Amp/Preamp Asylum

Posted by Tre' (P) on February 07, 2025 at 21:43:00

In Reply to: RE: Schematic sematics posted by 13th Duke of Wymbourne on February 07, 2025 at 21:16:23

" At higher power a push-pull stage will move to class B."

No, a Class AB amplifier is never a Class B amplifier. In a Class B amplifier all of the output devices are biased to off and they only conduct when presented with the positive portion of the signal. The devices presented with the negative portion of the signal stay off for the full half cycle and only conduct once they are presented with a positive signal.

That never happens in a Class AB amplifier. In a Class AB amplifier all output devices are conducting with no signal and half of the output devices only stop conducting when they are presented with enough negative signal to cause them to reach cutoff. The next half cycle, the roles are reversed.

"For single-ended stages the device must be biased to deliver all the rated load current."

Yes, single ended circuits for audio use have to operated Class A but push pull can be Class A as well.

Tre'
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