Class A, AB

OOPS- I should have said, "Most Solid State amplifiers".

Neilmc , if the amp is AB it will be class A (does not go into cutoff) to a certain point and above a certain power the amplifier will operate in the 'B' region, IOW part of the amp goes into cutoff as the waveform amplitude increases. There is no such thing as combining Class A with Class AB- such an amplifier is by definition Class AB only.

Class A means that at no time during the amplification of the signal does the amplifier or a portion of the amplifier go into cutoff, such that only a part of the circuit is handling the signal. All single-ended amps are Class A BTW.

"...There is no such thing as combining Class A with Class AB- such an amplifier is by definition Class AB only."

I beg to differ. I believe quite a few Plinius amps do exactly that, i.e., combine in a single amp either class A operation or class A/B. Which modality one employs/enjoys at any particular time is up to the end user via a simple toggle switch. In my mind, that is a simple yet monumentally significant design feature which even taken alone, shoots the Plinius amps way out in front of their competitors. Hard to fathom why it is not a more universally adopted design.

My Crown D-150 is described as a class AB + B. Which means, I guess, that it is a class AB up to power point and then switches to B.

Salut, Bob P.

I too have Class AB amps that run in class A mode until two-thirds power then run in AB mode. I a not sure of the design principles used - perhaps a sliding bias or the final ouput stage only goes to work at the higher operating range....