Single ended power amp sounding like it was class AB?

[changes]

:oops: Well it is probably a dumb question but is there a way to make a single ended tube power amp sound like it was class AB???

[R.G.]

What are you trying to do?

[changes]

Well I’m trying to emulate the sound of a marshall power amp(AB) with a single ended amp.i know that it is probably out of  the question but it is worth to ask…

[Doug_H]

What do you mean "sound like Class AB"? What kind of a sound are you trying to get, specifically?

Doug

[aron]

Well, here's a tidbit. According to O'Connor, the more powerful you make an SE amp, the less "SE" it sounds. Apparently a lot of it is how much you push the tube. So if the amp is louder, you tend to push the tube less.

Another thing you might want to check out is his SE "imitation" mod for Push/Pull. I haven't tried it but it's supposed to give you SE-like sound with push/pull.

londonpower.com

[changes]

thanks for the info guys
well what i mean with class AB sounding?
can't really describe it with words
but everybody can hear the difference between A and AB and i prefer AB especially for gainy tones.
this is what i'm after...
but i want it in a single ended amp (first project)

[aron]

You might want to try a parallel SE project. I played the BiValve (THD) WICKED!

[Johan]

I guess part of the "AB-sound" when pushed would be the X-over distortion. simulating that wouldnt have to be to hard. only problem is it would be static and act as a particular ugly noisegate on weak signals....but just puting two back to back diods in SERIES with the signal would definetly do that, put a pot in parrallell with the diods to vary the amount...ugly, but you'll get x-over distortion...even from a singel tube..
or you could always try to bias it into AB ( a little bit of math and a few resistors to play with, I guess.. ). that would give you very asymetrical distortion, wich many people seem to like in their stompboxes at least..
after all..amplifier classes are pretty much a result of where the designer decided to put the biaspoint..and just becouse an amplifier is cathodebiased ( wich many class A amps are ) doesnt mean they have to be..

Johan

[Doug_H]

can't really describe it with words

Well "describing it with words" is about the only choice you have in a forum like this. Unless you have a sound clip or a reference track on a cd or something that is descriptive of the sound you want.

but everybody can hear the difference between A and AB and i prefer AB especially for gainy tones.

And I'm sure everyone has a different idea of what the sound difference is.

I'm bowing out at this point, guys. Someone else will have to handle this one.


Doug

[brett]

Is it the phase-splitting effects you want?  I'm no expert, but could you use a simple, self-split 12AU7 or similar as a driver for a SE power amp?

Hope I haven't proved my ignorance.

[bwanasonic]

And I'm sure everyone has a different idea of what the sound difference is.

I'm bowing out at this point, guys. Someone else will have to handle this one.

Yes, this sounds like a case of putting the cart before the horse.

Kerry M

[zachary vex]

:oops: Well it is probably a dumb question but is there a way to make a single ended tube power amp sound like it was class AB???

sure!  rewind the output transformer with a center tap, and add another tube to the output section with a phase splitter before it!  then it will BE class AB... not just SOUND class AB!  8^)

[AL]

Well, if you want a Marshall, buy (or build) a Marshall. If you want a Vox... You're just not going to get the crossover distortion - sorry.

Is there a reason it has to be single-ended? I'm not trying to be negative but it seems like you either need to do build an AB or throw a pedal in front of it.

A friend of mine has been a tech for around 30 years and was of his biggest complaints is guys who come in and say "Can you make my Fender sound like a Marshall". There are a few tricks you can pull but it's still a Fender.

So, you may be stuck with it that way which isn't a bad thing. Have you built the BSIAB or Thunderchief? Maybe that's the way to go for what you need.

AL

[changes]

:oops: Well it is probably a dumb question but is there a way to make a single ended tube power amp sound like it was class AB???

sure!  rewind the output transformer with a center tap, and add another tube to the output section with a phase splitter before it!  then it will BE class AB... not just SOUND class AB!  8^)

sure i knew it was dumb question...
:oops:
sorry for the confusion i brought Doug i didn't mean that.
yes eberybody hears different...
what i really mean is the difference of a marshall power amp(AB) and a Laney power amp(Class A almost like Vox) and Peavey Classic (again class a i think)
i plugged a  marshall plexi like preamp into those and A/B them and i didn't like the sound so much with a class A poweramp.
i hope i gave you an idea

[AL]

Hey, it's not a dumb question if you didn't know the answer. People just needed a better explanation - that's all. Check out the schematics here  https://schematicheavencom.secure.powweb.com/  - it should give a good idea of the differences in the amps.

AL

[R.G.]

OK, here's the deal. AB has a number of artifacts that it does that are "non-ideal". So does class A. The artifacts are different. Making a class A amp (All single ended amps are class A, but not vice versa) sound like a class AB amp depends on making whatever artifact you associate with AB come through the SE amp.

You will probably not be able to elminate the SE class A artifacts, so it's going to sound like a mixture, which is what (likely) led to Doug and Z's comments.

The prominent artifiacts of AB are crossover distortion and symmetrical (usually) clipping. The prominent artifacts of A are no crossover distortion and assymetrical clipping, as well as (usually) soft even order distortion.

You can insert crossover distortion, you can insert symmetrical clipping. You can't easily eliminate soft even order distortion. That's why you got some of the answers you did.

In general, it's not always possible to make one amp sound just like another one. It can happen, but it's more of a happy accident than an intentional effort because of the large number of acoustic artifacts that someone might be hearing and keying on as the difference in sound.

It's not a dumb question - just a naive one, and loss of naivety is what we're all here for in one way or another.

[Doug_H]

Yeah, I said I was going to bow out but...

I apologize if I seemed impatient.  :oops:  As a s/w developer I'm a little sensitive about discerning between a requirement and an implementation.

Here's my thought: Class A or A/B is an implementation. It is a means to an end, not the end in itself. The end is the sound/tone/feel that you desire.  You have either plugged into an amp you really like or heard a recording of a guitar tone that you want to duplicate. Try to express what you want in those terms rather than in terms of how it gets built.

There are a number of variables that influence the sound of a guitar amp: operating class, cathode/fixed bias, NFB or not, tube choice, speaker(s), guitar pickups, etc, etc... Also, think about why you really want to do this Class A S/E. If it is for low power, for example, there are number of ways of doing Class A/B push-pull for lower output power by choosing appropriate output tubes etc etc...

So if you can express what you want in terms of a "Marshmallow Model 3719 turned to 11", or "Rip Snardley's guitar sound on the 'Rock or Die' cd", it makes it easier for people to suggest possibilities to you.

Doug