On Fri, 26 Oct 2007 13:35:09 +0000, John Byrns wrote:

In article ,
mick wrote:

On Thu, 25 Oct 2007 20:32:51 -0300, robert casey wrote:

snip
Okay, how about class AB? That's usually a push pull configuration
where, at or near zero crossing, both devices are conducting. But
get above, say 10% of maximum input signal level, one of the devices
stops conducting, and the other device is doing the work. Lets also
say that this is a 100W amplifier, if you run it with an input signal
that makes only 1 watt (the volume control is set low), then, sure
you could call it a 1 watt class A amp. But that'd be rather
silly...

Class B is where there is no class A overlap. Sure, you could have
low quiescent current, but you could easily have crossover
distortion. And it'd sound like a cheap op-amp...

snip


AFAIK classes AB and B are *always* PP, as they both depend on that
mode for cancellation of even harmonics. You just can't do that with SE
output.

That is presumably true in audio applications, but it isn't true in all
applications, for example single ended class AB and class B amplifiers
are often used in applications like Television broadcast transmitters.


dunno... What I know about TV broadcast transmitters can be written on
the screen grid of a 2A3. ;-)

I suppose you can run SE class AB by running the bias low though. Whether
you'd want to listen to it (on an audio system) is something else...

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net