[Arny Krueger]

"Bertie the Bunyip" wrote in message
.130
"Karl Uppiano" wrote in
news:NVxYg.706$AR6.264@trndny02:

**Like I said, It has been done before, with variable
success rates. In reality, however, the BEST
amplification is still high bias Class A/B, with no
dodgy power supply rail switching schemes. Such
schemes are really only ways to cut costs.

The idea that class G is only a way to cut costs is false. At low power
levels it costs more to build a class G amplifier than a class A/B amp. You
can see this in the product lines of say QSC, who are one of the industry
leaders when it comes to designing, producing and selling class G
amplifiers. Their low-end models are class A/B. Power levels have to rise to
a certain level before the added parts and complexity required for Class G
starts paying off. I suspect that QSC even tips the scales towards class G
before pure economics cut in, because of the convenience factors.

It's done to cut down dissipation primarily.

Totally agreed.

In high power amplifiers this eventually become a very
significant issue and might otherwise require
impossibly large heatsinks.

When people step up to the problems of building mulit-killowatt amplifiers,
the space, weight, and size savings provided by class G become very
important.

It's an excellent way of improving efficiency.

It is?

For sure.

Why?

In a word, efficiency. The efficiency of a pure class A/B amplifier over a
range of typical use isn't all that wonderful. Numbers like 40% come to
mind. Class A/B amplifiers are generally most efficient near full output.
Class G essentially provides multiple "full output" operating points (one
for each power supply voltage) as power rises.

All engineering is a compromise. Engineers
are always constrained by cost, size, performance,
reliability, complexity, esthetics, marketing B.S.

Right on, and add convenience and general practicality.

When
cost is no object, as is often the case for high-end
hi-fi enthusiasts, that removes a huge constraint.

Hi Fi enthusiasts don't have infinite resources. There are issues like WAF
and simple practicality - a pure class A/B near-killowatt power amp can be
hard to ship except by truck, and difficult to simply get out of the box and
put on the shelf or in a rack.