[Eeyore]

Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:
"Eeyore" wrote
Arny Krueger wrote:
"Eeyore" wrote

My intention is to entirely eliminate this with a kind
of 'hybrid' output stage.

How? Other than class-A you'd need to come up with
some kind of Gm-halving circuit.

It is a 'form' of Class A that indeed meets the classic
definition but without the very high idle current. It
involves quite a radical rethink of the output stage.

In the past the usual approach to this has been to use a
bias circuit that keeps the output devices from ever
turning fully off.

It's that kind of thing.

What do you know about previous examples of this.

Used in some Japanese amps from maybe the late 70s and early 80s.

I've just generally heard that they hadn't been brilliantly
succesful.

I think the usual phrase used to describe this is "sliding bias".

Yes.


It seems to me that sliding bias can make power amps less reliable, by
turning minor faults into situations where lots of power is dissipated in
the output stage. The trick might be to back out the sliding bias feature
when things start going awry, like a shorted load or some such.

I couldn't comment without seeing a schematic really. I can't imagine why
that should be so.

You haven't come across any then ?

Graham