Chris Morriss wrote:

In message , Ian Bell
writes
David wrote:


Btw - what thousand pound amplifiers have a several percent
distortion?

Single-ended triode amps do - and they can cost a *lot* more than
that!

But what are we measuring? Valve "distotion" is viewed as a rosie glow.
Transistor x/over or switching distortion in a poorly designed (or
over-driven) solid state amp of only a few 10ths % is unbearable!

Not all distotions are created eaqual - but they are all deviations from
the "straight wire with gain" model of the "ideal" amp.

David

Exactly. The thing most people forget is that *all* push pull systems are
very good a canceling even harmonic distortion (the type we don't
mind/like even) which just leaves odd harmonic distortions in the output
which the
ear abhors. This may explain why some people prefer the sound of single
ended class A amplifiers which produce predominantly second harmonic
distortion. This does not mean they are accurate. Aural exciters use this
very technique.

Ian


In all this, we mustn't forget that the even-harmonic cancellation
really only happens in class-A operation. When the amp goes into
class-B, and one of the active elements is cut off, then there is no
mechanism to cancel the even harmonics.

I beg to differ. In *all* push-pull systems successive half cycles are
similar so even harmonics are negligible.

Ian