[Arny Krueger]

wrote in message
oups.com...

Todd H. wrote:

IOW, if you used an "ideal transformer" with a flat FR from 0-infinity,

would the tube amp's harmonic content be the same as a transistor amp
(with no xfmr) of the same topology?

No, I don't think so. #include the even'odd harmonics stuff.

If it were this simple, you'd see transistor amps transformer coupled
and sold as botique. :-)

I've been convinced through my research thus far that the even/odd
harmonic stuff between tubes and transistor amps is hogwash, that it's
much () more related to the topology (class A, push/pull,
feedback/no-feedback, etc) than the technology (tube vs transistor).

Even/odd harmonic differences are generally due to the use of push-pull
versus single-ended circuitry. Push-pull or balanced circuits can reduce
even harmonics very dramatically, depending primarily on how well the halves
are matched.

Your last statement is what I'm getting at... Albeit added expense and
unnecessary for sales, I wonder if a transformer-coupled push-pull
transistor amp would sound more like a class-A tube amp.

No, but as Nelson Pass tries to show, a single-ended SS circuit can produce
harmonic structure that is similar to a single-ended tube circuit.

This of course assumes that a good bit of signal shaping is done by the
transformer... which may itself be hogwash.

Transformers are for impedance matching, They can shape the signal by adding
nonlinear distortion and also by adding phase shift and frequency response
variations. Most tube amp output transformers are marginal and start losing
efficiency at the low end, but still inside the audio band.

..dane
on a never-ending quest