Class A Power in A/B amplifiers?

Personally I find the arguments for/against Class A on technical terms alone lack overwhelming evidence.

@erik_squires The arguments are twofold for which there is a lot of evidence if not proof. The first is that you can bias the device in its most linear region. Given that most amps tube or solid state can't really be given the feedback they really need, this is a useful means of allegedly not having to have so much feedback to build a linear amplifier because distortion is lower to start with.


The second issue is that you get more accurate even ordered harmonic cancellation when both output devices are operating in the A region. With the even orders cancelled, there is less overall distortion and so the odd orders tend to be at a lower value (this particular aspect is more useful if the amplifier employs the push-pull/differential operation from input to output). This again is helping for the fact that its likely that insufficient feedback will be applied to the circuit.

The first is that you can bias the device in its most linear region.

This is correct, and why the "better" higher power Class-A’s use up to 24 sometimes 48 even 64 complimentary outputs as in the Threshold Stasis SA/12E monoblocks, so as to only use the "most linear part" of each transistors curve. https://ibb.co/d7BKwzL

The SA/12e, being fully class-A from input through to and including output stage, draws its maximum power from the line at idle—about 1000W for the pair.

https://www.stereophile.com/content/threshold-stasis-sa12e-power-amplifier-page-2

Cheers George

Hi @atmasphere

Your technical explanations are, as usual, spot on, but since I failed to explain what I meant by by "proof" I am afraid you made a counter argument to a point I did not mean to make.

What I meant to say that my own ears have yet to discern a preference of Class A over Class A/B or even D which is even moderately consistent. The behavior of class A circuits vs. A/B in technical terms is more or less well understood, as you show in your rebuttal to my post, but not in the realm of personal experience.

To me, there is no proof class A is consistently or even broadly better than any other class of amplifier when each class is well executed.

Yes, some stellar Class A amplifiers exist. Do they make me go "wow this is what Class A means?" No too many other middle of the road or poor sounding Class A amps out there.   At best, I could be convinced that class A amps are an acquired taste which some develop and then never grow tired of.  Fair enough! It's a happy man who finds what makes them happy early in life!

Best,

Erik

To me, there is no proof class A is consistently or even broadly better than any other class of amplifier when each class is well executed.

Of course Class-A is better if made correctly.

Once a low bias A/B amp leaves it’s low Class-A bias you get cross-over distortion. "NO" crossover distortion is better to listen to in anyone’s language, it’s one of the worst distortions there is, if it were second harmonic distortion then you could forgive it https://ibb.co/VpFSzSz

Do yourself a favor (here’s your proof) and listen to a Gryphon Antillion with switchable bias on the run while listening low, med, high (100w), if you can’t hear the difference then give it away and take up something else.
https://gryphon-audio.dk/shop/power-amplifiers/antileon-evo-stereo/
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