Feel free to ask Myles

[myles_rose]

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,

[myles_rose]

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,

[Guitarzan]

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.

[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.

[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

[myles_rose]

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,

[daddyelmis]

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

[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?

[myles_rose]

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,

[myles_rose]

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,

[daddyelmis]

Are they JJ EL-34 tubes or E34L tubes? If they are the E34L tubes, I'd have the bias checked.

 

Regards,[/QB]

 

They are JJ EL-84's (20 watt amp).

[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

[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.

[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

[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

[myles_rose]

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]

 

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,

[myles_rose]

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,

[myles_rose]

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,

[myles_rose]

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,

[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

[myles_rose]

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,

[GTO]

Originally posted by myles111:

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.

[myles_rose]

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

[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,,,

[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?

[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,

[myles_rose]

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,

[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.

[mikey_dup1]

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?

[myles_rose]

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,