amps that start Class A, switch to class A/B ?

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Early B.

Re: amps that start Class A, switch to class A/B ?
« Reply #20 on: 16 Nov 2017, 04:08 am »
My 30 watt Cairn 4808A amp does the first 10 watts in class A.

My amp also does the first 10 watts in Class A. But I'm only using about 4 watts at normal listening levels, so am I nearly always in class A mode? And whenever I cross into AB, how would I even know? If I can't tell the difference between A and AB, then is the supposed superiority of Class A overrated? I've been wondering about this for many years.

RDavidson

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Re: amps that start Class A, switch to class A/B ?
« Reply #21 on: 16 Nov 2017, 04:51 am »
When I had a Pass XA30.5, whenever it would shift to class A/B, the sound became very slightly hard or mechanical. It was barely noticeable, but over sustained periods I could tell that something just didn't sound right. It's difficult to pinpoint, but I'd describe it as a slight lessening of naturalness and flow. Of course, this is just my experience with one amp and there are likely other things at play (like distortion, both with the amp and speakers). I think it would be very difficult to prove either way whether class A or class A/B is better or worse than the other, to our ears. This is very subjective with a lot of variables.

*Scotty*

Re: amps that start Class A, switch to class A/B ?
« Reply #22 on: 16 Nov 2017, 05:03 am »
Early B., in most cases the class A rated power also includes the power used by the front end input stage which is operating in class A. You may be transitioning to class B well before you have dissipated 10 watts in the output stage.
Scotty