CLASS A AMPLIFIERS

Unsound

I agree and I didn't mean to suggest that single ended amps couldn't produce high power what I mean't, and I may be wrong here, is that they don't produce the power output of a push-pull design e.g. Pass xa versus x series amps. And yes I remember reading the Stereophile article concerning the power output of the XA200 at least I think it was the XA200 falling short of rated output.

In general, and my logic may be off here as well, I think of class A amps (SET vs. Push-Pull) like I think of tube amps (SET vs. Push-Pull). SET tube amps typically have power outputs in the range of 3-50 wpc while push-pull varieties have power outputs in the range of 50-500 wpc. Anyway sure is fun to have these discussions as I usually learn something in the process.

Chuck

Chuck, I think your right about single ended amps being less likely to produce as much power as push/pull, but, when it comes to solid state the differences aren't as great as in tube amps.......
I'd still like to know if those ss amps that are touted as being pure Class A and being capable of doubling down, maintain pure Class A operation as they double down.

Unsound,

The Krell FPB "Class A" series maintain Class A operation
from 8 ohms to 2 ohms.

They have well regulated power supplies that have the current
capacity to deliver the current that low load impedances
require.

Given the well regulated nature of the power supply [i.e.
the ability to put out the rated voltage independent of load ]
and the current capacity to back it up - that's WHY a
Class A Krell will double down.

Dr. Gregory Greenman
Physicist

Unsound,

You can also check out the reviews by Stereophile, such as
Martin Collums April 1997 review of the then current FPB-600.

http://stereophile.com/amplificationreviews/829/

In the Measurements segment, Martin addresses the power that
the amp can deliver into low impedances:

http://stereophile.com/amplificationreviews/829/index8.html

"I wasn't able to run my long-term continuous testing at
2 ohms, but compromised with five-second bursts-long by
peak-measurement practice (eg, 20ms). The FPB 600 could
sustain a 29.3dBW level into this load, corresponding to
3.4kWpc-an extraordinary figure."

Dr. Gregory Greenman
Physicist

Unless I missed something, everything in these aritcles suggest that the Krell's are capable of maintaining Class A operation as they double down, but, they don't actually make that claim. As for me, I believe they do. Wretched excess? I love it! I may be part of the minority here on Audiogon, but I really like the "real" Krells and thats based on what I've heard not on what I've read. Though it is pretty impressive reading.