[Arny Krueger]

"Phil Allison" wrote in message

"Eeyore"
Arny Krueger wrote:

"Phil Allison"

Yes, there are two problems with class A - both
related to the fact that with class A, the output stage always
has far more current flowing in it. (1) Power
transistors tend to be less
linear at high
currents - the beta falls off. Running an output
stage class A approximately doubles the current that the
output stage has to handle. So, you move the operating
point way out on the output devices. (2) Less SOA
from the perspective of
the load, because
the output devices are pulling so hard against each
other.


** What a load of complete DRIVEL !!!!

Arny - leave commenting on power amp design to people
who know something about it cos they spend their lives
dealing with it at component level.
Cos YOU do not have a bloody clue.

Phil, its real handy for that you seem to be so
mentally incapable of framing a proper technical
reply. Everybody is going to dismiss your ranting.

I'd personally like to see you claim that power
transistors get more linear
when run at very high currents and that there is no
such thing as beta fall-off at high currents.

Oh there is but since a classic Class A output has such
high standing dissipation you use more devices in
parallel and you're actually working them at
lower currents than in A/B.



** Correct.

Arny has made the same ASININE error in FOUR posts.

And as is your style, you've done nothing but posture about it, Phil. Why
not show us a worked-out example? You're capable of it, I've seen you do it.

A "class A amplifer" is one DESIGNED to work correctly
in that mode.

Whatever that means.

His wacky claim about peak device currents being higher
in class A is FALSE.

It's not wacky at all - I've seen it on the bench. It makes perfect sense.
The maximum current through an output device at peak current is increased
when you increase the quiescent current. Something about Kirchoff's law as
applied to the junction of the top and bottom of the output stage, and the
load.