Power tube tone: It’s not just hype!

teleman1

Silver Supporting Member
Messages
16,006
@teemuk, I can absolutely respect the choice not to fuss with tubes. My revelation came with a Traynor Guitarmate from the early 70s. I felt like it was an OK amp, better with the EV speaker for a bit more volume and sparkle. Then I put in a pair of Mullard EL84s (this was back when they weren't all that expensive). The clean tone didn't change, but the breakup tone was markedly different-crunchier and rawer, and much more satisfying. Turned it into a roots blues hero.

As you've said, that only speaks to THAT amp and THOSE tubes. And it does illustrate that, in the linear region, most power tubes are going to sound pretty similar, it's when you get to the non-linear "cutoff" regions that there may be more of a change. And the more the amp forces the power tubes to stay linear (negative feedback, ultra linear power supplies, fixed bias) the less difference tubes will make.
As did my Pevey Classic 20
 

mermermer

Member
Messages
132
Power tubes make a huge difference in how they break up and their effect on cleaning up with guitar volume knob....who ever said it was hype???

Badcat amps for one. They say what we think is power tube distortion is actually the phase inverter being distorted.
 

100% Zulu Boy

Gold Supporting Member
Messages
448
I'm old enough to have purchased a pristine '65 Princeton Reverb from a pawn shop in LA for $125. It was full of stock RCA glass and sounded wonderful.

I used to read Guitar Player, though, and soon learned that I needed to swap the power tubes out for "matched" Groove Tubes -- they were supposed to be even more wonderful, but they weren't. I've had a lot of tubes in it since then, and it's full of old glass today -- that amp, hands down, sounds best with RCA Blackplate 6V6's. Tung Sol's are probably my favorite new tubes in it, but the RCAs are glorious, especially when the amp is running higher up on the volume knob. I love RCA 12AX7s in V1 and V2 that amp, btw, but I have a magical ancient Mullard in V1 that reigns supreme -- it's gainy and juicy and makes every guitar I plug into it sound great.

I bought a very early Tone King Imperial not long after they were first released, and it came with "cheap" Chinese tubes. The amp sounded great, but knowing what I knew about my PR and old tubes being a lot more available back then I re-tubed it with vintage glass -- and ruined the amp. I finally found that a certain Chinese preamp tube in V1 and V2 sounded better in that amp than any vintage glass, and I don't remember what power tubes I settled on, but my takeaway was that there was much less "lift" from NOS power tubes in that amp than in my PR, for example.

So my point? I'm old enough to know that in some amps vintage glass can make an incredible difference, and in both directions. Any time someone tries to say, categorically, that one thing is true and that another isn't I just turn my head . . . that's not how any of this works.

Enjoy!
 

ProfRhino

Member
Messages
10,356
Badcat amps for one. They say what we think is power tube distortion is actually the phase inverter being distorted.
depends on the amp.
sounds like they were talking about their k-master volume which is post-phase inverter afaik, and would cause that effect indeed, if you roll it back.

in a classic NMV .circuit it's usually a combination of both, maybe 30%/70% or whatever - again, depending on amp, but also on some other factors like exact tubes, biasing, NFB and so on.
an amp designer can also tweak this behaviour to a large degree via gainstaging (read up on Kelleys or Trainwrecks for example).

if you use a good load box setup, it's fairly easy to distinguish which is which, by swapping out either the PI, or the power tubes (re-bias where applicable !), and comparing the tonal changes.
the elusive "clean up from the guitar while keeping volume mostly constant" effect for example can typically be attributed to power tube compression (a milder form of power tube distortion, already present in almost clean tones before obvious breakup).

ymmv,
Rhino
 

ProfRhino

Member
Messages
10,356
I'm old enough to have purchased a pristine '65 Princeton Reverb from a pawn shop in LA for $125. It was full of stock RCA glass and sounded wonderful.

I used to read Guitar Player, though, and soon learned that I needed to swap the power tubes out for "matched" Groove Tubes -- they were supposed to be even more wonderful, but they weren't. I've had a lot of tubes in it since then, and it's full of old glass today -- that amp, hands down, sounds best with RCA Blackplate 6V6's. Tung Sol's are probably my favorite new tubes in it, but the RCAs are glorious, especially when the amp is running higher up on the volume knob. I love RCA 12AX7s in V1 and V2 that amp, btw, but I have a magical ancient Mullard in V1 that reigns supreme -- it's gainy and juicy and makes every guitar I plug into it sound great.

I bought a very early Tone King Imperial not long after they were first released, and it came with "cheap" Chinese tubes. The amp sounded great, but knowing what I knew about my PR and old tubes being a lot more available back then I re-tubed it with vintage glass -- and ruined the amp. I finally found that a certain Chinese preamp tube in V1 and V2 sounded better in that amp than any vintage glass, and I don't remember what power tubes I settled on, but my takeaway was that there was much less "lift" from NOS power tubes in that amp than in my PR, for example.

So my point? I'm old enough to know that in some amps vintage glass can make an incredible difference, and in both directions. Any time someone tries to say, categorically, that one thing is true and that another isn't I just turn my head . . . that's not how any of this works.

Enjoy!
ain't that exactly what tube rolling is all about ?

in the big picture however, the right old glass is usually hard to beat, ime.
ymmv,
Rhino
 

KidAfterDark

Gold Supporting Member
Messages
68
I can hear and feel the difference between tube brands and types. As far as currently manufactured tubes, I prefer the Tung Sols.
But for my Morgan RCA35R vintage tubes work the best. I found a 50’s set of 6V6’s and a 50’s 5y3 for a rectifier. I have newer 12AX7’s in the preamp sections, all Tung Sol. The amp sounds great with these!
 

teemuk

Member
Messages
3,747
Badcat amps for one. They say what we think is power tube distortion is actually the phase inverter being distorted.

Sorry to break news to you bu it's not just about clipping. Power amp dynamics and touch sensitivity are controlled by current draw of output tubes, both from power supply ("sag"), overdriven grids (bias shifts and "swirl") and from screen supply ("compression"). PPIMV schemes have none of these effects because phase inverter's current draw is insufficient to cause power supply sag and attenuated output signal too low to cause grid conduction and dynamic bias shifts. Triodes also do not have the second screen of pentode tubes that could gain compress when screens draw current under overload.

There's a reason why attenuators and dummy loads haven't gone out of fashion and why people still fuzz about the importance of "real tube power amp" over just having a tube preamp alone.

People who neuter their tube power amp with a PPIMV would really be better off with modeling amps because those actually replicate associated tube power amp dynamics better than a plain clipping phase inverter.

I do realize that Bad Cat needs to market their master volume feature, though.
 
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Agramal

Member
Messages
1,221
I had an amp once with Ruby tubes in the power amp section and I thought it sounded awful, but I didn't bother to swap them out, I just traded it away. Was a Marshall DSL 100 I believe.
 
Messages
505
Yeah, I think it makes a big difference. I found some JanPhilips EL84 that didn't sound like an ice-pick to the ear! I also used JanPhilips NOS 6V6s, and really liked them.
 

Sessionguy

Member
Messages
57
Do power tubes brands really make a difference? In a fit of GAS induced boredom, I swapped out the TAD tubes in my ’68 DRRI for some Tun-Sols. These are said to have great smooth clipping for blues. And it’s no joke! The TAD tubes sounded like a wet fart when pushed. These Tung-Sols sound glorious! It’s like I have a new amp for the price of $45. But to be honest, I had to buy a pricey Ironman attenuator to push the amp without my wife murdering me.

What's your experience with tube swaps - good or bad?

With power tubes, there are 'exactly on spec' tubes and many that are slightly or well below the official spec. This is where the alleged 'tone' difference comes into play. Some of the lesser quality tubes are what different player like... others don't.

Tube spec tolerances are wide too, so they will vary greatly, even the same tube type within the same brand. And if you do like a particular tube, there's probably NO chance of ever buying replacements that will be exactly the same.

I'm a designer in the amp world and a player too. I gave up with tubes back in 1981 and I switched to working with solid state only. Some of you will know my UK amp brand... SESSION. I've designed for others too. Tubes are worse than playing the lottery now. At least when I worked with tubes, they were 'state of the art' - not any more. Big amp brands see 5/10 amp warranty returns based on tube failures alone. Tube amps are no way to make a living these days, sadly.

Sorry to be so blunt and please don't hate me for it. Just being honest!
 

Steviecaster

Member
Messages
804
I can't tell a difference in my amp. You can put EL34, 6L6, KT88, whatever. It sounds pretty much the same. My Bassman, too. I changed from 6l6 to el34, not much difference.
 

JB6464

Member
Messages
5,175
Tube amps are no way to make a living these days, sadly.
But yet 99% of your recording and touring pros use tube amps .
Even in the world of just ok tubes available , that's got to tell you something right there .
Tubes sound more musical and preferred than SS for guitar amps .
 

Britishampfan

Member
Messages
3,034
There was a time when I was working for an amp tech helping him fix amps, I played in three bands and played a lot of different amps, and I was into experimentation because I owned a large number of different tubes and he had shelves of them. I could tell the difference between tubes because I had a fresh Frame of reference and memory of the sound and characteristics.

Could I do that today? I doubt it because its not fresh in my mind. That being said I claimed one day that I could hear and tell the difference between new and NOS power tubes and brands, because I could. 6L6, 6V6, EL 34 and EL 84 power tubes.

The shop owner who was a bass player and I played in a couple bands with him cried BS! and challenged me to a double blind taste test on a few different amps starting off with my own.

I agreed and we bet some beer or joint or something and got to it. The amp was behind a cardboard curtain and I was to write the brand name down on every power tube change, and we also did input tubes which were easier to a certain degree although that same imprint would be needed as described above.

The brands were new sovtek, GE, RCA, Mullard, and JJ if I remember correctly I thought we tried 6 brands between old stock and new production.

I got one wrong in all the tests but the difference between modern and NOS was 100%.

He was pretty blown away, he couldn't believe it, and he was that kind of guy who believed everything was BS when it came to amps so he listed to me quite a bit more after that test when it came to sound.

It would be really difficult to describe what I listened for but none of the tubes sounded bad, the sovteks always sounded the worst to me and they were easy to Identify, He loved sovtek, mostly because he had the least amount of trouble with them on amp repairs, and after the test he started carrying more brands of modern production tubes.

I would also say, unless you have that imprint and keep up with using and listening to different tubes it would be really tough for anyone to describe power tube characteristics and the roundness of the notes and harmonically rich overtones and note separation.

Do I believe that most people can hear the differences in power tubes without this sound imprint. No I believe people are hearing something or at least they think they are, but No you really have to do a lot of playing and with different amps for me to believe you because that's my experience.
 

Sessionguy

Member
Messages
57
But yet 99% of your recording and touring pros use tube amps .
Even in the world of just ok tubes available , that's got to tell you something right there .
Tubes sound more musical and preferred than SS for guitar amps .

Well... perhaps things aren't quite how you see them. That 1% must have paid for my houses and cars over the years... so I'm not complaining! :p
 

Fulldrive-1

Member
Messages
5,926
I do remember one experience in the 90s.

My tech went through my Marshalls. The output tubes were new so we left them alone. They had GE 12ax7a preamp tubes. I didn't think there was anything wrong, but he changed them all out for Sovtek. That definitely woke those Marshalls up.
 

mcphoto

Member
Messages
15
Egnater Tweaker 40 head; I found some old Baldwin preamp tubes online and swapped 'em in. Not a massive difference, but sounds like the speakers had a blanket over them that suddenly got lifted off - a really papery, delicate brightness that made the tone more three-dimensional is how I'd describe it. Probably more apparent in recording than gigging. (And with a 4x12 Marhsall slant cab, the amp sounded damn good already). Well worth it, cost maybe sixty bucks. And then got bit by the bullsh*t Egnater "transformer blows a minute past warranty", so if I ever get that head repaired, they're tearing the logo plate off it. Lots of players got hosed in that deal.
 

guitars13339

Member
Messages
9
Do power tubes brands really make a difference? In a fit of GAS induced boredom, I swapped out the TAD tubes in my ’68 DRRI for some Tun-Sols. These are said to have great smooth clipping for blues. And it’s no joke! The TAD tubes sounded like a wet fart when pushed. These Tung-Sols sound glorious! It’s like I have a new amp for the price of $45. But to be honest, I had to buy a pricey Ironman attenuator to push the amp without my wife murdering me.

What's your experience with tube swaps - good or bad?
Keith: Power tubes absolutely DO have very audible differences in tone! Only the first 12AX7 preamp tube can have a more noticeable tonal effect. Every tube sounds different. Brand name means nothing. Older tubes were made better and sound better. Most new tubes sound shrill to me. Over 50 years of playing pro and fixing amps, I have gathered a lot of tubes from box lots and the trash. I never buy a new tube. When tuning in an amp I try a few different ones until I find the sound I like best. My favorite sounding power tubes are the incomparable 6550 aka KT88, and the universal workhorse 6V6. 6V6's ALL sound different! I have a couple of ancient big 'coke bottle' 6V6 in my Super Champ that utterly slay, and a 1950's US Navy 12AX7 in the first preamp socket.
 




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