"Eeyore" wrote in
message
Don Pearce wrote:

"Bret Ludwig" wrote:
Trevor Wilson wrote:
"Dave Plowman (News)" wrote in
message
Eeyore
wrote:
Have you ever spent any time listening to a true
Class A solid state amplifiers ?

Yes. A mate drove his ESLs with a Sugden. One of the
cleanest sounding systems I've ever heard. Wouldn't
shake the windows, though. ;-)

**Sugdens have never built pure Class A amps (whatever
that means). They have only ever built high bias Class
A/B designs. And, of course, Class A is only Class A
when specified into a particular load impedance.
Usually 8 Ohms. Given the fact that ESLs vary all over
the map, impedance-wise, suggesting that the amp is
Class A is even less likely.

This is actually true.

High bias AB amps operate in class A through most of
the power range they spend all their time in, giving
the advantage of Calss A operation where it is needed,
and rather than running out of power when this is
exceeded they simply transition into Class B.

So-called experts, and their toadies and asskissers
(such as Jeboo-selling Randy Slone) have pounded on the
idea that Class AB is a poor design methodology because
of "transconductance doubling". Obviously this is
nonexistant in the region of Class A operation.

Do you mean nonexistent in the region of class B
operation? It is class A that provides the
transconductance doubling because there are two active
devices operating in parallel.

Agreed. It's a real problem, and one that is thus far generally dealt with
indirectly.

I'm concerned about the transconductance 'modulation'
with signal level since this introduces non-linearity.

Again, covered in http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm