[Arny Krueger]

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Arny Krueger wrote:

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

I'm pretty sure I've heard some Technics amps with sliding bias. They sold
them in appliance stores around here in the days of. I seem to recall
their advertising buzzword was "New Class A" or some such.