How much do tube power sections differ?

[Shredder777]

I am always interested in picking up old Tube amps. Two decades ago had a Peavey XXX and then a JSX which were good amps with alot of headroom. The JSX had pres/res. I didn't care for the preamps in those amps, but I thought the power was good.

How does the power section of a Peavey XXX JSX 5150 compare to something like a Bogner Uberschall. If you get a Synergy Uber module and play it through a 5150 power amp, are you getting the Uber experience?

Top of my GAS list is an Uberschall Ultra, but I'm thinking a stopgap is ToneX profiles or synergy into an old 5150 or something similar.

 

[Orvillain]

very

 

[DrewJD82]

I was quite surprised how much of an effect they have.

Running Fractal models w/ the cab/poweramp disabled into the Return of any of my tube amps brings varying results. I thought for sure a Plexi into the return of a Mesa Electra Dyne would sound like a big ass Plexi, but it sounded dark and muddy regardless of the preamp settings, any Mesa’s into the Return of the same amp….sounded like Mesa’s and absolutely badass.

Between my Shiva, Electra Dyne and 5153, the 5153 has the most transparent power section. Considering the Electra Dyne uses a fair amount of power amp distortion, I’m not surprised by the results because the amp was obviously designed with some color from the power section. And while the Shiva isn’t really getting much/any dirt from the power section, that amp behaves very differently depending on where the Master is set. With the EVH relying on preamp gain and as much headroom as possible for high gain, I’m not surprised it’s a bit ‘cleaner’ sounding.

 

[Shredder777]

I was quite surprised how much of an effect they have.

Running Fractal models w/ the cab/poweramp disabled into the Return of any of my tube amps brings varying results. I thought for sure a Plexi into the return of a Mesa Electra Dyne would sound like a big ass Plexi, but it sounded dark and muddy regardless of the preamp settings, any Mesa’s into the Return of the same amp….sounded like Mesa’s and absolutely badass.

Between my Shiva, Electra Dyne and 5153, the 5153 has the most transparent power section. Considering the Electra Dyne uses a fair amount of power amp distortion, I’m not surprised by the results because the amp was obviously designed with some color from the power section. And while the Shiva isn’t really getting much/any dirt from the power section, that amp behaves very differently depending on where the Master is set. With the EVH relying on preamp gain and as much headroom as possible for high gain, I’m not surprised it’s a bit ‘cleaner’ sounding.

I noticed the same thing about the XXX and JSX power amps, they had alot of clean headroom, which made them punchy. I had assumed that all high gain designs would be similar, but I'm finding thats not the case, some are somehow able to dial in early saturation and they may not have same res/pres/eq.

 

[MirrorProfiles]

JSX and Triple XXX are very similar amps, based off the same circuit. Wouldn’t be surprised if they have the exact same poweramp

 

[Shredder777]

JSX and Triple XXX are very similar amps, based off the same circuit. Wouldn’t be surprised if they have the exact same poweramp

One has res/pres, the other a damping switch. I think they are roughly identical. The XXX was the better amp imo, the middle channel on the JSX was a bit muted but it was still too gained out to do low/mid gain stuff. The clean channels of both amps couldn't be coaxed into any kind of pleasing overdrive.

Those were shitty and unversatile. Only for metal or as pedal platform.

 

[spawnofthesith]

I was quite surprised how much of an effect they have.

Running Fractal models w/ the cab/poweramp disabled into the Return of any of my tube amps brings varying results. I thought for sure a Plexi into the return of a Mesa Electra Dyne would sound like a big ass Plexi, but it sounded dark and muddy regardless of the preamp settings, any Mesa’s into the Return of the same amp….sounded like Mesa’s and absolutely badass.

Between my Shiva, Electra Dyne and 5153, the 5153 has the most transparent power section. Considering the Electra Dyne uses a fair amount of power amp distortion, I’m not surprised by the results because the amp was obviously designed with some color from the power section. And while the Shiva isn’t really getting much/any dirt from the power section, that amp behaves very differently depending on where the Master is set. With the EVH relying on preamp gain and as much headroom as possible for high gain, I’m not surprised it’s a bit ‘cleaner’ sounding.

Haha yeah I’ve noticed with the HX stomp my 5153 by faaar sounds better for running a preamp into the return than any of my other amps


All my other amps (with fx loops at least) are Mesa a good luck making rhyme or reason of that’s going on with those FX loops/masters depending on what channel you’re on on most of them

 

[spawnofthesith]

And I know there was some popular discussion at least within the last year about power tubes allegedly not making a difference but that is total bullshit. Swapping out power tubes in amps that are capable of that makes significant differences

 

[ZEN Amps]

It can range from subtle to very significant, depending on what you're comparing.

If you get a Synergy Uber module and play it through a 5150 power amp, are you getting the Uber experience?

No, but that module sounds great with any good power amp. In fact I think it's my favourite of the Synergy line.

This came up in the another thread just before - running a bunch of different preamps through the same power amp can certainly sound excellent, but tone and response will be different than the 'real' thing, and there will be a certain homogeny you're stuck with.

e.g. I don't enjoy my Marshall tones through a modern, 6L6 power section - but it's hardly life or death.

 

[Eagle]

Certainly a better feel but not always a better sound.

 

[laxu]

And I know there was some popular discussion at least within the last year about power tubes allegedly not making a difference but that is total bullshit. Swapping out power tubes in amps that are capable of that makes significant differences

That's because the poweramp is designed around a particular power tube. Change from say an amp designed for 6L6s to EL34s, and you change the overall behavior of the circuit, even if those tubes are biased accordingly.

According to Rob Robinette (who has a wonderful site on tube amp circuits): True pentodes such as the EL34 and EL84 flow more screen current and therefore offer up more distortion than beam tetrode power tubes like the 6V6 and 6L6.

So how do you make an amp designed for 6L6 tubes behave the same with EL34s? You'd alter the resistors and capacitors used to control the tube behavior. But many of the amps that just let you slap in any octal tubes don't do this, so by using different tubes you have altered the circuit behavior.

You can find for example Marshall based amps built around every power tube known to man, but they still sound like Marshalls. Maybe a slightly different flavor of it compared to the common EL34 variants, but not a major one.

 

[GuitarBilly74]

The key is the filtering that is applied to different power sections, as well as the transformers design and quality. That makes more of a difference than the power tube themselves. Marshall is a good example of that, they had power amps with EL34s, 6550s, KT66s and 5881s and they all sound like Marshalls.
That's not to say power tubes don't make a difference, they certainly do, but they're secondary to other aspects of the power amp.

 

[Elric]

The key is the filtering that is applied to different power sections, as well as the transformers design and quality. That makes more of a difference than the power tube themselves. Marshall is a good example of that, they had power amps with EL34s, 6550s, KT66s and 5881s and they all sound like Marshalls.
That's not to say power tubes don't make a difference, they certainly do, but they're secondary to other aspects of the power amp.

Agree… A lot of folks have misunderstandings about how power tubes operate and how they are contributing to the sound. They *can* be a big deal or just subtle. It depends on the amp. Most people put far too much stock in tube type, f.ex.

Everything matters of course, but the degree that power amps contribute and in what way can be deceptive. It can be big deal for some designs but for many it is not a huge part of the equation beyond ‘dat wallop’.

Now, speakers? That sh*t cannot be ignored. LOL.

 

[unix-guy]

That's because the poweramp is designed around a particular power tube. Change from say an amp designed for 6L6s to EL34s, and you change the overall behavior of the circuit, even if those tubes are biased accordingly.

According to Rob Robinette (who has a wonderful site on tube amp circuits): True pentodes such as the EL34 and EL84 flow more screen current and therefore offer up more distortion than beam tetrode power tubes like the 6V6 and 6L6.

So how do you make an amp designed for 6L6 tubes behave the same with EL34s? You'd alter the resistors and capacitors used to control the tube behavior. But many of the amps that just let you slap in any octal tubes don't do this, so by using different tubes you have altered the circuit behavior.

You can find for example Marshall based amps built around every power tube known to man, but they still sound like Marshalls. Maybe a slightly different flavor of it compared to the common EL34 variants, but not a major one.

This is a great post from Cliff about this topic:

Why Power Tubes Sound Different

You'll often read that 6L6's sound "full" whereas EL34's have more midrange and other colloquial descriptions of the tone of a power tube. These myths are perpetuated by forum dwellers, uninformed tube "experts" and even amp manufacturers as marketing tools. Well, the fact is that power...

forum.fractalaudio.com

 

[Eagle]

They feel different and react differently with different speakers. I can always tell an EL84 power section because I don’t like them. It’s about the sound and the interaction.