CLASS A AMPLIFIERS


What are the sonic benefits of pure class A amps? Are they more "powerful"?
charlot
Atmasphere, thank you. I was aware of the above. I think your point about amps increasing power not necessarily being a good thing is well taken. As you well know as an amp may increase its power out-put into lower impedances, it will also decrease its power out-put into higher impedances. As you pointed out with some speakers that vary a great deal in impedance load this will have a rather negative effect. On the other hand speakers with steady low impdeance loads will benefit from such an amp. Once again its about using the right tool for the job at hand.
Atmasphere, thanks for your informative comments. But I'm not clear on why it is unacceptable for some speakers to have an amp that increases power into a lower impedance load. My Martin Logans are superb, but among their very few weaknesses is the fact that they roll off the topmost treble...and the impedance in the treble is 1 ohm or less. Surely an amp that can deliver more power into this tough load has the potential to provide better treble performance...?
Calanctus, I use Martin Logan clsiiz and Krell 350mcx. What a coincidence to this thread topic. What speakers do you use? I was wondering the same thing as you after reading this thread!
I hate answering my own questions but after several attempts to get Klipsch to answer with regards to my Palladium 1Ks running 125 watts in class A (and threatening to call Mondial directly). I finally got a response. A completely unqualified yes its absolutely the truth. I still find it kind of hard to believe given the amps' weight (each monobloc is about 70 lbs) and temperature, but that was a major company going on record by e-mail that it is true. No mention that you need to be playing them into 8 ohms but I'll save that for another day. Thanks for your patience and to you other secret Palladium owners out there in audioland now you know.
Atmasphere,

Careful here. The ability of the ss amp to "double down" is
really a function of the regulation of the power supply in
conjuction with its power reservers. This is not really
negative feedback.

Additionally, it's the feedback on the gain stages for the
signal that can have a deleterious effect on the sound
quality.

One can design a zero-feedback gain stage that is fed by
a well-regulated power supply that has, in essence feedback.
However, the sound of such an amp won't be compromised.

The only drawback is that the amount of headroom in such
an amp is not dynamic. As you pointed out, it doesn't
increase in power for short transients.

However, I'd wouldn't count on the dynamic headroom in any
case - I'd size the amp so that the continuous power level
meets my needs.

Dr. Gregory Greenman
Physicist