Class A, B, C? What do they mean?

Class C amps are used mainly in RF amplifers ie from
around 5Mhz to 1Ghz. After a 1Ghz you start using wave guides for amplification of a small voltage signal. Ham
operators use them. I do not believe it a distortion
problem per se, but a question of turn on/ turn off. A class
C is either turned on to MAX output or turned off. In
order to attenuate the signal you use a filtered network,
which would in that case cause distortion. But a ham operator, wants power on, and on full.

Sean: In power amplifiers operating at radio frequencies distortion of the rf waveform is relatively unimportant.
RF amplifers usually operate with tuned circuits and the
selectivity of such circuits filter out the rf harmonics resulting from distortion. Of course, a wideband class C
amplifier has tremendous amount of distortion, because the
operation angle is less than 180 degrees. A push-pull
amplifier operating at pure class B is exactly 180 degrees
and you take the the two waveforms one from the push and
one from the pull and add to give a 360 degree waveform.
A class C amp since each side of a push-pull is less
than 180 degrees can never give a 360 degree waveform, thus
the huge amount of distortion. A Class A amplifiers since
by definition gives a 360 degree waveform,does not need
a push/pull to define a full waveform. You only need one
output tube for class A operation, two for class AB or B
operation

Sean: Have you ever seen an AF Class C amplifier? I have not. RF amps, in particular, pulsed nuclear magnetic resonance instrumentation, I have seen many. Ham operators,many. Nada for audio.

I think the new Rowland Amp 301 is a class D or H switching
amp. So how does an audio company who makes class D amps
get around these problems. I assume the faster you oversample the better, but how much I am not sure. I assume
you would have to decimate the data back into the audio
frequency, again I am not sure. Does anybody know????