CLASS A AMPLIFIERS

Unsound, just so you know, Class A has nothing to do with push-pull vs single-ended. Also, a Class A amplifier's peak power will always be the same as its continuous power, IOW the 'headroom' rating will be 0db. An amp that has more that 0db headroom is likely an AB amp.

Krell's sliding class A approach (a similar form of that being first used by Brooks in the 50s if I recall right), allows the amp to run cool at low power. On account of its power supply regulation it should exhibit 0db headroom.

Changing the load impedance changes everything! Contary to popular belief it is not always a good thing that the amplifier power changes as the load impedance changes. There are speakers that are of course designed for this, and there are other speakers to which this behaviour is unacceptable (i.e. electrostatics, horns and full-range high efficinecy drivers to name a few).

This ability of transistor amplifiers has to do with feedback just as much as the fact that they are solid state. The effects of Negative Feedback in an amplifier runs counter to the way our ears have evolved over millions of years. As a result it is one of those things that we should always question. Once you do so *honestly*, a lot of other things get questioned too, but ultimately the right answers also yield better sound. BTW these comments have nothing to do with transistor vs tubes! -although many will think that they do. The underpinning issue is more fundamental.

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.