[paul packer]

On Tue, 08 Aug 2006 16:48:07 +0200, Sander DeWaal
wrote:


This is IMHO not always the case.
If what they are doing is something like in the old PM80, there is a
"class A" switch, where the power supply voltages are lowered, and the
bias current through the output devices is increased.
This lowers the output power capability of the amplifier.

To be honest, I don't believe in the way it is done in the PM-80.
To take advantage of class A biasing (where the power stage gets very
hot), one has to design the stage taking into account the high bias
current and some other factors like loop feedback etc.

Well, I owned a PM80 and I couldn't tell the difference between Class
A and A/B except that in Class A the room got strangely hot (great in
winter). Much the same has been said of the PM7200 in forums. The fact
is, both amps are good enough in A/B not to need this kind of
gimmickry.

Interestingly I also owned a PM8200 which was rated 60 watts with no
class A and it got nearly as hot as a class A.