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Are There Any Inherent Advantages to Class A amps?

All things being equal, power supply size, wpc into 2 ohms and everything else, Is a class A design inherently better than an A/B design? Disregarding the heat issue with class A amps, what makes them so desirable?

I'm saving my money for a pair of used serious monoblocs. I'm thinking a pair of used Pass X-600 monos or a pair of used Krell 750 monos. On the used market, the Krells are approx twice the cost of the Pass monos.

The Krells are pure class A, the Pass are class A for the first 160 watts, then they go to A/B.
128x128mitch4t
morbius396c
134 posts
 
Jeffrey,

We are NOT splitting hairs - go back and read Steve's post -
where he states, "Class A amps BY DEFINITION amplify
through 360 of the duty cycle. Class A amps ARE NOT
push pull!!!"

A true Class A amp does not have two "mirror-image"
amplifier chains - one for the positive half of the wave,
and one for the negative half of the wave - as is found in
push/pull.

In a true Class A amp, a single amplifier chain is biased
to conduct through all 360 degrees of the waveform.

Dr. Gregory Greenman
ozfly
887 posts
 
Please help me out here. There seem to be lots of conflicting definitions of class A. The references Tripper cites clearly indicate that class A can be a push pull design. Virtually everything I've read in the past here on the Gon also support that. I'm wondering if the definition that Stevechan cites is also consistent with that: The definition for class A reads that "a single output device is possible" -- I would interpret that as "possible", not "required". If someone elects to provide the bias for 360 operation but also elects push-pull, then it may still be class A. The definition for class B indicates that "push pull must be used". That is true. It must be used in class B designs for the full wave form -- and depending on bias, the full wave form may not be reproduced at some volumes even with push pull. I don't believe the definitions are at odds. The definitions per Steve allow for push-pull in A but insist on push-pull for B. That is consistent with the definitions supplied by Tripper. I may be missing something -- besides my mind, which I know is gone ;-)
Ag insider logo xs@2x
aldavis
202 posts
 
My personal experience says yes.I switched to a class A gryphon antileon signature from a very good chrord AB amp which had a much higher output rating.The gryphon has much better low level detail and much more powerful dynamics.It is a true class A amp throughout the signal path.With huge power supplies 150w/8ohm becomes 5000w/.5ohms of pure class A.I believe the pass amps are merely Class A biased and therefore become AB after a certain output is reached.Also be careful of most classA claims.They typically denote bias or dont include output section.In general if its not big and hot its not class A.
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