Feel free to ask Myles

[myles_rose]

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,

[mikey_dup1]

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.

[myles_rose]

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,

[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.

[myles_rose]

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,

[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.

[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

[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

[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!

[myles_rose]

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,

[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

[myles_rose]

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,

[myles_rose]

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,

[myles_rose]

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,

[myles_rose]

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,

[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

[myles_rose]

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,

[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

[myles_rose]

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,

[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

[Skip_dup1]

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?

[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?

[JamesPeters]

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.

[Skip_dup1]

thanks, mon. That basically answers my question.

[Slats]

Myles, I'm not sure what you mean by the #4 and the #8. Thanks

[mikey_dup1]

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.

[myles_rose]

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,

[myles_rose]

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_rose]

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,

[myles_rose]

Originally posted by JamesPeters:

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.

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