kids will just have to allow their ol' dad a few eccentricities and a little less inheritance.

the Torres was fun, I probably should rewire some of it to reduce the hum a bit but it was as you said a real learning experience, especially learning the hard way about capacitor discharge, wahooooo.

I felt the same way about the SG, it was what I wanted BAD in high school, I settled back then for an Epi w/ 2 mini buckers but that neck was even worse as far as neck play... I finally got my '67 to celebrate my 2nd daughter's birth but the reality was not as good as the dream. Turns out that one of the PU's had a short and was a single coil (previous owner removed the covers) I never realized it, so maybe I just didn't get the best it had to offer. The guy I traded it to for the Bad Cat sent the pu's to lindy fralin to get rewound. Looks like he's fixing it up to get some real $$$ for it. Maybe you'll see it on Ebay or someplace like that.

Same thing with the '78 Les Paul I got when my 1st daughter was born, I can now say I had one but it was also less than I expected and I traded it for some computer gear.

As you can probably tell I've been at this off and on for a long time and it pretty much coincides with times of major change in my life... some people opt for comfort food I seem to opt for the comfort of music. I suppose/know if I had the talent I would opt for a career somewhere in the biz.

Anyway thanks again for your advice and for the friendly conversation. The business may be nasty but you still meet some mighty nice people in it.

Mark
Posted By: myles_rose

Re: Feel free to ask Myles - 05/05/02 07:58 PM

Quote:
Originally posted by jetboy:
Hi Myles,

after reading everything I could find, I went crazy (must be the old age) ordered the NOS tubes including a mullard 4004 and a NOS GE 12ax7 and el84's and THEN ordered some JJ's from Bob at Eurotubes. The JJ's are a balanced ecc83 for the phase inverter and a variety of graded ecc83's with a set of lower value el84's to reduce some volume on the Bad Cat. Man I'll have enough tubes to last a lifetime, at least my lifetime.

Too much info!!!! I guess the analysis part of all this got to me, I'm just gonna try'em all and see what I like.

I figure ultimately it will be cheaper now then later and I'll pretty much know the limits of the Bad Cat and will be able to decide for myself whether all this NOS stuff is for real or just for people (like me I guess) with too much time on their hands.

Harkens back to my youth where I spent way too much time thinking about hifi gear ;-) or my (current) other hobby/job Mac computers.

talk about anal..... I'm starting to think like the posters at HC, looking for the holy grail. good thing I still have some $ left over from selling my Super. My kids will just have to allow their ol' dad a few eccentricities and a little less inheritance.

the Torres was fun, I probably should rewire some of it to reduce the hum a bit but it was as you said a real learning experience, especially learning the hard way about capacitor discharge, wahooooo.

I felt the same way about the SG, it was what I wanted BAD in high school, I settled back then for an Epi w/ 2 mini buckers but that neck was even worse as far as neck play... I finally got my '67 to celebrate my 2nd daughter's birth but the reality was not as good as the dream. Turns out that one of the PU's had a short and was a single coil (previous owner removed the covers) I never realized it, so maybe I just didn't get the best it had to offer. The guy I traded it to for the Bad Cat sent the pu's to lindy fralin to get rewound. Looks like he's fixing it up to get some real $$$ for it. Maybe you'll see it on Ebay or someplace like that.

Same thing with the '78 Les Paul I got when my 1st daughter was born, I can now say I had one but it was also less than I expected and I traded it for some computer gear.

As you can probably tell I've been at this off and on for a long time and it pretty much coincides with times of major change in my life... some people opt for comfort food I seem to opt for the comfort of music. I suppose/know if I had the talent I would opt for a career somewhere in the biz.

Anyway thanks again for your advice and for the friendly conversation. The business may be nasty but you still meet some mighty nice people in it.

Mark
Mark,

It does sound like you put together a nice tube inventory. What you will find in almost all probability, is you will like the 4004 for some things and the GE for others, and you will find yourself swapping tubes every so often, somewhat like folks change patches on a modeling amp \:\) Your amp really responds to different tube characteristics in V1. I think you will like the surprises and changes.

Bob at Eurotubes is a terrific fellow, and when it comes to output tubes, he already gets something of the "cream of the crop" from the factory as he has family back there and is thought of as part of the JJ family because his real family is from the area. Then he takes these tubes that were already hand picked for him, and goes through them himself, and matches them even closer. His output sets are typically matched within 1mA, and on an EL-84 that is a 98% match on a average characteristic tube. Usually a match of 90% is considered pretty good, and anything at 95% or over, and your output section gets nicer on something of an exponential scale on class A amps like Matchless and Vox types, and is even more apparent on Dr. Z. amps.

The NOS tubes are different. Whether that is good, bad, or whatever, is up to the listener. The GE's are really terrific but pricy. What you will hear there, is when you are at high levels with a lot of output distortion, you will still be able to hear individual notes within a chord as an example. At low levels, there is more texture and complexity where the amp appears louder and more full at reduced settings. If you want to hear a DRAMATIC difference, even for folks that think they have no interest in music or sound, plug in your GE's play a bit, and then replace those with Sovtek EL-84's. It sounds like a big felt blanket was tossed over the top of your amp.

But ... if you get the sound you are after, have effects and pedals in the front end, and are happy with what you get with inexpensive tubes that are easily available, then that's terrific, and less expensive! Some of the best sounds in the world are on very inexpensive amps with cheesy effects that are just magic. I have one of those little plastic Vox AC-1 amps. It gets used for a lot more than most could imagine. I also have a modified 100 watt Rivera Fandango head with a ported CS-410 cabinet, a sub system, and a 4x12 cabinet, running hand picked 6L6GC's and is fully blueprinted. It puts out about 170 watts max, and gets used less than anything else I own.

On your interest of Mac computers. I used to do a lot with them a decade or so back. I was the music consultant for Apple on the Vivarium project and worked for Alan Kay's group.

Stay away from those caps, and on pins 2 and 5 of preamp tubes on your Torres, get those wires off the chassis as much as you can, and that will get rid of a lot of your hum issue.

Working in the music biz is great at times, but like any other sort of job, can be a JOB at times. I worked in corporate environments for a few decades, since 1973, when I started with Control Data right out of school. I prefer this work, although financially it is more chicken and less steak, but I have never been as broke or as happy in my life.

Regards,

Myles
Posted By: NMBaum

Re: Feel free to ask Myles - 05/05/02 09:55 PM

OK Myles,
I took the hint and I've stopped trying to email you with all my questions and I am now posting a question on this forum. \:D

In an attempt to get rid of some of the buzziness in my Mesa Dual Rec, I replaced the stock pre-amp tube in the V1 position with a Chinese 12ax7 from Ruby Tubes. I noticed quite a difference - less buzz and more clarity and high end. The question is (drum roll) should I keep swapping out tubes? What other power tubes should I look at swapping or is the V1 the only one that makes a difference. I still run a duet of Mesa EL-34s, and they sound much better than the Mesa 6l6's. Of course, I am still contemplating your advice to have a variable bias pot put on my amp. I guess since I am low on funds, I need your advice before I start spending all my money on the elusive search for tone.

Thank again for all your help.
Brad (no new baby yet)
Posted By: not coaster MODERATOR

Re: Feel free to ask Myles - 05/05/02 10:28 PM

Myles-can you tell if there is any advantage to gold plated cables vs the normal stuff?
Posted By: jetboy

Re: Feel free to ask Myles - 05/06/02 03:27 AM

Posted By: sgguitarzz

Re: Feel free to ask Myles - 05/06/02 08:55 PM

Quote:
Hey Myles. Thanks for the tips. I was able to pick up two of the GT 12AX7C's at Sam Ash ($14 each). I checked and the both have the round halo thing under the silver getter flash. I was amazed SA had them. I will try putting the 5751 in V1, 12AX7C in V2 & V4, and put a 12AT7 in V5 (I have an Amperex Bugle Boy and a JJ to choose from). I will switch out the V3 Brimar and replace it with a JJ 12AX7 I have. I guess we will see what happens.

Well I did all the above as you have suggested and had nice results. This combination of tubes did bring down the overall output - not tremendously but a noticeable amout. Depending on the tone controls settings and EQ I could get a pretty decent range of base sounds. The way I had things set up the amp had kind of a Fender vibe to which worked real well on clean and also with my various effects. I could do the early Eagles country clean thing as well as the Neil Young distortion. Pretty cool. The band liked the sound and not one person complained at all about the volume.
Thanks very much for your help.

Dennis
Posted By: myles_rose

Re: Feel free to ask Myles - 05/06/02 11:22 PM

Quote:
Originally posted by NMBaum:
OK Myles,
I took the hint and I've stopped trying to email you with all my questions and I am now posting a question on this forum. \:D

In an attempt to get rid of some of the buzziness in my Mesa Dual Rec, I replaced the stock pre-amp tube in the V1 position with a Chinese 12ax7 from Ruby Tubes. I noticed quite a difference - less buzz and more clarity and high end. The question is (drum roll) should I keep swapping out tubes? What other power tubes should I look at swapping or is the V1 the only one that makes a difference. I still run a duet of Mesa EL-34s, and they sound much better than the Mesa 6l6's. Of course, I am still contemplating your advice to have a variable bias pot put on my amp. I guess since I am low on funds, I need your advice before I start spending all my money on the elusive search for tone.

Thank again for all your help.
Brad (no new baby yet)
Brad,

On the Ruby tube, was it a 12AX7C4? Their C4's are the selected tubes of their Chinese and are generally a bit better.

V1 and V2 in Mesa amps make a difference, but V1 is usually responsible for more of the initial character of the amp.

The problem today with preamp tubes is you have no idea what was in your amp or what you put in there. Its total chance. 12AX7's vary anywhere from -50% to +40% below and above industry spec from the 50's and 60's. At this time, the only way you can get what you might really want, is to contact Watford Valves in the U.K., and in your case, you want tubes for V1 and V2 that rate 250-260 for V2 and 220-230 for V1 which feeds V2. If V1 is too high, mush and lack of articulation results, and your volume/gain (not the master), has a range of usefulness that is very limited before it all mushes together. If too low on V1, you loose gain.

This is NOT the same for all Mesa products, as the non-rectifier amps have the tone control circuit pre-distortion and the rectifier series like a dual rectifier, have them post distortion, as in a Marshall amp.

When it comes to the power tubes, I need a LOT more info. Mesa's 6L6's can be Chinese, low grade Russian (Sovtek), high grade Russian (Svetlana), etc. Their EL-34's are much the same, and in EL-34's they also offer NOS tubes.

Your phase inverter has about an 80% chance of not being matched. If it does not put out the same power on the A and B side, a mis-matched output section is the result. There is a lack of sustain at certain frequencies, and the lack of lower harmonics which are cancelled out by the NFB loop will make your amp sound more thin, harsh and edgy. That is the next item you should check. If you have acess to a scope or a tech with a scope, put you amp into a load, run in a 40 cycle waveform, crank it up and look at the output. If it is not symmetrical top and bottom, then you have a mis-matched phase inverter and/or output tubes.

You do not need to alter your Mesa amp with an adjustible bias. Just use a higher range of tube than they offer, and you will also see on the scope, that your giant crossover notch at low levels, is gone at low levels and is just present at high levels, just where it is supposed to be when it comes to any Class A/B amp. Your amp will not be running as cool, so it will have more life, feel better dynamically, be much more touch sensitive, and loose some of the grainy quality.

I typically use Groove Tubes 6L6R2 (Svetlana) tubes with a rating of 7 in these amps if you are into 6L6's (which produce more massive distortion than EL-34's but with less articulation and definition). I use Groove Tubes E34Ls tubes with a rating of 6 for these amps when folks want EL-34's or EL-34R2 (svetlana again) in a range of 7 if you do not want the extra power of the E34Ls tubes.

These E34Ls tubes are from the JJ factory, but are just a touch different than the normal JJ tube, as GT has them make a few engineering changes under contract for them.

When it comes to preamp tubes, your only bet at this point if you want to really be sure, is Watford Valves in the UK. The offer what they call "balanced valves" for the phase inverter postion. If you use JJ tubes, then the 12AX7 / 12AT7 in a phase inverter slot can be supplied by Eurotubes in the USA, but they only sell the JJ tubes.

If you want V1 and V2 to be a known item, then you have to hit Watford Valves. Then next time, if you had a "200" and want more gain, then you can order a "230", etc. There are other factors such as rise time, but nobody I know offers those tubes other than myself, but they are for my clients - I am not a tube seller.

If you want a matched phase inverter, again, if its not a JJ tube, then its also Watford Valves. They also sell JJ tubes by the way.

For power tubes, I use Watford, Eurotubes and Groove Tubes. GT is generally my first choice as their tubes are tested dynamically rather than in a static environment. Watford also tests dynamically, but my best matches seem to come from GT when you put them on a curve tracer. I also prefer the tubes where GT rebases them with better pins than they come from the factories. The rough cadmium looking plating that you see on so many tubes is just rough enough to push old socket innards into a problem, and the smooth pins used by Groove Tubes keeps me from having to replace output sockets on amps that have tubes changed many times per year. ( I guess that is one of those aspects of GT they do not advertise or mention ).

I hope this was of some help.

Regards,
Posted By: Greazygeo

Re: Feel free to ask Myles - 05/07/02 12:12 AM

Hey,
I have been working on a silverface Fender Twin. The vibrato is not making any sound. THe light bulb is flashing and will speed up and slow down with the controls. It seems like there are no shorted resistors or open caps. I can stop the bulb from flashing with the footswitch too. I guess I don't understand the circuit's signal flow to know where it begins and ends...The vibrato seems to want to work except i can't hear it.......any suggestions??
Posted By: snoz65

Re: Feel free to ask Myles - 05/07/02 01:59 AM

Hi Myles and all, I have an 12AU7 that is made in Japan. There are no other markings on the tube and I was wondering what brand of tube this might be. Any ideas?
Posted By: Fols

Re: Feel free to ask Myles - 05/07/02 07:20 AM

Myles - thanks millions - I've been lurking for the last few weeks, and have soaked up tons from your discussions. One of these weekends I need to make it down your way for one of your Saturday clinics.
I've just traded for a used Mesa Boogie Mark IV, and am thinking of retubing, but it doesn't appear to have original tubes, so I was wondering what advice you can offer for tube slots. My musical styles are predominantly classic rock, contemporary rock, with a little of everything in between, from country to pop. The tubes I'm considering, aiming for a quiet amp in the higher gain settings, smooth, but crunchy, gain (if that makes sense), not too bright, to the point of being brittle, but chimey enough, with complex harmonies, are as follows:

V1 (input/tone recovery stages)
Telefunken ECC83, JJ/Tesla ECC83-S, Mesa SPAX7

V2 (3rd gain-rhythm/5th gain-lead/FX return)
Sovtek 12AX7EH, Mullard CV4004

V3 (1st lead hi-gain/reverb return)
??? 12AT7, Sylvania ECC83/12AX7, Mullard ECC83

V4 (2nd lead hi gain/reverb send)
Phillips NOS JAN 12AT7WC, ??? 5751, Sovtek 12AX7EH

V5 (Phase Inverter:
GE NOS JAN 12AT7WC, RCA 12AT7, or RCA 5751

I'd be interested in hearing what you (or anyone else, for that matter) has to offer for discussion on these choices. Most of the selection is based on internet research, and not actual tone tests, other than the Sovtek 12AX7EH's which I liked the tone of, but had a little trouble with hissing in higher gain settings, as well as the lead tones were somewhat grainy.

The amp currently has GrooveTube GT6L6S (4's), and Mesa 12AX7-A/ECC83's in it. the Groove Tubes are replacemetns, I'm sure, but the 12AX7's may be originals. the amp appears to be about a 1992 vintage, but I haven't confirmed the serial # dating, yet (anyone know a website to check date of Mesa's, based on serial #'s, BTW?)

Thanks again for all your help - I've learned more here in the last few weeks than the last couple of years!
Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 06:15 PM

Quote:
Originally posted by Cereal:
Myles-can you tell if there is any advantage to gold plated cables vs the normal stuff?
Cereal,

Gold is a very good conductor and does not corrode.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 06:33 PM

Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 06:37 PM

Quote:
Originally posted by sgguitarzz:
Quote:
Hey Myles. Thanks for the tips. I was able to pick up two of the GT 12AX7C's at Sam Ash ($14 each). I checked and the both have the round halo thing under the silver getter flash. I was amazed SA had them. I will try putting the 5751 in V1, 12AX7C in V2 & V4, and put a 12AT7 in V5 (I have an Amperex Bugle Boy and a JJ to choose from). I will switch out the V3 Brimar and replace it with a JJ 12AX7 I have. I guess we will see what happens.

Dennis,

Sometimes you hear a bigger change, and sometimes a smaller one. Its because the characteristics of the tubes are so inconsistant.

Watford Valves has "graded" preamp tubes, and from what I hear, Groove Tubes is about to offer this also on a limited basis, but you may have to order them directly from GT. I also think they will have matched phase inverters but will have a few more twists over some other tubes.

Regards,

Well I did all the above as you have suggested and had nice results. This combination of tubes did bring down the overall output - not tremendously but a noticeable amout. Depending on the tone controls settings and EQ I could get a pretty decent range of base sounds. The way I had things set up the amp had kind of a Fender vibe to which worked real well on clean and also with my various effects. I could do the early Eagles country clean thing as well as the Neil Young distortion. Pretty cool. The band liked the sound and not one person complained at all about the volume.
Thanks very much for your help.

Dennis
Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 06:50 PM

Quote:
Originally posted by Greazygeo:
Hey,
I have been working on a silverface Fender Twin. The vibrato is not making any sound. THe light bulb is flashing and will speed up and slow down with the controls. It seems like there are no shorted resistors or open caps. I can stop the bulb from flashing with the footswitch too. I guess I don't understand the circuit's signal flow to know where it begins and ends...The vibrato seems to want to work except i can't hear it.......any suggestions??
Greazygeo,

Have you changed the preamp tube?

If that does not help, its time to look at it with a meter and scope.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 06:52 PM

Quote:
Originally posted by snoz65:
Hi Myles and all, I have an 12AU7 that is made in Japan. There are no other markings on the tube and I was wondering what brand of tube this might be. Any ideas?
snoz65,

Its hard to tell without seeing the tube, but I do not know of any Japanese manufactured tubes. It was probably OEM'd from China or Europe and silkscreened with a Japanese name or logo.

Regards,
Posted By: Greazygeo

Re: Feel free to ask Myles - 05/07/02 07:43 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by Greazygeo:
Hey,
I have been working on a silverface Fender Twin. The vibrato is not making any sound. THe light bulb is flashing and will speed up and slow down with the controls. It seems like there are no shorted resistors or open caps. I can stop the bulb from flashing with the footswitch too. I guess I don't understand the circuit's signal flow to know where it begins and ends...The vibrato seems to want to work except i can't hear it.......any suggestions??
Greazygeo,

Have you changed the preamp tube?

Did that first.....no difference. This is the 100 watt twin w master volume, no mods or anything changed either. Where does the circuit actually start and end?? It looks like it feeds in at the 220 K mixing resistors......thanks for any help.......

If that does not help, its time to look at it with a meter and scope.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 08:26 PM

Quote:
Originally posted by Fols:
Myles - thanks millions - I've been lurking for the last few weeks, and have soaked up tons from your discussions. One of these weekends I need to make it down your way for one of your Saturday clinics.
I've just traded for a used Mesa Boogie Mark IV, and am thinking of retubing, but it doesn't appear to have original tubes, so I was wondering what advice you can offer for tube slots. My musical styles are predominantly classic rock, contemporary rock, with a little of everything in between, from country to pop. The tubes I'm considering, aiming for a quiet amp in the higher gain settings, smooth, but crunchy, gain (if that makes sense), not too bright, to the point of being brittle, but chimey enough, with complex harmonies, are as follows:

V1 (input/tone recovery stages)
Telefunken ECC83, JJ/Tesla ECC83-S, Mesa SPAX7

V2 (3rd gain-rhythm/5th gain-lead/FX return)
Sovtek 12AX7EH, Mullard CV4004

V3 (1st lead hi-gain/reverb return)
??? 12AT7, Sylvania ECC83/12AX7, Mullard ECC83

V4 (2nd lead hi gain/reverb send)
Phillips NOS JAN 12AT7WC, ??? 5751, Sovtek 12AX7EH

V5 (Phase Inverter:
GE NOS JAN 12AT7WC, RCA 12AT7, or RCA 5751

I'd be interested in hearing what you (or anyone else, for that matter) has to offer for discussion on these choices. Most of the selection is based on internet research, and not actual tone tests, other than the Sovtek 12AX7EH's which I liked the tone of, but had a little trouble with hissing in higher gain settings, as well as the lead tones were somewhat grainy.

The amp currently has GrooveTube GT6L6S (4's), and Mesa 12AX7-A/ECC83's in it. the Groove Tubes are replacemetns, I'm sure, but the 12AX7's may be originals. the amp appears to be about a 1992 vintage, but I haven't confirmed the serial # dating, yet (anyone know a website to check date of Mesa's, based on serial #'s, BTW?)

Thanks again for all your help - I've learned more here in the last few weeks than the last couple of years!
Fols,

The next clinic is this Saturday 5/11. If you can't make it for this one, there will be another in two or three weeks.

Mesa Mk IV's have been around for a bit of time now, so it does not surprise me that it does not have the original tubes.

On your amp, you can do many styles as their gain structure is pretty versitile. Because of the cascading gain structure, and because the tone controls are pre distortion rather than post distortion, I like lower gain 12AX7 in V1 of those amps. That way they are clean and quiet in the cleaner settings.

V1 (input/tone recovery stages)
Telefunken ECC83, JJ/Tesla ECC83-S, Mesa SPAX7

These are all very different sounding tubes. The current Mesa SPAX7 is the Electro Harmonix tube. The JJ and Telefunkens are a bit different, with the JJ having a bit more of an extended mid and mid high range. This is going to be personal preference, but I'd opt for a tube that is a bit lower in gain than average for any of the chosen types. I normally use tubes with my rating of about 80 in that position.

V2 (3rd gain-rhythm/5th gain-lead/FX return)
Sovtek 12AX7EH, Mullard CV4004

Id save your money here, and go with the EH.

V3 (1st lead hi-gain/reverb return)
??? 12AT7, Sylvania ECC83/12AX7, Mullard ECC83

You should try the 12AT7 and a 12AX7 here, and see what you prefer. Of the 12AX7's, this is personal preference.

V4 (2nd lead hi gain/reverb send)
Phillips NOS JAN 12AT7WC, ??? 5751, Sovtek 12AX7EH

I like 12AT7's here as they have more current drive for the reverb send than a 12AX7, even with less gain.

V5 (Phase Inverter:
GE NOS JAN 12AT7WC, RCA 12AT7, or RCA 5751

Again, I prefer AT7's in phase inverter positions, but make sure it is balanced on the A and B sides.

Any tube with higher gain, especially in a Mark amp, will have more background noise. That is why I prefer one with a lower initial gain, as its noise will be amplified throughout the rest of the signal chain.

You may want to contact Kelly or Rick over at Groove Tubes, as they are in the process of having some hand selected tubes. Maybe they can get you what I call an "80" or what Watford Valves would call a "200". You can call them at 818-361-4500. Its worth a try.

The 6L6S is a JJ tube that Groove Tubes rebases and uses a nicer base and better quality pins. The 4 rating is too cold for your amp though, and if you go up to a 7 rating, you will lose a lot of the grain and gravelly sound you hear a bit, especially in the cleaner settings.

You're more than welcome.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 09:01 PM

Quote:
Originally posted by Greazygeo:
Quote:
Originally posted by myles111:
Quote:
Originally posted by Greazygeo:
Hey,
I have been working on a silverface Fender Twin. The vibrato is not making any sound. THe light bulb is flashing and will speed up and slow down with the controls. It seems like there are no shorted resistors or open caps. I can stop the bulb from flashing with the footswitch too. I guess I don't understand the circuit's signal flow to know where it begins and ends...The vibrato seems to want to work except i can't hear it.......any suggestions??
Greazygeo,

Have you changed the preamp tube?

Did that first.....no difference. This is the 100 watt twin w master volume, no mods or anything changed either. Where does the circuit actually start and end?? It looks like it feeds in at the 220 K mixing resistors......thanks for any help.......

If that does not help, its time to look at it with a meter and scope.

Regards,
What you need to do is an interference test where with the prints, you start at end back of the circuit and work forward listening to the pops increase in volume. When the pop stops, there is the problem.

Regards,
Posted By: MikeS_dup1

Re: Feel free to ask Myles - 05/07/02 10:46 PM

Myles,

I have a couple of questions regarding 6L6's. First, are 6CL6 tubes the same as 6L6's? And if they are, would $25 for a set of five NIB JAN/GE be a good price? I would image if they are 6L6's $25 would be a great price. I guess it would be a crapshoot if 2 or more were matched.

Thanks,

MikeS
Posted By: AgentOrange

Re: Feel free to ask Myles - 05/07/02 11:15 PM

Yo miles, this is James from the HC Forum

First off, upon recommendation from Watford Valves over here in the UK (i noticed you have a link to them on your page), I have ordered two Harma 6L6s which they plugged over all the other stuff they have. How do you think they will affect my sound if all other things are kept constant? Well onto the real question......

If i wanted a tighter more focused sound from my rectoverb, would this be possible/worth the money, in terms of an audible difference, by changing the preamp valves. If so, what valves would you recommend? I have 5 12AX7s in there all MESA tubes so id unno what they were b4
any help would be greatly appreciated

------------------
Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 11:16 PM

Quote:
Originally posted by MikeS:
Myles,

I have a couple of questions regarding 6L6's. First, are 6CL6 tubes the same as 6L6's? And if they are, would $25 for a set of five NIB JAN/GE be a good price? I would image if they are 6L6's $25 would be a great price. I guess it would be a crapshoot if 2 or more were matched.

Thanks,

MikeS
Mike,

Stay away from those, they are very different.

They do not even share the same pinout at as 6L6, and there are other differences too.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/07/02 11:23 PM

Quote:
Originally posted by AgentOrange:
Yo miles, this is James from the HC Forum

If i wanted a tighter more focused sound from my rectoverb, would this be possible/worth the money, in terms of an audible difference, by changing the preamp valves. If so, what valves would you recommend? I have 5 12AX7s in there all MESA tubes so id unno what they were b4
any help would be greatly appreciated

------------------
AgentOrange,

Your are in the right part of the globe, as you have Watford Valves in your own backyard.

You want to do a few things:

1. Replace V1 with one of their 12AX7's with a rating of about 225 on their scale.

2. Replace V2 with one of their 12AX7's with about a 200 rating on their scale.

These first two changes will allow a much wide usable range between your volume (gain) and master and will get rid of a lot of the smudge that comes in at gain settings over 3-4.

3. Replace your phase inverter with one of the Watford "balanced valves". If you want more clean headroom, use one of their 12AT7's and for more gain use a 12AX7. This is personal taste. In the phase inverter position, you don't have to spend a lot of money, as we are looking at current drive here, not tone shaping.

On the V1 and V2 tubes, expensive NOS tubes are not really as noticible in these amps, as their circuits are designed for a different type of response than the vintage curcuits of the older tweed a blackface amps that had way less than 200 volts on their plates.

Regards,
Posted By: villainvomit

Re: Feel free to ask Myles - 05/07/02 11:54 PM

Myles,

First let me say thanks for sharing all the tube info so freely.

Secondly, here is a lightweight question for you. Have you ever run across Korean 12ax7's and if so what do you think about them. I wouldn't think there would be too many manufacturers in that local. They were in a second hand '78 JMP 100 watt I purchased months ago (also had JJ E34L's which I have recently bought more of). No markings on the 12ax7's except 12ax7 and made in Korea.

Any thoughts?

Thanks again,
VV
Posted By: myles_rose

Re: Feel free to ask Myles - 05/08/02 01:19 AM

Quote:
Originally posted by villainvomit:
Myles,

First let me say thanks for sharing all the tube info so freely.

Secondly, here is a lightweight question for you. Have you ever run across Korean 12ax7's and if so what do you think about them. I wouldn't think there would be too many manufacturers in that local. They were in a second hand '78 JMP 100 watt I purchased months ago (also had JJ E34L's which I have recently bought more of). No markings on the 12ax7's except 12ax7 and made in Korea.

Any thoughts?

Thanks again,
VV
villainvomit,

A free beer for you at an amp clinic! You stumpped me on on this one for sure! I did not even know there were any tube factories in Korea!

On your Marshall though, check the bias, as somebody may have plugged in the JJ's without re-biasing, and they have about a 15% different bias requirement than 25 watt EL-34 tubes.

If you're in my area (Los Angeles) drop me a line and I will check this for you gratis, and if necessary, I will also adjust it for free since you stumpped me \:\)

Regards,
Posted By: overcomer

Re: Feel free to ask Myles - 05/08/02 03:09 AM

hi, i the new 6L6ge's from rick on monday, and he said you were"in the building" at the time. anyway, i told him about what you had said that "get some matched 12aT7's" to which he replied "you dont have to match preamp tubes" i was unable to explain what i meant. i ordered two 12at7s from him also to retube my super reverb. iwant to spend the right money on it now and get it fixed up so i wont have to spend any later. I think maybe i see now that what you meant was to get some balanced phase inverter tubes from watford or another place. right? well, thanks again for you replies,,
Posted By: MikeS_dup1

Re: Feel free to ask Myles - 05/08/02 05:27 AM

Thanks Myles I had my doubts.

MikeS
Posted By: Dave M

Re: Feel free to ask Myles - 05/08/02 11:06 AM

Hi Myles (visiting from Harmony Central)

I have a Boogie 50/50 power amp and would like to check with you that I'm using the correctly rated (?) valves. I'm currently using Harma STR 6L6GC valves (30 MA, 3.1M/AV) as supplied by Watford Valves. How would these compare to Mesa Boogie 'branded' valves. i.e. what colour rating would they equal.

The guy that serviced my amp set he could not change the bias of my power amp. Is this correct ?

I am asking all this as I only seem to go 5-6 months without a tube going bad. Would failing capacitors cause premature valve failure ?

Any help would be appreciated.

Thanks
Dave
Posted By: villainvomit

Re: Feel free to ask Myles - 05/08/02 04:05 PM

Quote:
Originally posted by myles111:
[QUOTE]
[qb]Myles,

A free beer for you at an amp clinic! You stumpped me on on this one for sure! I did not even know there were any tube factories in Korea!

On your Marshall though, check the bias, as somebody may have plugged in the JJ's without re-biasing, and they have about a 15% different bias requirement than 25 watt EL-34 tubes.

If you're in my area (Los Angeles) drop me a line and I will check this for you gratis, and if necessary, I will also adjust it for free since you stumpped me \:\)

Regards,
Myles,

Yes sir, I will get the bias checked, as this amp sounds better than any I have or have played through. It might sound even better, huh?

I live in Atlanta, but you can bet I will look you up next time I am in your area. Hell, I might even drive to LA the next time I am in Vegas (not quite the same as it used to be, but still fun).

With much appreciation,

VV
Posted By: Henrionov

Re: Feel free to ask Myles - 05/08/02 08:32 PM

Hey Myles, thanks for all the excellent advise. I have been reading your many posts and have learned a lot.
I have a couple of old Fender amps I'm thinking of taking down to your free amp clinic this weekend and am wondering what to expect. I won't be able to make to until about 3pm. Will there be a line, 20 guys long waiting for amp checkups? How long do you spend with each amp? I'll be driving about an hour and don't want to endure a total zoo, but I would love to have my amps checked out.
Thanks in advance, and keep up the great work!
Posted By: myles_rose

Re: Feel free to ask Myles - 05/08/02 08:35 PM

Quote:
Originally posted by overcomer:
hi, i the new 6L6ge's from rick on monday, and he said you were"in the building" at the time. anyway, i told him about what you had said that "get some matched 12aT7's" to which he replied "you dont have to match preamp tubes" i was unable to explain what i meant. i ordered two 12at7s from him also to retube my super reverb. iwant to spend the right money on it now and get it fixed up so i wont have to spend any later. I think maybe i see now that what you meant was to get some balanced phase inverter tubes from watford or another place. right? well, thanks again for you replies,,
overcomer,

Groove Tubes and I am now working together to hand select so tubes that I might call something like "Ultra" or who knows what (open to suggestions). Its not a product of their's yet, and if it ever becomes a product, it will be in very short supply, as I have to go through 20-50 tubes to get one that is matched. If you are a friend or Ricks or a relation of GT, let Rick know to contact me, and I will find you some matched 12AT7s. I think they will be about $25 rather than the normal $18 due to the extra searching around and testing each one by hand.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/08/02 08:45 PM

Quote:
Originally posted by Dave M:
Hi Myles (visiting from Harmony Central)

I have a Boogie 50/50 power amp and would like to check with you that I'm using the correctly rated (?) valves. I'm currently using Harma STR 6L6GC valves (30 MA, 3.1M/AV) as supplied by Watford Valves. How would these compare to Mesa Boogie 'branded' valves. i.e. what colour rating would they equal.

The guy that serviced my amp set he could not change the bias of my power amp. Is this correct ?

I am asking all this as I only seem to go 5-6 months without a tube going bad. Would failing capacitors cause premature valve failure ?

Any help would be appreciated.

Thanks
Dave
Dave,

I need to know at what B+ voltage Watford came up with the 30mA figure.

If this a "mid-range" tube for them, they would be fine in your Mesa without a bias adjustment. You can also ask them how their rating would covert to a Groove Tubes rating. If it is in GT 4-7 rating, you would be fine.

To convert fro GT to Mesa ratings, there is a table and a writeup on my website.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/08/02 08:53 PM

Quote:
Originally posted by villainvomit:
Quote:
Originally posted by myles111:
[QUOTE]
[qb]Myles,

A free beer for you at an amp clinic! You stumpped me on on this one for sure! I did not even know there were any tube factories in Korea!

On your Marshall though, check the bias, as somebody may have plugged in the JJ's without re-biasing, and they have about a 15% different bias requirement than 25 watt EL-34 tubes.

If you're in my area (Los Angeles) drop me a line and I will check this for you gratis, and if necessary, I will also adjust it for free since you stumpped me \:\)

Regards,
Myles,

Yes sir, I will get the bias checked, as this amp sounds better than any I have or have played through. It might sound even better, huh?

I live in Atlanta, but you can bet I will look you up next time I am in your area. Hell, I might even drive to LA the next time I am in Vegas (not quite the same as it used to be, but still fun).

With much appreciation,

VV
Next time you are going to Vegas, drop me a note. Maybe I'll meet you there, and we can look at your amp(s) and then hit the casinos.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/08/02 08:59 PM

Quote:
Originally posted by Henrionov:
Hey Myles, thanks for all the excellent advise. I have been reading your many posts and have learned a lot.
I have a couple of old Fender amps I'm thinking of taking down to your free amp clinic this weekend and am wondering what to expect. I won't be able to make to until about 3pm. Will there be a line, 20 guys long waiting for amp checkups? How long do you spend with each amp? I'll be driving about an hour and don't want to endure a total zoo, but I would love to have my amps checked out.
Thanks in advance, and keep up the great work!
Henrionov,

This weekend will probably be a quiet one as I have not sent out my mailing to the folks I know, so they have not also told their friends.

Just try to come about 12-1, and it will be slower than later in the afternoon. If you tell me you had a drive, then if there is a line, you will go to the front. There is normally not a wait, maybe 1 amp in front of anybody else at the most, and it goes pretty fast with plenty of time for questions.

Its normally goes pretty smoothly.

Regards,
Posted By: boldo

Re: Feel free to ask Myles - 05/09/02 10:57 AM

hi myles I've read your article 'bout tubes but I'd like to ask you some specific advice.I own a marshall jtm 612 I've got svet el34 as power tubes.I got a 12at7 as ph.inv. and It works great. Now I just want to find the right tubes for pos v1 and v2 : I want the best performance in clean-going-distorted situations , lots of sustain , clarity and "fullness" - a nice blues-rock tone.I mostly use the boost channel to get my best tone , expecially at reasonable (doesn't mean very low, just not eazr splitting) volumes. A thing that I really hate about stock tubes is that they get nasal and a bit "boxy-and-dark-sounding" when pushed hard with a stompbox.I play a strat, mostly in the neck position.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/09/02 07:50 PM

Quote:
Originally posted by boldo:
hi myles I've read your article 'bout tubes but I'd like to ask you some specific advice.I own a marshall jtm 612 I've got svet el34 as power tubes.I got a 12at7 as ph.inv. and It works great. Now I just want to find the right tubes for pos v1 and v2 : I want the best performance in clean-going-distorted situations , lots of sustain , clarity and "fullness" - a nice blues-rock tone.I mostly use the boost channel to get my best tone , expecially at reasonable (doesn't mean very low, just not eazr splitting) volumes. A thing that I really hate about stock tubes is that they get nasal and a bit "boxy-and-dark-sounding" when pushed hard with a stompbox.I play a strat, mostly in the neck position.
boldo,

These are the "hard" questions, as they are not technically black and white.

Normally, I sit down with folks, and change tubes in V1 while they are listening and playing. Then we get into the "do you like that more or less" aspects, and then I get an idea of where they really want to go, rather than their interpretation of a "rock" or "blues" label.

Marshalls are really tricky amps. They may seem pretty straightforard, but I am sure you have heard great ones and others. This is all in setup. Bias is really important in these amps, not for tube wear as much as for the characteristic sound that Marshall's are identified as to having.

I (myself) prefer ECC83's in V1 and V2, if no pedals are ever used. If pedals are used, then I use a 7025 in V1 and that tube will get back some of the lost highs.

Now the other big thing with Marshalls, is that their tone stack is post preamp distortion, rather than the Fender pre topology. This makes V2 really important in Marshalls too. V2 needs to be chosen for its specs, not its articulation. As an example, if you are a Mullard fan, putting an expensive Mullard in V2 of a Marshall for its sonic qualities would not show you as much of a sonic result as putting in a less expensive tube.

If you like how your amp sounds now, that is a bit of a problem, because when you change preamp tubes in the future, even to the same make and type, the amp will sound and feel different. That is because preamp tubes are generally not rated as are output tubes, so you have no idea what is in there now.

The first step is to start with something that is known.

In your amp, I'd go for an ECC83 in V1 with a rating from Watford Valves of 250-260. Then in V2, I'd use a ECC83 from Watford with a spec of 200-220.

Bob over at Eurotubes can hand pick you some ECC83's also, if you want to use him, let me know and I can give you some numbers to give to him. On my scale that I use for my own clients, I'd use a 116 in V1 and a 80-90 in V2, but unlike Watford Valves, I also look at rise time, and for your style I'd want a specific rise time on your V1 tube.

Another option is to call Groove Tubes in California and ask for Kelly. I work with him every now and then, and they do sell tubes directly to their "artists and relations" folks. If he can get me some of their ECC83's to test, then I could find a few with some luck for you and you could buy them from them. I would think with all the handling and what I'd have to charge them, they'd probably want a few more dollars for the tubes, but you'd have a baseline on gain and structure, which you don't have now, and that's the biggest plus, as then you can go up or down or repeat what you did before.

On your Svetlana's .... they are great in Marshalls, and if you like the way they sound in there, keep them!

Regards,
Posted By: mikey_dup1

Re: Feel free to ask Myles - 05/09/02 11:45 PM

Miles,
I have a Fender DeVille that I am putting Svets 6L6's in. Do I need to have the amp biased. Right now it has a groove tube 6L6 and a ruby tube 6L6, that were in it when I bought it. Thanks.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/10/02 12:54 AM

Quote:
Originally posted by mikey:
Miles,
I have a Fender DeVille that I am putting Svets 6L6's in. Do I need to have the amp biased. Right now it has a groove tube 6L6 and a ruby tube 6L6, that were in it when I bought it. Thanks.
mikey,

You definately need to have that bias checked. Since there is an unmatched set in there now, your amp is not sounding anywhere close to how it can sound, and I am pretty confident that if somebody did that mismatch, the either did not adjust the bias or did not do it right.

If the bias was not touched, and you are sure of that, Svets in a mid range will work safely, but you should have the bias looked at.

Regards,
Posted By: jazzcaster

Re: Feel free to ask Myles - 05/10/02 02:53 AM

Hello Myles,

I am really enjoying the new Pro Tube Reverb, and am still astounded by the sound with the tube change. Your advice was excellent and very much appreciated. Thank-you again.

I have a general speaker question though. I have read some postings on other sites respecting speaker upgrades (specifically to Weber speakers...a C10CA, and a C12N). A number of the postings state that the speakers need to be "played/broken" in, and that the sound keeps improving as this happens. Years ago I was assured by a credible source that my Hi-Fi stereo speakers did not have to be "broken in". The sound I heard now was the sound I was always going to hear. I assume Amp speakers would be the same? (no play-in/break-in). Is this an old wives tale or truth?

kind regards,

Paul.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/10/02 08:10 PM

Quote:
Originally posted by jazzcaster:
Hello Myles,

I am really enjoying the new Pro Tube Reverb, and am still astounded by the sound with the tube change. Your advice was excellent and very much appreciated. Thank-you again.

I have a general speaker question though. I have read some postings on other sites respecting speaker upgrades (specifically to Weber speakers...a C10CA, and a C12N). A number of the postings state that the speakers need to be "played/broken" in, and that the sound keeps improving as this happens. Years ago I was assured by a credible source that my Hi-Fi stereo speakers did not have to be "broken in". The sound I heard now was the sound I was always going to hear. I assume Amp speakers would be the same? (no play-in/break-in). Is this an old wives tale or truth?

kind regards,

Paul.
Paul,

You're welcome first off.

Speakers ... that is a personal taste issue, but the Jensen C12N that comes as stock in your amp is pretty much the sound of the 60's and 70's Fender amps. I'd play it a while before considering a change, its a pretty nice speaker.

On the issue of break in of speakers, some believe it, some don't, but to me, when a speaker is very old and very used, it will sound a bit looser because the suspension is worn more. Today's surround materials are similar though not perhaps exact as in the past, but behave the same in most instances.

I think you can play hard from the first minute.

Regards,
Posted By: jazzcaster

Re: Feel free to ask Myles - 05/11/02 03:56 AM

Thank-you Myles. My speaker question had nothing to do with my Pro Reverb though....I'm totally happy with it now (as a result of the tube changes!). The speaker question was for an old Princeton Chorus I have (a righteous little amp btw!).
keep playin'

Paul.
Posted By: Tony M

Re: Feel free to ask Myles - 05/12/02 02:56 AM

Hi Myles,

I talked to you on the phone today about retubing my Badcat Hotcat. It currently has groove tubes EL34LS and a mix of GT and Ruby 12ax7's. You mentioned GE 6CA7's for the EL34's. How do these compare to Siemans or Svetlana's. Any other suggestions for power tubes. I have another amp which has a tele and GE NOS 12ax7's and tried those in the hotcat in V1 and V2 and smoothed out the tone. Would these be a good choice? There are 4 12ax7's labeled channel 1 2 input gain
channel 2 2nd gain stage
tone selection
phase inverter

It also has a ruby 5ar4 rectifier tube and wanted to also try a 5Y3GT since the amp is suppose to take either tube or a 5U4.
Also any suggestions on where to buy tubes.
I've heard Hi Test has good reputation.

Thanks, Tony
Posted By: jetboy

Re: Feel free to ask Myles - 05/13/02 06:29 AM

Hi Myles,

Just checking in with the prelims on my tube search:

got the JJ's first and basically swapped them for the oem's except for the reverb and rectifier tubes. a 90/90 balanced ECC83 for the phase inverter and a low gain 78/79 ECC83 for v1, an unvalued ECC83 for v2 and a matched low gain (40) set of EL84's. the sound was good, a bit more clarity but not particularly remarkable.

switched to the high gain ECC83 (114/118) in v1, very bright, pretty much too bright for me. very articulate. all other tubes remained the same.

switched to the normal 97/98 ECC83 and that was better, good articulation, good highs but not too bright. overall the winner.

went back and forth between the high gain and normal just to see if I was remembering it all. pretty much ended there with the normal tube being my fav.

then I got the NOS tubes from Kcanostubes.com.

left the ECC83 phase inverter but swapped the JJ EL84's for a matched set of NOS JAN GE EL84's, a NOS Mullard 4004 at V1 and a NOS JAN GE 12AX7WA at v2.

WOW, this appears to be the combo. very good tone at all volumes (except totally wide open master and volume) very sweet sounding, very articulate without being harsh, good bottom and very nice mids.

Now this was all very unscientific, since I changed many variables from the JJ's to the NOS, but right now the Cub sounds just great.

I want to experiment more and try combining the JJ's and NOS here and there. Any suggestions? How important is v2 to the total sound. I know from reading your articles on preamp tubes and power tubes that they both make differences but since I got low gain JJ EL84's would that make a bigger difference then the NOS Preamp tubes?

any thoughts would be helpful especially since I'm starting to doubt how much I remember about each setup.

Also how careful should I be regarding touch the tubes with my fingers (skin oils, not being burned) I know that tungsten light tubes will get hot spots where you touch them, do tubes get weaker from that kind of handling? So far I've been wearing exam gloves to reduce finger prints.

anyway I'm going to start swapping tubes again and see where that killer tone is coming from.

Is there any problem putting the high gain ECC83 into v2 with the Mullard? how about the GE 12ax7WA into v1 and something else into v2.

and is there any real advantage to another Mullard in v2? matched tubes?

I guess I'll find out, eh?

thanks for your support, Mark
Posted By: slide_blues

Re: Feel free to ask Myles - 05/13/02 07:32 AM

If you use a hotplate with a channel switching amp (clean - dirty channels), can you still have a clean channel at the same volume level as the dirty side?
I'm thinking if the dirty channel is maxed out for the power tube saturation, the clean channel (set for NOT alot of breakup) would not be loud enough, given that the hotplate would be cutting the overall volume.

Obviously I need to actually try one out with my classic 30, just wondering if you have any thoughts on using a hotplate with a channel switching small combo amp like the c30.

Thanks!
Posted By: myles_rose

Re: Feel free to ask Myles - 05/13/02 06:16 PM

Quote:
Originally posted by jazzcaster:
Thank-you Myles. My speaker question had nothing to do with my Pro Reverb though....I'm totally happy with it now (as a result of the tube changes!). The speaker question was for an old Princeton Chorus I have (a righteous little amp btw!).
keep playin'

Paul.
Paul,

I like the Jensens with the Alnico magnets, but that is just personal preference.

Regards,
Posted By: Slats

Re: Feel free to ask Myles - 05/13/02 06:47 PM

Hey Myles, I'm wondering about the tonal characteristics of a 12AX7WA compared to the 12AX7. I came across some in my father-in-laws tube stash, and I'm thinking of trying them in my AC30. Any thoughts would be much appreciated
Posted By: myles_rose

Re: Feel free to ask Myles - 05/13/02 07:03 PM

Quote:
Originally posted by Tony M:
Hi Myles,

I talked to you on the phone today about retubing my Badcat Hotcat. It currently has groove tubes EL34LS and a mix of GT and Ruby 12ax7's. You mentioned GE 6CA7's for the EL34's. How do these compare to Siemans or Svetlana's. Any other suggestions for power tubes. I have another amp which has a tele and GE NOS 12ax7's and tried those in the hotcat in V1 and V2 and smoothed out the tone. Would these be a good choice? There are 4 12ax7's labeled channel 1 2 input gain
channel 2 2nd gain stage
tone selection
phase inverter

It also has a ruby 5ar4 rectifier tube and wanted to also try a 5Y3GT since the amp is suppose to take either tube or a 5U4.
Also any suggestions on where to buy tubes.
I've heard Hi Test has good reputation.

Thanks, Tony
Tony,

The 6CA7's are very strong tubes as they have a higher vacuum than the Europe or China EL-34's, but they are not the taste of everybody. I like them, but you may want to check around with some other folks. These are stronger than the Siemens or Svetlana tubes.

If you want a very strong amp, you can also consider the JJ E34L or Groove Tubes E34LS tube. These are used by a lot of Matchless folks on V-85's.

If you want to try to find some GE 6CA7's, I know Rick or Kelly out at Groove Tubes has some NOS ones that are really great, and a lot less expensive than the NOS folks sell them for. You can give either one of them a call at 818-361-4500. They also have the E34LS tubes as you have in there now, which are pretty terrific, so you may just want to keep those unless you are looking for a more refined sound that is tighter and more articulate, with about a 15% wider sound picture that the 6CA7's will give you.

On your preamp tubes that are in there now, I'd either have your output driver tube looked at to see if its balanced, which it is probably not. This tube is really important in these amps. This is what you call your phase inverter. This is perhaps the 2nd most overlooked tube in your amp.

The Telefunken and GE NOS tubes are really nice, and they would really help any amp, not just yours.

You can use a 5Y3, 5U4, or 5AR4 rectifier in your amp. They will all give a different feel to your amp. If you go to my website in tube reviews area, there is an area for rectifiers that you may want to look at. It will show voltages and rise times of the various rectifier types.

As far as where to buy tubes, I have not dealt with "Hi Test", so I can't give you any feedback on them, sorry. I have a few folks on my website that I use all the time and like.

Maybe ask some of the folks in here where they like to get their tubes, they might also have some good feedback. I typically get most of our tubes that we use for clients (rather than for tests, as those come from a lot of folks), from Groove Tubes. There are a few reasons we like GT tubes. They have a few tubes nobody else has, such as their different version of the E34Ls, KT-66HP, and NVM 6L6GE. They also rebase some of their tubes with socket pins that are plated smoothly and don't rip up vintage sockets like the dipped plated pins that come from other folks. Their tube packaging with those little foam do-dads is the only packaging that holds up on a tour environment on the road, and they are one of the few that test output tubes dynamically rather than at a fixed static voltage, so their output sets are more closely matched than a lot of other vendors.

Hope that helped,

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/13/02 07:31 PM

Quote:
Originally posted by jetboy:
Hi Myles,

Just checking in with the prelims on my tube search:

got the JJ's first and basically swapped them for the oem's except for the reverb and rectifier tubes. a 90/90 balanced ECC83 for the phase inverter and a low gain 78/79 ECC83 for v1, an unvalued ECC83 for v2 and a matched low gain (40) set of EL84's. the sound was good, a bit more clarity but not particularly remarkable.

switched to the high gain ECC83 (114/118) in v1, very bright, pretty much too bright for me. very articulate. all other tubes remained the same.

switched to the normal 97/98 ECC83 and that was better, good articulation, good highs but not too bright. overall the winner.

went back and forth between the high gain and normal just to see if I was remembering it all. pretty much ended there with the normal tube being my fav.

then I got the NOS tubes from Kcanostubes.com.

left the ECC83 phase inverter but swapped the JJ EL84's for a matched set of NOS JAN GE EL84's, a NOS Mullard 4004 at V1 and a NOS JAN GE 12AX7WA at v2.

WOW, this appears to be the combo. very good tone at all volumes (except totally wide open master and volume) very sweet sounding, very articulate without being harsh, good bottom and very nice mids.

Now this was all very unscientific, since I changed many variables from the JJ's to the NOS, but right now the Cub sounds just great.

I want to experiment more and try combining the JJ's and NOS here and there. Any suggestions? How important is v2 to the total sound. I know from reading your articles on preamp tubes and power tubes that they both make differences but since I got low gain JJ EL84's would that make a bigger difference then the NOS Preamp tubes?

any thoughts would be helpful especially since I'm starting to doubt how much I remember about each setup.

Also how careful should I be regarding touch the tubes with my fingers (skin oils, not being burned) I know that tungsten light tubes will get hot spots where you touch them, do tubes get weaker from that kind of handling? So far I've been wearing exam gloves to reduce finger prints.

anyway I'm going to start swapping tubes again and see where that killer tone is coming from.

Is there any problem putting the high gain ECC83 into v2 with the Mullard? how about the GE 12ax7WA into v1 and something else into v2.

and is there any real advantage to another Mullard in v2? matched tubes?

I guess I'll find out, eh?

thanks for your support, Mark
Mark,

It sounds like you've been pretty busy!

How does the scale work, such as you saying "unvalued ECC83 for v2 and a matched low gain (40)" ? What is their "40" value? This does not look like a Watford scale or my scale, or an industry scale from the 1950's.

The ECC83's will be brighter than a 12AX7, but the ECC83 was the Brit class A sound. Its a matter of preference. The 7025 is even more bright than an ECC83 by the way, in most amps.

KCA has some pretty nice stuff. The USA GR EL-84's are much nicer than any of the available new ones today. The JJ's are also nice, the best of the new EL84's to me anyway. The 4004 is perhaps the nicest tube you can stick in V1 of your amp, so I am not surprised if you liked that. V2 is more of a tone control stage, so you will not see the same sort of difference here, but a JAN tube here will be quiet and has nice current drive capabilities.

The issue of tone from a personal sense is usually pretty unscientific. Its taste. But, with your setup now, you will have nicer frequency response that is linear over the range of the amp, without dips and peaks. Your sound dispersion will be wider, and there will be a nicer harmonics and overtones.

V2 is less important than V1 for your initial gain stage, headroom, and tone. In amps like Marshalls and a lot of others, it is just giving a bit more to what was created by V1. Both the preamp and poweramp stage are equally important and work together. The matching of the output section in your amp is very important, more important than in most other amps.

Tubes are not like halogen bulbs ... the main aspects in handling are: (1) don't burn yourself, and (2), let tubes cool a few minutes before moving them around. Some of the internal parts are a lot more prone to moving around if shocked phsically when still hot.

There is no problem using the ECC83 in V2. At this point, its all personal preference, and all your preamp section can be mixed all you want.

Having a matched triode in V2 is not all that necessary, and really won't have any effect in V2 other than making your wallet thinner. Its the phase ingerter/driver where this is important.

Good luck.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/13/02 07:34 PM

Quote:
Originally posted by slide_blues:
If you use a hotplate with a channel switching amp (clean - dirty channels), can you still have a clean channel at the same volume level as the dirty side?
I'm thinking if the dirty channel is maxed out for the power tube saturation, the clean channel (set for NOT alot of breakup) would not be loud enough, given that the hotplate would be cutting the overall volume.

Obviously I need to actually try one out with my classic 30, just wondering if you have any thoughts on using a hotplate with a channel switching small combo amp like the c30.

Thanks!
slide_blues,

The Hot Plate is just going to impact the signal from your power amp to your speaker. If you had equal levels with your setup before the hotplate, you will have the same ratio after, just at a lower level.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/13/02 07:37 PM

Quote:
Originally posted by Slats:
Hey Myles, I'm wondering about the tonal characteristics of a 12AX7WA compared to the 12AX7. I came across some in my father-in-laws tube stash, and I'm thinking of trying them in my AC30. Any thoughts would be much appreciated
Slats,

These tubes are very similar. What mfg of 12AX7 did you find?

The best way to see is to plug one into V1 of your AC-30. The ECC83's that came in AC-30's were a lot different sounding, the original sound of these amps, but today these amps are being also used from everything from rock to country, and the country folks use more 12AX7's for less high end.

Regards,
Posted By: Slats

Re: Feel free to ask Myles - 05/13/02 08:58 PM

Thanks for the response Myles. Most of the 12AX7's are GE with mfg. dates of '63 and '64. One is a Sylvania with a 1955 date. My father-in-law is a retired Air Force Pilot and would get first crack at the military surplus tubes.
I've put a Telefunken ECC82 in the phase inverter spot, a Telefunken ECC83 in the V1 position, and now the GE 12AX7's in the other pre-amp positions. I've got a matched set of JJ EL84's from Bob at Eurotubes in the power section.
Maybe I can find someone to trade the GE 12AX7's for some EL84's to try for a more original VOX sound.
I'm wondering if you have any thoughts or suggestions on the tube set-up I've just described.
Thanks again
Frank
Posted By: myles_rose

Re: Feel free to ask Myles - 05/13/02 09:40 PM

Quote:
Originally posted by Slats:
Thanks for the response Myles. Most of the 12AX7's are GE with mfg. dates of '63 and '64. One is a Sylvania with a 1955 date. My father-in-law is a retired Air Force Pilot and would get first crack at the military surplus tubes.
I've put a Telefunken ECC82 in the phase inverter spot, a Telefunken ECC83 in the V1 position, and now the GE 12AX7's in the other pre-amp positions. I've got a matched set of JJ EL84's from Bob at Eurotubes in the power section.
Maybe I can find someone to trade the GE 12AX7's for some EL84's to try for a more original VOX sound.
I'm wondering if you have any thoughts or suggestions on the tube set-up I've just described.
Thanks again
Frank
Frank,

Those are all great tubes.

On your particular setup, I think its a great start, and try it for a while that way and play for at least a week or so.

Regards,
Posted By: Slats

Re: Feel free to ask Myles - 05/13/02 10:53 PM

The combination makes for an interesting complex sound that is rich and musical, and has almost an adicting sound the way it draws you in.
I'll leave the Telefunkens and the GE 12AX7's in and maybe trade the others, I've got about 15 or so of the GE 12AX7's
Would trying to get some old stock RCA, GE or some other EL 84's be the next logical step?
Thanks
Frank
Posted By: myles_rose

Re: Feel free to ask Myles - 05/14/02 01:00 AM

Quote:
Originally posted by Slats:
The combination makes for an interesting complex sound that is rich and musical, and has almost an adicting sound the way it draws you in.
I'll leave the Telefunkens and the GE 12AX7's in and maybe trade the others, I've got about 15 or so of the GE 12AX7's
Would trying to get some old stock RCA, GE or some other EL 84's be the next logical step?
Thanks
Frank
Frank,

I think you are in pretty great shape. Most of what is out there now is not as nice as what you have now. I'd loose the JJ #4's maybe, and go for a #8 or so set of those so you can really see what they can do.

Other than that, sell some of those extra nice NOS tubes you have on e-bay and go out with your wife or girlfriend for a weekend getaway at a spa or something. Girls really like that spa stuff, and for you, bring an acoustic guitar and hang in the room. It will pay off when she gets back for dinner.

Regards,
Posted By: macafied

Re: Feel free to ask Myles - 05/14/02 02:58 AM

hello Myles,
i am very new to this preamp valve stuff but here goes...

i have a marshall valvestate 265 combo and my preamp valve is going on me. (im getting a strange hiss type of noise when i play through it)

my question is: In this kind of an amp that has a single valve, how much does this valve actually affect my sound?

also, what valves would you recommend in this situation and will any preamp valves work like 12ax7's or do i need ecc83's or what should i be using?

thanks in advance,
Nick
Posted By: Skip_dup1

Re: Feel free to ask Myles - 05/14/02 05:11 AM

Myles, sorry if this is a dumb question-
you stress the importance of output matching in class A/B amplifiers. I`ve been looking at several `boutique`, low-wattage amps for several months now and all of them seem to be class A amps. Does this mean it`s less of an issue?
Posted By: Tedster

Re: Feel free to ask Myles - 05/14/02 05:58 AM

Calling Dr. Howard, Dr. Rose, Dr. Howard...

Nyuk nyuk...

One of my students came in with a pawnshop prize. A Magnatone Custom 413...it's a 1x12 combo, looks like from the early 60s...perhaps even late 50s. Cool, all tube amp...but...it makes horrible hissing, crackling noises. Kinda like the sound of a dirty pot...but it won't stop no matter what you do...it's constant, and so loud you really can't use the amp. I'd like to see this kid get the old thing in working order. Any ideas?
Posted By: JamesPeters

Re: Feel free to ask Myles - 05/14/02 08:16 AM

Quote:
Originally posted by skip:
Myles, sorry if this is a dumb question-
you stress the importance of output matching in class A/B amplifiers. I`ve been looking at several `boutique`, low-wattage amps for several months now and all of them seem to be class A amps. Does this mean it`s less of an issue?
Just happened to read this (as I learn so much from Myles, I tend to follow this thread! \:\) )

With single-ended class A, it's a "non-issue". There's nothing to match a tube with (it's only one tube in the poweramp). As for other amps that work in class A other than single-ended, it shouldn't be as critical as class A/B amps--because the multitude of tubes (whatever number) are supposed to be amplifying signal "simultaneously all the time" (which isn't necessarily true either, but you know). Class A/B amps have tubes that share the responsibility of amplifying the signal, and there's the critical crossover point which should be a smooth transition (where one tube or pair of tubes "lets the other pair" take over the other half of the signal). That's a big part of it.

There's also the response curve of the tubes to consider, as class A/B amps have little current draw when no signal is present on the power tubes' grids, but ramp up to higher current draw when there is signal present there. Class A, generally speaking, has a more or less constant current draw going on.

Exactly how this all sounds, that's harder to describe. Just felt like throwing my two cents in I guess. \:D
Posted By: Skip_dup1

Re: Feel free to ask Myles - 05/14/02 10:00 AM

thanks, mon. That basically answers my question.
Posted By: Slats

Re: Feel free to ask Myles - 05/14/02 02:51 PM

Myles, I'm not sure what you mean by the #4 and the #8. Thanks
Posted By: mikey_dup1

Re: Feel free to ask Myles - 05/14/02 04:51 PM

Miles,
I guess I am starting to get confused. This is the first tube amp I've had so I'm a novice, soory. In regards to the Fender DeVille - Is the "phase inverter" considered V3? Could you just give me some good ideas about preamp tubes for this amp. I like that vintage Fender tone. I have a 12ax7EH in V1 and some chinese 12ax7 in V2,V3. I am putting Svets 6L6's in the output. Thanka again for all your help.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/14/02 08:13 PM

Quote:
Originally posted by macafied:
hello Myles,
i am very new to this preamp valve stuff but here goes...

i have a marshall valvestate 265 combo and my preamp valve is going on me. (im getting a strange hiss type of noise when i play through it)

my question is: In this kind of an amp that has a single valve, how much does this valve actually affect my sound?

also, what valves would you recommend in this situation and will any preamp valves work like 12ax7's or do i need ecc83's or what should i be using?

thanks in advance,
Nick
Nick,

The preamp tube in the Marshall Valvestate amps is just as critical as in all tube amps. It sets your initial gain and tone color for the rest of the circuit. Put a crummy tube in there and your amp will lack gain, articulation, and life.

You have two choices here. The standard ECC83 gives you more of the British flavor, but the 12AX7 will give you a bit less bright of an amp and what some folks think of as a more versitile amp. For the 12AX7, in that amp I like the 12AX7C (Chinese, but new mfg. Chinese), or the GT-12AX7R2 (A Russian 12AX7 with a long plate structure that is sold by Groove Tubes). Its a matter of taste.

My clients that use AVT Marshalls that use pedals plugged into the input use 7025's as with the Marshall input loading of the guitar pickup, they find the added high end of the 7025 gets back some of the lost high end when pedals are used with Marshall post distortion gain structure amps.

Hope that helped,

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/14/02 08:28 PM

Quote:
Originally posted by skip:
Myles, sorry if this is a dumb question-
you stress the importance of output matching in class A/B amplifiers. I`ve been looking at several `boutique`, low-wattage amps for several months now and all of them seem to be class A amps. Does this mean it`s less of an issue?
Skip,

I saw James Peters below answer this a bit, and his answer is pretty spot on.

I'd like to add a touch though. Class A amps that are single ended with one tube do not need a matched phase inverter. There is nothing to match, and there would be no benefit.

In class A amps that use an output pair, such as Dr. Z amps and Vox, Matchless, etc ... these Class A amps, when driven at mid to high levels, operate in push-pull, or class A/B. A matched phase inverter, which in this case is really an output driver, really helps these amps. In Dr Z. amps it makes them even nicer. In Vox AC-30 amps is seems to make the output tubes last longer as they seem to be under less stress from imbalances. I am still trying to study this and figure out why from a scientific standpoint \:\)

If you want to forget all this "amp tuning" and amp "blueprinting" trouble, and just have a geat amp, then go to the guy that I listen to and learn from .... James Peters \:\) His amp is a super product, and if you need to play a gigantic venue, use a open back 1x12 cabinet and mic it ... throw it into the house system with a few mega watts of amps, and now you will have terrific tone and sound that you can control, rather than the 100+ watt amp that is trying to control you (and that sounds it's best at only very high drive levels).

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/14/02 08:49 PM

Quote:
Originally posted by Tedster:
Calling Dr. Howard, Dr. Rose, Dr. Howard...

Nyuk nyuk...

One of my students came in with a pawnshop prize. A Magnatone Custom 413...it's a 1x12 combo, looks like from the early 60s...perhaps even late 50s. Cool, all tube amp...but...it makes horrible hissing, crackling noises. Kinda like the sound of a dirty pot...but it won't stop no matter what you do...it's constant, and so loud you really can't use the amp. I'd like to see this kid get the old thing in working order. Any ideas?
Tedster,

If its a hum where you can hear the note play but there is also hum present, its filter caps.

If its hiss, crackle, pop, its probably the preamp tube in the first position, the one closest to the input jack.

Try the preamp tube change first, then if that does not work, drop me another note.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/14/02 08:53 PM

Quote:
Originally posted by JamesPeters:
Quote:
Originally posted by skip:
Myles, sorry if this is a dumb question-
you stress the importance of output matching in class A/B amplifiers. I`ve been looking at several `boutique`, low-wattage amps for several months now and all of them seem to be class A amps. Does this mean it`s less of an issue?
Just happened to read this (as I learn so much from Myles, I tend to follow this thread! \:\) )

With single-ended class A, it's a "non-issue". There's nothing to match a tube with (it's only one tube in the poweramp). As for other amps that work in class A other than single-ended, it shouldn't be as critical as class A/B amps--because the multitude of tubes (whatever number) are supposed to be amplifying signal "simultaneously all the time" (which isn't necessarily true either, but you know). Class A/B amps have tubes that share the responsibility of amplifying the signal, and there's the critical crossover point which should be a smooth transition (where one tube or pair of tubes "lets the other pair" take over the other half of the signal). That's a big part of it.

There's also the response curve of the tubes to consider, as class A/B amps have little current draw when no signal is present on the power tubes' grids, but ramp up to higher current draw when there is signal present there. Class A, generally speaking, has a more or less constant current draw going on.

Exactly how this all sounds, that's harder to describe. Just felt like throwing my two cents in I guess. \:D
James,

Thanks for keeping me on my toes \:\)

When is your amp slated for shipping in quantity?

If you'd like, I would like to talk to the folks at Guitar Player Magazine and see about doing a review on it.

Regards,

Myles
Posted By: Tedster

Re: Feel free to ask Myles - 05/14/02 08:54 PM

Muchos Gracias, Senor Rose... \:D
Posted By: myles_rose

Re: Feel free to ask Myles - 05/14/02 08:58 PM

Quote:
Originally posted by Slats:
Myles, I'm not sure what you mean by the #4 and the #8. Thanks
Slats,

The #4 and #8 refer to output tube ratings that are used by Groove Tubes. A #8 will distort later and at higher levels than a #4 as an example. When I want a "mid-range" tube that is a great all around tube, I just call my vendors and tell them "send me a tube in the same range as a Groove Tubes #5", as an example.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/14/02 09:15 PM

Quote:
Originally posted by mikey:
Miles,
I guess I am starting to get confused. This is the first tube amp I've had so I'm a novice, soory. In regards to the Fender DeVille - Is the "phase inverter" considered V3? Could you just give me some good ideas about preamp tubes for this amp. I like that vintage Fender tone. I have a 12ax7EH in V1 and some chinese 12ax7 in V2,V3. I am putting Svets 6L6's in the output. Thanka again for all your help.
mikey,

Yes, your phase inverter is V3, and from Fender it is a 12AX7A.

Unless you are having problems, it sounds like you have a pretty nice setup as the Svets are really great in that amp, MUCH nicer (at least to my taste) than the stock 6L6B's or 5881's that are shipped with the amp.

The best things you can do for that amps is:

1. Get a good matched phase inverter in V3. Use a matched 12AT7. These amps like a longer plate 12AX7 in this slot, like a Sovtek 12AX7LP/LPS style tube.

2. Make sure your bias is set to about 55% idle dissapation. If higher, you get more background hiss and noise, and if lower than 50%, you loose some headroom and the amp gets a bit gainy.

3. Maybe try a 7025 in V1 if you want more of the original Fender bright sound as an experiment. You may like it, you may hate it, but at least it will give you "two amps" for a very small investment.

Happy playing,
Posted By: macafied

Re: Feel free to ask Myles - 05/14/02 09:51 PM

yes, thats exactly what i wanted to know!
thanks for clearing that up for me.
-Nick
Posted By: myles_rose

Re: Feel free to ask Myles - 05/14/02 10:25 PM

Quote:
Originally posted by Tedster:
Muchos Gracias, Senor Rose... \:D
Tedster,

I always think your pictures are great \:\)

Myles
Posted By: Skip_dup1

Re: Feel free to ask Myles - 05/15/02 09:33 AM

Quote:
Originally posted by myles111:
Quote:
Originally posted by skip:
Myles, sorry if this is a dumb question-
you stress the importance of output matching in class A/B amplifiers. I`ve been looking at several `boutique`, low-wattage amps for several months now and all of them seem to be class A amps. Does this mean it`s less of an issue?
Skip,

I saw James Peters below answer this a bit, and his answer is pretty spot on.

I'd like to add a touch though. Class A amps that are single ended with one tube do not need a matched phase inverter. There is nothing to match, and there would be no benefit.

In class A amps that use an output pair, such as Dr. Z amps and Vox, Matchless, etc ... these Class A amps, when driven at mid to high levels, operate in push-pull, or class A/B. A matched phase inverter, which in this case is really an output driver, really helps these amps. In Dr Z. amps it makes them even nicer. In Vox AC-30 amps is seems to make the output tubes last longer as they seem to be under less stress from imbalances. I am still trying to study this and figure out why from a scientific standpoint \:\)

If you want to forget all this "amp tuning" and amp "blueprinting" trouble, and just have a geat amp, then go to the guy that I listen to and learn from .... James Peters \:\) His amp is a super product, and if you need to play a gigantic venue, use a open back 1x12 cabinet and mic it ... throw it into the house system with a few mega watts of amps, and now you will have terrific tone and sound that you can control, rather than the 100+ watt amp that is trying to control you (and that sounds it's best at only very high drive levels).

Regards,
Myles-
Many thanks for thi info, as always. I am looking for a 1x12-is Mr. Peters online? I`d like to see what`s available.
Posted By: GrantsV

Re: Feel free to ask Myles - 05/15/02 10:05 AM

Hi Myles,
Heres a quick one for you:

Two cases:
1) I run my preamp master at 10 and clean valve poweramp (Marshall 20/20) at 1.

2) I run my the preamp master on 1 and clean valve poweramp (Marshall 20/20) on 10.

The question is, if the perceived volume is the same in both cases, will I get a better tone due to poweramp valve compression in case 2?

Appreciate for your time.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/15/02 06:41 PM

Quote:
Originally posted by GrantsV:
Hi Myles,
Heres a quick one for you:

Two cases:
1) I run my preamp master at 10 and clean valve poweramp (Marshall 20/20) at 1.

2) I run my the preamp master on 1 and clean valve poweramp (Marshall 20/20) on 10.

The question is, if the perceived volume is the same in both cases, will I get a better tone due to poweramp valve compression in case 2?

Appreciate for your time.
GrantsV,

The volume will not be even close in most cases. Pots are not linear in most cases, and even if you have the volume at 2 and the master at 10 (which will be loud), that will be different than the volume at 10 and the master at two, as their gain structures are very different in the preamp section vs. the output section.

Regards,
Posted By: oyo

Re: Feel free to ask Myles - 05/16/02 03:53 AM

Myles- What an awesome amount of information here!
Thank you!
Now for my question(s):
I have a SVP bass pre-amp that came with 4 old type Sovtek 12AX7 tubes and 1 US made 12AU7 (GE?)
The tubes are all mounted on a daughter card from L-R AX-AX-AX-AU-AX. The input jack is closest to the left so I think V1 is on the left? Can you tell me if my guess is right, and what the other tubes are for?
I would like to end up with a compressed, punchy but bright clean tone (just on the edge of audible distortion) that will turn to a nasty punchy distorted growl (Rush on steroids but with full bass), when I crank the drive control to 3 o'clock and beyond.
Right now I have a mix of tubes in there: a Mesa/Boogie SPAX7, a JJ "high gain" ECC83 from Eurotubes and a GT 12AX7R-2 in ther, all left overs in a tube tone quest in my guitar pre, an ART SGX 2000 Express. (The winner in *that* quest was another JJ ECC83)
Have you worked with blueprinting any SVPs (or SVTs, as they use similar pre-amps)? I would really like to get this sounding better for bass than my guitar pre-amp does (since I found the right JJ for the SGX from Eurotubes).
Thanks!
John York
Posted By: myles_rose

Re: Feel free to ask Myles - 05/16/02 08:18 PM

Quote:
Originally posted by oyo:
Myles- What an awesome amount of information here!
Thank you!
Now for my question(s):
I have a SVP bass pre-amp that came with 4 old type Sovtek 12AX7 tubes and 1 US made 12AU7 (GE?)
The tubes are all mounted on a daughter card from L-R AX-AX-AX-AU-AX. The input jack is closest to the left so I think V1 is on the left? Can you tell me if my guess is right, and what the other tubes are for?
I would like to end up with a compressed, punchy but bright clean tone (just on the edge of audible distortion) that will turn to a nasty punchy distorted growl (Rush on steroids but with full bass), when I crank the drive control to 3 o'clock and beyond.
Right now I have a mix of tubes in there: a Mesa/Boogie SPAX7, a JJ "high gain" ECC83 from Eurotubes and a GT 12AX7R-2 in ther, all left overs in a tube tone quest in my guitar pre, an ART SGX 2000 Express. (The winner in *that* quest was another JJ ECC83)
Have you worked with blueprinting any SVPs (or SVTs, as they use similar pre-amps)? I would really like to get this sounding better for bass than my guitar pre-amp does (since I found the right JJ for the SGX from Eurotubes).
Thanks!
John York
John,

O.K.... here we go ...

Your AU7 could be a GE, RCA, or Philips. I'd have to look at the tube to tell, but they are all good ones.

You are correct, V1 is the closest to the input jack. The others are for various gain stages for the most part with V2 also doing tone control duties.

For what you are looking for, in V1 and V2 you have a few options. One option to brighten things up is to try a 7025 in V1.

For more compression, you want V1 to have a longer rise time, and for this you need to find somebody that can find you a tube that was looked at on some pretty sophisticated equipment. Most folks only look at emissions, and that measurement is not the same as rise time. The only folks I know that do this are Groove Tubes, and thats for some of their select clients. I'd use a GT-12AX7R in that position, but have it picked for a MS (medium slow) rise time with a rating of 108 or higher. The rating of "108" is a rating I use for my clients, but some of the folks at GT know my rating system. They have a group over there called SAG or Special Applications Group, that might be able to get you that tube. You'd have to call them direct as I don't think those are dealer stocked items at all.

I have blueprinted a number of SVT's. There are a lot of factors involved with them, as there are 6550 versions and 6146 versions. It also depends a LOT of the player's style, and 4,5,6 string instruments, and even the string guage comes into play.

If you talk to GT, the guy to talk to is Rick Benson. He's the head of their sales department, but very technical, and maybe the only one that knows of their SAG (sort of GT's Skunkworks). He may not admit much, as like the Skunkworks, is sort of kept under wraps.

Hope this helped.

Regards,
Posted By: oyo

Re: Feel free to ask Myles - 05/16/02 10:54 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by oyo:
Myles- What an awesome amount of information here!
Thank you!
Now for my question(s):
I have a SVP bass pre-amp that came with 4 old type Sovtek 12AX7 tubes and 1 US made 12AU7 (GE?)
The tubes are all mounted on a daughter card from L-R AX-AX-AX-AU-AX. The input jack is closest to the left so I think V1 is on the left? Can you tell me if my guess is right, and what the other tubes are for?
I would like to end up with a compressed, punchy but bright clean tone (just on the edge of audible distortion) that will turn to a nasty punchy distorted growl (Rush on steroids but with full bass), when I crank the drive control to 3 o'clock and beyond.
Right now I have a mix of tubes in there: a Mesa/Boogie SPAX7, a JJ "high gain" ECC83 from Eurotubes and a GT 12AX7R-2 in ther, all left overs in a tube tone quest in my guitar pre, an ART SGX 2000 Express. (The winner in *that* quest was another JJ ECC83)
Have you worked with blueprinting any SVPs (or SVTs, as they use similar pre-amps)? I would really like to get this sounding better for bass than my guitar pre-amp does (since I found the right JJ for the SGX from Eurotubes).
Thanks!
John York
John,

O.K.... here we go ...

Your AU7 could be a GE, RCA, or Philips. I'd have to look at the tube to tell, but they are all good ones.

You are correct, V1 is the closest to the input jack. The others are for various gain stages for the most part with V2 also doing tone control duties.

For what you are looking for, in V1 and V2 you have a few options. One option to brighten things up is to try a 7025 in V1.

For more compression, you want V1 to have a longer rise time, and for this you need to find somebody that can find you a tube that was looked at on some pretty sophisticated equipment. Most folks only look at emissions, and that measurement is not the same as rise time. The only folks I know that do this are Groove Tubes, and thats for some of their select clients. I'd use a GT-12AX7R in that position, but have it picked for a MS (medium slow) rise time with a rating of 108 or higher. The rating of "108" is a rating I use for my clients, but some of the folks at GT know my rating system. They have a group over there called SAG or Special Applications Group, that might be able to get you that tube. You'd have to call them direct as I don't think those are dealer stocked items at all.

I have blueprinted a number of SVT's. There are a lot of factors involved with them, as there are 6550 versions and 6146 versions. It also depends a LOT of the player's style, and 4,5,6 string instruments, and even the string guage comes into play.

If you talk to GT, the guy to talk to is Rick Benson. He's the head of their sales department, but very technical, and maybe the only one that knows of their SAG (sort of GT's Skunkworks). He may not admit much, as like the Skunkworks, is sort of kept under wraps.

Hope this helped.

Regards,
Posted By: Slats

Re: Feel free to ask Myles - 05/17/02 05:47 PM

Myles, I'm wondering if you can help me troubleshoot an AC 30 that has developed some noise. It's got a loud static sound with intermittent popping. The only control knob that has an effect on the hiss is the cut knob. Taking the guitar cord out, or putting in in any input has no effect.
I'd like to isolate the problem. I was thinking of gently tapping on the tubes while the amp is on to see if it makes a difference. Can I safely swap out tubes while the amp is on?
Any help and advice is much appreciated!
Thanks again
Frank
Posted By: myles_rose

Re: Feel free to ask Myles - 05/17/02 08:06 PM

Quote:
Originally posted by Slats:
Myles, I'm wondering if you can help me troubleshoot an AC 30 that has developed some noise. It's got a loud static sound with intermittent popping. The only control knob that has an effect on the hiss is the cut knob. Taking the guitar cord out, or putting in in any input has no effect.
I'd like to isolate the problem. I was thinking of gently tapping on the tubes while the amp is on to see if it makes a difference. Can I safely swap out tubes while the amp is on?
Any help and advice is much appreciated!
Thanks again
Frank
Frank,

You can swap the preamp tubes with the amp on but not the power tubes. When you do that, turn down the volume all the way though, or the popping may damage a speaker.

I'd start with V1, because when you get popping, its usually from V1 or V2 and gets amplified down the chain. After a while, depending on the loudness and clarity of the pops, you can usually tell which preamp tube it is.

Maybe get one new ECC83 and put it in each position, starting closest to the input jack.

Keep me up to date and I will try to help.

Regards,
Posted By: oyo

Re: Feel free to ask Myles - 05/17/02 08:23 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by oyo:
Myles- What an awesome amount of information here!
Thank you!
Now for my question(s):

John York
John,

O.K.... here we go ...

Your AU7 could be a GE, RCA, or Philips. I'd have to look at the tube to tell, but they are all good ones.

You are correct, V1 is the closest to the input jack. The others are for various gain stages for the most part with V2 also doing tone control duties.

For what you are looking for, in V1 and V2 you have a few options. One option to brighten things up is to try a 7025 in V1.

For more compression, you want V1 to have a longer rise time, and for this you need to find somebody that can find you a tube that was looked at on some pretty sophisticated equipment. Most folks only look at emissions, and that measurement is not the same as rise time. The only folks I know that do this are Groove Tubes, and thats for some of their select clients. I'd use a GT-12AX7R in that position, but have it picked for a MS (medium slow) rise time with a rating of 108 or higher. The rating of "108" is a rating I use for my clients, but some of the folks at GT know my rating system. They have a group over there called SAG or Special Applications Group, that might be able to get you that tube. You'd have to call them direct as I don't think those are dealer stocked items at all.

I have blueprinted a number of SVT's. There are a lot of factors involved with them, as there are 6550 versions and 6146 versions. It also depends a LOT of the player's style, and 4,5,6 string instruments, and even the string guage comes into play.

If you talk to GT, the guy to talk to is Rick Benson. He's the head of their sales department, but very technical, and maybe the only one that knows of their SAG (sort of GT's Skunkworks). He may not admit much, as like the Skunkworks, is sort of kept under wraps.

Hope this helped.

Regards,
Sorry for the last post with no new text- I must have hit "Add Reply" too soon
This is what I meant to post:
Thanks Myles. As allways, good info.
(By the way, I read the whole "ask Myles" thread over the course of a couple of days. What an education!)
Now for the next question(s): If this was the pre- of an SVT, then I would assume that the 12AU7 was a phase inverter/ driver and having a ballanced tube would be important. The SVP has line outs, and I would guess they are driven a little differently... do I need a ballanced tube here to give a strong, pure output? I tried a US made GT 12AT7 -not sold as ballanced- without much change in tone, or seemingly, output.
Next...
Something I could try if GT doesnt't think a guy who mainly plays bass for his own ammusement is worthy of specially tested "skunkworks" tubes, is to order a mess of ECC83/12AX7 tubes from Eurotubes and just listed till I find the tone I'm after. I liked the sound of the Mesa SPAX7
in there too, so I could try a few more of those, but the JJs are almost 1/3 the price and have the same odds of finding one I really like.
So V1 and V2 are the main tone shapers? What about the tube on the other end (Right side, viewed from the front)of the daughter card? Whatever it does, it seems to respond to the Mesa/Boogie nicely...
John
P.S. If GT told me about the SAG, would they then have to kill me? ;\)
Posted By: myles_rose

Re: Feel free to ask Myles - 05/17/02 10:44 PM

Posted By: JamesPeters

Re: Feel free to ask Myles - 05/18/02 05:50 PM

Quote:
Originally posted by myles111:
Thanks for keeping me on my toes \:\)

When is your amp slated for shipping in quantity?

If you'd like, I would like to talk to the folks at Guitar Player Magazine and see about doing a review on it.

Regards,

Myles
Hey Myles. This forum doesn't normally move that quickly, so I must've forgotten to check back. "The guy that I listen to and learn from", oh come on! \:D I'm just some bum who's making amps...

(This isn't going to turn into a "you're the best" / "no, you're the best" type of thing, is it? \:D )

Wow, "shipping in quantity"...hadn't thought about that yet. I'm just rounding out my first ten orders this week. So far that in itself has been almost incredible for me, to have that much interest in less than two weeks since my site has been "complete" with the purchase page.

I'm still working full time as the manager of a service center (for a vending machine company), and before I go full-on amp building I have to at least make sure the center is ready to move ahead without me. I've been there 5 years now and have been treated well, so I figure the least they deserve is that they're taken care of before I move on. There have been a few changes there recently and I've had to hire and train again, so I'm not quite ready to take the plunge yet.

For now I'll just sell the amps from my site, or locally. Speaking of which, I have an interview today with a local paper--Mark (my friend who's making my enclosures, and soon speaker cabs) and I are going to try to get the point across to Calgary that we're "in business", something that has been almost ignored here so far (which is really weird considering that I have 9 orders from the last two weeks from the USA!)

Anyway, one step at a time I guess. Man, a review in Guitar Player...that would rock! \:\)

I'll keep you posted (no pun intended!) as to my "gearing up" progress. I'll probably be staying at my current job for the next couple months anyway to make sure things are going well. In the meantime, I want to see if I can get to know guitarists in Calgary and get the grassroots thing going on. I'd almost not feel comfortable selling lots to the USA before having "paid my dues" locally...call me naive I guess. \:\)

Talk to you later!
Posted By: ToneDoctor

Re: Feel free to ask Myles - 05/19/02 11:55 PM

Hey, Myles. It`s me Doc. Hope you remember me.
I talked with the folks at VHT, and it seemed to
be too much trouble to deal with the whole switch thing from KT-88`s/6550`s to EL-34`s with my 2902.
So I ended up trading it in on a new 2502. It`s fifty watts a side, has a class A and class A/B mode, plus can run either EL-34`s or 6L6`s. It came with Svet EL34`s. I A/B`d the two amps and found the 2502 to have just the right amount of give to it, and not so stiff like the 2902 could be. I also switched because there are so many more tube options with this amp. A set of Genalex KT-88`s would have cost me a fortune with the other amp. This amp was cheaper than those tubes would have been. I can also turn it up without peeling the paint off the walls. I would like to know what tube options you might suggest. Now that I have all these choices;I might have shot myself in the foot(lol).
I know you`ve been saying a lot of good things about the GT/GE NVM 6L6`s. I wonder what tonal changes I would hear going from Svet EL-34`s to GT/GE NVM 6L6`s. Anyways, I`m bouncing off the walls loving this new amp and choices. BTW,The class A mode is particuarly sweeet. I`d sure appreciate any suggestions you may have.
Thanks for your help as always.
Posted By: Slats

Re: Feel free to ask Myles - 05/20/02 12:12 AM

Myles, success! I went down the line of the preamp tubes gently wiggling them. When I got to the last one it made the popping sound and changed the hiss. I pulled the tube out then put it back in, and all the noise went away. It's very quiet now on all chanells and at any volume.
Thank you once again!
Frank
Posted By: Dave da Dude

Re: Feel free to ask Myles - 05/20/02 07:48 PM

I just bought (have not received yet) a '93 Randall Pro 1000. It has a bias switch to switch between 6L6 tubes and EL34 tubes. The seller included a pair of 6L6 tubes in the deal.

During emails back and forth (before buying) about the "sound", the seller (an amp repairer) said that another trick (he mentioned many with controls that would "soften" the sound) was to put in 6L6 tubes and set the bias switch for EL34. That the only negative would be that the life of the tubes would be shorter, but it gave a "..REAL nice hot overdrive sound out of it this way."

When I posted this info on Guitar Forum to let everyone know I had FINALLY bought a tube amp, what it was, the seller's comments about its versatility and to thank them all for their help; Gabriel replied that when the tubes "blew" they could wipe out some other parts of the amp. When I asked if there was a way to avoid that, he referred me to you.

What should I do?
Posted By: mikey_dup1

Re: Feel free to ask Myles - 05/20/02 08:22 PM

Hi Miles,
I am getting ready to order some preamp tubes from Watford for the Fender DeVille and want to make sure I have this right. What do you think?

V1- 7025
V2 - 12AX7EH
V3 - 12AT7.
Any suggestions would be greatly appreciated for that classic Fender sound but would like to sweeten up the dirty channel a little. Thanks!!
Posted By: myles_rose

Re: Feel free to ask Myles - 05/20/02 08:58 PM

Quote:
Originally posted by JamesPeters:
Quote:
Originally posted by myles111:
Thanks for keeping me on my toes \:\)

When is your amp slated for shipping in quantity?

If you'd like, I would like to talk to the folks at Guitar Player Magazine and see about doing a review on it.

Regards,

Myles
Hey Myles. This forum doesn't normally move that quickly, so I must've forgotten to check back. "The guy that I listen to and learn from", oh come on! \:D I'm just some bum who's making amps...

(This isn't going to turn into a "you're the best" / "no, you're the best" type of thing, is it? \:D )

Wow, "shipping in quantity"...hadn't thought about that yet. I'm just rounding out my first ten orders this week. So far that in itself has been almost incredible for me, to have that much interest in less than two weeks since my site has been "complete" with the purchase page.

I'm still working full time as the manager of a service center (for a vending machine company), and before I go full-on amp building I have to at least make sure the center is ready to move ahead without me. I've been there 5 years now and have been treated well, so I figure the least they deserve is that they're taken care of before I move on. There have been a few changes there recently and I've had to hire and train again, so I'm not quite ready to take the plunge yet.

For now I'll just sell the amps from my site, or locally. Speaking of which, I have an interview today with a local paper--Mark (my friend who's making my enclosures, and soon speaker cabs) and I are going to try to get the point across to Calgary that we're "in business", something that has been almost ignored here so far (which is really weird considering that I have 9 orders from the last two weeks from the USA!)

Anyway, one step at a time I guess. Man, a review in Guitar Player...that would rock! \:\)

I'll keep you posted (no pun intended!) as to my "gearing up" progress. I'll probably be staying at my current job for the next couple months anyway to make sure things are going well. In the meantime, I want to see if I can get to know guitarists in Calgary and get the grassroots thing going on. I'd almost not feel comfortable selling lots to the USA before having "paid my dues" locally...call me naive I guess. \:\)

Talk to you later!
James ....

OK ... be like that. I'll just say "you're the best" and we'll drop it at that \:\)

In any case, paying your local Canada dues is all well and good, but I think there is a pretty nice market for your amp here in the USA too .... so get your plans for increased production in he back of your mind. I have a lot of folks that are interested.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 05/20/02 09:12 PM

Quote:
Originally posted by ToneDoctor:
Hey, Myles. It`s me Doc. Hope you remember me.
I talked with the folks at VHT, and it seemed to
be too much trouble to deal with the whole switch thing from KT-88`s/6550`s to EL-34`s with my 2902.
So I ended up trading it in on a new 2502. It`s fifty watts a side, has a class A and class A/B mode, plus can run either EL-34`s or 6L6`s. It came with Svet EL34`s. I A/B`d the two amps and found the 2502 to have just the right amount of give to it, and not so stiff like the 2902 could be. I also switched because there are so many more tube options with this amp. A set of Genalex KT-88`s would have cost me a fortune with the other amp. This amp was cheaper than those tubes would have been. I can also turn it up without peeling the paint off the walls. I would like to know what tube options you might suggest. Now that I have all these choices;I might have shot myself in the foot(lol).
I know you`ve been saying a lot of good things about the GT/GE NVM 6L6`s. I wonder what tonal changes I would hear going from Svet EL-34`s to GT/GE NVM 6L6`s. Anyways, I`m bouncing off the walls loving this new amp and choices. BTW,The class A mode is particuarly sweeet. I`d sure appreciate any suggestions you may have.
Thanks for your help as always.
Hello Doc ....

The Genelex Gold Lion KT-88's go at times now from some places for over $300 each! Yep .... pretty steep. I prefer KT-66's or 6L6's as at least they will distort at rational levels.

There is a big change between the EL-34 and 6L6, let alone the Svet EL-34 vs. GE 6L6. The EL-34's are nice for articulate distortion in a way of trying to articuate it, but the 6L6 is stronger in the mass distortion area when its over the top.

The GE tube is much more articulate and anything I have heard, and its sound stage is wider too. It is perhaps my favorite tube these days.

You are more than welcome for any feeble help I provided.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/20/02 09:14 PM

Quote:
Originally posted by Slats:
Myles, success! I went down the line of the preamp tubes gently wiggling them. When I got to the last one it made the popping sound and changed the hiss. I pulled the tube out then put it back in, and all the noise went away. It's very quiet now on all chanells and at any volume.
Thank you once again!
Frank
Frank....

Considering 70% of amp problems are tubes, 20% are sockets, pots, caps, etc, and the last 10% the rest of the amp .... looks to me like you now qualify as an amp tech yourself!

Well done, and watch the high voltages if you get deeper inside the amp!

Regards,

Myles
Posted By: JamesPeters

Re: Feel free to ask Myles - 05/20/02 10:59 PM

Quote:
Myles said:In any case, paying your local Canada dues is all well and good, but I think there is a pretty nice market for your amp here in the USA too .... so get your plans for increased production in he back of your mind. I have a lot of folks that are interested.
You're right. Well, I'm taking step #1 tomorrow, and that's getting the metal shop that makes my chassis to do all the drilling on the chassis. It's far too time consuming for me, more than anything else so far that I do on the amps. I'd originally thought I should leave the drilling until later in case I wanted to make changes on individual amps, or start a new design...but that's just not practical at all (and I have enough sales now to justify letting them do the drilling).

I tell ya, if we did get "quantity orders" it would sure make Mark happy too. I handed him his pay for the enclosures and I think he got an idea how this could turn into something really big.

Later!
Posted By: myles_rose

Re: Feel free to ask Myles - 05/21/02 12:17 AM

Quote:
Originally posted by Dave th Dude:
I just bought (have not received yet) a '93 Randall Pro 1000. It has a bias switch to switch between 6L6 tubes and EL34 tubes. The seller included a pair of 6L6 tubes in the deal.

During emails back and forth (before buying) about the "sound", the seller (an amp repairer) said that another trick (he mentioned many with controls that would "soften" the sound) was to put in 6L6 tubes and set the bias switch for EL34. That the only negative would be that the life of the tubes would be shorter, but it gave a "..REAL nice hot overdrive sound out of it this way."

When I posted this info on Guitar Forum to let everyone know I had FINALLY bought a tube amp, what it was, the seller's comments about its versatility and to thank them all for their help; Gabriel replied that when the tubes "blew" they could wipe out some other parts of the amp. When I asked if there was a way to avoid that, he referred me to you.

What should I do?
Dave,

I would not run EL-34's with the bias in the 6L6 position. The bias on these two tubes is very different.

The negative that was not brought up here, is that your putput transformer will be under a lot more stress and there will be a mismatch in output impedience.

If you want a hotter overdrive sound, get a hotter preamp tube in V1 and V2.

If you want to use 6L6's use them in the correct bias setting, as for EL-34's, use them in the proper setting.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/21/02 12:21 AM

Quote:
Originally posted by mikey:
Hi Miles,
I am getting ready to order some preamp tubes from Watford for the Fender DeVille and want to make sure I have this right. What do you think?

V1- 7025
V2 - 12AX7EH
V3 - 12AT7.
Any suggestions would be greatly appreciated for that classic Fender sound but would like to sweeten up the dirty channel a little. Thanks!!
mikey,

Good choices. The 7025's can be a bit bright, they were used in the older blackface amps, but a lot of folks love these in the Hot Rod DeVille and Deluxe amps.

From Watford, you want your 7025 to be about a 225 range, for your V2 tube, go for 200-220, and for your 12AT7, order their "balanced valve". It should sound really sweet.

Regards,
Posted By: sgguitarzz

Re: Feel free to ask Myles - 05/21/02 01:45 AM

Hey Myles. What do you think of teh Fender Blues Junior? I am considering getting a low power tube amp to use in very small clubs/bars. Volume is always such a problem and my Boogie Mark IIB is just way too loud. With something this small I can actually drive the power tubes for some nice smooth tube distortion. I am a little worried about the 15 watts being to low (I have never used anything this small) but my guess is that in some places it will be more than enough. We play classic rock.
I understand that changing the tubes and speaker really make a big difference in this amp. I already have the speaker and a set of JJ EL-84's are cheap. I have some preamp tubes to try also.

Dennis
Posted By: myles_rose

Re: Feel free to ask Myles - 05/21/02 01:59 AM

Quote:
Originally posted by JamesPeters:
Quote:
Myles said:In any case, paying your local Canada dues is all well and good, but I think there is a pretty nice market for your amp here in the USA too .... so get your plans for increased production in he back of your mind. I have a lot of folks that are interested.
You're right. Well, I'm taking step #1 tomorrow, and that's getting the metal shop that makes my chassis to do all the drilling on the chassis. It's far too time consuming for me, more than anything else so far that I do on the amps. I'd originally thought I should leave the drilling until later in case I wanted to make changes on individual amps, or start a new design...but that's just not practical at all (and I have enough sales now to justify letting them do the drilling).

I tell ya, if we did get "quantity orders" it would sure make Mark happy too. I handed him his pay for the enclosures and I think he got an idea how this could turn into something really big.

Later!
James,

Keep posting or emailing to let me know how its going!

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 05/21/02 02:05 AM

Quote:
Originally posted by sgguitarzz:
Hey Myles. What do you think of teh Fender Blues Junior? I am considering getting a low power tube amp to use in very small clubs/bars. Volume is always such a problem and my Boogie Mark IIB is just way too loud. With something this small I can actually drive the power tubes for some nice smooth tube distortion. I am a little worried about the 15 watts being to low (I have never used anything this small) but my guess is that in some places it will be more than enough. We play classic rock.
I understand that changing the tubes and speaker really make a big difference in this amp. I already have the speaker and a set of JJ EL-84's are cheap. I have some preamp tubes to try also.

Dennis
Dennis,

The Blues Jr. is a amp that is a blast. You can move them anywhere with ease, and the EL-84's are plenty loud for most smaller places. The EL-84's have a great output section breakup, and are very touch sensitive in that amp, which makes it even more fun to play.

On Tubes, just use the EL-84S (JJ) and you're in business. Try and ECC83 in V1 for the Brit sound, or a 12AX7C for a bit less brightness.

Regards,
Posted By: halcyon

Re: Feel free to ask Myles - 05/21/02 11:09 AM

hey myles i was thinking of ordering a pair of those usa groove tubes 6l6 and am wondering how close groove tubes matches there pairs? what number should i get for my rectoverb? im also thinking of picking up one of the matched pre amp tubes from them as a phase inverter too. \:\) thanks.
Posted By: sgguitarzz

Re: Feel free to ask Myles - 05/21/02 09:32 PM

Dennis,
Thanks Myles. The Blues Junior looks like a pretty good pick at that price. Other considerations would be a Peavey Clasic 30, the new Carvin Vintage 16 and someone mentioned and H&K Edition. ANy thoughts on the Fender vs. these amps?

Dennis
Posted By: hechtdavid

Re: Feel free to ask Myles - 05/21/02 09:47 PM

Hi Myles,

I just ordered a matched quad of the GT 6L6GE's for my 1999 "Evil" Twin and was wondering if I should replace the phase invert tube with one of their SAG-AT7-MPI's. Right now I have a balanced JJ AT7 thats only a few months old (thanks to Bob@Eurotubes). I understand that GT may have a more rigorous testing/matching system than Bob, but would I notice any difference in sound?

Am I correct in assuming that the PI tube has more to do with the lifespan of the power tubes than the sonic quality?

On a related subject, this amp has the bias and balance test points on the back panel. The manual says to set the bias with a DVM at between .04VDC and .08VDC. What would be optimal for these tubes?

Do these test points give as acurate a reading as as in-line bias meters?

OR

Should I take it to a tech and have it done with a scope and a signal?


Kudos and thanks again for all your help.

David
Posted By: myles_rose

Re: Feel free to ask Myles - 05/21/02 10:52 PM

Quote:
Originally posted by sgguitarzz:
Dennis,
Thanks Myles. The Blues Junior looks like a pretty good pick at that price. Other considerations would be a Peavey Clasic 30, the new Carvin Vintage 16 and someone mentioned and H&K Edition. ANy thoughts on the Fender vs. these amps?

Dennis
Dennis,

I think it all boils down to personal preference. Maybe post that question here for all the folks and see what you get back?

I like the inside layout of the Fender and its packaging in general. The Classic 30 is .... well .... a classic in a number of ways, and I have owned a lot of Carvin gear over the years that I have been very happy with. Like I said, tough choice.

Generally, I think any amp that competes in this price range has to have a degree of features and reliability, and they all fare nicely in that department.

I guess all I can say here is .... "good luck" \:\)

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/21/02 11:25 PM

Quote:
Originally posted by hechtdavid:
Hi Myles,

I just ordered a matched quad of the GT 6L6GE's for my 1999 "Evil" Twin and was wondering if I should replace the phase invert tube with one of their SAG-AT7-MPI's. Right now I have a balanced JJ AT7 thats only a few months old (thanks to Bob@Eurotubes). I understand that GT may have a more rigorous testing/matching system than Bob, but would I notice any difference in sound?

Am I correct in assuming that the PI tube has more to do with the lifespan of the power tubes than the sonic quality?

On a related subject, this amp has the bias and balance test points on the back panel. The manual says to set the bias with a DVM at between .04VDC and .08VDC. What would be optimal for these tubes?

Do these test points give as acurate a reading as as in-line bias meters?

OR

Should I take it to a tech and have it done with a scope and a signal?


Kudos and thanks again for all your help.

David
David,

Bob at Eurotubes does a great matching job, and your phase inverter is a LOT better than anything you'' ever get off the shelf at random. The JJ tubes are pretty consistant in rise time, so I'd just keep that in there for now. If the rise time was off by a bit, if you had a very critical ear, you might notice a difference. I can tell you that at below 100 Hz, I can sure see a difference on a scope when I look at the output waveform when I use one of the SAG tubes.

On the GE's .... get ready to be surprised !

The PI has a LOT to do with sonic quality. Sure, the output section tubes will last longer too, as they are being driven more evenly, but the sonic quality is the BIG factor. In certain amps they make a major noticible improvement.

In your amp I set the GE's at about .05VDC from their testpoints. This makes the amp run a touch on the cool side, but the Twins don't get as grainy when cool as a Mesa amp as an example.

The test points on the Fender amps are every bit as accurate as any bias measuring device with a meter. I wish they would have done that system 50 years ago \:\) On Fender amps I like the current draw method more than with a scope. It is something that is repeatable, and a scope view is not ... it is open to interpretation. On Marshall amps I like to use a scope as there is a certain amount of crossover notch that is needed to give them their Marshall sound.

So ... save your money on the tech and buy a cheap $30 meter, and you are in business \:\)

Regards,
Posted By: oyo

Re: Feel free to ask Myles - 05/21/02 11:28 PM

Major snippage below to keep post length down.

[/qb][/QUOTE]John,

The phase inverters, as there are two of them in an SVT, are important to be matched.

The line outs are used to slave additional power amps if the need ever arose (which is pretty humorous as the SVT family, old or new, are pretty extreme amps just standing alone. I mean, they were big enough to do the original Woodstock without the help of sound reinforcement \:\)

A balanced phase inverter will not give you a change in level or tone. What it will do is give you sustain across the entire fret board, especially on bass and its lower frequencies that really tax amps.

So .... in comes GT SAG folks. Now you plug in a tube that is a #100. Down the road you want more compression and less front end distortion, so you order a #80 or so. Or ... you want LOTS of gain, so you go for a #125 maybe.

V1 and V2 are your basic tone shaping tubes, others are used for the tone controls and EQ. Your most important tubes are V1 and your two phase inverters.

Regards,[/QB][/QUOTE]

Thanks again Myles. I wanted to know specificaly about the newer SV P, the preamp only unit from SLM. Does the 12AU7 tube drive the line outs? Even more specificly, does each side of the 12AU7 amplify half the waveform (push-pull style as in a normal SV T ), thus needing a balanced tube, or is there a difference between the stand- alone preamp (SVP) and say the integrated pre in the SVT 2 Pro or SVT 4 Pro heads?

Hope I'm making sense...
Posted By: myles_rose

Re: Feel free to ask Myles - 05/21/02 11:51 PM

Quote:
Originally posted by oyo:
Major snippage below to keep post length down.

John,

The phase inverters, as there are two of them in an SVT, are important to be matched.

The line outs are used to slave additional power amps if the need ever arose (which is pretty humorous as the SVT family, old or new, are pretty extreme amps just standing alone. I mean, they were big enough to do the original Woodstock without the help of sound reinforcement \:\)

A balanced phase inverter will not give you a change in level or tone. What it will do is give you sustain across the entire fret board, especially on bass and its lower frequencies that really tax amps.

So .... in comes GT SAG folks. Now you plug in a tube that is a #100. Down the road you want more compression and less front end distortion, so you order a #80 or so. Or ... you want LOTS of gain, so you go for a #125 maybe.

V1 and V2 are your basic tone shaping tubes, others are used for the tone controls and EQ. Your most important tubes are V1 and your two phase inverters.

Regards,[/QB][/QUOTE]

Thanks again Myles. I wanted to know specificaly about the newer SV P, the preamp only unit from SLM. Does the 12AU7 tube drive the line outs? Even more specificly, does each side of the 12AU7 amplify half the waveform (push-pull style as in a normal SV T ), thus needing a balanced tube, or is there a difference between the stand- alone preamp (SVP) and say the integrated pre in the SVT 2 Pro or SVT 4 Pro heads?

Hope I'm making sense... [/QB][/QUOTE]

John,

The 12AU7 for the outputs does not need to be balanced all that much as there is more inconsistancy in the power amps that may be driven from the line out or a board from the preamp only unit as opposed to the preamp/amp configuration of the old SVT and SVT II products.

Regards,
Posted By: hechtdavid

Re: Feel free to ask Myles - 05/21/02 11:55 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by hechtdavid:
Hi Myles,

I just ordered a matched quad of the GT 6L6GE's for my 1999 "Evil" Twin and was wondering if I should replace the phase invert tube with one of their SAG-AT7-MPI's. Right now I have a balanced JJ AT7 thats only a few months old (thanks to Bob@Eurotubes). I understand that GT may have a more rigorous testing/matching system than Bob, but would I notice any difference in sound?

Am I correct in assuming that the PI tube has more to do with the lifespan of the power tubes than the sonic quality?

On a related subject, this amp has the bias and balance test points on the back panel. The manual says to set the bias with a DVM at between .04VDC and .08VDC. What would be optimal for these tubes?

Do these test points give as acurate a reading as as in-line bias meters?

OR

Should I take it to a tech and have it done with a scope and a signal?


Kudos and thanks again for all your help.

David
David,

Bob at Eurotubes does a great matching job, and your phase inverter is a LOT better than anything you'' ever get off the shelf at random. The JJ tubes are pretty consistant in rise time, so I'd just keep that in there for now. If the rise time was off by a bit, if you had a very critical ear, you might notice a difference. I can tell you that at below 100 Hz, I can sure see a difference on a scope when I look at the output waveform when I use one of the SAG tubes.

On the GE's .... get ready to be surprised !

The PI has a LOT to do with sonic quality. Sure, the output section tubes will last longer too, as they are being driven more evenly, but the sonic quality is the BIG factor. In certain amps they make a major noticible improvement.

In your amp I set the GE's at about .05VDC from their testpoints. This makes the amp run a touch on the cool side, but the Twins don't get as grainy when cool as a Mesa amp as an example.

The test points on the Fender amps are every bit as accurate as any bias measuring device with a meter. I wish they would have done that system 50 years ago \:\) On Fender amps I like the current draw method more than with a scope. It is something that is repeatable, and a scope view is not ... it is open to interpretation. On Marshall amps I like to use a scope as there is a certain amount of crossover notch that is needed to give them their Marshall sound.

So ... save your money on the tech and buy a cheap $30 meter, and you are in business \:\)

Regards,
Great Myles! Once again, you've got me excited to plug and play. I'm very anxious for those GE's to arrive.

One more question: When you say to set the GE's at about .05VDC from their testpoints, does that mean up or down? Since Fender recommends from .04 to .08 VDC, and seeing that .06 is in the middle, should I set it at .11 or .01 VDC?

OK, I lied... one MORE question: I've been told that running them cold will yield a longer tube life, but what sonic differences would you expect to hear between running at the upper and lower ends of the bias scale?

Thanks again,

David
Posted By: myles_rose

Re: Feel free to ask Myles - 05/22/02 12:39 AM

Posted By: goodsgtr

Re: Feel free to ask Myles - 05/23/02 08:18 PM

I have a pretty bad buzz(not that kind) in my Musicman 112RD. Is it the tubes if so 6L6GC's are in it now and have been since I bought it 10 years ago. Is this the problem? If so should they be replaced with the same or do you have suggestions? I mostly play a Strat, bluesy, rock.
If this isn't the problem what might it be?

Thanks,
Rob
Posted By: myles_rose

Re: Feel free to ask Myles - 05/23/02 08:52 PM

Quote:
Originally posted by goodsgtr:
I have a pretty bad buzz(not that kind) in my Musicman 112RD. Is it the tubes if so 6L6GC's are in it now and have been since I bought it 10 years ago. Is this the problem? If so should they be replaced with the same or do you have suggestions? I mostly play a Strat, bluesy, rock.
If this isn't the problem what might it be?

Thanks,
Rob
I'd have to see the amp, but wuth tubes over 10 years old, that would be the first change I would make as it is long overdue, especially in this amp that runs over 600 volts on the plates of the tubes.

Regards,

Rob,
Posted By: Dylan

Re: Feel free to ask Myles - 05/24/02 05:11 AM

Hey Miles....I just ordered a new set of pickups for my 90's Japanese Custom Tele. I haven't ever installed my own pickups before and was wondering if anyone could point me in the right direction. I have no problem paying a pro if need be, but if it's something easy I'd rather do it myself. The pickups are a Fender Custom Shop NOS and a Texas Special.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/24/02 07:02 PM

Quote:
Originally posted by Dillweed:
Hey Miles....I just ordered a new set of pickups for my 90's Japanese Custom Tele. I haven't ever installed my own pickups before and was wondering if anyone could point me in the right direction. I have no problem paying a pro if need be, but if it's something easy I'd rather do it myself. The pickups are a Fender Custom Shop NOS and a Texas Special.
Dillweed,

Wiring pickups is not all that tough if you are fair with a soldering iron. The pickups should have come with a wiring diagram. If they did not, I would go to the Fender website and look for Mr. Gearhead. They should have a wiring diagram for a Tele.

Regards,
Posted By: jazzcaster

Re: Feel free to ask Myles - 05/25/02 04:14 AM

Hello Myles,

A quick amateur question here, if you don't mind. I have an 8" speaker (from a Randall practice amp)that has absolutely no markings of any kind on it (nada, zilch, zero!). No spec sheets or anything at the website to help, either. If I want to determine the impedance, and do not have the means (or know-how) to conduct an impedance bench test (ie: under load), can I simply measure the DC resistance? I believe the DC ohm reading will always be less than the "nominal" rating of the speaker, but it will be close. Is this correct??? Thanks in advance!
Posted By: trucidation

Re: Feel free to ask Myles - 05/25/02 08:40 AM

hello,
i have the MesaBoogie Bassis M-2000
i bought it used and was thinking of replacing the tubes. would it make a difference if the phaze inverter was balanced in this amp? and what would be the best set of Groove Tubes to put in to get the fattest deepest bass tones?
thank you very much.
trucidation
Posted By: myles_rose

Re: Feel free to ask Myles - 05/26/02 05:38 AM

Quote:
Originally posted by jazzcaster:
Hello Myles,

A quick amateur question here, if you don't mind. I have an 8" speaker (from a Randall practice amp)that has absolutely no markings of any kind on it (nada, zilch, zero!). No spec sheets or anything at the website to help, either. If I want to determine the impedance, and do not have the means (or know-how) to conduct an impedance bench test (ie: under load), can I simply measure the DC resistance? I believe the DC ohm reading will always be less than the "nominal" rating of the speaker, but it will be close. Is this correct??? Thanks in advance!
jazzcaster ....

Speakers that are 8 ohms as as example, can go from about 8 to much higher at different frequencies, but its "nominal" value is about 8 ohms.

Therefore, you are right .... take a conventional ohm meter, and measure across the speaker terminals, and if it is close to 8 ohms, its an 8 ohm speker .... 4 ohm speakers read from 3.7 to maybe 5 as an example.

So ... you are in business.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/26/02 05:49 AM

Quote:
Originally posted by trucidation:
hello,
i have the MesaBoogie Bassis M-2000
i bought it used and was thinking of replacing the tubes. would it make a difference if the phaze inverter was balanced in this amp? and what would be the best set of Groove Tubes to put in to get the fattest deepest bass tones?
thank you very much.
trucidation
trucidation ....

Save your money and put away the screwdriver !

The 12AX7 front end of this amp is set up for compression characteristics and not for gain. This amp lets you choose between a tube front end or an FET front end, both with a different character .... OR .... you can blend the too, which is cool.

On the back end, there are no tubes to replace. They use a big SS backend with a terrific power supply with a lot of reserve capacity. Their power transformer is particularly impressive.

In any case, there is a lot of processing done in the front end of these amps, so changing the tubes from the Mesa stock ones is something of an un-necessary expense. These preamp tubes will also last for many years.

Now ... if you want to try something really impressive .... plug that amp into a 4x12 cabinet, crank it up on the FET front end, and plug in a Rickenbacker 12 string and play some rhythm guitar! Its a great bass amp for sure, but its also a pretty amazing rhythm guitar amp too and its EQ works pretty nice for some tastes on guitar too!

So ... save your money ... save your time, and just play. You have a great rig there just the way it is.

Regards,
Posted By: jivey311

Re: Feel free to ask Myles - 05/29/02 04:13 AM

I'm going to be retubing my JCM900 and would yellow jacket's or Ruby Tube's Tone Bone's both come with EL84's. How is the difference in tone between 6L6's and EL84's in the yellow jacket's??? More or less gain?
Posted By: myles_rose

Re: Feel free to ask Myles - 05/29/02 06:48 PM

Quote:
Originally posted by jivey311:
I'm going to be retubing my JCM900 and would yellow jacket's or Ruby Tube's Tone Bone's both come with EL84's. How is the difference in tone between 6L6's and EL84's in the yellow jacket's??? More or less gain?
jivey311,

I prefer the Yellow Jackets and these are what most of my clients use, and we have never had a single failure of the Yellow Jacket itself, the tube supplied (a really great JJ), or any sort of amp problem when using the Yellow Jackets.

6L6's will not fit in a Yellow jacket.

Regards,
Posted By: Mikibis

Re: Feel free to ask Myles - 05/30/02 12:49 AM

Hi, Myles.. finally can i write to you on this forum...i found a tube...on which was labeled Philips Miniwatt ecc83....i found it in an old valve television....
could i try it in my amps.? is a regular 12ax7...
and why is called miniwatt?...thanks..any suggestion..should i try it in V1...what about this tube...is better to try in my rectoverb or in my jubilee
thanks
Michele
Posted By: jivey311

Re: Feel free to ask Myles - 05/30/02 02:11 AM

I wanted to know, what the tone differences are between a EL84 and a 6L6? Like is the EL84 a more built for high gain rather than the 6L6.
Posted By: myles_rose

Re: Feel free to ask Myles - 05/30/02 08:04 PM

Quote:
Originally posted by Mikibis:
Hi, Myles.. finally can i write to you on this forum...i found a tube...on which was labeled Philips Miniwatt ecc83....i found it in an old valve television....
could i try it in my amps.? is a regular 12ax7...
and why is called miniwatt?...thanks..any suggestion..should i try it in V1...what about this tube...is better to try in my rectoverb or in my jubilee
thanks
Michele
Mikibis...

That tube is a conventional ECC83, which is part of the 12AX7 family. The "mini-watt" came from their use in some low powered class A amps of about 1/4 - 1/2 watt back in the 50's.

It is probably a very good tube to try in any preamp section of most amps, or any amp that uses a 12AX7/7025/ECC83/12AT7/12AU7/12AY7.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 05/30/02 08:07 PM

Quote:
Originally posted by jivey311:
I wanted to know, what the tone differences are between a EL84 and a 6L6? Like is the EL84 a more built for high gain rather than the 6L6.
jivey311 ...

The EL84 is something of a mini EL-34 in a nine pin bottle. It is much lower in output (about 12 watts max) than a 6L6. It has a nice distortion character that is easy to distort and lower levels, and its distortion builds smoothly throughout its range.

They are very different tubes, each with their own great applications.

Regards,
Posted By: plexiglass

Re: Feel free to ask Myles - 05/30/02 08:46 PM

Hey Myles...

I just purchased a new Peavey 5150 II... and I'm picking it up from my local dealer tomorrow. I saw your comments about preamp tubes on the Harmony Central forum. How can I tell if I need to replace a preamp tube that is only running at 50-60%??? Does the amp just sound weak or do the preamp tubes glow with less intensity than ones running at full capacity?? I'm not sure how many preamp tubes the 5150 II has... but it's almost certain now, after reading your posts, that some of them may not be up to PAR. I love high gain... so I guess I should stick to the standard Chinese preamp tubes. Thoughts???

Plexiglass
Posted By: myles_rose

Re: Feel free to ask Myles - 05/30/02 11:49 PM

Quote:
Originally posted by plexiglass:
Hey Myles...

I just purchased a new Peavey 5150 II... and I'm picking it up from my local dealer tomorrow. I saw your comments about preamp tubes on the Harmony Central forum. How can I tell if I need to replace a preamp tube that is only running at 50-60%??? Does the amp just sound weak or do the preamp tubes glow with less intensity than ones running at full capacity?? I'm not sure how many preamp tubes the 5150 II has... but it's almost certain now, after reading your posts, that some of them may not be up to PAR. I love high gain... so I guess I should stick to the standard Chinese preamp tubes. Thoughts???

Plexiglass
The only way to know for sure is to test your present tubes. If you look on my website in the "friends" section, you will see a fellow there named Tom Dunn. He has what Peavey considers the best sounding 5150 II's around. You can probably find him on Harmony Central once in a while and ask him what he went through with his amps.

His amps use hand selected preamps tubes and 6L6GE's in the output section with a matched phase inverter.

There is a LOT you can do with these amps.

Regards,
Posted By: Seegs

Re: Feel free to ask Myles - 05/31/02 09:51 AM

Hi Myles,

Long time! I've been busy trying to earn a living at this music stuff, unsuccessful thus far, but things are looking up!

Question: I remember you stating that the Fender BF and SF deluxes were the only amp unaffected by the CBS buyout. Meaning SF=BF specs. Right???

Does that mean totally unaffected, no circuit changes, no lesser quality components, or cabinet material or what exactly was the extent of the changes.

Was that the only amp unaffected? ie. champs, princetons??

Where can I find more info on this?

Thanks in advance.

Chow,
Seegs
Posted By: Dave da Dude

Re: Feel free to ask Myles - 05/31/02 05:26 PM

Myles, I am just about to receive (it's shipping today) my first tube amp (Randall Pro 1000, 1993).

I seem to remember somewhere in the deep, dark recesses of my memory (boy it's scary in there) something about the handling of tubes that said the oil from your fingers (that create fingerprints), if left on a power tube, will create a hot spot and cause early failure.

Is there any truth to this? Or was I just smoking wacky tobacee?

Dave \:D
Posted By: myles_rose

Re: Feel free to ask Myles - 05/31/02 08:57 PM

Quote:
Originally posted by Seegs:
Hi Myles,

Long time! I've been busy trying to earn a living at this music stuff, unsuccessful thus far, but things are looking up!

Question: I remember you stating that the Fender BF and SF deluxes were the only amp unaffected by the CBS buyout. Meaning SF=BF specs. Right???

Does that mean totally unaffected, no circuit changes, no lesser quality components, or cabinet material or what exactly was the extent of the changes.

Was that the only amp unaffected? ie. champs, princetons??

Where can I find more info on this?

Thanks in advance.

Chow,
Seegs
Seegs,

The amps from the Deluxe Reverb on down were pretty much left un-touched, as they did not sell for enough to warrant changes from CBS.

For really exact details, I'd look at the Fender Amp Field Guide as they may have minute types of info.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 05/31/02 09:00 PM

Quote:
Originally posted by Dave th Dude:
Myles, I am just about to receive (it's shipping today) my first tube amp (Randall Pro 1000, 1993).

I seem to remember somewhere in the deep, dark recesses of my memory (boy it's scary in there) something about the handling of tubes that said the oil from your fingers (that create fingerprints), if left on a power tube, will create a hot spot and cause early failure.

Is there any truth to this? Or was I just smoking wacky tobacee?

Dave \:D
Dave,

I guess from a pure physics point of view this may have some point, but tubes are not like halogen bulbs. They are more like conventional light bulbs, and I do not wear gloves when I replace light bulbs or tubes.

The main point of handling tubes is .... watch out for leaving some of your skin on output tubes when they are super hot ... won't hurt the tube much, but causes people a bit of pain \:\)

Regards,
Posted By: rsf1977

Re: Feel free to ask Myles - 06/01/02 12:53 AM

I have a Mesa-Boogie Dual Rec (2 Channel)

I wanted to know how I should go dialing in my ideal tone. Do you set everything at middle of the road and then tweak? Also should I adjust certain frequencies before others?

These are the controls I have:
1. Master Volume
2. Channel Volume
3. Presence
4. Bass
5. Mid
6. Treble
7. Gain

I like a really thick saturated distortion I play hardcore-metal. If that changes anything?

Also is there any tips you can give about the Dual Rec that might really make it sing? Like the mid range is where it's at on this amp so focus around that? or anything that might help.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/01/02 01:37 AM

Quote:
Originally posted by rsf1977:
I have a Mesa-Boogie Dual Rec (2 Channel)

I wanted to know how I should go dialing in my ideal tone. Do you set everything at middle of the road and then tweak? Also should I adjust certain frequencies before others?

These are the controls I have:
1. Master Volume
2. Channel Volume
3. Presence
4. Bass
5. Mid
6. Treble
7. Gain

I like a really thick saturated distortion I play hardcore-metal. If that changes anything?

Also is there any tips you can give about the Dual Rec that might really make it sing? Like the mid range is where it's at on this amp so focus around that? or anything that might help.
rsf1977 ...

Front panel controls are all set to preference and there is really no specific method. I start with everything flat, because with passive tone controls, in some circuits, if one of them is off, then there is no sound at all.

For a thick sound with a lot of articulation still, I use the E34L-S tubes in your amp if you have the bias set for EL-34's, but for max sound, I like the 6L6GE's or the 6L6S tubes for the output tubes.

In Mesa amps I use a GT range of 6's or even 7's. 6's are the same as Mesa's hottest tubes, but even these are a bit cool running.

On preamp tubes for my clients, I use either 12AX7R3's for V1 and V2 or ECC83's for the folks that want even more mids and sparkle. In either case, I hand pick these to make sure their rating is at least 100 on the scale I use.

I always used a Matched Phase Inverter, and I have spoken about this in detail, and it is also explained on my website.

Regards,
Posted By: rsf1977

Re: Feel free to ask Myles - 06/01/02 02:00 AM

Hey Myles just curious why you use 12AX7R3's for V1 and V2. I currently have 12AX7EH for entire preamp do you think this is a wise decision?

also what is the 100 rating, how do I request that Groove Tube only has low/med/high in the SAG sections

"On preamp tubes for my clients, I use either 12AX7R3's for V1 and V2 or ECC83's for the folks that want even more mids and sparkle. In either case, I hand pick these to make sure their rating is at least 100 on the scale I use."
Posted By: myles_rose

Re: Feel free to ask Myles - 06/01/02 05:28 AM

Quote:
Originally posted by rsf1977:
Hey Myles just curious why you use 12AX7R3's for V1 and V2. I currently have 12AX7EH for entire preamp do you think this is a wise decision?

also what is the 100 rating, how do I request that Groove Tube only has low/med/high in the SAG sections

"On preamp tubes for my clients, I use either 12AX7R3's for V1 and V2 or ECC83's for the folks that want even more mids and sparkle. In either case, I hand pick these to make sure their rating is at least 100 on the scale I use."
rsf1977....

Actually, the GT-12AX7R3 is the 12AX&EH tube made by the Relector Factory in Russia ... on the west side of the Reflector factory where the EH tooling is set up. On the East side of the factory is where the Sovtek tooling is set up.

So... if you have EH's in there now, you are in business.

Regards,
Posted By: Dave da Dude

Re: Feel free to ask Myles - 06/01/02 04:54 PM

quote:
--------------------------------------------------------------------------------
Originally posted by Dave th Dude:
Myles, I am just about to receive (it's shipping today) my first tube amp (Randall Pro 1000, 1993).

I seem to remember somewhere in the deep, dark recesses of my memory (boy it's scary in there) something about the handling of tubes that said the oil from your fingers (that create fingerprints), if left on a power tube, will create a hot spot and cause early failure.

Is there any truth to this? Or was I just smoking wacky tobacee?

Dave
--------------------------------------------------------------------------------
quote:

Dave,

I guess from a pure physics point of view this may have some point, but tubes are not like halogen bulbs. They are more like conventional light bulbs, and I do not wear gloves when I replace light bulbs or tubes.

The main point of handling tubes is .... watch out for leaving some of your skin on output tubes when they are super hot ... won't hurt the tube much, but causes people a bit of pain

Regards,

--------------------
Myles S. Rose

That's IT ! Halogen bulbs. I knew I remembered that from somewhere. I don't wear gloves to replace light bulbs either. \:D

Thanks for jogging my web clouded memory, Dave. \:\)
Posted By: rsf1977

Re: Feel free to ask Myles - 06/02/02 09:35 PM

Hey Myles I was looking at my Dual Rect manual and this is what it says for the preamp:

V1 A= Input Stage
V1 B= NOT USED
V2 A= 2nd Stage
V2 B= 3rd Stage
V3 A= 4th Stage
V3 B= 5th Stage

V4 A= FX Send
V4 B= FX Return
V5 A/B= Phase Splitter/Output

If V1 is the Phase Inverter and the B side of the V1 position is not used does that mean a matched 12AX7 wont do anything or should I still get a matched one anyway?

Also should I use the 12AX7EHs for all the positions or do some tubes work better in certain applications generally, just wondering your opinion on this?
Posted By: myles_rose

Re: Feel free to ask Myles - 06/03/02 02:45 AM

Quote:
Originally posted by rsf1977:
Hey Myles I was looking at my Dual Rect manual and this is what it says for the preamp:

V1 A= Input Stage
V1 B= NOT USED
V2 A= 2nd Stage
V2 B= 3rd Stage
V3 A= 4th Stage
V3 B= 5th Stage

V4 A= FX Send
V4 B= FX Return
V5 A/B= Phase Splitter/Output

If V1 is the Phase Inverter and the B side of the V1 position is not used does that mean a matched 12AX7 wont do anything or should I still get a matched one anyway?

Also should I use the 12AX7EHs for all the positions or do some tubes work better in certain applications generally, just wondering your opinion on this?
Hey Myles I was looking at my Dual Rect manual and this is what it says for the preamp:

V1 A= Input Stage
(this is where you want a high gain tube)
V1 B= NOT USED

V2 A= 2nd Stage
(this is where you want the 2nd high gain tube)
V2 B= 3rd Stage

V3 A= 4th Stage
V3 B= 5th Stage

V4 A= FX Send
V4 B= FX Return
V5 A/B= Phase Splitter/Output
(this is where you want the matched phase inverter, not V1.

Only use the MPI in V5.

If you want more gain in the other channels, then you can put a high output tube also in V3, but since V3 is fed off earlier stages, you may have so much front end gain that you loose articulation and anything above "2" or so will not be useful anymore as it will be too distorted in the front end.

I prefer the GT-12AX7R3 in those amps. That is the same tube as the 12AX7EH but selected a bit more closely.

Regards,
Posted By: rsf1977

Re: Feel free to ask Myles - 06/03/02 07:27 AM

Thanks Myles for all your help.
You mentioned earlier about using the 6L6GE or the 6L6-S at a ratting of 6-7. I just wanted to know the tonal qualities of each tube and why you suggested both. I am also not familiar with the 6L6-S who makes these?

Also so what do I stick in the V3? another EH12AX7 with low gain or another kind of tube? Sorry if I'm a little slow on this stuff I've only recently become addicted to knowing everything I can about my gear and everything else, my girlfriend thinks I'm crazy...
Posted By: snoz65

Re: Feel free to ask Myles - 06/03/02 01:08 PM

Hi there Miles,
I am looking for a new preamp tube for the first position of channel 2 and 3 of my Marshall 30th aniversary. I currently have an old Brimar 12AX7 which has gone microphonic and I am seriously considering some Mullard CV4004's as a replacement.
Do you have any comments or experience with these Mullards and why are they known as CV4004's rather than 12AX7's.
Regards,
Shaun.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/03/02 07:45 PM

Quote:
Originally posted by rsf1977:
Thanks Myles for all your help.
You mentioned earlier about using the 6L6GE or the 6L6-S at a ratting of 6-7. I just wanted to know the tonal qualities of each tube and why you suggested both. I am also not familiar with the 6L6-S who makes these?

Also so what do I stick in the V3? another EH12AX7 with low gain or another kind of tube? Sorry if I'm a little slow on this stuff I've only recently become addicted to knowing everything I can about my gear and everything else, my girlfriend thinks I'm crazy...
rsf1977,

The 6L6S has more of a midrange bump and is less linear than the GE. It's really a matter of personal preference. The sound image is larger by about 10-15 degrees with the GE's but a lot of hard rock players love the "in your face" aspects of the 6L6S. The 6L6S is made by the JJ factory.

In V3, you can use most anything as the initial gain and tone have already been set and defined for the most part by V1.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 06/03/02 07:50 PM

Quote:
Originally posted by snoz65:
Hi there Miles,
I am looking for a new preamp tube for the first position of channel 2 and 3 of my Marshall 30th aniversary. I currently have an old Brimar 12AX7 which has gone microphonic and I am seriously considering some Mullard CV4004's as a replacement.
Do you have any comments or experience with these Mullards and why are they known as CV4004's rather than 12AX7's.
Regards,
Shaun.
Shaun,

CV4004 is just another designation that has been used at times. The Mullard CV is in the same family as the 12AX7, ECC83, 7025, etc, but has its own unique plate structure and some other unique aspects that give it it's tonal qualitles.

These are great in V1 of a Marshall (or just about any other amp) as they had very high Quality Control and at least you generally get a tube that is putting out what it was supposed to put out. It is also very articulate and all in all, just a beautiful sounding tube in general.

Regards,
Posted By: Seth

Re: Feel free to ask Myles - 06/05/02 05:44 PM

Hi Myles,

I'm looking to maximize my Peavey Classic VT 50 for blues.

That's the model with the SS front end, a multitude of channels with an "automix" (cascades one channel into the other for an extra muddy sound) feature, and 2 6L6GC's for power. I got these from Bob at Eurotubes.

2 - 12" Eminence OEM speakers.

By bridging the bright channel into one of the normal inputs, and by very careful eq-ing and gain adjustment, I can get a "pretty good" sound with very little (but some!) ss harshness buried in the background.

Any ideas how I might be able to take this platform further?

Thanks.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/05/02 06:41 PM

Quote:
Originally posted by Seth:
Hi Myles,

I'm looking to maximize my Peavey Classic VT 50 for blues.

That's the model with the SS front end, a multitude of channels with an "automix" (cascades one channel into the other for an extra muddy sound) feature, and 2 6L6GC's for power. I got these from Bob at Eurotubes.

2 - 12" Eminence OEM speakers.

By bridging the bright channel into one of the normal inputs, and by very careful eq-ing and gain adjustment, I can get a "pretty good" sound with very little (but some!) ss harshness buried in the background.

Any ideas how I might be able to take this platform further?

Thanks.
Seth,

The 6L6 JJ tubes are a bit "in your face" for blues, and with your SS front end, may be even a bit more sterile.

I would go to something like an NOS 5881 or a KT-66, and with something in the rating area of a GT #3-4.

Regards,
Posted By: Seth

Re: Feel free to ask Myles - 06/05/02 07:08 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by Seth:
Hi Myles,

I'm looking to maximize my Peavey Classic VT 50 for blues.

That's the model with the SS front end, a multitude of channels with an "automix" (cascades one channel into the other for an extra muddy sound) feature, and 2 6L6GC's for power. I got these from Bob at Eurotubes.

2 - 12" Eminence OEM speakers.

By bridging the bright channel into one of the normal inputs, and by very careful eq-ing and gain adjustment, I can get a "pretty good" sound with very little (but some!) ss harshness buried in the background.

Any ideas how I might be able to take this platform further?

Thanks.
Seth,

The 6L6 JJ tubes are a bit "in your face" for blues, and with your SS front end, may be even a bit more sterile.

I would go to something like an NOS 5881 or a KT-66, and with something in the rating area of a GT #3-4.

Regards,
Thanks Myles!

This is a "fixed bias" amp, but I'm very ignorant about biasing.

If I try 5881's or KT-66's will I need to have a tech do any biasing or adjusting?

I've heard that KT-66's are large. How much space do I need for them to be an option?

Thanks again for anly info.
Posted By: rsf1977

Re: Feel free to ask Myles - 06/05/02 07:36 PM

Hey Myles not that I'm doubting your knowledge, but I thought maybe you could respond to what someone told me on Harmony-Central when I asked about the new GE6L6:

"You might like to know that at least one, and maybe more, boutique amp builder has disliked the the new GT 6L6 enough to ask Miles to stop recommending it for their amps. They do not feel that it is a good sounding tube, despite how and where it was made. Please remember that Myles is a paid employee of Groove Tubes and you should take that into consideration when thinking about his "advice".

Just something to think about!"

http://acapella.harmony-central.com/foru...2&postid=324392
Posted By: myles_rose

Re: Feel free to ask Myles - 06/05/02 07:37 PM

Quote:
Originally posted by Seth:
Quote:
Originally posted by myles111:
Quote:
Originally posted by Seth:
Hi Myles,

I'm looking to maximize my Peavey Classic VT 50 for blues.

That's the model with the SS front end, a multitude of channels with an "automix" (cascades one channel into the other for an extra muddy sound) feature, and 2 6L6GC's for power. I got these from Bob at Eurotubes.

2 - 12" Eminence OEM speakers.

By bridging the bright channel into one of the normal inputs, and by very careful eq-ing and gain adjustment, I can get a "pretty good" sound with very little (but some!) ss harshness buried in the background.

Any ideas how I might be able to take this platform further?

Thanks.
Seth,

The 6L6 JJ tubes are a bit "in your face" for blues, and with your SS front end, may be even a bit more sterile.

I would go to something like an NOS 5881 or a KT-66, and with something in the rating area of a GT #3-4.

Regards,
Thanks Myles!

This is a "fixed bias" amp, but I'm very ignorant about biasing.

If I try 5881's or KT-66's will I need to have a tech do any biasing or adjusting?

I've heard that KT-66's are large. How much space do I need for them to be an option?

Thanks again for anly info.
I would have a tech check the bias, and remember, the KT-66 is a 25 watt tube, a bit different than some 5881's or some 6L6's.

On height, give yourself at least 4 7/8".

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 06/05/02 07:46 PM

Quote:
Originally posted by rsf1977:
Hey Myles not that I'm doubting your knowledge, but I thought maybe you could respond to what someone told me on Harmony-Central when I asked about the new GE6L6:

"You might like to know that at least one, and maybe more, boutique amp builder has disliked the the new GT 6L6 enough to ask Miles to stop recommending it for their amps. They do not feel that it is a good sounding tube, despite how and where it was made. Please remember that Myles is a paid employee of Groove Tubes and you should take that into consideration when thinking about his "advice".

Just something to think about!"
rsf1977 ...

Interesting news to me, but everybody is entitled to their opinion. It would be nice to know who the "boutique" maker was that did not like the tube, as some feedback would be nice, but since the first 6 month run off the GE's were gone in 3 1/2 weeks, most folks may tend to feel differently than the "boutique" amp maker I guess.

Regards,
Posted By: rsf1977

Re: Feel free to ask Myles - 06/05/02 07:57 PM

so no one has told you to stop recommending them? or anything? Have the tubes been getting positive feedback from users or is it to early to tell?
Posted By: sgguitarzz

Re: Feel free to ask Myles - 06/05/02 09:17 PM

Hey Myles. Still searching for that small amp. I have decided that the Blues Jr. is too small. I am now currently checking out the Peavey Delta Blues amps but can't decide on 1x15 or 2x10. Do you have any experience with these and tube recommendations? Thanks.

Dennis
Posted By: myles_rose

Re: Feel free to ask Myles - 06/05/02 09:40 PM

Quote:
Originally posted by rsf1977:
so no one has told you to stop recommending them? or anything? Have the tubes been getting positive feedback from users or is it to early to tell?
The only person that has said something to me has been Ed from THD where I mention the GE and reference a review on the original GE that Watford Valves had written. Since during testing, the curves, specs, parts, and every other aspect was identical to the original GE, right down to the machines they are made on, I felt it was OK to reference that review. Ed did not like me using an old review on the new GE in the same reference as the THD Univalve name, possibly as GT has a similar product that competes in some markets with the Univalve. Both amps have their strong points, and I personally own a Univalve, but when I get the money, I will also purchase a GT Solo-Single.

The feedback from those that have used or purchased the 6L6GE has been more positive than was expected. In the initial 6 month run, the tubes were gone in less than a month. The second run was completed, and the tubes are now back in stock. One pretty famous 5150 user purchased a LOT of them, all that GT was willing to ship to a single individual. In the past, this fellow used the NOS GE's in his amps.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 06/05/02 09:43 PM

Quote:
Originally posted by sgguitarzz:
Hey Myles. Still searching for that small amp. I have decided that the Blues Jr. is too small. I am now currently checking out the Peavey Delta Blues amps but can't decide on 1x15 or 2x10. Do you have any experience with these and tube recommendations? Thanks.

Dennis
Dennis,

I'd post that question here, and over at Harmony Central. You'll probably get a lot of responses. Also check the Harmony Central user's review, as there is a lot of good feedback there.

I like 2x10 configs a lot, as the speaker cones are lighter than a 12" (and much lighter than a 15"), have nice midrange detail because of less cone mass in a lot of cases, and provide good low end when 2 10's are used.

Myles
Posted By: rsf1977

Re: Feel free to ask Myles - 06/05/02 10:46 PM

Cool, just wondering don't mean to put you on the spot. Well I ordered the GE6L6 I'll let you know how it goes when I get them and popem' in my Dual Rect. Thanks for the help.

Do you know if there is a backorder wait and if there have been any changes with the second run of these tubes like any adjustments for the better? Thanks.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/05/02 10:56 PM

Quote:
Originally posted by rsf1977:
Cool, just wondering don't mean to put you on the spot. Well I ordered the GE6L6 I'll let you know how it goes when I get them and popem' in my Dual Rect. Thanks for the help.

Do you know if there is a backorder wait and if there have been any changes with the second run of these tubes like any adjustments for the better? Thanks.
rsf1977,

There is no backorder as the 2nd run was finished on last Thursday and the first 200 finished testing on Monday (two days ago). Just as a matter of info, out of the first 200, there was a 0% reject rate, which is quite unique compared to the up to 50% reject rate on some other tubes.

Regards,
Posted By: El Glom-o

Re: Feel free to ask Myles - 06/06/02 12:36 AM

Hi, Myles - Are you familiar with the Tel-Ray Adineko device, sometimes referred to as the "oil-can reverb"? I have a couple of them that I'd like to have in optimum working condition. I've gathered info about them, including schematic and owner's instructions for the Gibson GA4-RE (Gibson's version), as well as copies of the patents for the device, but I've been unable to find service or troubleshooting info. Can you help me with this? Either with advice or perhaps with servicing it yourself?
Posted By: El Glom-o

Re: Feel free to ask Myles - 06/06/02 12:39 AM

Hi, Myles - Are you familiar with the Tel-Ray Adineko device, sometimes referred to as the "oil-can reverb"? I have a couple of them that I'd like to have in optimum working condition. I've gathered info about them, including schematic and owner's instructions for the Gibson GA4-RE (Gibson's version), as well as copies of the patents for the device, but I've been unable to find service or troubleshooting info. Can you help me with this? Either with advice or perhaps with servicing it yourself?
Posted By: rsf1977

Re: Feel free to ask Myles - 06/06/02 12:54 AM

hey Myles is there someone out there that knows as much about guitars as you do about amps I can ask stuff.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/06/02 01:03 AM

Quote:
Originally posted by El Glom-o:
Hi, Myles - Are you familiar with the Tel-Ray Adineko device, sometimes referred to as the "oil-can reverb"? I have a couple of them that I'd like to have in optimum working condition. I've gathered info about them, including schematic and owner's instructions for the Gibson GA4-RE (Gibson's version), as well as copies of the patents for the device, but I've been unable to find service or troubleshooting info. Can you help me with this? Either with advice or perhaps with servicing it yourself?
The hot shot on these is a guy named Jimmy who is the tech at Groove Tubes.

He can be reached at 818-361-4500, just ask for Jimmy, or I think his email is:

lab@groovetubes.com

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 06/06/02 01:13 AM

Quote:
Originally posted by rsf1977:
hey Myles is there someone out there that knows as much about guitars as you do about amps I can ask stuff.
The best guitar folks around that I know are:

David Neely ... a guitar builder from Nashville that is in So Cal now. On my website there is a link to him (his website) and he has an email there where you can write him or call him also. Tell him I said hello.

"The Amazing Nick" at Norm's Rare Guitars .... also a link on my website with contact info. If you know who Norm Harris is, and realize that Nick is the one that does all his repair and restoration work, then that gives you an idea about Nick. If Nick seems "harsh", its just his personality, and he's really a fun guy but some folks do not understand his humor. Some folks that can give him references are folks like Van Halen, David Lee Roth, and folks from the Jazz and Blues world from decades.

Those are the two best guys for my money.

Regards,
Posted By: Skapunxter

Re: Feel free to ask Myles - 06/06/02 01:27 AM

Hey myles got a couple of questions for you:
First off i got a rocktron piranha preamp the other day and noticed that the hi-gain channel is kinda cheezy sounding. I can get some good distortoin outta it, but i want more thick shred and not so much tinny biting tone and theres just something it lacks, and i gotta play with the eq a bunch to get it sounding how i like it. Is it probable that this is the result of a crappy pair of tubes? its a real pain in the ass to open this preamp up, so if it wont really help too much id rather not risk anything.

Next question: I run this piranha into a peavy classic 50/50. One channel has a quartet of GT el84's #7, and the other channel has a new set of sovteks i think. This preamp/poweramp combination can really scream at a low volume... sounds really nice. But when i crank them up, it just doesnt seem to put out the advertised 100 watts. I have a hard time keeping up with the rest of the band in terms of balaced volume. When i do max out all my volume knobs it is (barely) loud enough, but sounds flabby and my tone looses all its balls. All my patches start to sound really alike. What can i tweak to fix this problem, or is it just going to be like that forever? I can go into each of my patches and max out their levels, but that doesnt leave me with a lot of room for level variation beween patches. I also Have an ADA mp-1 and it sounds pretty loud through the 50/50, but still not near loud enough. Im getting my ass drowned out by a peavey ultra 100 watt head with its volume on 5. Something just doesnt seem right... Thanks a ton.
randy
Posted By: El Glom-o

Re: Feel free to ask Myles - 06/06/02 01:31 AM

[/qb][/QUOTE]The hot shot on these is a guy named Jimmy who is the tech at Groove Tubes.[/QB][/QUOTE]

I just spoke to Jimmy. He was quite helpful. Thank you.

El Glom-o
Posted By: dave251

Re: Feel free to ask Myles - 06/06/02 07:09 AM

Myles- Been a while...thought I'd fill you in on the electroCoustic amp project/progress...

We've settled on a tube layout...#2 will have a pair of 12AX7's, a 6SL7 for the driver and a pair of 300B's for output. It will have a buffered EFX loop, and Hammond transformers. SS recto. We feel like we can eliminate the big filter choke...Brett routed around it on the first one and didn't have any added noise problems. We're going to DC for the filament heater...

With any kind of luck we'll have this one together by midsummer...and in a cab ready for demo shortly thereafter...I'd like to be building my first "production" amp by the first of the year...this will be quite a plunge for this old woodbutcher...but I'd sure like to be able to build the whole shootin' match...guitar AND amp. Speaking of which...here's a pic of the latest delivery...

We need recommendations on the best/most consistently available 12AX7 for our purposes....preamp stage and EFX buffering...

Regards, Dave

Posted By: myles_rose

Re: Feel free to ask Myles - 06/06/02 06:50 PM

Quote:
Originally posted by El Glom-o:
[/qb]
The hot shot on these is a guy named Jimmy who is the tech at Groove Tubes.[/QUOTE]

I just spoke to Jimmy. He was quite helpful. Thank you.

El Glom-o[/QB][/QUOTE]

El Glom-o ... you are welcome.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/06/02 07:03 PM

Quote:
Originally posted by Skapunxter:
Hey myles got a couple of questions for you:
First off i got a rocktron piranha preamp the other day and noticed that the hi-gain channel is kinda cheezy sounding. I can get some good distortoin outta it, but i want more thick shred and not so much tinny biting tone and theres just something it lacks, and i gotta play with the eq a bunch to get it sounding how i like it. Is it probable that this is the result of a crappy pair of tubes? its a real pain in the ass to open this preamp up, so if it wont really help too much id rather not risk anything.

Next question: I run this piranha into a peavy classic 50/50. One channel has a quartet of GT el84's #7, and the other channel has a new set of sovteks i think. This preamp/poweramp combination can really scream at a low volume... sounds really nice. But when i crank them up, it just doesnt seem to put out the advertised 100 watts. I have a hard time keeping up with the rest of the band in terms of balaced volume. When i do max out all my volume knobs it is (barely) loud enough, but sounds flabby and my tone looses all its balls. All my patches start to sound really alike. What can i tweak to fix this problem, or is it just going to be like that forever? I can go into each of my patches and max out their levels, but that doesnt leave me with a lot of room for level variation beween patches. I also Have an ADA mp-1 and it sounds pretty loud through the 50/50, but still not near loud enough. Im getting my ass drowned out by a peavey ultra 100 watt head with its volume on 5. Something just doesnt seem right... Thanks a ton.
randy
Randy ....

On your Rocktron, there is a lot of processing and EQ in there already, so the sound it makes is, well, sort of the sound it makes. If you change anything inside, it won't do much as there are too many other things going on and the signal path is anything but simple.

The Sovtek's don't have anywhere near the output sound image of the JJ (EL-84-s) tubes. They may also be far from being close to match also. If you are in my area (So Cal), I would be happy to scope your amp and let you know actual power output. (I do this for no charge for forum folks from here .... and I also adjust bias for N/C if you are a player that is NOT signed or NOT famous, and just are trying to get by like most of us. If you have an agent, manager, or record label, then you PAY ... LOTS).

What you should do is put in all new EL-84's. Also make sure the driver tube (called the phase inverter in a lot of amps) is also fresh on each output set.

If you want another tip, email me about this from my website as there are some things I would mention but would not think this forum is the proper avenue.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 06/06/02 07:14 PM

Quote:
Originally posted by dave251:
Myles- Been a while...thought I'd fill you in on the electroCoustic amp project/progress...

We've settled on a tube layout...#2 will have a pair of 12AX7's, a 6SL7 for the driver and a pair of 300B's for output. It will have a buffered EFX loop, and Hammond transformers. SS recto. We feel like we can eliminate the big filter choke...Brett routed around it on the first one and didn't have any added noise problems. We're going to DC for the filament heater...

With any kind of luck we'll have this one together by midsummer...and in a cab ready for demo shortly thereafter...I'd like to be building my first "production" amp by the first of the year...this will be quite a plunge for this old woodbutcher...but I'd sure like to be able to build the whole shootin' match...guitar AND amp. Speaking of which...here's a pic of the latest delivery...

We need recommendations on the best/most consistently available 12AX7 for our purposes....preamp stage and EFX buffering...

Regards, Dave

Dave,

Its great to hear you are progressing.

On 12AX7's, frankly, today's 12AX7's have tolerances that are so wide ( from 0.6mA to 1.8mA ) that it is just hopeless to suggest any off the shelf one that would work best in your amp.

You are not going to sell 100,000 of these (well, if you do, then we'll deal with that), but for limited production of a very high end amp like yours, I'd go with selected 12AX7R3 tubes. These are available from the SAG (Special Applications Group) over at Groove Tubes. Actually, that is how I ended up at GT last month, as I needed more and more selected tubes all the time for my own clients.

I'd go with a "medium" selection as the rise time will be really nice in that amp, but on the high side of the medium range so the rise time is on the fast side of medium ... to keep the articulation and attack of an acoustic instrument.

You can see these tubes at: http://www.groovetubes.com/product.cfm?Product_ID=1733

For your amp I'd specify a rating of 85-95.

I would also be happy to put you in contact with the head of GT sales as since you are an amp maker, you'd probably have a corporate account set up with whatever associated discounts sales does with those sort of folks.

Keep me informed!

Myles
Posted By: rsf1977

Re: Feel free to ask Myles - 06/07/02 12:01 AM

Hey Myles so I wanted to know what rating of 12AX7s to put in my Dual Rect. for V1 and V2 if I were to buy them from groove tubes (low, med, High) and if I were to get SAG tubes what should I get. Also what tuge is good to use in the Phase Inverter.

Just a reminder I play High gain Metal with a tight bottom and I just ordered the GE6L6s if that matters in your recommendation, thanks.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/07/02 07:40 PM

Quote:
Originally posted by rsf1977:
Hey Myles so I wanted to know what rating of 12AX7s to put in my Dual Rect. for V1 and V2 if I were to buy them from groove tubes (low, med, High) and if I were to get SAG tubes what should I get. Also what tuge is good to use in the Phase Inverter.

Just a reminder I play High gain Metal with a tight bottom and I just ordered the GE6L6s if that matters in your recommendation, thanks.
I use GT-12AX7R3's in Mesa Dual and Triple rectifiers, with a HIGH/Fast rating, but on the "low" side of the HIGH scale. The Recto's have high gain already, and too HIGH of a HIGH will limit the range of volume controls as it will get too much distorion too fast, and turn it all to gribble-hash.

For my own clients, I use a V1 of 100-125.

For the phase inverter, I use any of the 12AX7's as they are not part of the tone generation stage and are chosen for current drive and rise time. There is normally not a rating pull down over on the GT website for this tube.

You can see them both at:

http://www.groovetubes.com/product.cfm?Product_ID=1723

and

http://www.groovetubes.com/product.cfm?Product_ID=1733

Some folks like the longer plate R2 but about 70% of my clients prefer the R3 as do I.

Regards,
Posted By: rsf1977

Re: Feel free to ask Myles - 06/07/02 10:24 PM

Is there a certain preamp tube that deals with the clean channel only, or do both channels use all the preamp tubes equally?

Also do you think NOS tubes are a good idea for the Dual Rec I'm considering getting 2 Mullard ECC83 for V1 and V2?
Posted By: myles_rose

Re: Feel free to ask Myles - 06/08/02 12:05 AM

Quote:
Originally posted by rsf1977:
Is there a certain preamp tube that deals with the clean channel only, or do both channels use all the preamp tubes equally?

Also do you think NOS tubes are a good idea for the Dual Rec I'm considering getting 2 Mullard ECC83 for V1 and V2?
Most circuits, and I will say "most" but not all, use V1 as the first gain stage (or in a blackface fender, V1 for the Normal channel and V2 as the first gain stage for the vibrato channel), and the first stage "usually" will feed additional gain stages in a multi channel amp.

Regards,
Posted By: Dave da Dude

Re: Feel free to ask Myles - 06/08/02 02:28 AM

I've finally got my 1993 Randall Pro 1000 II amp.

I checked the tubes before I turned it on (it's warming up now).

The Pre-Amp tubes are "Randall" brand (I assume original 1993) 12AX7A. Can I do better?

The amp has a bias switch for EL34 or 6L6.

Right now it has Sylvania (looks like )626 ABU tubes in it. Can I do better than those?

The EL34's are Chinese tubes. What's your best suggestion for their replacement?

I know this is a lot and very general, I'm just looking for some place to get started.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/09/02 07:52 PM

Quote:
Originally posted by Dave th Dude:
I've finally got my 1993 Randall Pro 1000 II amp.

I checked the tubes before I turned it on (it's warming up now).

The Pre-Amp tubes are "Randall" brand (I assume original 1993) 12AX7A. Can I do better?

The amp has a bias switch for EL34 or 6L6.

Right now it has Sylvania (looks like )626 ABU tubes in it. Can I do better than those?

The EL34's are Chinese tubes. What's your best suggestion for their replacement?

I know this is a lot and very general, I'm just looking for some place to get started.
Dave,

If all the tubes are "original" and 1993, it may be time to replace all of them.

Without looking at the tubes, its hard to say what they are from my point of reference.

There is no such thing as "Randall" tubes, their name was silkscreened on them at some point, so their origin is unknown.

The Chinese EL-34's can be improved upon from tube from just about any source. I am surprised that they have held up this long. That is one indication that the amp was not played hard too often.

I would have the amp gone over, the bias checked, pots cleaned, noise floor checked to verify the condition of the filter caps, and then replace those power tubes and their associated phase inverter for a start. Make sure the bias is checked, don't rely on the switch to do this properly.

Regards,
Posted By: throb13

Re: Feel free to ask Myles - 06/10/02 07:27 PM

Hi Myles,
I sent you an e-mail last week at the Groove tubes tech address. I don't know if you responded to it yet because the e-mail address I gave you is experiencing problems with incoming mail. I haven't received any outside e-mails for days at that address. So, I figured I better do this the right way and send it here. The main text of the e-mail was this: I own a Marshall JCM 2000 TSL100 head. The Groove Tubes SAG kits seem to have only 3 pre amp tubes. My Marshall has 4. Will you eventually be selling kits for JCM 2000's? If not, then what would you recommend for each input (rating wise) for that elusive "brown sound? " I know...you probably get a zillion people who want to capture EVH in a tube. Well, make me a zillion and one then.
Also, what GT EL 34 power tube rating would be best?
Thanks for taking the time to read this,
Pasquale
Posted By: myles_rose

Re: Feel free to ask Myles - 06/10/02 08:15 PM

Quote:
Originally posted by throb13:
Hi Myles,
I sent you an e-mail last week at the Groove tubes tech address. I don't know if you responded to it yet because the e-mail address I gave you is experiencing problems with incoming mail. I haven't received any outside e-mails for days at that address. So, I figured I better do this the right way and send it here. The main text of the e-mail was this: I own a Marshall JCM 2000 TSL100 head. The Groove Tubes SAG kits seem to have only 3 pre amp tubes. My Marshall has 4. Will you eventually be selling kits for JCM 2000's? If not, then what would you recommend for each input (rating wise) for that elusive "brown sound? " I know...you probably get a zillion people who want to capture EVH in a tube. Well, make me a zillion and one then.
Also, what GT EL 34 power tube rating would be best?
Thanks for taking the time to read this,
Pasquale
I don't have any outstanding mail at GT that I have not answered, and I did answer this one.

I will send it again, just send your email address back to me at techsupport@groovetubes.com so I can look for my response from there.

Myles
Posted By: DrMr

Re: Feel free to ask Myles - 06/10/02 11:46 PM

Hello!

I have a problem with my low sound.I play down to B on 6-string guitar(Ibanez RG550LTD with EMG-81) and I think that distortion doesn't sound soo deep
.Some people say that you need special amp to generate sounds like 7-string guitar.Should I buy new amp, new cabinet,new tubes or 7-string guitar????!!!
Setup:
CARVIN X-100B TUBE
Power tubes: National Electronics 6CA7/EL 34
Preamb tubes:EuD or Dub(idon'tknow??) ECC83/12AX7A
Cabinet/Box:Marshall 4x12,4x30W, very old box(Is this 8 or 16ohms????)

Thanx

Tomaz
Posted By: myles_rose

Re: Feel free to ask Myles - 06/11/02 12:08 AM

Quote:
Originally posted by DrMr:
Hello!

I have a problem with my low sound.I play down to B on 6-string guitar(Ibanez RG550LTD with EMG-81) and I think that distortion doesn't sound soo deep
.Some people say that you need special amp to generate sounds like 7-string guitar.Should I buy new amp, new cabinet,new tubes or 7-string guitar????!!!
Setup:
CARVIN X-100B TUBE
Power tubes: National Electronics 6CA7/EL 34
Preamb tubes:EuD or Dub(idon'tknow??) ECC83/12AX7A
Cabinet/Box:Marshall 4x12,4x30W, very old box(Is this 8 or 16ohms????)

Thanx

Tomaz
Tomaz,

I don't think you need a special amp, you just need an amp that is set up right most of the time. You amp has a nice power supply, and the National 6CA7's are good tubes, with more vacuum than a EL-34 from the other side of the pond.

First I would have the bias checked. If the tubes are worn or out of match, that would cause all sorts of problems.

If those look okay, then have somebody look at your phase inverter that drives the output section. Chances are this is not a balanced valve, and you may want to procure a balanced valve or as we call it on this side of the pond, a matched phase inverter.

http://www.groovetubes.com/product.cfm?Product_ID=1723

Regards,

Myles
Posted By: dondottcomm

Re: Feel free to ask Myles - 06/11/02 07:26 AM

Hey Myles,I've got a 25/50 Jubilee Marshall 1/2 stack..And when Im playin the sound drops it gets real soft{volume} I know the chord is good ect. What is goin on with it..is it a pre tube or power tube or something like that??Thanks in advance!
Posted By: truls

Re: Feel free to ask Myles - 06/11/02 04:22 PM

I've read with great interest your web page about blueprinting amplifiers, and I have some questions for you, mainly regarding Marshall Valvestate amps.

I use my VS100 for mostly playing rythm metal stuff, and I think my ideal sound can be described as medium/high gain, well defined, thight midrange, scoped off high and moderate lows. To make this possible I use a TC.Electronics parametric equalizer, and the amplified signal is led to a single Vintage 30 in a custom cabinet. For studio applications I run the amp 100% dry into the mix, then adding desired effects afterwards. The eq on the amp is set flat.

Is it possible to by-pass and/or disassemble the eq-pots on the amp??

What happen if I switch the capacitors in the output section to some of a higher or lower capacitance??

Would it add much a difference just changing the capacitors to a high-end metal film type??

What pre-amp tube would you recommend for this application??

Any other suggestions regarding modifications??

Any replies would be much appreciated

Regards

Truls Herland
Posted By: myles_rose

Re: Feel free to ask Myles - 06/11/02 06:09 PM

Quote:
Originally posted by dondottcomm:
Hey Myles,I've got a 25/50 Jubilee Marshall 1/2 stack..And when Im playin the sound drops it gets real soft{volume} I know the chord is good ect. What is goin on with it..is it a pre tube or power tube or something like that??Thanks in advance!
dondottcomm,

First exchange V1 and some other tube, and see if that changes anything. If it does, it is a bad preamp tube. If not, try V2, etc.

This sounds more like a power tube problem though, how old are the output tubes?

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/11/02 06:12 PM

Quote:
Originally posted by truls:
I've read with great interest your web page about blueprinting amplifiers, and I have some questions for you, mainly regarding Marshall Valvestate amps.

I use my VS100 for mostly playing rythm metal stuff, and I think my ideal sound can be described as medium/high gain, well defined, thight midrange, scoped off high and moderate lows. To make this possible I use a TC.Electronics parametric equalizer, and the amplified signal is led to a single Vintage 30 in a custom cabinet. For studio applications I run the amp 100% dry into the mix, then adding desired effects afterwards. The eq on the amp is set flat.

Is it possible to by-pass and/or disassemble the eq-pots on the amp??

What happen if I switch the capacitors in the output section to some of a higher or lower capacitance??

Would it add much a difference just changing the capacitors to a high-end metal film type??

What pre-amp tube would you recommend for this application??

Any other suggestions regarding modifications??

Any replies would be much appreciated

Regards

Truls Herland
Truls,

Anything is possible when it comes to mods. THE MAN for mods is Trace over at Voodoo Amps.

It sounds like the easier thing to do than radically mod an amp that has a solid state output section would be to purchase another amp that has the sound you are after.

Regards,
Posted By: dondottcomm

Re: Feel free to ask Myles - 06/12/02 01:17 AM

They are the original tubes I bet..I got this used in mint shape from a studio..I will give it a shot ..Thank you sir!
Posted By: Dave da Dude

Re: Feel free to ask Myles - 06/12/02 04:11 AM

Myles, more on the Randall Amp (or any amp, I guess).

I figure the two power amp tubes (6L6 or EL34) are one for clean channel, one for dirty channel. How do I know which one is which?

There are four pre amp tubes. What are they for? Should I use different types (i.e clean and dirty channels)?

Sorry for the VERY basic questions, but I'm still a neophite at guitar ELECTRONICS.

Thanks, Dave Phoenix. \:D
Posted By: WDC

Re: Feel free to ask Myles - 06/12/02 09:19 AM

Miles,

Great info. I've been geeking in this forum and on your site. One day I hope to acquire a thimbleful of your knowledge.

Here is my question. I am the owner of a Soldano Supercharger G.T.O. and love the tone. The only thing disappointing about the pedal is the noise when engaged and not playing. Is there anything I can do to alleviate this? From what I've read, this symptom seems to be inherent with all the pedals. I've called Soldano and was told that because this is a tube pedal, the noise is inherited. I guess I'm just waiting for someone to mod this fine pedal to take away some of the noise. Any suggestions?

Sorry that if I'm posting this in the wrong area, but as this pedal runs plate voltage and has 2 12ax7 tubes, I figured I would ask here. Can this pedal be blueprinted?

Thanks in advance,

World Driving Champion
Posted By: hechtdavid

Re: Feel free to ask Myles - 06/12/02 10:00 PM

Hi Myles,

Evil one needs help... I just got a new set of GT 6L6GE's for my 1999 Evil Twin and it now won't bias properly. (I think it may have had this problem before the new tubes.) To get the balance to read correctly, I have to set the bias up around 80mV (too hot for me) - and then the balance adjustment pot is set at the maximum (counterclockwise) range. Any ideas? Time to take it in for a checkup? :rolleyes:
Posted By: myles_rose

Re: Feel free to ask Myles - 06/12/02 10:34 PM

Quote:
Originally posted by dondottcomm:
Hey Myles,I've got a 25/50 Jubilee Marshall 1/2 stack..And when Im playin the sound drops it gets real soft{volume} I know the chord is good ect. What is goin on with it..is it a pre tube or power tube or something like that??Thanks in advance!
dondottcomm ....

it is probably power tubes, but a quick way to check is to swap your preamp tubes around a bit and see if this makes a change.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/12/02 10:41 PM

Quote:
Originally posted by Dave th Dude:
Myles, more on the Randall Amp (or any amp, I guess).

I figure the two power amp tubes (6L6 or EL34) are one for clean channel, one for dirty channel. How do I know which one is which?

There are four pre amp tubes. What are they for? Should I use different types (i.e clean and dirty channels)?

Sorry for the VERY basic questions, but I'm still a neophite at guitar ELECTRONICS.

Thanks, Dave Phoenix. \:D
Dave,

The power tubes always work together ... clean or dirty.

The preamp tubes are generally for your first and second gain stages, and the last preamp tube is the phase inverter that drives the output tubes.

Other preamp tubes are for effects loops, reverb drivers, and vibrato drivers.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/12/02 10:43 PM

Quote:
Originally posted by WDC:
Miles,

Great info. I've been geeking in this forum and on your site. One day I hope to acquire a thimbleful of your knowledge.

Here is my question. I am the owner of a Soldano Supercharger G.T.O. and love the tone. The only thing disappointing about the pedal is the noise when engaged and not playing. Is there anything I can do to alleviate this? From what I've read, this symptom seems to be inherent with all the pedals. I've called Soldano and was told that because this is a tube pedal, the noise is inherited. I guess I'm just waiting for someone to mod this fine pedal to take away some of the noise. Any suggestions?

Sorry that if I'm posting this in the wrong area, but as this pedal runs plate voltage and has 2 12ax7 tubes, I figured I would ask here. Can this pedal be blueprinted?

Thanks in advance,

World Driving Champion
WDC ....

Pedals can be a noise issue. A lot of folks resort to using noise gates. If I could test the tubes in the pedal and see what they were doing, then perhaps we could replace them with ones that are less noisy and have a lower noise floor.

Other than that, its either live with the noise, or the noise gate idea.

Sorry,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/12/02 10:52 PM

Quote:
Originally posted by hechtdavid:
Hi Myles,

Evil one needs help... I just got a new set of GT 6L6GE's for my 1999 Evil Twin and it now won't bias properly. (I think it may have had this problem before the new tubes.) To get the balance to read correctly, I have to set the bias up around 80mV (too hot for me) - and then the balance adjustment pot is set at the maximum (counterclockwise) range. Any ideas? Time to take it in for a checkup? :rolleyes:
80mA is WAY too high. Did you check before the install of the new tubes to see what it was reading? I would think it was too high already.

The Twin is a four output tube variant of the Pro and Concert. On the two tube variants, 30mA is the Fender spec. I would think that 60mA would be your spec, as your bias/balance looks at two of the tubes rather than just one, as the B+ voltage on this amp is the same as the two tube output sections.

If you know somebody with a bias tool, bias probe, bias king, etc., look at just a single tube and see if it is around 30mA.

Make sure your meter is on the left and center test points, red on the left (facing the rear of the amp) and black lead in the center. Then for balance, move the left red probe to the right, leaving the black probe in the center and adjust for 0mA to balance.

Who told you to set this at 80mA? This is pretty wrong. Set it to 60mA, or 0.6 on your meter.

Regards,

Myles
Posted By: hechtdavid

Re: Feel free to ask Myles - 06/13/02 12:31 AM

Hi Myles,

I guess I didn't phase my question very well. Sorry about that.. I CAN set the bias on my evil twin at a lower setting, but at that lower bias setting, I can NOT set the balance properly. The only way to set the balance to 0 is to raise the bias setting to 77mV or more; the balance will be set to 0 - but only at the furthest conterclockwise postion on the pot. BTW, I am using a cheap radio shack DVM, and its worked fine in the past. I'm sure I'm checking bias and balance properly on this amp.

Thanks again for all your generous wisdom.

David
Posted By: Dave da Dude

Re: Feel free to ask Myles - 06/13/02 05:23 PM

QUOTE

Myles, more on the Randall Amp (or any amp, I guess).

I figure the two power amp tubes (6L6 or EL34) are one for clean channel, one for dirty channel. How do I know which one is which?

There are four pre amp tubes. What are they for? Should I use different types (i.e clean and dirty channels)?

Sorry for the VERY basic questions, but I'm still a neophite at guitar ELECTRONICS.

Thanks, Dave Phoenix.
--------------------------------------------------------------------------------

QUOTE

Dave,

The power tubes always work together ... clean or dirty.

The preamp tubes are generally for your first and second gain stages, and the last preamp tube is the phase inverter that drives the output tubes.

Other preamp tubes are for effects loops, reverb drivers, and vibrato drivers.

Myles

Myles,

Is there a way to KNOW which tube is first gain, second gain, phase inverter, etc.? Do all tubes need to be of equal quality and / or output?

Lastly (I, and I imagine, you, hope), I have four tubes, and one is first gain, one second gain, one phase inverter and I have BOTH reverb and effects loop what's going on? That would be five tubes!

I'm just trying to understand if I need to spend the same (high) amount of money on all four tubes. I thought I remembered you saying someplace in this ongoing posting, that a certain tube or tubes was not as important to be high quality.

Thanks for any help, Dave.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/13/02 05:46 PM

Quote:
Originally posted by hechtdavid:
Hi Myles,

I guess I didn't phase my question very well. Sorry about that.. I CAN set the bias on my evil twin at a lower setting, but at that lower bias setting, I can NOT set the balance properly. The only way to set the balance to 0 is to raise the bias setting to 77mV or more; the balance will be set to 0 - but only at the furthest conterclockwise postion on the pot. BTW, I am using a cheap radio shack DVM, and its worked fine in the past. I'm sure I'm checking bias and balance properly on this amp.

Thanks again for all your generous wisdom.

David
Dave,

It sounds like you are doing things properly, and the cheap Radio Shack DVM is not the problem, as those meters work just fine for ohms, volts, current, etc. If the meter makes numbers that change on its display, it is fine and dandy.

Try swapping the tubes around, as to try to isolate a possible bad tube. Shipping damage or other physical damage in not all that uncommon, and one tube may be way out of wack. If you can put your old tubes back in and bias properly, that right there rules out your dvm, amp, procedure, and everything else.

What area are your from? If you are close to Los Angeles, I would be more than happy to look at this for you at no charge.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/13/02 05:52 PM

Quote:
Originally posted by Dave th Dude:
QUOTE

Myles, more on the Randall Amp (or any amp, I guess).

I figure the two power amp tubes (6L6 or EL34) are one for clean channel, one for dirty channel. How do I know which one is which?

There are four pre amp tubes. What are they for? Should I use different types (i.e clean and dirty channels)?

Sorry for the VERY basic questions, but I'm still a neophite at guitar ELECTRONICS.

Thanks, Dave Phoenix.
--------------------------------------------------------------------------------

QUOTE

Dave,

The power tubes always work together ... clean or dirty.

The preamp tubes are generally for your first and second gain stages, and the last preamp tube is the phase inverter that drives the output tubes.

Other preamp tubes are for effects loops, reverb drivers, and vibrato drivers.

Myles

Myles,

Is there a way to KNOW which tube is first gain, second gain, phase inverter, etc.? Do all tubes need to be of equal quality and / or output?

Lastly (I, and I imagine, you, hope), I have four tubes, and one is first gain, one second gain, one phase inverter and I have BOTH reverb and effects loop what's going on? That would be five tubes!

I'm just trying to understand if I need to spend the same (high) amount of money on all four tubes. I thought I remembered you saying someplace in this ongoing posting, that a certain tube or tubes was not as important to be high quality.

Thanks for any help, Dave.
Dave,

On less expensive amps, the reverb or effects loop does not need to be tube driven, it is transistor driven such as the reverb on the Fender Hot Rod series amps.

As far as what tube does what, there is a lot of basic background that you may want to start learning, rather than just get the answers to disjointed parts of a particular area. I would suggest a good tube book. There are a number of them available from: http://www.tubesandmore.com

Myles
Posted By: Dave da Dude

Re: Feel free to ask Myles - 06/13/02 07:26 PM

Myles,

I went to http://www.tubesandmore.com as you recommended and they have QUITE a few books on tube amps.

Are there any that you can recommend for a neophyte like myself that wants to understand how the amp works and what type of tubes to put where?

Dave
Posted By: myles_rose

Re: Feel free to ask Myles - 06/13/02 07:36 PM

Quote:
Originally posted by Dave th Dude:
Myles,

I went to http://www.tubesandmore.com as you recommended and they have QUITE a few books on tube amps.

Are there any that you can recommend for a neophyte like myself that wants to understand how the amp works and what type of tubes to put where?

Dave
The "bible" from most folks point of view, that covers amps, history, theory, mods, has prints, etc is the GT book:

http://www.groovetubes.com/product.cfm?Product_ID=1188

Which I think they also stock.

Myles
Posted By: hechtdavid

Re: Feel free to ask Myles - 06/13/02 08:36 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by hechtdavid:
Hi Myles,

I guess I didn't phase my question very well. Sorry about that.. I CAN set the bias on my evil twin at a lower setting, but at that lower bias setting, I can NOT set the balance properly. The only way to set the balance to 0 is to raise the bias setting to 77mV or more; the balance will be set to 0 - but only at the furthest conterclockwise postion on the pot. BTW, I am using a cheap radio shack DVM, and its worked fine in the past. I'm sure I'm checking bias and balance properly on this amp.

Thanks again for all your generous wisdom.

David
Dave,

It sounds like you are doing things properly, and the cheap Radio Shack DVM is not the problem, as those meters work just fine for ohms, volts, current, etc. If the meter makes numbers that change on its display, it is fine and dandy.

Try swapping the tubes around, as to try to isolate a possible bad tube. Shipping damage or other physical damage in not all that uncommon, and one tube may be way out of wack. If you can put your old tubes back in and bias properly, that right there rules out your dvm, amp, procedure, and everything else.

What area are your from? If you are close to Los Angeles, I would be more than happy to look at this for you at no charge.

Myles
Damn Myles,

You are a generous guy! I wish I was close to LA, but Madison, WI. is a bit far to lug an Evil Twin. If you ever get out this way, I'd like to buy you a few of your favorite libations. But I digress... enough about how great you are. You are, and I'll leave it at that.

The ET: It exhibits the same problems after swapping tubes back to the old Svets, so I don't think its a tube problem. The amp works, but I'm reluctant to use it right now because of the hot bias I have to run just to get the balance to 0. I noticed when I first removed the Svets that the bases were discolored from the heat. I'd rather not run the GT 6L6GE's and burn them up too quickly since they're a bit on the pricey side. I'm assuming its time to take it in to the local amp tech. Any hypotheses?

Thanks again

David
Posted By: myles_rose

Re: Feel free to ask Myles - 06/13/02 11:16 PM

Quote:
Originally posted by hechtdavid:
Quote:
Originally posted by myles111:
Quote:
Originally posted by hechtdavid:
Hi Myles,

I guess I didn't phase my question very well. Sorry about that.. I CAN set the bias on my evil twin at a lower setting, but at that lower bias setting, I can NOT set the balance properly. The only way to set the balance to 0 is to raise the bias setting to 77mV or more; the balance will be set to 0 - but only at the furthest conterclockwise postion on the pot. BTW, I am using a cheap radio shack DVM, and its worked fine in the past. I'm sure I'm checking bias and balance properly on this amp.

Thanks again for all your generous wisdom.

David
Dave,

It sounds like you are doing things properly, and the cheap Radio Shack DVM is not the problem, as those meters work just fine for ohms, volts, current, etc. If the meter makes numbers that change on its display, it is fine and dandy.

Try swapping the tubes around, as to try to isolate a possible bad tube. Shipping damage or other physical damage in not all that uncommon, and one tube may be way out of wack. If you can put your old tubes back in and bias properly, that right there rules out your dvm, amp, procedure, and everything else.

What area are your from? If you are close to Los Angeles, I would be more than happy to look at this for you at no charge.

Myles
Damn Myles,

You are a generous guy! I wish I was close to LA, but Madison, WI. is a bit far to lug an Evil Twin. If you ever get out this way, I'd like to buy you a few of your favorite libations. But I digress... enough about how great you are. You are, and I'll leave it at that.

The ET: It exhibits the same problems after swapping tubes back to the old Svets, so I don't think its a tube problem. The amp works, but I'm reluctant to use it right now because of the hot bias I have to run just to get the balance to 0. I noticed when I first removed the Svets that the bases were discolored from the heat. I'd rather not run the GT 6L6GE's and burn them up too quickly since they're a bit on the pricey side. I'm assuming its time to take it in to the local amp tech. Any hypotheses?

Thanks again

David
David ....

Well, if the same problem shows up with the svets, then its something in the amp.

Perhaps a resistor failed that in in the bias balance circuit. It could be a number of things, but its an area easily trouble shot.

Get it over to Fender shop, as these amps have a pretty long warranty.

Drop me a line to keep me in the loop if you want me to talk to your tech.

Myles
Posted By: sgriff

Re: Feel free to ask Myles - 06/14/02 02:40 AM

Have you had a chance to check out the Rivera Quiana 212 amp? I'm going to check one out this weekend and and wanted to get as much feedback as possible. the vintage /modern function in particular. I'm into vintage stuff but need the flexibility at times.
Posted By: rsf1977

Re: Feel free to ask Myles - 06/14/02 08:41 AM

Hey Myles I got a 12AX7 MPI from Groove Tubes. I play in CGCFAD with alot of gain through my Dual Rec. And I put that tube in and it was like my amp woke up. The sound seemed to come together like a geneal increase in definition. It sounded great, thanks.

Ok I was looking into some NOS tubes the Mullard ECC83 and the Mullard CV4004. Whats the differences between these 2 tubes. And I read this site (http://www.tubeman.com/item9.htm) that the Mullard CV4004 tubes aren't good for guitar amps. Just wanted an opinion?

what would be your opinion on a Matched EH12AX7 vs. a Matched Mullard CV4004 in the phase inter slot in the Dual Rec?
Posted By: kolya

Re: Feel free to ask Myles - 06/14/02 04:34 PM

Hi myles, just joined this forum and you seem too know your s!*t, so please help me with something if you can. I use EMG 89's/85's thru a Boss DS1, usual effects(delay,EQ,etc) and compression at the last stage-currently the tiny POD-thru a Fender Twin Rev with Celestion speakers. Now, with recording things are almost fine, I have near enough the sound I want which is based on a live recording of Living Colour's 'postman' track on their 'Bi' single, released 6/7 years ago-a huge focused sound in all regions with considerable sustain and distortion, Compression creating alot of this I feel-but when I play live or in a rehearsal studio I find it hard to get all the points of the sound! I've come to the conclusion I'm going to have to spend alot of money to get such a sound, or is possible to get it by changing just the amp, just the speakers or simply by buying a great compressor??? I've no idea! Apart maybe by getting in-touch with Vernon Reid, but how would he remember?!!! Thanks
Posted By: myles_rose

Re: Feel free to ask Myles - 06/14/02 06:33 PM

Quote:
Originally posted by sgriff:
Have you had a chance to check out the Rivera Quiana 212 amp? I'm going to check one out this weekend and and wanted to get as much feedback as possible. the vintage /modern function in particular. I'm into vintage stuff but need the flexibility at times.
Check it out ???? ... I play one a few times a month that belongs to a close friend. Prince and his guitarist also are using Quiana's as well as the guitarist for Madonna.

I love the amp, as it has two voicings, British (channel 1) and USA (Channel 2). I love Ch 2, probably because I am OLD ( 52 ) and stuck in the Fender / Marshall / 60's thing. Channel 2 gives you all the Fender sounds, and then for the younger guys, Channel 1 gives you the Marshall thing.

There is boost on each channel two, but somebody my age would never use that \:\)

They are terrific amps, but don't get too distracted by only the sound, look at their construction too, its pretty terrific.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/14/02 10:24 PM

Quote:
Originally posted by rsf1977:
Hey Myles I got a 12AX7 MPI from Groove Tubes. I play in CGCFAD with alot of gain through my Dual Rec. And I put that tube in and it was like my amp woke up. The sound seemed to come together like a geneal increase in definition. It sounded great, thanks.

Ok I was looking into some NOS tubes the Mullard ECC83 and the Mullard CV4004. Whats the differences between these 2 tubes. And I read this site (http://www.tubeman.com/item9.htm) that the Mullard CV4004 tubes aren't good for guitar amps. Just wanted an opinion?

what would be your opinion on a Matched EH12AX7 vs. a Matched Mullard CV4004 in the phase inter slot in the Dual Rec?
rsf1977....

Glad you are happy ... that is the reaction of most folks \:\)

In the phase inverter position, we are looking for current drive and not voltage gain. The PI is not part of the tone generation stage, so the use of an NOS nice Mullard etc, would not be of any sonic benefit, but as a stock off the shelf tube, it may sound great as it is probably closer in the match of the two sides, as back then there was much better QC.

I know a lot of folks using NOS 4004's in the tone generation stages that love them, so I guess its a matter of preference.

Myles
Posted By: rsf1977

Re: Feel free to ask Myles - 06/14/02 10:34 PM

Hey Myles does anyone make Tube carrying cases or anything like that to keep tubes protectected for travel or just to get rid of those boxes
Posted By: myles_rose

Re: Feel free to ask Myles - 06/14/02 10:44 PM

Quote:
Originally posted by kolya:
Hi myles, just joined this forum and you seem too know your s!*t, so please help me with something if you can. I use EMG 89's/85's thru a Boss DS1, usual effects(delay,EQ,etc) and compression at the last stage-currently the tiny POD-thru a Fender Twin Rev with Celestion speakers. Now, with recording things are almost fine, I have near enough the sound I want which is based on a live recording of Living Colour's 'postman' track on their 'Bi' single, released 6/7 years ago-a huge focused sound in all regions with considerable sustain and distortion, Compression creating alot of this I feel-but when I play live or in a rehearsal studio I find it hard to get all the points of the sound! I've come to the conclusion I'm going to have to spend alot of money to get such a sound, or is possible to get it by changing just the amp, just the speakers or simply by buying a great compressor??? I've no idea! Apart maybe by getting in-touch with Vernon Reid, but how would he remember?!!! Thanks
Your biggest problem is effects and pedals in the front end of a Fender.

Guitar pickups are high impedance low output devices, while effects and boxes are low impedance high output devices. This high output causes the preamp stage of most amps to become overloaded, and voila ... there goes your headroom.

A compressor in the front end really helps, and old Dyna Comps work pretty nicely, even the reissue ones work fine.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/14/02 10:46 PM

Quote:
Originally posted by rsf1977:
Hey Myles does anyone make Tube carrying cases or anything like that to keep tubes protectected for travel or just to get rid of those boxes
I am sure somebody must do that, but I don't know who off the top of my head.

I use a shoe box stuffed with paper .... not too high tech....

Some folks I know use foam camera cases.

Myles
Posted By: jetboy

Re: Feel free to ask Myles - 06/17/02 11:56 AM

Quote:
Originally posted by rsf1977:
Hey Myles I got a 12AX7 MPI from Groove Tubes. I play in CGCFAD with alot of gain through my Dual Rec. And I put that tube in and it was like my amp woke up. The sound seemed to come together like a geneal increase in definition. It sounded great, thanks.

Ok I was looking into some NOS tubes the Mullard ECC83 and the Mullard CV4004. Whats the differences between these 2 tubes. And I read this site (http://www.tubeman.com/item9.htm) that the Mullard CV4004 tubes aren't good for guitar amps. Just wanted an opinion?

what would be your opinion on a Matched EH12AX7 vs. a Matched Mullard CV4004 in the phase inter slot in the Dual Rec?
check out http://www.kcanostubes.com or http://www.watfordvalves.com for different opinions of the CV4004.

I'm currently using a CV4004 in V1 of my BadCat Cub and like it very much, V2 is a JAN NOS GE 12AX7WA. I like those better than either the OEM Sovteks or the various JJ ECC 83's although the JJ's are better than the OEMs
Posted By: sgriff

Re: Feel free to ask Myles - 06/17/02 11:19 PM

Sound hole pick up(the one that covers the sound hole entirely) VS. the bar styled pick up. Sound quality and feedback are my concerns. Any comments on these matters? Also does anyone know of an acoustic forum like this one.
Posted By: dave251

Re: Feel free to ask Myles - 06/18/02 04:34 AM

Quote:
Originally posted by sgriff:
Sound hole pick up(the one that covers the sound hole entirely) VS. the bar styled pick up. Sound quality and feedback are my concerns. Any comments on these matters? Also does anyone know of an acoustic forum like this one.
http://www.acousticguitar.com

Tons of info on acoustic pickups and such. JUst use their search engine. Several e-articles too....
Posted By: Dave da Dude

Re: Feel free to ask Myles - 06/18/02 10:26 AM

Is it possible on my Randall Pro-Tube 1000 (has a bias switch for 6L6 or EL34) to set up a parallel rung (of the circuit) for another set of power tubes with a (ON/OFF) switch and an On/Off switch for the exitsing circuit?

This is to switch from one type of tube to another while they are still hot.

Maybe just a pipe drean.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/18/02 06:35 PM

Quote:
Originally posted by Dave th Dude:
Is it possible on my Randall Pro-Tube 1000 (has a bias switch for 6L6 or EL34) to set up a parallel rung (of the circuit) for another set of power tubes with a (ON/OFF) switch and an On/Off switch for the exitsing circuit?

This is to switch from one type of tube to another while they are still hot.

Maybe just a pipe drean.
I think you are making things too hard .... buy a second amp and use an A/B/Y switch.

Myles
Posted By: MMazurek

Re: Feel free to ask Myles - 06/19/02 06:57 PM

Hey Myles, could you recomend a few tube amps for my next purchase. I need them for a home studio to record with. Looking for versatility a wide variety (don't mind getting multiple amps either).

I HAVE: Mesa Dual Rectifier Trem-o-verb; THD Univalve (with a few different tubes); Fender Vibrolux; Mesa 4x12 slant w/vintage 30's; Marshall slant w/greenbacks.

Any ideas for next on the list???
Posted By: myles_rose

Re: Feel free to ask Myles - 06/19/02 08:08 PM

Quote:
Originally posted by MMazurek:
Hey Myles, could you recomend a few tube amps for my next purchase. I need them for a home studio to record with. Looking for versatility a wide variety (don't mind getting multiple amps either).

I HAVE: Mesa Dual Rectifier Trem-o-verb; THD Univalve (with a few different tubes); Fender Vibrolux; Mesa 4x12 slant w/vintage 30's; Marshall slant w/greenbacks.

Any ideas for next on the list???
Talk about a HARD question !

Okay ....

First off, your Trem-o-verb is one of the best amps Mesa ever made. I prefer it to the Dual and Triple rectifier as it does have a nice reverb and tremolo. So ... you are great there already.

The Vibrolux is another winner, and I have a Deluxe Reverb but prefer your amp in ways of my personal taste to mine, so you have that base covered. If you can find a used Groove Tubes STP-G guitar preamp, you can forget the emulator function (although it works great for direct recording) and just plug in a speaker only, as its a great 25 watt amp in its own right, based on the Deluxe (same transformers) but has an extra high gain stage that can be switched in or out (more gain than my Mesa Mk. 1) and can used 6V6's or EL-34's. It also has mid boost, a mid control, presence, and tone controls that really work. Perhaps you can find one on E-bay or something. They were originally $1000+, but I would think you could find one for less than $500.

The Univalve is the most used amp in my studio, and my most borrowed amp by FAR! Just make sure you have a great 6L6, or a few ( I use a Svetlana, 6L6B/5881 Sovtek, GE, a EL-34B (Tesla/JJ), a JJ EL-84 in the THD adaptor, a chinese 6550C in the low and high setting, and the most popular setup is a Electro Harmonix or RCA 6V6 with a JAN Philips 12AX7 in V1 and a JAN NOS 12AT7 in V2.

A good open back 1x12 cabinet .... the Mesa cabinets work great and are not all that expensive.

I also put the Univalve on top of a Fender Deluxe Reverb and use the Jensen P12R in that cabinet.

A THD 2x12 cabinet .... perhaps the nicest cabinet I have ever heard, and much nicer than my Marshall 4x12 cabs, with more outout, more low end and much wider dispersion.

If you want the AC-30 sound in the studio or the Matchless DC-30 sound, stick with the Univalve with the EL-84 JJ tube unless you have tons of cash. The DC-30 is a great amp, but the AC-30's need tender care to keep running at their best.

A nice range of effects is pretty much a must have, but look for a Lexicon PCM-70 used on Ebay, a few Rane SM-26 submixers, etc.

For the true Marshall sound, the reissue 50 watt model 1987 is terrific.

A Fender Twin Reverb is also standard issue in a lot of cases, but their new Pro, which has a single Jensen C-12N, has classis clean black face in channel clean mode, and has less phase cancellation than the 2x12 Twin Reverb, with all its magic .... and a VERY high gain channel to boot. Its a versitile amp that a lot of my clients are into these days. Its one of their new amps, so they do not have the inflated prices of some of the vintage amps and are discounted at places like Guitar Center and Musicians Friend etc.

For the high gain 80's and 90's sound, if you have any money left, a Peavey 5150 or 5150 II.

If you have money left, a Roccaforte Amp. These are "Marshall" amps taken to the highest level that an amp can be taken to, with the finest construction and components that you can imagine. You can also make money by renting these out to performing folks as they are hard to come by and pretty amazing amps. You can see more about these at http://www.roccaforteamps.com I think ... hope I got the URL right.

Then lastly .... Microphones, the most important part of any studio. Dynamics, condensors, FET and tube mics .... you need them all.

Hope that was of some benefit ... all based on personal preference, so feel free to ignore any part of this or all of it \:\)

Myles
Posted By: MMazurek

Re: Feel free to ask Myles - 06/19/02 11:37 PM

Thanks Myles, every word was of some benefit.
(the tube info as much as the amp issue)

I've got mics covered (414's, sm57's, 421's, royer ribbon, 451's, sm81's, atm25, d112, beta52, Lawson tube mic, etc...)

TIME TO GO SHOPPIN!
Posted By: myles_rose

Re: Feel free to ask Myles - 06/19/02 11:47 PM

Quote:
Originally posted by MMazurek:
Thanks Myles, every word was of some benefit.
(the tube info as much as the amp issue)

I've got mics covered (414's, sm57's, 421's, royer ribbon, 451's, sm81's, atm25, d112, beta52, Lawson tube mic, etc...)

TIME TO GO SHOPPIN!
NICE MIC COLLECTION! Well, at least no money there to spend for a while \:\)

By the way, i LOVE 451's ! ... and ribbon mics for vocals are the only way to go if you are as old as I am or want to smooth out somebody who had the style of Janis Joplin!

Good luck with your studio, and if you are close to L.A., or here for a visit, drop me a line and I will be happy to show you around.

Myles
Posted By: hechtdavid

Re: Feel free to ask Myles - 06/20/02 08:54 PM

The ET: It exhibits the same problems after swapping tubes back to the old Svets, so I don't think its a tube problem. The amp works, but I'm reluctant to use it right now because of the hot bias I have to run just to get the balance to 0. I noticed when I first removed the Svets that the bases were discolored from the heat. I'd rather not run the GT 6L6GE's and burn them up too quickly since they're a bit on the pricey side. I'm assuming its time to take it in to the local amp tech. Any hypotheses?

Thanks again

David[/qb][/QUOTE]David ....

Well, if the same problem shows up with the svets, then its something in the amp.

Perhaps a resistor failed that in in the bias balance circuit. It could be a number of things, but its an area easily trouble shot.

Get it over to Fender shop, as these amps have a pretty long warranty.

Drop me a line to keep me in the loop if you want me to talk to your tech.

Myles[/QB][/QUOTE]

Hi Myles,

Here's an up-date on the Evil Twin: I took it to my local Fender amp tech and he checked it out - looking for failed resistors etc.. and said that he could find nothing wrong with it. The amp checked out OK and that it was just a function of the tubes - GT 6L6GE's (GT rating #7). The balance is set properly at 0 but the lowest I can set the bias is around 72mV (with the bias pot fully counterclockwise). Everything seems to be working properly and the amp sounds great. Should I still be concerned that I can't dial in a lower bias, or is this one of those *if it ain't broke, don't fix it* situations?

Thanks again

David
Posted By: myles_rose

Re: Feel free to ask Myles - 06/20/02 10:36 PM

Quote:
Originally posted by Dave th Dude:
Myles,

I went to http://www.tubesandmore.com as you recommended and they have QUITE a few books on tube amps.

Are there any that you can recommend for a neophyte like myself that wants to understand how the amp works and what type of tubes to put where?

Dave
Dave,

The basic standby is our own Aspen Pittman's book, "The Tube Amp Book" .... about three pounds and close to 800 pages !

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/20/02 10:43 PM

Quote:
Originally posted by hechtdavid:
The ET: It exhibits the same problems after swapping tubes back to the old Svets, so I don't think its a tube problem. The amp works, but I'm reluctant to use it right now because of the hot bias I have to run just to get the balance to 0. I noticed when I first removed the Svets that the bases were discolored from the heat. I'd rather not run the GT 6L6GE's and burn them up too quickly since they're a bit on the pricey side. I'm assuming its time to take it in to the local amp tech. Any hypotheses?

Thanks again

David
David ....

Well, if the same problem shows up with the svets, then its something in the amp.

Perhaps a resistor failed that in in the bias balance circuit. It could be a number of things, but its an area easily trouble shot.

Get it over to Fender shop, as these amps have a pretty long warranty.

Drop me a line to keep me in the loop if you want me to talk to your tech.

Myles[/QB][/QUOTE]

Hi Myles,

Here's an up-date on the Evil Twin: I took it to my local Fender amp tech and he checked it out - looking for failed resistors etc.. and said that he could find nothing wrong with it. The amp checked out OK and that it was just a function of the tubes - GT 6L6GE's (GT rating #7). The balance is set properly at 0 but the lowest I can set the bias is around 72mV (with the bias pot fully counterclockwise). Everything seems to be working properly and the amp sounds great. Should I still be concerned that I can't dial in a lower bias, or is this one of those *if it ain't broke, don't fix it* situations?

Thanks again

David[/QB][/QUOTE]

David,

I have a problem with the techs logic.

First off, GE #7's are even well within Fender's rating scale, the same as their mid range "white" tubes.

Second, the GE's are 25 watt tubes, the same as the stock Fender 6L6B/5881 tubes.

If you have the same problem with the Svets and the GT's, I would find a different Fender tech and find out what the problem is. You don't want to eat up a new nice set of tubes because something may be wrong in the bias circuit.

You should be able to bias at 60mA per pair, and then balance the two pairs for 0-2mA of difference.

Regards,

Myles
Posted By: jazzcaster

Re: Feel free to ask Myles - 06/21/02 03:39 AM

Hello Myles,

I have no question, I just wanted to mention how much I appreciate your forum and the professional advice and help that you offer people. You helped me a while back with my new Fender Pro Reverb, and it's been singin' ever since. I often check in here for my "amp educating" and am never disappointed. You have no idea how refreshing it is to read (and get!) some intelligent, accurate technical advice without an overbearing or sarcastic tone. And it requires a lot of talent to communicate those things to the many non-technical people, over the internet, to boot! Your mom should be proud of you!
Posted By: myles_rose

Re: Feel free to ask Myles - 06/21/02 08:42 PM

Quote:
Originally posted by jazzcaster:
Hello Myles,

I have no question, I just wanted to mention how much I appreciate your forum and the professional advice and help that you offer people. You helped me a while back with my new Fender Pro Reverb, and it's been singin' ever since. I often check in here for my "amp educating" and am never disappointed. You have no idea how refreshing it is to read (and get!) some intelligent, accurate technical advice without an overbearing or sarcastic tone. And it requires a lot of talent to communicate those things to the many non-technical people, over the internet, to boot! Your mom should be proud of you!
Thanks for the compliments. As far as my mom, I think she's about 76 now, and I did way too many "weird" things in my past to try to cheer her up now \:\)

By the way .... when you had your Pro Reverb issues, I was working on two of them for a group I was supporting. By the time I was done, I went out and bought one of my own. The clean channel is everything my Twin Reverbs are, but with the single Jensen 12 and the lack of phase cancellation, it is even more impressive with a Rickenbacker 12 string than the Twins. The deeper cabinet is also nicer than the Twin for a lot of things I do.

The gain channel .... too much for me .... more than my Mesa Mk 1 .... I guess I am too old .... but a lot of my under 40 friends love it \:\)

Myles
Posted By: RoughDraft

Re: Feel free to ask Myles - 06/25/02 12:44 AM

Hi Myles,

My dad had some old tube radios and amps around, and I found a few nice preamp tubes in there. There were telefunkens, amperex, and ITT which ive never heard of. I was comparing them , putting each in V1 of my Hellhound. I couldnt hear a major difference, but i think that was due to sucha long time between hearing them. How would i go about changing tubes quickly? But so far the telefunkens sounded smoother than my EH 12ax7, and the amperex had a little more gain. The Hellhound is a single channel amp, what is V2 for? ALso how would i be able to put EL-34s instead of 6l6's in it? Ive found mods for Marhshalls and Fenders, but not for the Hellhound. Ive done mods to other amps before. Thanks

Jon
Posted By: myles_rose

Re: Feel free to ask Myles - 06/25/02 01:28 AM

Quote:
Originally posted by RoughDraft:
Hi Myles,

My dad had some old tube radios and amps around, and I found a few nice preamp tubes in there. There were telefunkens, amperex, and ITT which ive never heard of. I was comparing them , putting each in V1 of my Hellhound. I couldnt hear a major difference, but i think that was due to sucha long time between hearing them. How would i go about changing tubes quickly? But so far the telefunkens sounded smoother than my EH 12ax7, and the amperex had a little more gain. The Hellhound is a single channel amp, what is V2 for? ALso how would i be able to put EL-34s instead of 6l6's in it? Ive found mods for Marhshalls and Fenders, but not for the Hellhound. Ive done mods to other amps before. Thanks

Jon
Jon,

Swapping preamp tubes and hearing the differences is a matter of playing style and touch. If one just plays at the same level or with the same touch, a lot of this is harder to hear. Also, audio memmory is the most difficult and short term. It is best to hit the standby switch and have somebody pull and replace V1.

If you start doing complex chording with hitting of other single or double strings while the chord is still ringing, then you hear the difference pretty nicely. At higher levels, the sound stage and sound image is much wider, as much as 25 degrees with a lot of the NOS tubes, even the moderately priced JAN Philips and GE's .... they just made them better back then .... carbonized nickel plates (look at an RCA 6V6 Blackplate sometime).

Regards,
Posted By: rsf1977

Re: Feel free to ask Myles - 06/26/02 05:12 PM

I tried the new Groove Tube GE6L6 in my dual rectifier the other day and it stsrted humming so I tried switching back to my original Svetlanas that I had no problem with and the hum didn't go away? So I tried flipping the amp between channels, with and without the effects loop, between the tube and silicone diode rectifiers. Nothing removed it. It doesn't really seem to get louder with volume or gain just a constant humming. Any suggestions?
Posted By: RoughDraft

Re: Feel free to ask Myles - 06/26/02 05:55 PM

Thanks Myles.

How can I change my tubes from 6L6's to El-34's. THanks

Jon
Posted By: myles_rose

Re: Feel free to ask Myles - 06/26/02 08:32 PM

Quote:
Originally posted by rsf1977:
I tried the new Groove Tube GE6L6 in my dual rectifier the other day and it stsrted humming so I tried switching back to my original Svetlanas that I had no problem with and the hum didn't go away? So I tried flipping the amp between channels, with and without the effects loop, between the tube and silicone diode rectifiers. Nothing removed it. It doesn't really seem to get louder with volume or gain just a constant humming. Any suggestions?
Try swapping your first preamp tube ( V1 ) with one of the others, and if that does not work, go down the line.

Let me know what happens.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/26/02 08:38 PM

Quote:
Originally posted by RoughDraft:
Thanks Myles.

How can I change my tubes from 6L6's to El-34's. THanks

Jon
Jon ....

In what type of amp?

In some amps the increased heater current requirement of an EL-34 may be an issue.

The output impedance of these two tubes is different, so that will be a bit of a factor, that does not matter to most folks.

Usually, all that is required is a bias adjustment fot the different tubes.

Myles
Posted By: rsf1977

Re: Feel free to ask Myles - 06/27/02 04:22 AM

Ok Itried doing the preamp tubes one by one and still had the same problem so I swapped them all with the original mesa 12AX7s. And the problem seemed to stop. So now I'm gonna go through each EH12AX7 in the V1 to see if I can find the bad one(s), thanks for the help.

Ok power tube question when I flip from standby into the on position I noticed the 6L6s kind of gave off a slight blue kinda glow. I noticed it in the 3 seperate sets of 6L6s I had (Svetlana, EH, and Mesa) is that normal or a problem?

Thanks again!

Quote:
Originally posted by myles111:
Quote:
Originally posted by RoughDraft:
Thanks Myles.

How can I change my tubes from 6L6's to El-34's. THanks

Jon
Jon ....

In what type of amp?

In some amps the increased heater current requirement of an EL-34 may be an issue.

The output impedance of these two tubes is different, so that will be a bit of a factor, that does not matter to most folks.

Usually, all that is required is a bias adjustment fot the different tubes.

Myles
Posted By: rsf1977

Re: Feel free to ask Myles - 06/27/02 04:24 AM

Oh Myles is there anyone in the NYC or New Jersey area that is good at repairing Mesa Boogie Amps, if I should need repairs at some point?
Posted By: RoughDraft

Re: Feel free to ask Myles - 06/27/02 05:21 AM

My amp is a Reverend Hellhound. You may not know much about it since its not too popular. The website states that in order to change to EL-34 there is some kind of mod done. Also the amp is fixed bias.

Jon
Posted By: rsf1977

Re: Feel free to ask Myles - 06/27/02 08:40 AM

Ok there is something wierd going on now.

I put all the original meas 12AX7s back in and everything sounded whisper quiet and perfect. So then I began checking all my EH12AX7s to try and fing the one that was causing the hum. It seems that most of them are humming when I have it set to the clean channel (which is actually the Red Modern channel cloned with the clean switch on, if that means anything). Some are blatant offenders and others have a slight hum to them. I had to try all the tubes one-by-one in the v2 slot cause the v1 only uses one side of the tube. But it seems that they all go whisper quiet except one when it's on channel 2 the high gain channel but on the clean channel is where the problem seems to be hapening.

So what do you think is happening or happened to my preamp tubes. Again this all started happening when I swapped in the Groove Tube GE6L6s (6 rating) could they have over loaded them or something. I have a show this Sat. night and this is starting to stress me out. What should I do.
Posted By: myles_rose

Re: Feel free to ask Myles - 06/27/02 08:57 PM

Quote:
Originally posted by RoughDraft:
My amp is a Reverend Hellhound. You may not know much about it since its not too popular. The website states that in order to change to EL-34 there is some kind of mod done. Also the amp is fixed bias.

Jon
Jon,

I know these amps, they are not too popular because Reverend does not flood the advertising market, and has a home waiting for every amp they make.

The mod is to change the bias, so it would be best to contact Reverend directly and ask them what resistor change(s) need to be done.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/27/02 09:08 PM

Quote:
Originally posted by rsf1977:
Ok there is something wierd going on now.

I put all the original meas 12AX7s back in and everything sounded whisper quiet and perfect. So then I began checking all my EH12AX7s to try and fing the one that was causing the hum. It seems that most of them are humming when I have it set to the clean channel (which is actually the Red Modern channel cloned with the clean switch on, if that means anything). Some are blatant offenders and others have a slight hum to them. I had to try all the tubes one-by-one in the v2 slot cause the v1 only uses one side of the tube. But it seems that they all go whisper quiet except one when it's on channel 2 the high gain channel but on the clean channel is where the problem seems to be hapening.

So what do you think is happening or happened to my preamp tubes. Again this all started happening when I swapped in the Groove Tube GE6L6s (6 rating) could they have over loaded them or something. I have a show this Sat. night and this is starting to stress me out. What should I do.
The output section would not affect your preamp section. The #6 rating is the same as Mesa's top two ratings of their six scale system.

Mesa amps are high front end gain amps, and the most critical tube is V1, as any noise with it, will be sent and amplified down the signal chain.

I would find the MOST quiet of your 12AX7 preamp tubes and put that in V1.

If that is not quiet enough, then let me know. Also let me know again what happend on what channel.

Myles
Posted By: johnny5

Re: Feel free to ask Myles - 06/27/02 10:18 PM

i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

any thoughts or recomendations?
Posted By: myles_rose

Re: Feel free to ask Myles - 06/27/02 10:27 PM

Quote:
Originally posted by johnny5:
i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

any thoughts or recomendations?
johnny5 ...

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

Myles
Posted By: rsf1977

Re: Feel free to ask Myles - 06/27/02 10:30 PM

ok when the buzzing originally started it was equal on both channels with all EH12AX7s in. Then I replaced them with the original stock mesa 12AX7s and it was perfectly fine. Then in the V2 position I started swapping in and out all my EH12AX7s to try to find the bad one(s). So I then started to notice that all of them had a certain hum, one of which was really bad. The only thing was all but one I believe hummed on the clean channel and then was whisper quiet on the high gain channel. It seemed like the clean channel was not liking the EH12AX7s all of a sudden. But no problems with the Mesa 12AX7s in either channel.

Any Ideas?

Oh and I forgot I had aNOS Mullard ECC83 in the V1 position which as I remember now when I switched it back to the EH12AX7 was at the same moment I switched to the GE6L6 could the mullard have screwed the rest of the tubes up some how?
Posted By: Brilliant

Re: Feel free to ask Myles - 06/27/02 10:47 PM

Hey Myles,, do you ever get tired of answering all these questions? I see we keep you pretty busy.
Just in case your answer is no(you don't ever get tired). I am sure you have answered this question many times before, but how do you know when it is time to change a tube? I ask this, because I have a Crate blueVoodoo 6212 combo. I bought it about eight years ago, because it had an awesome clean channel, and a helacious overdrive channel. I would say the clean sounded very Fender, and the dirty definitely had the hot rodded Marshall sound. Back then, it was almost unheard of to get that in one amp. Anyhow, I changed the output tubes on the thing about two years ago, and then the preamp tubes this year, and I just don't hear the Magic in the clean channel that it used to have. It was there before I changed the preamp tubes. Anyhow, now it is very Bright, and I can hear the attack on the strings, it is very painful at loud volumes. I was thinking about going back with the old tubes one by one, until I found one that I liked, but I keep thinking that if they were bad, they were bad, and I don't know if this will help. I don't know much about tubes, so going into a store and asking for a specific one seems kinda scary to me.
Posted By: johnny5

Re: Feel free to ask Myles - 06/27/02 11:38 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by johnny5:
i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

any thoughts or recomendations?
johnny5 ...

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

Myles
myles,
can i just directly replace the EH's with the KT's with out changing anything (considering the amp does not have a bias adjustment))?

thanks for the tip,
john
Posted By: myles_rose

Re: Feel free to ask Myles - 06/28/02 12:21 AM

Quote:
Originally posted by rsf1977:
ok when the buzzing originally started it was equal on both channels with all EH12AX7s in. Then I replaced them with the original stock mesa 12AX7s and it was perfectly fine. Then in the V2 position I started swapping in and out all my EH12AX7s to try to find the bad one(s). So I then started to notice that all of them had a certain hum, one of which was really bad. The only thing was all but one I believe hummed on the clean channel and then was whisper quiet on the high gain channel. It seemed like the clean channel was not liking the EH12AX7s all of a sudden. But no problems with the Mesa 12AX7s in either channel.

Any Ideas?
For now I'd get rid of the EH's.

Where did they come from?

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/28/02 12:24 AM

Quote:
Originally posted by johnny5:
Quote:
Originally posted by myles111:
Quote:
Originally posted by johnny5:
i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

any thoughts or recomendations?
johnny5 ...

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

Myles
myles,
can i just directly replace the EH's with the KT's with out changing anything (considering the amp does not have a bias adjustment))?

thanks for the tip,
john
John,

You should still have the bias checked as the draw of a KT-66HP is different than that of a 6L6EH.

Let me know your B+ voltage and I will be happy to give you a mA range that if you are within, will be fine.

Myles
Posted By: El Glom-o

Re: Feel free to ask Myles - 06/28/02 12:47 AM

Hi, Myles - When wiring a single speaker to an amp, is there a particular way the wires should be attached? What I mean is, does it matter which way the cone moves when the string is first put into motion by the pick or finger? Should the cone move forward as the string is being moved by the pick, or should the forward motion of the cone occur as the string snaps off of the pick? Or does it matter at all? Also, it would matter if one were using multiple amps, the cones should all be moving in the same direction at any one time, so is there a standard as to which speaker terminals the output wires attach to?

Thank you.

El Glom-o
Posted By: rsf1977

Re: Feel free to ask Myles - 06/28/02 01:17 AM

So you think it's just bad tubes at this point and I got them from thetubestore.com

Oh and I forgot I had aNOS Mullard ECC83 in the V1 position which as I remember now when I switched it back to the EH12AX7 was at the same moment I switched to the GE6L6 could the mullard have screwed the rest of the tubes up some how?

Quote:
Originally posted by myles111:
Quote:
Originally posted by rsf1977:
ok when the buzzing originally started it was equal on both channels with all EH12AX7s in. Then I replaced them with the original stock mesa 12AX7s and it was perfectly fine. Then in the V2 position I started swapping in and out all my EH12AX7s to try to find the bad one(s). So I then started to notice that all of them had a certain hum, one of which was really bad. The only thing was all but one I believe hummed on the clean channel and then was whisper quiet on the high gain channel. It seemed like the clean channel was not liking the EH12AX7s all of a sudden. But no problems with the Mesa 12AX7s in either channel.

Any Ideas?
For now I'd get rid of the EH's.

Where did they come from?

Myles
Posted By: RoughDraft

Re: Feel free to ask Myles - 06/28/02 05:27 PM

Hey Myles, thanks for taking the time to answer my questions. Could I just install a bias pot? What would the range have to be to change between these tubes? Would it just go in place of the bias resistor that is in there now?

Jon
Posted By: myles_rose

Re: Feel free to ask Myles - 06/28/02 08:56 PM

Quote:
Originally posted by tundrkys:
Hey Myles,, do you ever get tired of answering all these questions? I see we keep you pretty busy.
Just in case your answer is no(you don't ever get tired). I am sure you have answered this question many times before, but how do you know when it is time to change a tube? I ask this, because I have a Crate blueVoodoo 6212 combo. I bought it about eight years ago, because it had an awesome clean channel, and a helacious overdrive channel. I would say the clean sounded very Fender, and the dirty definitely had the hot rodded Marshall sound. Back then, it was almost unheard of to get that in one amp. Anyhow, I changed the output tubes on the thing about two years ago, and then the preamp tubes this year, and I just don't hear the Magic in the clean channel that it used to have. It was there before I changed the preamp tubes. Anyhow, now it is very Bright, and I can hear the attack on the strings, it is very painful at loud volumes. I was thinking about going back with the old tubes one by one, until I found one that I liked, but I keep thinking that if they were bad, they were bad, and I don't know if this will help. I don't know much about tubes, so going into a store and asking for a specific one seems kinda scary to me.
tundrkys...

I've been answering them for years, over two decades, but in the past it was in person, via mail and email, and phone. Now its also in this forum. Guess I am not sick of it yet \:\)

Your problem is pretty common. Your preamp tubes, when changed, probably had drastically different values than the replacements. Preamp tube are a crap shoot. Tubes of the same type, same vendor, same date code, all are different. They range from -50% below 1960's spec to +40%, with the vast range (80+% of them) below spec by at least 30%.

So .... say you had a tube in V1 that was putting out 1.1mA .... and now its replaced with a "new" tube ... that happens to be 0.7mA. Voila ... you are now down 37% on gain than the "old tube". The transconductance and rise time of the tube will also be very different. The life in the amp is gone.

What I do with my clients, before any work is started, is pull ALL their tubes and throw them on test equipment and tracing equipment. That is how we get a "baseline", and then in the future, we can go up or down on gain, compression and rise time. That's where the SAG came from (Special Applications Group) over at Groove Tubes. I had enough customers that required "graded tubes" that GT asked me to come to work for them in May, and start the SAG.

There is info on this on my personal website and on the GT website in the preamp tube area.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/28/02 09:02 PM

Quote:
Originally posted by El Glom-o:
Hi, Myles - When wiring a single speaker to an amp, is there a particular way the wires should be attached? What I mean is, does it matter which way the cone moves when the string is first put into motion by the pick or finger? Should the cone move forward as the string is being moved by the pick, or should the forward motion of the cone occur as the string snaps off of the pick? Or does it matter at all? Also, it would matter if one were using multiple amps, the cones should all be moving in the same direction at any one time, so is there a standard as to which speaker terminals the output wires attach to?

Thank you.

El Glom-o
Yes, it does matter.

If two speakers are out of phase, there will be phase cancellation.

USA amps are generally set up where the string when hit produces forward speaker movement. Some Marshall amps are the opposite. In live applications I wire the amps (when different) to be in the same phase.

I wire the tip to + and the Sleeve to -

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 06/28/02 09:24 PM

Quote:
Originally posted by RoughDraft:
Hey Myles, thanks for taking the time to answer my questions. Could I just install a bias pot? What would the range have to be to change between these tubes? Would it just go in place of the bias resistor that is in there now?

Jon
Jon,

Installing a bias resistor that is adjustable is easy, fast, and cheap. I'd need to see the print to know what value is in there now, but you can probably just call the factory and ask their advice, as they probably do this as special order for a lot of their customers.
Posted By: steve f

Re: Feel free to ask Myles - 07/01/02 02:12 AM

Myles,

I believe that you have commented on the fact that Marshall amps need to be biased a bit cold to retain the traditional Marshall tone.

I'm going to be biasing a friends JCM 600 (2 EL 34s) shortly. Since I don't know the plate voltage yet I'll just speak to the static dissipation figures. Normally I'd figure on approx 17.5 - 18.0 watts for EL34s. How much below that would you recommend for a Marshall?

I'm thinking of putting in either Svetlana EL34s or JJ E34Ls. I don't know if you have any recommendations as far as Svets vs JJs in master volume Marshalls, but feel free to state your preference if you have one. I'm just looking for good tone over the entire range, with tight bottom end.

Also I think you may have referred to the JJ E34Ls as being a higher powered tube. Would you suggest adjusting upward for this when biasing?
Posted By: dondottcomm

Re: Feel free to ask Myles - 07/01/02 05:39 AM

Quote:
Originally posted by myles111:
Quote:
Originally posted by dondottcomm:
Hey Myles,I've got a 25/50 Jubilee Marshall 1/2 stack..And when Im playin the sound drops it gets real soft{volume} I know the chord is good ect. What is goin on with it..is it a pre tube or power tube or something like that??Thanks in advance!
dondottcomm,

First exchange V1 and some other tube, and see if that changes anything. If it does, it is a bad preamp tube. If not, try V2, etc.

This sounds more like a power tube problem though, how old are the output tubes?

Myles
Myles Thanks, it was a bad Pre tube..I changed all three out..Works perfect now..Just wanted to say thank you!

Don
Posted By: myles_rose

Re: Feel free to ask Myles - 07/01/02 09:39 PM

Quote:
Originally posted by steve f:
Myles,

I believe that you have commented on the fact that Marshall amps need to be biased a bit cold to retain the traditional Marshall tone.

I'm going to be biasing a friends JCM 600 (2 EL 34s) shortly. Since I don't know the plate voltage yet I'll just speak to the static dissipation figures. Normally I'd figure on approx 17.5 - 18.0 watts for EL34s. How much below that would you recommend for a Marshall?

I'm thinking of putting in either Svetlana EL34s or JJ E34Ls. I don't know if you have any recommendations as far as Svets vs JJs in master volume Marshalls, but feel free to state your preference if you have one. I'm just looking for good tone over the entire range, with tight bottom end.

Also I think you may have referred to the JJ E34Ls as being a higher powered tube. Would you suggest adjusting upward for this when biasing?
Steve,

Marshall's are a bit different in some regards to a lot of other amps as setting by idle dissapation does not always yield the best results. Typically I set up Marshall amps using a scope and a 1000 Hz signal, so when the amp is set to about "7", there is still a hint of crossover notch.

The EL-34's are 25 watt tubes, therefore using 50% ID as a guideline, we are talking 12 1/2 watts. As far as mA, with 450 B+ volts, this is about 28mA.

The E34LS is a 30 watt tube, and a lot stronger than the other EL-34's. It needs a different bias.... 33mA in the same example with the same B+ as above.

The Svetlana is the closest to the original Siemens tubes from the response curves of the currently made tubes, more linear than the LS, but not as strong .... boils down to personal preference I guess.

I like the Svets and the LS (JJ) for different reasons, but they are both very nice tubes. In my own Marshall amps I have used both, but being an old guy, I prefer the Svets a lot of the time as in a low range, I can get a 50 watt amp to breakup earlier and at a lower level. The LS's (JJ's) in a model 1987 will produce well over 70 watts in most Marshall 1987's, so the Svets in a rating of #3's for me, help quiet things down a bit .... but then again, most younger folks prefer the JJ's when you want to go for broke.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/01/02 09:41 PM

Quote:
Originally posted by dondottcomm:
Quote:
Originally posted by myles111:
Quote:
Originally posted by dondottcomm:
Hey Myles,I've got a 25/50 Jubilee Marshall 1/2 stack..And when Im playin the sound drops it gets real soft{volume} I know the chord is good ect. What is goin on with it..is it a pre tube or power tube or something like that??Thanks in advance!
dondottcomm,

First exchange V1 and some other tube, and see if that changes anything. If it does, it is a bad preamp tube. If not, try V2, etc.

This sounds more like a power tube problem though, how old are the output tubes?

Myles
Myles Thanks, it was a bad Pre tube..I changed all three out..Works perfect now..Just wanted to say thank you!

Don
Don ... you are more than welcome....

Myles
Posted By: mikey_dup1

Re: Feel free to ask Myles - 07/02/02 10:26 PM

Miles,
I am working with a Fender DeVille 410. I would like to get some more gain and smooth distortion. It hs quite a bit of harsh bark now. I've got a lot of headroom and this thing is so loud I rarely have enough space to open it up. I recently had Svetlana 6L6's put in and I mistakingly told them to match them for a lot of headroom. Had just got the amp. Can I offset it with some preamp tubes and if so what would they be (without breaking the bank). God Bless.
Posted By: myles_rose

Re: Feel free to ask Myles - 07/02/02 11:42 PM

Quote:
Originally posted by mikey:
Miles,
I am working with a Fender DeVille 410. I would like to get some more gain and smooth distortion. It hs quite a bit of harsh bark now. I've got a lot of headroom and this thing is so loud I rarely have enough space to open it up. I recently had Svetlana 6L6's put in and I mistakingly told them to match them for a lot of headroom. Had just got the amp. Can I offset it with some preamp tubes and if so what would they be (without breaking the bank). God Bless.
Mikey,

The first thing you may want to try is a 12AX7C in your V1 position. These are a bit warmer and darker than the probable Sovtek 12AX7WA that is stock in these amps.

There are a lot of folks that have these ... and most any guitar store that has tubes should have these in stock.

If you are not concerned about the random nature of preamp tubes, any "new tooling" 12AX7C will be fine. You can get those from a number of folks on my website from the links below on my website.

Info on the GT 12AX7C is at:
http://www.groovetubes.com/product.cfm?Product_ID=1158

If you want a 12AX7C with a specific character and rise time, then it's going to cost a lot more for a curve traced tube.

Info on this tube is at:
http://www.groovetubes.com/product.cfm?Product_ID=1730 but these are not stocked items, they are specifically made per request.

For a start though, you should be able to get a decent 12AX7C for under $15 at the most.

Myles
Posted By: Oscar

Re: Feel free to ask Myles - 07/05/02 09:32 PM

Myles,

I have a '98 HotRod DeLuxe. When playing on the clean channel, on certain chords and notes a glassy, rattling sound comes out of the amp that's very annoying. This does not occur on the overdrive channels. It really sounds as if a small part in a tube is rattling, so I replaced the preamp tubes one-at-a-time with a NOS '60's Telefunken 12AX7 but the problem remained. I turned up the amp with no guitar connected and softly tapped the 6L6's with the back of a pencil - no weird noises. This leads me to conclude that the tubes are OK. I also disconnected the reverb tank - the problem persisted. I can't think of anything else to do. Do you have any suggestions? Thanks!

Regards,
Oscar
Posted By: Jamesian

Re: Feel free to ask Myles - 07/08/02 02:59 AM

Myles, I have a mid-80's 60 watt Boogie Mk III head run through a Marshall cab. It is an absolute tone-machine for recording and I have no complaints, but I would like to expand its range if possible. I'm looking for: 1. that warm,early Fender,soft-attack tone (in the clean channel). 2. more of a British voice (Vox/Hi-Watt). Is there any kind of tube swap that will give me either of these changes in tone and response? Thanks. J.
Posted By: myles_rose

Re: Feel free to ask Myles - 07/08/02 10:25 PM

Quote:
Originally posted by Oscar:
Myles,

I have a '98 HotRod DeLuxe. When playing on the clean channel, on certain chords and notes a glassy, rattling sound comes out of the amp that's very annoying. This does not occur on the overdrive channels. It really sounds as if a small part in a tube is rattling, so I replaced the preamp tubes one-at-a-time with a NOS '60's Telefunken 12AX7 but the problem remained. I turned up the amp with no guitar connected and softly tapped the 6L6's with the back of a pencil - no weird noises. This leads me to conclude that the tubes are OK. I also disconnected the reverb tank - the problem persisted. I can't think of anything else to do. Do you have any suggestions? Thanks!

Regards,
Oscar
Oscar,

I wish I could get the amp on a scope. You have done all the normal things.

The issue with the Hot Rod Deluxe/Deville series, is the ribbon interconnects and the design of the overdrive circuit and reverb drive circuit are all solid state generated. There are a few tuning tricks to getting rid of the interactions that come up, but I'd need to get the amp on the bench.

Sorry ....

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/09/02 12:21 AM

Quote:
Originally posted by Jamesian:
Myles, I have a mid-80's 60 watt Boogie Mk III head run through a Marshall cab. It is an absolute tone-machine for recording and I have no complaints, but I would like to expand its range if possible. I'm looking for: 1. that warm,early Fender,soft-attack tone (in the clean channel). 2. more of a British voice (Vox/Hi-Watt). Is there any kind of tube swap that will give me either of these changes in tone and response? Thanks. J.
J...

This is a real common request. My personal buisness clients had me make kits up for them for years, so when I came to GT in May of this year, part of what was on my list was to do the same thing here. I finally got around to it:

http://www.groovetubes.com/product.cfm?Product_ID=1768

Myles
Posted By: johnny5

Re: Feel free to ask Myles - 07/10/02 02:46 AM

Quote:
Originally posted by myles111:
Quote:
Originally posted by RoughDraft:
Hey Myles, thanks for taking the time to answer my questions. Could I just install a bias pot? What would the range have to be to change between these tubes? Would it just go in place of the bias resistor that is in there now?

Jon
Jon,

Installing a bias resistor that is adjustable is easy, fast, and cheap. I'd need to see the print to know what value is in there now, but you can probably just call the factory and ask their advice, as they probably do this as special order for a lot of their customers.
Jon and/or myles,
i also have the hellhound and am curious in your results / sounds. would be neat to be able to use 6L6's OR EL34's though!

let us know!
Posted By: myles_rose

Re: Feel free to ask Myles - 07/10/02 09:37 PM

Quote:
Originally posted by johnny5:
Quote:
Originally posted by myles111:
Quote:
Originally posted by RoughDraft:
Hey Myles, thanks for taking the time to answer my questions. Could I just install a bias pot? What would the range have to be to change between these tubes? Would it just go in place of the bias resistor that is in there now?

Jon
Jon,

Installing a bias resistor that is adjustable is easy, fast, and cheap. I'd need to see the print to know what value is in there now, but you can probably just call the factory and ask their advice, as they probably do this as special order for a lot of their customers.
Jon and/or myles,
i also have the hellhound and am curious in your results / sounds. would be neat to be able to use 6L6's OR EL34's though!

let us know!
Jon,

You can also modify the bias circuit with a switch and resistor network to all the use of 6L6's or EL-34's as some amps do, but I'd rather use a wider range adjustable system than a switch, as 6L6's are very different in bias (from about -49 volts to - 62 volts .... and a lot of older Fender's were factory set at -52 as a matter of info I guess for you folks), which can be way far from optimum.

In the case of EL-34's, it can range from about -45 to -50, and with 6550's -63 to -68 or so (which is why the 70's Marshalls initially shipped with 6550's didn't even have the bias adjusted, so they were way off, and that is why people said "the old Marshalls were better than the new ones" back then, when in actuality, they were made a bit better. Once the USA Marshalls that were shipped with 6550's that were correctly biased, they were a lot better sounding than the 6550 versions with the wrong bias.

If you look at an E34Ls and a 6L6S, the bias is very close. The 6L6S is more of a EL-34 than a 6L6 when it comes to bias, and has a sound to me that is half way between an EL-34 and 6L6. Its a great tube in Mesa amps for me.

The best bet is always to be able to properly adjust an amp for top performance. The ones that are not done that way are the vintage amps that sound good, but don't have "the magic" that some amps have that folks just figure they are just one of the rare examples.

If you look at the +/- 20% parts, and get those closer, look at transformers, tubes, voltages, etc., any amp that has the magic can have its settings applied to any amp in the same type and model, and greatly improve the "average" amp.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/18/02 08:15 PM

Bumping for new forum folks
Posted By: johnny5

Re: Feel free to ask Myles - 07/24/02 01:52 AM

Posted By: johnny5

Re: Feel free to ask Myles - 07/24/02 02:07 AM

Quote:
Originally posted by myles111:
Quote:
Originally posted by johnny5:
i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

any thoughts or recomendations?
johnny5 ...

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

Myles
why are the KT-66HP's your favorate in the hellhound? i'm looking for good rock / blues / rockin blues tone (FYI).
Posted By: myles_rose

Re: Feel free to ask Myles - 07/24/02 05:48 PM

Posted By: myles_rose

Re: Feel free to ask Myles - 07/24/02 05:55 PM

Quote:
Originally posted by johnny5:
Quote:
Originally posted by myles111:
Quote:
Originally posted by johnny5:
i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

any thoughts or recomendations?
johnny5 ...

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

Myles
why are the KT-66HP's your favorate in the hellhound? i'm looking for good rock / blues / rockin blues tone (FYI).
Its just personal preference.

Myles
Posted By: Dave da Dude

Re: Feel free to ask Myles - 07/24/02 08:16 PM

Myles, This two questions.

1) What is bias? I'm an (Mechanical) Engineer and I may be a little weak on this, but as far as I know the only three things that matter to an electrical device are Volts, Amps and Resistance. Which is bias? Are you (generically/plurally) adjusting the resistance to make the voltage or amperage correct?

If so, what do you look for. I have a wealth of equipment available to me and I'm fairly good at this kind of "stuff". Can I do it myself?

2)This is a repeat and I already know that your opinion is it's too complicated. BUT, if I want to do it anyway, is there any HARM in switching "hot" tubes (via circuit) to change from EL34's to 6L6's?

Thanks for any help you can offer. You're a wealth of knowledge and feel very fortunate to find someone as knowledgeable as you that is willing to help ignoramuses like me that need help.

Thanks, Dave.
Posted By: myles_rose

Re: Feel free to ask Myles - 07/24/02 08:58 PM

Quote:
Originally posted by Dave th Dude:
Myles, This two questions.

1) What is bias? I'm an (Mechanical) Engineer and I may be a little weak on this, but as far as I know the only three things that matter to an electrical device are Volts, Amps and Resistance. Which is bias? Are you (generically/plurally) adjusting the resistance to make the voltage or amperage correct?

If so, what do you look for. I have a wealth of equipment available to me and I'm fairly good at this kind of "stuff". Can I do it myself?

2)This is a repeat and I already know that your opinion is it's too complicated. BUT, if I want to do it anyway, is there any HARM in switching "hot" tubes (via circuit) to change from EL34's to 6L6's?

Thanks for any help you can offer. You're a wealth of knowledge and feel very fortunate to find someone as knowledgeable as you that is willing to help ignoramuses like me that need help.

Thanks, Dave.
Dave,

Take a look on my website.

Myles
Posted By: kirschke

Re: Feel free to ask Myles - 07/24/02 10:40 PM

Hi Miles,
what Bias resp. Anode current-mA-do You recommend
with a B+ 435 V.
Does a PT-Fender 022798 4A/6,3V- take the extra
heater current? I have 2 12AX7 and 2 12AT 7 in the
preamp.
What did Marshall use in his original Bluesbreaker
combo?
Thanks,
Wolfgang
Posted By: kirschke

Re: Feel free to ask Myles - 07/24/02 10:41 PM

I forgot I mean KT66 tubes,
Sorry,
Wolfgang
Posted By: steve f

Re: Feel free to ask Myles - 07/25/02 02:22 AM

Myles,

Are the Groove Tubes KT-66HP considered 25watt or 30watt tubes (or something in between)? Just wondering about biasing them. I couldn't pass them up at the reduced price GT has them at.
Posted By: Razor

Re: Feel free to ask Myles - 07/25/02 09:11 AM

I have recently purchased a mesa boogie road king. The tubes are whatever
>are stock in it.
>
>I have two groove tubes ahh.umm el 34? Well the tubes that would go into a
>mesa boogie nomad 55. I bought the tubes for that amp but never used them.
>Can I use these tubes in the mesa and will that help this lack luster amp.?
>
>I would be happpy to replace the tubes in this amp if you could advise me
>as
>to what the best solution is and where I can puchase them/what tubes?
>
>I also wish to get a 'vox ac 30 sound", and I doubt I can out of this amp?
>Can I with the univalve? This is another tasty amp I would like, but I dont
>think I can get the vox chimy sound. I have to play at lower levels, but I
>dont play live and I do mostly recording at home. Any other amps? Someone
>said a mesa boogie blue angel with a 30 watt speaker to replace the stock
>90
>watt..or laney amps., not sure of what model..
>
>Any thoughts/
>
>THe tubes for the mesa are my main question to you cause I know this is
>your
>expertise. But any help on the others would be helpful.
>thankyou
ps what do you think of top hat royals...Im thinking of getting the new ac 30 tbx HW..but way more money
Posted By: RockNRoll

Re: Feel free to ask Myles - 07/25/02 04:04 PM

Hi Myles, I put up this post but couldn't get a response...i dunno if I'm asking the right question. Appreciate any advice you can offer.

I'm looking for a volume pedal and was wondering if getting a mono pedal or stereo was better? I use mainly clean and distortion sounds perhaps with some reverb, chorus, and delay...Would getting a stereo pedal offer more versatility if I decide to get a stereo effect down the road? I've heard about some power loss when using primarily mono effects with a stereo volume pedal...or is it that noticeable? I was thinking something like the Boss FV50H which is a stereo pedal which seemed to get some good user reviews and it seems a little more convenient to carry compared to those huge heavy duty volume pedals...Not sure which way to go..could use some tips..thanks!
--------------------------------------------------------------------------------
Posted By: myles_rose

Re: Feel free to ask Myles - 07/25/02 07:20 PM

Quote:
Originally posted by kirschke:
Hi Miles,
what Bias resp. Anode current-mA-do You recommend
with a B+ 435 V.
Does a PT-Fender 022798 4A/6,3V- take the extra
heater current? I have 2 12AX7 and 2 12AT 7 in the
preamp.
What did Marshall use in his original Bluesbreaker
combo?
Thanks,
Wolfgang
For the KT-66 with your plate voltage, the idle dissapation would be as follows:

50% 60% 70%

29 34 40 mA

I like 30-32 or so myself.

The original Bluesbreaker used 3 eCC83's and
two KT-66's.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/25/02 07:23 PM

Quote:
Originally posted by steve f:
Myles,

Are the Groove Tubes KT-66HP considered 25watt or 30watt tubes (or something in between)? Just wondering about biasing them. I couldn't pass them up at the reduced price GT has them at.
Steve,

They are 25 watters, as the original GEC's.

The price was $85.00 a duet a few weeks ago, so yes, they are cheaper now which is nice. The reason was we made a lot more so the price per tube dropped. The non-HP version is actually more now, which is sort of strange I guess. I don't know if GT will even have all that many request in the future for those since they are more money and handle about 50 less plate volts.

Myles

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/25/02 07:32 PM

Quote:
Originally posted by Razor:
I have recently purchased a mesa boogie road king. The tubes are whatever
>are stock in it.
>
>I have two groove tubes ahh.umm el 34? Well the tubes that would go into a
>mesa boogie nomad 55. I bought the tubes for that amp but never used them.
>Can I use these tubes in the mesa and will that help this lack luster amp.?
>
>I would be happpy to replace the tubes in this amp if you could advise me
>as
>to what the best solution is and where I can puchase them/what tubes?
>
>I also wish to get a 'vox ac 30 sound", and I doubt I can out of this amp?
>Can I with the univalve? This is another tasty amp I would like, but I dont
>think I can get the vox chimy sound. I have to play at lower levels, but I
>dont play live and I do mostly recording at home. Any other amps? Someone
>said a mesa boogie blue angel with a 30 watt speaker to replace the stock
>90
>watt..or laney amps., not sure of what model..
>
>Any thoughts/
>
>THe tubes for the mesa are my main question to you cause I know this is
>your
>expertise. But any help on the others would be helpful.
>thankyou
ps what do you think of top hat royals...Im thinking of getting the new ac 30 tbx HW..but way more money
Razor,

Road King .... more knobs and switches on the back panel alone and any three of my amps have on their front panels ! \:\)

The stock tubes are Russian or Chinese. If you tell me the STR number on the tube I can tell you. Also let me know the color code on the small label on the base.

There are a lot of different Groove Tubes EL-34 tubes. I would need to know which.

For EL-34 tubes, I prefer the:

http://www.groovetubes.com/product.cfm?Product_ID=1690

Your amp will never sound like an AC-30. Very different amps and circuits.

The Univalve can get the VOX sound with an ECC83 in V1, an ECC83 or 12AX7 in V2, and an EL-84 in the adaptor that THD has for the amp.

The Blue Angel in 33 watt mode (using its EL-84's) is very different than an AC-30. The tone stacks of the two amps are not even close.

The Top Hat amps are very nice.

The AC-30 reissues are fine too, but still one of the most difficult amps in the world to work on physically.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/25/02 07:37 PM

Quote:
Originally posted by RockNRoll:
Hi Myles, I put up this post but couldn't get a response...i dunno if I'm asking the right question. Appreciate any advice you can offer.

I'm looking for a volume pedal and was wondering if getting a mono pedal or stereo was better? I use mainly clean and distortion sounds perhaps with some reverb, chorus, and delay...Would getting a stereo pedal offer more versatility if I decide to get a stereo effect down the road? I've heard about some power loss when using primarily mono effects with a stereo volume pedal...or is it that noticeable? I was thinking something like the Boss FV50H which is a stereo pedal which seemed to get some good user reviews and it seems a little more convenient to carry compared to those huge heavy duty volume pedals...Not sure which way to go..could use some tips..thanks!
--------------------------------------------------------------------------------
RockNRoll....

The choice of a stereo or mono pedal is pretty simple ... are you going to run into a stereo rack or not.

They both work well, more of a choice by model of features, price, feel, and range of travel.

Myles
Posted By: Razor

Re: Feel free to ask Myles - 07/26/02 06:40 AM

Myles.

Re Road king/Info you need

In my Road King , this is what I found, and remember, I know very little about Tubes.

The EL 34 has a mesa engineering logo on them, and say
"Handtested in Amplifiers and computer Matched. At the bottom of the tube on a silver tabbed area it only says " 49 AC GRN "
Thats all that are on that tube that I can see.

Now, for the 6aL6 GC tube.
Again it says 'mesa engineering on it" and a "STR 430" on the tube itself. On the bottom silver area tab, i see a 47 AC gry. This is the same for all these four tubes.

Now the 5U4G tubes, which there are two, have again "mesa engineering' on them and abosolutely nothing else. The base of this tube is Brown and I can see scratched on the top metal place "inside' the tube itself, just below the glass on the very top of the tube, 10-10, if thats of any use.

Curious, I notice on each and every tube, a man made 'scratch' about maybe 1/4 or so inch long at the base of each tube. No real reason but they are there..

I do not see any color label other than the gry or silver that the writing is on ie '49 ac grn'etc.

The tubes I have in my possession which I have never used, bought for another amp thus sold are..
GT 34Ls. A the bottom they have a 'performance 4" and matched with a DDK on the tube, written in handwright on both.

What do you think of this amp myles. I am a home recordist, probably will never play live, but who knows.

I have bid and won a univalve on ebay.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=893835163

The seller is unhappy now to sell it but he will sell it to me, but wishes also to not, if i so choose to walk away.
I'm looking for a 'vox' sound, for one thing. I like the idea of some good 'aerosmith' sounds too, edgy, with a bite to it..aka Tragically hip , will this amp provide this? and more?

Also looking at bidding on a top hat for the vox sound (tom petty ish or the knack sound), but if I can get mostly this sound with the univavle, great, I'll stop there. How do you feel about the univalve?

Last thing myles. Komet amps. I heard the samples on the net. Sounds amazing. I feel perhaps the road king is not up to this standard of the komet , how do you feel? I could sell the king and get a komet I guess is where Im headed with this.

Natuarlly only I can decide and my ears, but Id be very happy to hear your opinions. Im not into 'creed' or dark sounds, I love the beatles later stuff, tragically hip, queen, aerosmith, eagles, so quite diverse.
As a home recordist I need the most options with the least amount of complexity involved. I do have a pod btw...and thats ...well Im not sure what to say about that.

THanks myles, if I can supply you with anymore data please ask. If keeping the road king is smart, I will. btw..its RK 169 serial number.

THanks
Posted By: myles_rose

Re: Feel free to ask Myles - 07/26/02 09:46 PM

Quote:
Originally posted by Razor:
Myles.

Re Road king/Info you need

In my Road King , this is what I found, and remember, I know very little about Tubes.

The EL 34 has a mesa engineering logo on them, and say
"Handtested in Amplifiers and computer Matched. At the bottom of the tube on a silver tabbed area it only says " 49 AC GRN "
Thats all that are on that tube that I can see.

Now, for the 6aL6 GC tube.
Again it says 'mesa engineering on it" and a "STR 430" on the tube itself. On the bottom silver area tab, i see a 47 AC gry. This is the same for all these four tubes.

Now the 5U4G tubes, which there are two, have again "mesa engineering' on them and abosolutely nothing else. The base of this tube is Brown and I can see scratched on the top metal place "inside' the tube itself, just below the glass on the very top of the tube, 10-10, if thats of any use.

Curious, I notice on each and every tube, a man made 'scratch' about maybe 1/4 or so inch long at the base of each tube. No real reason but they are there..

I do not see any color label other than the gry or silver that the writing is on ie '49 ac grn'etc.

The tubes I have in my possession which I have never used, bought for another amp thus sold are..
GT 34Ls. A the bottom they have a 'performance 4" and matched with a DDK on the tube, written in handwright on both.

What do you think of this amp myles. I am a home recordist, probably will never play live, but who knows.

I have bid and won a univalve on ebay.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=893835163

The seller is unhappy now to sell it but he will sell it to me, but wishes also to not, if i so choose to walk away.
I'm looking for a 'vox' sound, for one thing. I like the idea of some good 'aerosmith' sounds too, edgy, with a bite to it..aka Tragically hip , will this amp provide this? and more?

Also looking at bidding on a top hat for the vox sound (tom petty ish or the knack sound), but if I can get mostly this sound with the univavle, great, I'll stop there. How do you feel about the univalve?

Last thing myles. Komet amps. I heard the samples on the net. Sounds amazing. I feel perhaps the road king is not up to this standard of the komet , how do you feel? I could sell the king and get a komet I guess is where Im headed with this.

Natuarlly only I can decide and my ears, but Id be very happy to hear your opinions. Im not into 'creed' or dark sounds, I love the beatles later stuff, tragically hip, queen, aerosmith, eagles, so quite diverse.
As a home recordist I need the most options with the least amount of complexity involved. I do have a pod btw...and thats ...well Im not sure what to say about that.

THanks myles, if I can supply you with anymore data please ask. If keeping the road king is smart, I will. btw..its RK 169 serial number.

THanks
Razor

On your EL-34's they are hard to say without seeing the tube. They are probably either Chinese or Sovtek. They are in the same range as a GT #5 for the most part.

The 6L6 is a Sovtek 6L6B / WXT tube. Its a fine sturdy tube. The 454's were the Svetlana upgrade, but are more expensive for Mesa to buy, so they don't use as many of these.

My favorite tube in these amps are the 6L6S, or JJ 6L6.

Your Rectifiers. These are Chinese rectifiers, with a very high initial failure rate. BUT ... if they have worked for ten hours, then chances are they will hang in there for a while.

The scratch is from their testing, either to index the tube when the paint on their logo, or to perhaps say the tube went through their testing. It is fine. Mesa does very nice testing on their power tubes by the way.

The GT E34Ls that you have in #4 will work great to replace your current ones in there. The DDk are the initials of who tested the tubes. They will give you about 20% more output and headroom also, then the stock EL34 tubes.

On the THD ... the photos are gone, but for $710 its great, especially with the acessories.

Frankly, to be blunt and totally confused, I can never understand why anybody that ever bought a Univalve would ever sell it. It boggles me to try to figure that out unless it was financial issues where they were selling everything. If I ever had to raise money by selling things, my UV would go as perhaps the last item. If its a matter of not liking the tone, then that is a matter of pilot error to my thinking. Its a great recording too, live tool for more gigs than most give it credit for (15 watts class A is a LOT louder than my 25 watt Deluxe Reverb, and with a 1x12 open back cabinet, it is louder than my Marshall JTM-45 with it's 4x12 closed back cab.

The accessories that were included:

Celestion Vintage 30 1x12 speaker cabinet (8 ohm, closed back, mfg by Crate)

This will work fine, but if you can open the back, try that too. Vintage 30's are great with the UV.

THD Yellowjacket w/ JJ EL84 tube (Vox AC30 sound)

.... You bet ... but also BOTH versions ... Brian May AC-30/4 and the more common AC-30/6 (top boost). The tone controls on the UV are much more effective, but you can dial the amp in to be as AC-30 as you want. This is something the UV does MUCH better than our GT version of this type of amp. Those adaptors are worth about $50.00. It is ONLY for the Univalve, don't try to plug this in to a class A/B amp. THD had other Yellow Jackets for that.

6L6GC Mesa Boogie Tube (Fender/Boogie sound)
... a fair tube .... get a nice 6L6 ... maybe an NOS since you need only one.

Svetlana EL34 tube (Marshall sound)
This will be fine.

Electro Harmonix EH12AX7 preamp tubes (2)
Good, but get a 12AT7 for V2, and swap them around a little. An ECC83 and 7025 are also good in V1. With your EL-84, use an ECC83 in V1.

Manual, speaker cable, power cable.
Manual? Mine did not even have a manual, but its when they first started making them I guess.

The seller is unhappy now to sell it but he will sell it to me, but wishes also to not, if i so choose to walk away.

NO .... talk to him, keep him happy ... tell him all the other great things he can buy with that like a Fender Deluxe Reverb reissue ... or an original Silver Face Fender whatever (still great deals). I guess after thinking about it he might feel he made a bit of a mistake, but even if he sold that setup for $1200, it would still be a mistake. It's not the price ... it was a good and fair deal for each of you .... its more of like that credit card commercial .... sort of ...

"Marshall Plexi 1966 .... $2500 ...... Fender Tweed magic amp ..... $3500 ....... THD Univalve .... priceless"

Before you buy anything else, including the Top Hat (great amps by the way), play with the THD Univalve for 30 days. I still learn things about mine continually. You may find you need a lot less amps than you were using.

Ahhhh .... put a NOS 6L6 in there ... a NOS 12AX7 in V1, a NOS 12AT7 in V2, the high gain input but the volume turned to maybe 9 '0clock ... not much at all ... plug in a solid body P-90 guitar, and play the BLUES. (sorry ... off on a tangent)

Komet .... also very good amps.

The Road King is nowhere close to these other amps in constrution or basic tone, but you cannot compare a high volume production amp to these others, its not fair. The Road King has different uses, and has lots of knobs and setting for folks into that. They offer a lot of hardware and poundage for the buck. One of the problems today is with all the high gain amps around, folks forget about "tone". Sure these amps make great "sounds", but tone is something more complex ... details ... playability ... dynamics ... touch ... etc.

When you design in a lot of front end gain in the first stage (as do most folks today, because it sells a lot of amps), you loose dynamic range, and all sorts of other things as the trade off.

You hear about "tone" in reference to the old tweed this or that, the blackface whatever, or the old plexi Marshalls and Bluesbreaker amps. These had a lot less gain by the way than later Marshalls. You rarely here "tone" used to describe newer amps ... unless the term is sort of mis-used to my way of thinking. Maybe the amps have a great sound ... killer sound, etc., but that is different than tone.

There are some folks that get tone by using classis designs, such as Victoria, Matchless, Bad Cat, Carr, and a few others.

Then there are the folks that take classic designs, and re-engineer and redesign them such as Doug Roccaforte. His amps have touch, feel, headroom. He does not build excessive gain and noise into the front end of his designs, and thus, they are much more versitile.

Paul Rivera ... also a great line of versitile amps. Listen to a Quiana sometime on the clean channel (2), with its 6L6's, with the master on about 8-9 and the volume down at 4.

Regards,

Myles
Posted By: alevinthal

Re: Feel free to ask Myles - 07/28/02 06:03 AM

Hi Myles, I have a Randall RT-30, an amp that I love, with a wonderful and unique sound, but it needs an hour to warm up, sounds great for about an hour, and then 'loses the magic' over the next hour.

What makes an amp do this, and what can I do to get it to 'warm-up' faster, and then stay in that great tonal zone? I have 2 old boogies (studio 22 and MKII) that act the same way.

I have the schematics (as .pdf files) if you are interested in seeing them.

-Adam-
Posted By: rsf1977

Re: Feel free to ask Myles - 07/29/02 07:26 PM

Hey Myles, I was practicing yesterday and infrequently my amp would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.
Posted By: rsf1977

Re: Feel free to ask Myles - 07/29/02 07:27 PM

Hey Myles, I was practicing yesterday and infrequently my amp (mesa Dual Rectifier 2 channel Solo Head) would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.
Posted By: Chris Kemp

Re: Feel free to ask Myles - 07/29/02 09:26 PM

Hi Myles -

trivia question - ever see/hear of a single EL34 amplifier? Is there some reason this would not be possible?

Sorry I missed you guys at the lunch with Lee last Saturday - hope you might make it to our dinner on Tuesday?

Cheers!
Christopher
Posted By: myles_rose

Re: Feel free to ask Myles - 07/30/02 05:50 PM

Quote:
Originally posted by aleinthal:
Hi Myles, I have a Randall RT-30, an amp that I love, with a wonderful and unique sound, but it needs an hour to warm up, sounds great for about an hour, and then 'loses the magic' over the next hour.

What makes an amp do this, and what can I do to get it to 'warm-up' faster, and then stay in that great tonal zone? I have 2 old boogies (studio 22 and MKII) that act the same way.

I have the schematics (as .pdf files) if you are interested in seeing them.

-Adam-
Adam,

If you have three tube amps that act the same way in your place, the first thing I would do is check your AC or borrow a variac and try one of the amps on there for a bit.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/30/02 05:56 PM

Quote:
Originally posted by rsf1977:
Hey Myles, I was practicing yesterday and infrequently my amp (mesa Dual Rectifier 2 channel Solo Head) would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.
rsf1977...

It could be a few things. On your rectifier, switch to the solid state setting when this happens and see if there is a change.

It very well could be one of your power tubes, they are fragile in shipping and that is why GT has their warranty.

If you have the set that came out of the amp, try them, and if they don't do the same thing, then I'd suspect one of the tubes as a possibility if once the GE tube goes off its prime, it does not come back when the amp is turned on another time.

Keep me in the loop, and you may feel free to call me at work for more detailed help over at GT.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/30/02 06:02 PM

Quote:
Originally posted by Christopher Kemp:
Hi Myles -

trivia question - ever see/hear of a single EL34 amplifier? Is there some reason this would not be possible?

Sorry I missed you guys at the lunch with Lee last Saturday - hope you might make it to our dinner on Tuesday?

Cheers!
Christopher
Christopher ....

There are a few terrific single EL-34 amps at the moment:

THD Univalve (best amp in the world for under $5000.00)

James Peters

GT Solo Single

Take your pick ... all a bit different, all terrific.

Its too bad you missed the lunch. Aspen Pittman sent some "party favors" with me that were passed out, the food was great, the company was a blast and we all made new friends. Lee and Kyle were great at the show, and I was very impressed with Paul (the song writer).

Tuesday I am booked .... Thursday I have another concert somewhere in Santa Monica (I don't even know where I am supposed to be yet), but hopefully we will catch up.

Myles
Posted By: kirschke

Re: Feel free to ask Myles - 07/30/02 08:42 PM

Hello Myles,
I learned by Your replies,that You are a great friend of KT 66, me too.Had You ever problems with
a PT,because the KT66 has a higher heater current
than the 6L6.
I have a NEW SENSOR 022798 PT in my amp-ALLEN OLD
FLAME,which I built myself,-which can handle 4A/6,3V.I have 2 12AX7 and 2 12AT7 which I think
have together 1,2A.Is this safe enough?
The last thing I would like to have is a blown PT at a gig.
How did Marshall handle this with the early Blues-
breaker combo?
Thanks,
Wolfgang
Posted By: myles_rose

Re: Feel free to ask Myles - 07/30/02 11:57 PM

Quote:
Originally posted by kirschke:
Hello Myles,
I learned by Your replies,that You are a great friend of KT 66, me too.Had You ever problems with
a PT,because the KT66 has a higher heater current
than the 6L6.
I have a NEW SENSOR 022798 PT in my amp-ALLEN OLD
FLAME,which I built myself,-which can handle 4A/6,3V.I have 2 12AX7 and 2 12AT7 which I think
have together 1,2A.Is this safe enough?
The last thing I would like to have is a blown PT at a gig.
How did Marshall handle this with the early Blues-
breaker combo?
Thanks,
Wolfgang
Wolfgang,

You actually have more than enough reserve. In the Bluebreaker it was also not an issue.

The heater current of a 6L6 is 0.9mA

KT-66's are 1.27mA

EL-34's are 1.5mA

But you are still just fine with any of those as your transformer is rated at less than a 100% duty cycle.

No Problem ...

Have fun .... KT-66's are great.

Myles
Posted By: alevinthal

Re: Feel free to ask Myles - 07/31/02 09:04 AM

Quote:
Originally posted by myles111:
Quote:
Originally posted by aleinthal:
Hi Myles, I have a Randall RT-30, an amp that I love, with a wonderful and unique sound, but it needs an hour to warm up, sounds great for about an hour, and then 'loses the magic' over the next hour.

What makes an amp do this, and what can I do to get it to 'warm-up' faster, and then stay in that great tonal zone? I have 2 old boogies (studio 22 and MKII) that act the same way.

I have the schematics (as .pdf files) if you are interested in seeing them.

-Adam-
Adam,

If you have three tube amps that act the same way in your place, the first thing I would do is check your AC or borrow a variac and try one of the amps on there for a bit.

Myles
Hi Myles,

I guess I misspoke, the MKII is reasonably stable. The Studio 22 definitely drifts. The RT30 is my biggest concern though, since I prefer it to the Mesa's. The mains are probably not the issue since I play out a lot and it happens everywhere.

How stable should I expect the tone of a tube amp to be? What might I consider doing to make it more stable? How stable are the tranconductance curves of power tubes, in general? Are they sensitive to changes in temperature, or plate voltage? Might amps running class A be less stable than amps running class AB, since everything gets hotter? This amp runs four el84's at 380V with minimal regulation. A single emitter resistor biases all four tubes.

-Adam-

P.S. Dan Torres said he wasn't too surprised at this behaviour, and that some/most tube amps will drift, but I hate to have to just accept this. I was going to try a fan at the next show (thursday).
Posted By: rsf1977

Re: Feel free to ask Myles - 07/31/02 10:34 AM

Quote:
Originally posted by myles111:
Quote:
Originally posted by rsf1977:
Hey Myles, I was practicing yesterday and infrequently my amp (mesa Dual Rectifier 2 channel Solo Head) would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.
rsf1977...

It could be a few things. On your rectifier, switch to the solid state setting when this happens and see if there is a change.

It very well could be one of your power tubes, they are fragile in shipping and that is why GT has their warranty.

If you have the set that came out of the amp, try them, and if they don't do the same thing, then I'd suspect one of the tubes as a possibility if once the GE tube goes off its prime, it does not come back when the amp is turned on another time.

Keep me in the loop, and you may feel free to call me at work for more detailed help over at GT.

Myles
Hey Myles I'll try swapping the tubes and see what happens. I always use the solid state rectifier so I guess that's not it right? And what were you saying about the GE Tubes, "if once the GE tube goes off its prime, it does not come back when the amp is turned on another time" what exactly did you mean. I'll let you know what happens, thanks again
Posted By: myles_rose

Re: Feel free to ask Myles - 07/31/02 10:49 PM

Quote:
Originally posted by alevinthal:
Quote:
Originally posted by myles111:
Quote:
Originally posted by aleinthal:
Hi Myles, I have a Randall RT-30, an amp that I love, with a wonderful and unique sound, but it needs an hour to warm up, sounds great for about an hour, and then 'loses the magic' over the next hour.

What makes an amp do this, and what can I do to get it to 'warm-up' faster, and then stay in that great tonal zone? I have 2 old boogies (studio 22 and MKII) that act the same way.

I have the schematics (as .pdf files) if you are interested in seeing them.

-Adam-
Adam,

If you have three tube amps that act the same way in your place, the first thing I would do is check your AC or borrow a variac and try one of the amps on there for a bit.

Myles
Hi Myles,

I guess I misspoke, the MKII is reasonably stable. The Studio 22 definitely drifts. The RT30 is my biggest concern though, since I prefer it to the Mesa's. The mains are probably not the issue since I play out a lot and it happens everywhere.

How stable should I expect the tone of a tube amp to be? What might I consider doing to make it more stable? How stable are the tranconductance curves of power tubes, in general? Are they sensitive to changes in temperature, or plate voltage? Might amps running class A be less stable than amps running class AB, since everything gets hotter? This amp runs four el84's at 380V with minimal regulation. A single emitter resistor biases all four tubes.

-Adam-

P.S. Dan Torres said he wasn't too surprised at this behaviour, and that some/most tube amps will drift, but I hate to have to just accept this. I was going to try a fan at the next show (thursday).
alevinthal ...

Dan Torres is right on the money. Amps drift, and mostly because of AC variances. I always use a variac when I work on amps, as everytime something turns on or off, even if not on the same circuit, things go way off.

380 volts on EL-84's is also a bit high, so they will run hot also. Class A amps run a LOT hotter, and this heats up everything, not just the tubes. Remember, a class A amp with no signal, is running at 100%, flat out ... so use the standby switch when not playing. This is the reason that AC-30's used to actually catch fire in some cases.

You can also drop the heat by using a cooler range of output tubes with the Mesa amps, but the amp will distort more quickly.

Regards,

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 07/31/02 10:51 PM

Quote:
Originally posted by rsf1977:
Quote:
Originally posted by myles111:
Quote:
Originally posted by rsf1977:
Hey Myles, I was practicing yesterday and infrequently my amp (mesa Dual Rectifier 2 channel Solo Head) would all of a sudden lose almost all volume and as it went down the sound got really grainy, do you know what could cause this?

I recently had couple weeks before had my pickup changed could it be a bad connection or something, About a month ago I switched to the Groove Tube GE-6L6s do you think it could be a bad power tube? Let me know, thanks.
rsf1977...

It could be a few things. On your rectifier, switch to the solid state setting when this happens and see if there is a change.

It very well could be one of your power tubes, they are fragile in shipping and that is why GT has their warranty.

If you have the set that came out of the amp, try them, and if they don't do the same thing, then I'd suspect one of the tubes as a possibility if once the GE tube goes off its prime, it does not come back when the amp is turned on another time.

Keep me in the loop, and you may feel free to call me at work for more detailed help over at GT.

Myles
Hey Myles I'll try swapping the tubes and see what happens. I always use the solid state rectifier so I guess that's not it right? And what were you saying about the GE Tubes, "if once the GE tube goes off its prime, it does not come back when the amp is turned on another time" what exactly did you mean. I'll let you know what happens, thanks again
rsf1977 ....

If one tube of an output set does something different than the others, but after a bit of rest, comes back, the tube may be faulty.

Myles
Posted By: ehv

Re: Feel free to ask Myles - 08/01/02 03:40 AM

Hi Myles, first post here.....

I am having a problem with my 94' Fender "Twin Amp" (not Twin Reverb) that I'm wondering if you can help with. When I turn my reverb level above about 4, I start getting a ringing/feedback/high-pitched tone. The higher I turn my reverb level, the louder the feedback gets (gets very loud at 10). If I turn the reverb level down to 4 or below, the feedback goes away. The feedback builds slowly in level, takes 10-20 seconds to build up. It does it whether I'm in channel 1 or 2. If the volume level is turned to 0, and the reverb level is turned up, it still feeds back.

Any idea what's causing this? If it's a potential tube problem, do you know which tube/tubes drive the reverb? I have schematics (though I don't know much about reading them) and my best guess is that V5 (12AT7) and /or V6 (12AX7) are the reverb tubes.

If it needs to be serviced, do you have any recomendations for an amp tech in the Denver/Boulder CO area?

From reading many of the above posts, I know it's been said many times, but it really is great of you to take your time to help so many people out here!

Thanks for any help you can give on this!

Eric V
Posted By: not coaster MODERATOR

Re: Feel free to ask Myles - 08/01/02 07:24 AM

Myles, I'm sure you have an opinion on this:

http://www.harmony-central.com/Newp/2002/RM50.html
Posted By: alevinthal

Re: Feel free to ask Myles - 08/01/02 09:35 AM

Quote:
Originally posted by myles111:

alevinthal ...

Dan Torres is right on the money. Amps drift, and mostly because of AC variances. I always use a variac when I work on amps, as everytime something turns on or off, even if not on the same circuit, things go way off.

380 volts on EL-84's is also a bit high, so they will run hot also. Class A amps run a LOT hotter, and this heats up everything, not just the tubes. Remember, a class A amp with no signal, is running at 100%, flat out ... so use the standby switch when not playing. This is the reason that AC-30's used to actually catch fire in some cases.

You can also drop the heat by using a cooler range of output tubes with the Mesa amps, but the amp will distort more quickly.

Regards,

Myles
Hi Myles,

Thanks again for your time. What is your opinion about this idea:

since the RT30 sounds good when first turned on, but really sweet after running for an hour or so, might I put it on the bench, measure it at turn-on, run it into a load for an hour, measure it again, and then (maybe) figured out how to swap components to get it to run at those measured currents/voltages normally, and *then* try to keep it cool so it stays there? Is this likely to work?

If it does make sense, I could try it myself, but all I have is an EE degree, a basic iron/meter/scope, and limited knowledge of tubes and high voltage design. I am interested in trying, but I'm concerned about killing my best-sounding amp. Maybe Mr Torres can do this, but I don't know if he is willing to do this sort of 'experimental' work (or if I could afford it). Either way, I'll be trying a fan next time out.

just wondering,

-Adam-

P.S. The amp is supposed to be running at 350V B+ but I measured 380V, and I have felt the mains transformer get (too) hot, but it's intermittent. I suspect there might be a short in the primary windings of a turn or two. What would you suspect? I mean to replace it, but haven't gotten around to it.

P.P.S What do you think about implementing auto-bias in guitar amps with solid-state regulators? Here's a link to a paper on the subject: http://www.glass-ware.com/tubecircuits/Tube_Auto_Biasing.html
Posted By: myles_rose

Re: Feel free to ask Myles - 08/01/02 10:33 PM

Quote:
Originally posted by cereal:
Myles, I'm sure you have an opinion on this:

http://www.harmony-central.com/Newp/2002/RM50.html
\\

cereal ...

Haven't seen one of these yet, but its an old idea that has been done by a lot of others in the past.

Seymour Duncan did an amp like this, a combo, that was pretty cool. The problem was that they were pricy (but worth it for the work that went into making them), and complicated. The modules were also expensive too.

Generally, when you have more interconnects and things that move around, there is more that can go wrong.

The bottom line, is the concept is interesting, but as I said earlier ... it has been done before, and never seemed to gain a foothold.

These days, I would think that modeling amps would offer a lot of bang for the buck in this area. You can make a POD sound very nice now if you use something like a DITTO box on it, so the field is getting narrower all the time when it comes to being versitile in a compact package.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 08/01/02 10:38 PM

Quote:
Originally posted by ehv:
Hi Myles, first post here.....

I am having a problem with my 94' Fender "Twin Amp" (not Twin Reverb) that I'm wondering if you can help with. When I turn my reverb level above about 4, I start getting a ringing/feedback/high-pitched tone. The higher I turn my reverb level, the louder the feedback gets (gets very loud at 10). If I turn the reverb level down to 4 or below, the feedback goes away. The feedback builds slowly in level, takes 10-20 seconds to build up. It does it whether I'm in channel 1 or 2. If the volume level is turned to 0, and the reverb level is turned up, it still feeds back.

Any idea what's causing this? If it's a potential tube problem, do you know which tube/tubes drive the reverb? I have schematics (though I don't know much about reading them) and my best guess is that V5 (12AT7) and /or V6 (12AX7) are the reverb tubes.

If it needs to be serviced, do you have any recomendations for an amp tech in the Denver/Boulder CO area?

From reading many of the above posts, I know it's been said many times, but it really is great of you to take your time to help so many people out here!

Thanks for any help you can give on this!

Eric V
Eric ...

For your reverb problem, first replace the reverb driver tube with a new one. You may have too much gain. I prefer the 12AT7 as a reverb driver, and some folks just slap in a 12AX7.

Your tube chart will have the reverb driver (which parallels the two sides of the tube for send), and the return. You may want to just try to swap out both the send and return to save a bit of time.

I do not know of anybody in your area off the top of my head. Perhaps somebody else in here may have an idea, or post something over at http://www.harmony-central.com in their forum and ask there ... they are a good bunch for the most part too \:\)

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 08/01/02 10:40 PM

Quote:
Originally posted by alevinthal:
Quote:
Originally posted by myles111:

alevinthal ...

Dan Torres is right on the money. Amps drift, and mostly because of AC variances. I always use a variac when I work on amps, as everytime something turns on or off, even if not on the same circuit, things go way off.

380 volts on EL-84's is also a bit high, so they will run hot also. Class A amps run a LOT hotter, and this heats up everything, not just the tubes. Remember, a class A amp with no signal, is running at 100%, flat out ... so use the standby switch when not playing. This is the reason that AC-30's used to actually catch fire in some cases.

You can also drop the heat by using a cooler range of output tubes with the Mesa amps, but the amp will distort more quickly.

Regards,

Myles
Hi Myles,

Thanks again for your time. What is your opinion about this idea:

since the RT30 sounds good when first turned on, but really sweet after running for an hour or so, might I put it on the bench, measure it at turn-on, run it into a load for an hour, measure it again, and then (maybe) figured out how to swap components to get it to run at those measured currents/voltages normally, and *then* try to keep it cool so it stays there? Is this likely to work?

If it does make sense, I could try it myself, but all I have is an EE degree, a basic iron/meter/scope, and limited knowledge of tubes and high voltage design. I am interested in trying, but I'm concerned about killing my best-sounding amp. Maybe Mr Torres can do this, but I don't know if he is willing to do this sort of 'experimental' work (or if I could afford it). Either way, I'll be trying a fan next time out.

just wondering,

-Adam-

P.S. The amp is supposed to be running at 350V B+ but I measured 380V, and I have felt the mains transformer get (too) hot, but it's intermittent. I suspect there might be a short in the primary windings of a turn or two. What would you suspect? I mean to replace it, but haven't gotten around to it.

P.P.S What do you think about implementing auto-bias in guitar amps with solid-state regulators? Here's a link to a paper on the subject: http://www.glass-ware.com/tubecircuits/Tube_Auto_Biasing.html
Adam ...

I guess go and try ... cannot hurt.

As far as your transformer ... I would need to bench the amp and look.

Myles
Posted By: Oscar

Re: Feel free to ask Myles - 08/05/02 03:02 PM

Myles,

On the one hand, I have box of old tubes, including:
-4 Siemens ECC83's
-a Brimar ECC83
-a Philips Miniwatt ECC83
-a Philips 12AT7 and a 12AY7
-a GE 6L6 GC
-a couple of Sylvania 6L6GC USA
-a couple of Philips EL34's
The pre-amp tubes are all in good shape, the power amp tubes vary. Some are worn, others are good.

On the other hand, I have a Fender HotRod Deluxe combo with Fender/Groove Tubes 12AX7's and 6L6's.

Now, how to combine the two....? Are the Siemens ECC83's, for example, to be used in stead of the Fender/Groove Tubes 12AX7's? What sound differences can I expect? Or would the Brimar be a great choice for V1, or which would be a good choice for the phase inverter, or, or, or....

***Oscar<---------option anxiety***

Any suggestions would be appreciated!
Posted By: myles_rose

Re: Feel free to ask Myles - 08/05/02 10:03 PM

Quote:
Originally posted by Oscar:
Myles,

On the one hand, I have box of old tubes, including:
-4 Siemens ECC83's
-a Brimar ECC83
-a Philips Miniwatt ECC83
-a Philips 12AT7 and a 12AY7
-a GE 6L6 GC
-a couple of Sylvania 6L6GC USA
-a couple of Philips EL34's
The pre-amp tubes are all in good shape, the power amp tubes vary. Some are worn, others are good.

On the other hand, I have a Fender HotRod Deluxe combo with Fender/Groove Tubes 12AX7's and 6L6's.

Now, how to combine the two....? Are the Siemens ECC83's, for example, to be used in stead of the Fender/Groove Tubes 12AX7's? What sound differences can I expect? Or would the Brimar be a great choice for V1, or which would be a good choice for the phase inverter, or, or, or....

***Oscar<---------option anxiety***

Any suggestions would be appreciated!
Oscar,

Anything in the 12AX7 family (ECC83, etc.,) can be exchanged with no adjustment.

I prefer 12AT7's for phase inverters as they have about 10 times the current drive of a AX7, but a less gain. Its all personal preference.

I'd look at the 12AX7 section on my website, it may give you some ideas.

There are power tube areas on my website also.

Myles
Posted By: What Will Become

Re: Feel free to ask Myles - 08/05/02 10:57 PM

Hi Myles-

I recently sold my 5150 II and have switched to a Triple XXX. I've found the Triple XXX has more low end crunch which better suits my needs as I use 7 strings and play very heavy music. Anyway I want to '86 my stock tubes and need help deciding if I should go with JJ 6L6's or E-34L's. I like a lot of low end and am afraid that the E-34L will lack bottom as opposed to the 6L6. I also hear that the E-34L has a way better definition as well. What would you do?

Thanks for any advice..
Posted By: Chris Kemp

Re: Feel free to ask Myles - 08/06/02 12:02 AM

Hey Myles -

Sorry you couldn't make it - good food, good chattin'! Maybe next time.

Thanks for the tip on the amps - the THD looks interesting - I'll have to start saving my pennies.

Another warranty-voiding, don't-try-this-at-home-kids sort of question \:D - currently, I have a Peavey Classic 30 (pretty nice for a REALLY cheap amp!). I've been wondering about the Mid Boost circuit - I've always thought that it should have been foot-switchable, rather than a pushbutton. I asked somebody at Peavey about this once, but they claimed it wasn't possible.

Personally, i thought he was BSing me in order to protect Peavey - any idea? Seems that, in theory, one switch should be replaceable with another, given appropriate rating, # of poles & type of switch - am I missing something here? Obviously, it would have to be wired to accept a jack, or hard-wired to a switch, but is there really any reason something like this should be "impossible"?
Posted By: myles_rose

Re: Feel free to ask Myles - 08/06/02 08:46 PM

Quote:
Originally posted by What Will Become:
Hi Myles-

I recently sold my 5150 II and have switched to a Triple XXX. I've found the Triple XXX has more low end crunch which better suits my needs as I use 7 strings and play very heavy music. Anyway I want to '86 my stock tubes and need help deciding if I should go with JJ 6L6's or E-34L's. I like a lot of low end and am afraid that the E-34L will lack bottom as opposed to the 6L6. I also hear that the E-34L has a way better definition as well. What would you do?

Thanks for any advice..
Pretty easy actually.

In most amps where you want the low and mids of the 6L6, but the articulation in the higher ranges when pushed of the EL-34, the 6L6S:

http://www.groovetubes.com/product.cfm?Product_ID=1680

is what I use in my clients amps. These bias closer to an EL-34 than a 6L6, and are also a 30 watt tube, rather than a 25 watter as most EL-34's and most 6L6's too. Be sure to check the bias. I use these in a #5 or #6, unless you want a LOT of volume and a LOT of clean headroom. If you get the version of this tube from JJ, be sure to get it from Bob Pletka over at Eurotubes (if you don't get it from Groove Tubes), and tell Bob to pick you a set that at 250 volts with a -14 bias, will run at about 80mA. The standard spec for a 6L6 is 72.0mA, and one at 78-82 will be right in the super range for your amp.

DO NOT use other vendors for the JJ 6L6S other than Eurotubes, Watford Walves, the folks on my website, or GT unless you have had good luck with them in the past on prior purchases.

You will like them. If you are in the LA area, I would be happy to bias your amp gratis, as you are in this forum.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 08/06/02 08:52 PM

Quote:
Originally posted by Christopher Kemp:
Hey Myles -

Sorry you couldn't make it - good food, good chattin'! Maybe next time.

Thanks for the tip on the amps - the THD looks interesting - I'll have to start saving my pennies.

Another warranty-voiding, don't-try-this-at-home-kids sort of question \:D - currently, I have a Peavey Classic 30 (pretty nice for a REALLY cheap amp!). I've been wondering about the Mid Boost circuit - I've always thought that it should have been foot-switchable, rather than a pushbutton. I asked somebody at Peavey about this once, but they claimed it wasn't possible.

Personally, i thought he was BSing me in order to protect Peavey - any idea? Seems that, in theory, one switch should be replaceable with another, given appropriate rating, # of poles & type of switch - am I missing something here? Obviously, it would have to be wired to accept a jack, or hard-wired to a switch, but is there really any reason something like this should be "impossible"?
Christopher ...

Be sure to catch us next time ... it was a blast.

The THD is pretty amazing. If you are in my area, you are more than welcome to try mine.

The Peavey Classic 30 ... a really fun amp. I have a lot of clients with these that play gigs with them all the time, and in some fairly large venues. It is possible to add a mod to switch the mid boost, but would be more cost than it may be worth. Its a matter of a switch latch off the circuit. I'd leave the amp stock.

At the moment, I have a few folks out testing some new tubes off new tooling in "your" amp. I may post something soon on this new tube that may be stronger than the EL84S (JJ) tube. It would be nice to have three choices for new tubes for an EL84 ... although the current Russian tube is not a viable option in most cases.

Regards,
Posted By: What Will Become

Re: Feel free to ask Myles - 08/06/02 08:55 PM

Thanks Myles. I ordered the 6L6's from Bob. Should I adjust the bias to the 33-44 MA range that he recommends?
Posted By: myles_rose

Re: Feel free to ask Myles - 08/07/02 10:58 PM

Quote:
Originally posted by What Will Become:
Thanks Myles. I ordered the 6L6's from Bob. Should I adjust the bias to the 33-44 MA range that he recommends?
You can go anywhere in that range, but it will work fine, not be great.

On the Fender test line, they have a procedure that for bias says .... "set to -52 volts". A 6L6 can bias between 46 and 62 volts ... so that is not the best sort of deal, as all tubes are different and all circuits a bit different.

Let me know your amp again, and if you can tell me your B+ voltage, that would be even better, and I will narrow that wide range way down for you. That is one reason some amps are magic and some are just nice.

Myles
Posted By: gearup

Re: Feel free to ask Myles - 08/08/02 04:45 AM

I just put a pair of Tesla el-34s in a Blues Jr. I did not have the amp biased because Bob at Eurotubes said it would not be necessary. He sent me two tubes matched to within 1 milliamp. The rating he wrote on the boxes for these tubes was 37, I do not know what this means. If you know what it is , please help. Will these tubes be ok? The amp does sound very nice now.
Posted By: myles_rose

Re: Feel free to ask Myles - 08/08/02 07:12 PM

Quote:
Originally posted by gearup:
I just put a pair of Tesla el-34s in a Blues Jr. I did not have the amp biased because Bob at Eurotubes said it would not be necessary. He sent me two tubes matched to within 1 milliamp. The rating he wrote on the boxes for these tubes was 37, I do not know what this means. If you know what it is , please help. Will these tubes be ok? The amp does sound very nice now.
Bob is quite correct. I am not sure what his "37" is, but it may be the milliamp current. He uses different test equipment than I use, and he may use a higher plate voltage with a higher bias. My number that I look for is about 48, but I test at different spec.

Your tubes will work better than "ok" by a very wide margin. Any tubes we have ever gotten from Bob are of super quality and match, even when we get them from outside sources so he could not pick "ringers" for our testing.

Regards,
Posted By: gearup

Re: Feel free to ask Myles - 08/09/02 06:06 AM

I was wondering if a Fender Blues Jr. will run a 4x12 cabinet. If so how will this affect the tone and overall volume vs. the single 12 that is in the BJ? If it will work well I will build my own cab. Does anyone know where I can get specs to build a cab?
Posted By: johnny5

Re: Feel free to ask Myles - 08/09/02 08:00 PM

myles, sorry to have so many questions but you have so much knowledge. my plate voltage / B+ voltage in the hellhound is about 480V. i tried the KT66 (not sure of the brand, they were my tech's) and they did not physically fit. i believe they might have a smaller bottle one. can i achieve a tighter, maybe slightly more throaty tone with a power tube change? if so, which direction should i look. i did have a bias pot installed so i have more room to work now.

i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

any thoughts or recomendations?
[/QUOTE]johnny5 ...

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

Myles[/qb][/QUOTE]why are the KT-66HP's your favorate in the hellhound? i'm looking for good rock / blues / rockin blues tone (FYI).[/qb][/QUOTE]Its just personal preference.

Myles[/QB][/QUOTE]
Posted By: johnny5

Re: Feel free to ask Myles - 08/09/02 08:37 PM

Quote:
Originally posted by myles111:
Quote:
Originally posted by Christopher Kemp:
Hey Myles -

Sorry you couldn't make it - good food, good chattin'! Maybe next time.

Thanks for the tip on the amps - the THD looks interesting - I'll have to start saving my pennies.

Another warranty-voiding, don't-try-this-at-home-kids sort of question \:D - currently, I have a Peavey Classic 30 (pretty nice for a REALLY cheap amp!). I've been wondering about the Mid Boost circuit - I've always thought that it should have been foot-switchable, rather than a pushbutton. I asked somebody at Peavey about this once, but they claimed it wasn't possible.

Personally, i thought he was BSing me in order to protect Peavey - any idea? Seems that, in theory, one switch should be replaceable with another, given appropriate rating, # of poles & type of switch - am I missing something here? Obviously, it would have to be wired to accept a jack, or hard-wired to a switch, but is there really any reason something like this should be "impossible"?
Christopher ...

christopher,
check out blueguitar.org. steve Ahola has got several cool mods on the Classic 30 (52 pages of discrptions to be exact), including a foot switchable boost circuit. lots of very tone improving tips. many of which are quite easy to do. i did alot of them on my C30. the amp is SOO much better now.

good luck,
john

Be sure to catch us next time ... it was a blast.

The THD is pretty amazing. If you are in my area, you are more than welcome to try mine.

The Peavey Classic 30 ... a really fun amp. I have a lot of clients with these that play gigs with them all the time, and in some fairly large venues. It is possible to add a mod to switch the mid boost, but would be more cost than it may be worth. Its a matter of a switch latch off the circuit. I'd leave the amp stock.

At the moment, I have a few folks out testing some new tubes off new tooling in "your" amp. I may post something soon on this new tube that may be stronger than the EL84S (JJ) tube. It would be nice to have three choices for new tubes for an EL84 ... although the current Russian tube is not a viable option in most cases.

Regards,
Posted By: myles_rose

Re: Feel free to ask Myles - 08/09/02 11:24 PM

Quote:
Originally posted by gearup:
I was wondering if a Fender Blues Jr. will run a 4x12 cabinet. If so how will this affect the tone and overall volume vs. the single 12 that is in the BJ? If it will work well I will build my own cab. Does anyone know where I can get specs to build a cab?
The Blues Jr. works nicely with a 4x12 cab, just make sure it is an 8 ohm cabinet. It will sound louder, but the sound image will be more constricted as it will probably be a closed back cabinet.

If you ever want to hear something that will make your eyes pop out, hook your amp up to a THD 2x12 cabinet. They are stronger and fuller than any 4x12 around.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 08/09/02 11:30 PM

Quote:
Originally posted by johnny5:
myles, sorry to have so many questions but you have so much knowledge. my plate voltage / B+ voltage in the hellhound is about 480V. i tried the KT66 (not sure of the brand, they were my tech's) and they did not physically fit. i believe they might have a smaller bottle one. can i achieve a tighter, maybe slightly more throaty tone with a power tube change? if so, which direction should i look. i did have a bias pot installed so i have more room to work now.

i have Reverend Hellhound combo (2 6L6's, 60W, 1X12) that has Electro Harmonics 6L6's in it. i have read that these tubes are not very good. and in listening i notice that when these suckers are pushed, they get less and less sweet. almost flabby. i was looking the groove tubes site at the CB's looks like i can get a little more power tube distortion out of those.

any thoughts or recomendations?
johnny5 ...

The CB's are Chinese with a softer vacuum, but do have more mids than the EH's .... most 6L6 tube actually do.

In your amp my favorite tube is the KT-66HP, that is also now one of the least expensive in the GT line as we dropped price from $85 a duet to $60.00 a duet ( $5.00 cheaper than the Chinese KT-66 we also carry with the price drop now ).

I like these with a #5 rating in your amp and in the Dr. Z Route 66 amp (that was designed around this particular tube if you check with them). I also use this in a JTM-45 and a GT Solo 45.

Myles
[/QUOTE]why are the KT-66HP's your favorate in the hellhound? i'm looking for good rock / blues / rockin blues tone (FYI).[/qb][/QUOTE]Its just personal preference.

Myles[/QB][/QUOTE][/QB][/QUOTE]

That is one KT-66 issue ... their height. A problem in a lot of amps. There is a Sovtek version, that is not as nice, but still fun, that is shorter with a metal base. These are what I use at times when folks want KT-66's. A lot of folks these days are now switching to the GE's.

The EH's are perhaps my least favorite 6L6, but that is personal preference and bias from my testing.

The KT-66 is mostly personal preference in a lot of amps for me, but I also switch between those, GE's and 6L6S's.

Myles
Posted By: Jotown

Re: Feel free to ask Myles - 08/12/02 09:47 AM

Myles.

I have a post called "Nashville Nails". So far no luck.

You are supposed to know everything so check it out and solve my problem.

Thanks in advance.

Jotown:)
Posted By: myles_rose

Re: Feel free to ask Myles - 08/12/02 07:36 PM

Quote:
Originally posted by Jotown:
Myles.

I have a post called "Nashville Nails". So far no luck.

You are supposed to know everything so check it out and solve my problem.

Thanks in advance.

Jotown:)
I don't know what you are talking about, and I do not know everything.

Myles
Posted By: Jotown

Re: Feel free to ask Myles - 08/12/02 11:10 PM

I was trying to be funny with the "you are supposed to know everything remark", I guess I failed there.

About the Nashville Nails, did you read my post?
I know someone out there knows about it.

Sorry, did not mean to offend.

Jotown:)
Posted By: myles_rose

Re: Feel free to ask Myles - 08/13/02 12:39 AM

Quote:
Originally posted by Jotown:
I was trying to be funny with the "you are supposed to know everything remark", I guess I failed there.

About the Nashville Nails, did you read my post?
I know someone out there knows about it.

Sorry, did not mean to offend.

Jotown:)
Jotown ....

No offense was taken.

I try to have folks post here, as it forms something of an FAQ section for the benefit of others. I also check this post on a regular basis as I get email alerts.

So .... if you can just repost (just cut and paste) from wherever it is, I will try to answer what ever it is ....

Myles
Posted By: Jotown

Re: Feel free to ask Myles - 08/13/02 07:14 AM

Here you go Myles:

Post 1

Quote:
I was reading a article in Guitar Player about a year ago and there was an interview with a hot country guitar player whose name escapes me.

He refered to the term "Nashville nails". Because he plays with a pick and the nails on his other three fingers. He would get his nails done so that they woudl act like picks, and not break.

The reason I am interested is that last year I got my first new acoustic guitar in 20 years and I have been adding a lot of finger picking things into my show. Songst that I use to do years ago.

My problem is that I am always breaking nails which really sucks. I have used Nutri-nails and a couple of othet clear products, but my nails are stil cracking.

Anybody out there know what I am talking about?

Thanks in advance.
Post 2

Quote:
The Nashville Nails article was refering to a kind of nail polish that is extremely durable.

The truth is I usually break a nail moving my gear into a gig, not playing.

Hard is not good because hard cracks.
Durable is the key.

The search continues.
Thanks for your response Myles,any info would be helpful.
Posted By: myles_rose

Re: Feel free to ask Myles - 08/13/02 07:07 PM

Quote:
Originally posted by Jotown:
Here you go Myles:

Post 1

Quote:
I was reading a article in Guitar Player about a year ago and there was an interview with a hot country guitar player whose name escapes me.

He refered to the term "Nashville nails". Because he plays with a pick and the nails on his other three fingers. He would get his nails done so that they woudl act like picks, and not break.

The reason I am interested is that last year I got my first new acoustic guitar in 20 years and I have been adding a lot of finger picking things into my show. Songst that I use to do years ago.

My problem is that I am always breaking nails which really sucks. I have used Nutri-nails and a couple of othet clear products, but my nails are stil cracking.

Anybody out there know what I am talking about?

Thanks in advance.
Post 2

Quote:
The Nashville Nails article was refering to a kind of nail polish that is extremely durable.

The truth is I usually break a nail moving my gear into a gig, not playing.

Hard is not good because hard cracks.
Durable is the key.

The search continues.
Thanks for your response Myles,any info would be helpful.
Jotown ...

Sorry ... I cannot help you here ... I am more of a technical type. Maybe somebody else around here will be able to answer this.

My wife is always getting on my case for not even knowing many of the folks I work with, as far as what band they are in, etc. I generally know folks as "steve ... plays a 5150 .... rocker ... high gain type ... 6L6GE's @ 34mA .... 470 B+ ... 12AX7R3 in V2 at 108/100 .... etc..

Myles
Posted By: johnny5

Re: Feel free to ask Myles - 08/13/02 08:54 PM

myles,
i promise this is the last. i asked groove tubes but they would not give me a straight answer. i would like to know the idle (approx.) bias current for KT66-HP and 6L6S, given i'm running a plate voltage of 480V and both tubes are #5 GT rated.

would appriciate the help,
thanks
Posted By: myles_rose

Re: Feel free to ask Myles - 08/13/02 09:33 PM

Quote:
Originally posted by johnny5:
myles,
i promise this is the last. i asked groove tubes but they would not give me a straight answer. i would like to know the idle (approx.) bias current for KT66-HP and 6L6S, given i'm running a plate voltage of 480V and both tubes are #5 GT rated.

would appriciate the help,
thanks
johnny5 ....

If you asked Groove Tubes and did not get a straight answer, who did you talk to? I happen to be "Groove Tubes" and I don't remember talking to you.

In any case.... on each of these tubes, the milliamp draw at idle will be the same, although the bias voltage will be different to get the same ID on the tubes.

It also depends a bit on the amp ....

but ....

For the KT-66HP:

50% 60% 70% Idle dissapation

26 31 36 milliamps

I like these at 32-34mA at your plate voltages.

What amp? and did you measure B+ with ALL the tubes in place? If you pulled one tube to read pin 3 to ground, the loss of one tube in the circuit will cause a false high B+ reading.

For the 6L6S:

50% 60% 70%

31 38 44

I like these at 34-36mA personally, at this sort of plate voltage in most amps.

Next time you need to talk to GT, either ask for me directly, or email me from the GT website (techsupport@groovetubes.com)

Myles
Posted By: Jotown

Re: Feel free to ask Myles - 08/14/02 06:07 AM

Hey Myles,
Thanks for the response.
Posted By: myles_rose

Re: Feel free to ask Myles - 08/14/02 11:12 PM

Quote:
Originally posted by Jotown:
Hey Myles,
Thanks for the response.
You're welcome ... any time.
Posted By: Brilliant

Re: Feel free to ask Myles - 08/15/02 04:32 PM

Myles, I have a loud anoying hum in channel one only. What could cause this problem, and how do I rtemedy it? I have a Crate Blues Voodoo 6212 combo. Thanks for your help.
Posted By: Brilliant

Re: Feel free to ask Myles - 08/15/02 06:19 PM

Hey, I have just been reading your posts and visited your website, really good stuff. I also visited some of your links, and I like what I see. But Dude, I am a poeBoy from Texas, these things are way out of my reach. I would love to just play one of these amps, just to hear if they are all you say. Alas, I know of no dealers in my immediate area(Houston is like 90 miles away). If you could help me find a dealer or any of manufacturers on your site, I would appreciate it. I have played Boogies, and while they are nice, I don't think they are all that. I am talking about the Roccafortes and the THDs.
I have experience in electronics, and I have experience working with high voltage(13KV). I would like to build my own amplifier that would deliver this class of tone. But where do I start?
Do I just copy an old Fender or Marshall design? Do I try to get a schematic of a Roccoforte? Will they send me one?
Posted By: Dylan

Re: Feel free to ask Myles - 08/15/02 07:22 PM

Yo Miles!

I just started this new thread and would appreciate if you could check it out. It's regarding my recently purchased used Fender Twin that isn't working right. Thanks in advance!

-Dylan
Posted By: myles_rose

Re: Feel free to ask Myles - 08/15/02 07:55 PM

Quote:
Originally posted by tundrkys:
Myles, I have a loud anoying hum in channel one only. What could cause this problem, and how do I rtemedy it? I have a Crate Blues Voodoo 6212 combo. Thanks for your help.
tundrkys ...

If it is only in channel 1, first try swapping out V1 with another tube in the amp.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 08/15/02 07:58 PM

Quote:
Originally posted by tundrkys:
Hey, I have just been reading your posts and visited your website, really good stuff. I also visited some of your links, and I like what I see. But Dude, I am a poeBoy from Texas, these things are way out of my reach. I would love to just play one of these amps, just to hear if they are all you say. Alas, I know of no dealers in my immediate area(Houston is like 90 miles away). If you could help me find a dealer or any of manufacturers on your site, I would appreciate it. I have played Boogies, and while they are nice, I don't think they are all that. I am talking about the Roccafortes and the THDs.
I have experience in electronics, and I have experience working with high voltage(13KV). I would like to build my own amplifier that would deliver this class of tone. But where do I start?
Do I just copy an old Fender or Marshall design? Do I try to get a schematic of a Roccoforte? Will they send me one?
tundrkys ....

All of the folks on my site have direct links to their site, usually by clicking on the green amp company name. On some amps, clicking on this takes you to other areas of my website where there is more info, but there will be another place to click to get to the mfg website directly.

The mfg usually has dealer info, or an email where you could ask them directly for info or dealer info.

Myles
Posted By: myles_rose

Re: Feel free to ask Myles - 08/15/02 08:00 PM

Quote:
Originally posted by Dylan Walters:
Yo Miles!

I just started this new thread and would appreciate if you could check it out. It's regarding my recently purchased used Fender Twin that isn't working right. Thanks in advance!

-Dylan
Dylan ... this is my usual response to some of these requests:

I have been getting a lot of mail or questions in the Harmony Central forums. I have an obligation for Guitar Player Magazine, and their forum first, and its been getting a little hard to keep everything organized, so if you don't mind, can you just cut and paste your question in this forum or from your email over at http://www.musicplayer.com in the guitar area.
This way, it also helps others benefit from what you may have asked, and it forms something of a FAQ list.

To get directly to my post, you may follow this link:

http://www.musicplayer.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=19;t=001711

Regards,

Myles
Posted By: Dylan

Re: Feel free to ask Myles - 08/15/02 08:15 PM

I recently purchased a used "evil" Twin amp on e-Bay and I think something is definitely wrong with it. This is the model with a 25/100 watt selectable power. In audio engineering terms I would say that the amp sounds like it has a phase problem, as the sound is not as directional as it should be, and there is literally *no* low end response. I compared this to my Fender Hot Rod Deluxe and Tech 21 Trademark 10 amps and both sound much better than the Twin. The Twin should be much louder and have a much bigger and beefier sound, but it doesn't, The second channel is a total joke, it sounds like a tin machine. I looked at all of the tubes (Groove Tubes I think) and from what I can tell they look OK, but I don't really know enough about tubes to tell for sure. Do you have any idea to what might be wrong? Also, the power wattage switch doesn't seem to do anything, which strikes me as *very* odd. I e-mailed the seller this morning so hopefully he'll have some ideas for me.
Posted By: myles_rose

Re: Feel free to ask Myles - 08/16/02 12:03 AM

Quote:
Originally posted by Dylan Walters:
I recently purchased a used "evil" Twin amp on e-Bay and I think something is definitely wrong with it. This is the model with a 25/100 watt selectable power. In audio engineering terms I would say that the amp sounds like it has a phase problem, as the sound is not as directional as it should be, and there is literally *no* low end response. I compared this to my Fender Hot Rod Deluxe and Tech 21 Trademark 10 amps and both sound much better than the Twin. The Twin should be much louder and have a much bigger and beefier sound, but it doesn't, The second channel is a total joke, it sounds like a tin machine. I looked at all of the tubes (Groove Tubes I think) and from what I can tell they look OK, but I don't really know enough about tubes to tell for sure. Do you have any idea to what might be wrong? Also, the power wattage switch doesn't seem to do anything, which strikes me as *very* odd. I e-mailed the seller this morning so hopefully he'll have some ideas for me.
Dylan,

I know your amp very well. It is one of three in the newer Fender Pro Tube series.

In any case, the first point that may be misunderstood is the power switch. At lower levels, dropping the power to 25%, will have little effect on overall volume. Dropping from 100 watts to 50 watts is only 3db, barely perceptable, and down to 25 watts is only another 3db. But at higher levels, the amp will distort sooner and play differently. That is why folks from Jeff Beck to Hendrix used 50 watters when they recorded (Beck uses 50 watters in concerts) rather than 100 watters. Even pulling two tubes in a 100 watter will not make it sound or play like a 50 watter, as the power supply will not sag like a 50 watter when pushed.

So ... that power switch is mostly for feel and more output stage distortion when the amp is run flat out.

You other problems are; the bias on these amps as set at the factory is usually wrong by the time the amp has 20 or so hours on it. The stock 6L6GC GT/Fender tubes are not even close to the best choice. They are nice and sturdy, but that is about all. They are also known as the Groove Tubes 6L6B or Sovtek 5881 WXT.

The only tubes that bring these amps to life, and make them do the magic of the Black Face era are the:

http://www.groovetubes.com/product.cfm?Product_ID=1693 - which are my second choice for most of my clients ...

and ....

http://www.groovetubes.com/product.cfm?Product_ID=1714 - which are my first choice.
The GE's will widen your sound stage area by 15 degrees on each side and give you a huge sound, rather than the sound you have now ... a blanket of wet felt over the amp.

Be sure to bias these at 80mA per side.

If you look at my website at:
http://www.guitaramplifierblueprinting.com/pastinfo.html - look for my equipment, and look at the tubes used in my Pro Reverb. This is the same amp as yours, but with a 50 watt output section.

The preamp stages in this amp are very unique, and the gain channel is useless unless a few things are done. They tried to (and accomplished) generating so much gain, that there is no frequency response there for harmonics. Turning the volume to 3 and gain to 3, you are already out of the range of anything usefull, and it sounds awful. The trick here is knowing what is in the preamp section, and what the tubes are doing. You cannot do this by chance, you will chase your tail forever. If you look at my website at: http://www.guitaramplifierblueprinting.com/12ax7.html at the bottom of that section, it shows just how inconsistant today's preamp tubes are, and that is also part of the problem.

Your amp uses Chinese 12AX7's (which Fender calls 12AX7A's) in V1 and V2. They are tested for microphonics and quality, but are still not what one would call a SAG tube. You need to get a good tube in V1 with the correct rating, and in V2, replace the 12AX7 as I do for my clients with the stuff you'll see in my equipment section on the website.

You also need a matched phase inverter in V4 (these amps are diffferent in layout from other Fender amps of the past), and Fender also used the 12AT7's in the past as phase inverters. For economy of stocking and cost, they use 12AX7's in these amps. The gain is close, but a 12AT7 can push almost ten times the current that a 12AX7 can. You need a 12AT7, and a matched one at that. There is data on my website on MPI's. GT has them at:
http://www.groovetubes.com/product.cfm?Product_ID=1722

If you want tubes specifically selected for your amp, GT now offers this as a serice also at:

http://www.groovetubes.com/product.cfm?Product_ID=1773

There is nothing wrong with your amp, it is just that there is a lot to be done to make it do what it is capable of doing. That is what "blueprinting" is partially about.

Hope that helped ....
Posted By: Brilliant

Re: Feel free to ask Myles - 08/16/02 03:28 AM

Quote:
If it is only in channel 1, first try swapping out V1 with another tube in the amp.

Myles, I tried that and there was no change. I also checked again on CH2, it is there, but only when turned up past 7(hardly ever)
Posted By: Brilliant

Re: Feel free to ask Myles - 08/16/02 04:52 AM

Here's an update Myles, Last time, I just swapped V1 with V2, and there was no change. I then replaced V1 with an older tube I had lying around. Reduced the hum considerably.
Only now, whenever I hit the G string hard, I get a rattling vibrating noise from the amp, most notable on the seventh fret. Any Ideas?
Posted By: myles_rose

Re: Feel free to ask Myles - 08/16/02 07:49 PM

Quote:
Originally posted by tundrkys:
Here's an update Myles, Last time, I just swapped V1 with V2, and there was no change. I then replaced V1 with an older tube I had lying around. Reduced the hum considerably.
Only now, whenever I hit the G string hard, I get a rattling vibrating noise from the amp, most notable on the seventh fret. Any Ideas?
Microphonic tube probably. These amps are really sensitive to them. If you notice, the stock tubes in V1 and V2 have shrink wrap covering them from Fender to try to help in this regard.

Try another preamp tube like a good 12AX7C.
Posted By: Dylan

Re: Feel free to ask Myles - 08/17/02 01:32 AM

Thanks a ton for the info, Miles. I'll see what I can do from here.

-Dylan
Posted By: gtrkid

Re: Feel free to ask Myles - 08/17/02 05:58 AM

I got an Sg with 490's i want a kick'n amp. Maybe a cabinet with a head or a 2 speaker combo. I want a beefy classic rock sound like REO or AC/DC. I'm kind've on a budget like around 700$ and i like a good one with a DEAL.and where can i get that deal
Posted By: halcyon

Re: Feel free to ask Myles - 08/19/02 01:58 AM

hello myles i have a couple questions. how closely does groove tubes match their power tubes and phase inverters. also whats a good power tube to put in my 66 bassman head to give it a slighty dirty clean? good for open chords and clean rythem at band practice levels. thanks \:\)
Posted By: Outrider

Re: Feel free to ask Myles - 08/19/02 06:36 PM

Hi Myles

I have a Fender Hot Rod Deville 2x12...60w 3-channel. I've been playing it with the factory tubes and have been pretty happy with it. The 6L6's in th epower section were groove tubes with "Fender" also painted on them. They also had the "B" notation...whatever that means.

Anyway...the amp received a nasty blow this weekend which broke off the protective panel on the back (which was not reinforced to the body in any way) and broke the 6L6 power tubess off at the base. I got all the pieces out and replaced them with a pair of Sovteks that I bought from a salesman who knew even less about them than I do.

For example, I asked him in all earnestness (based on my limited knowledge) "are these tubes matched?" to which he held them up to the light and said "Sure...look at 'em. They're the same."

Anyway...the amp cranked back up and volumes sound relatively comparable but one thing I noticed was that on my rhythm channel (the first level distortion) I now had to turn it up to, say, 6 in order to get a comparable tone that I used to get on 4. I thought this strange because I figured the 12ax7's were responsible for the distortion levels. Does this sound like a likely scenario or am I imagining it? Why would that happen?

Also, as long as I'm replacing bitz on the amp, what tubes have you found most agreeable with the DeVille? I usually prefer a full boomy clean and a light/mid distorted rhythm channel. I don't use the lead channel much unless I want lots of sustain for short bursts. I mostly play classic-style hard rock with a Strat, and I really have enjoyed the growly sound of the DeVille so far.

Thanks!
Posted By: myles_rose

Re: Feel free to ask Myles - 08/19/02 09:31 PM