Class A and B differences?

I've owned amps that were rated class A up to a certain output and then transitions over to class AB. I can't say I've have heard much of a difference. Basically, class A amps have their output devices on all the time, where as class B devices are on only 1/2 the time. One device handles the positive waveform and another handles the negative. The crossover point is where distortions can occur. Whether it's audible or not depends on the resolution of your entire system. Not to nitpick, but when you mention class B I believe you are refrring to class A/B. Class B amps are very efficient but would not really make a good audio amp.

Jim

The differences between various classes of amps can be very confusing, to say the least.

My take is this: For an amp to be rated class A, it's output devices (tube or transister) must be turned on all the time. Class B output devices are on 1/2 the time. Fact is, most amps are class A/B which is not, I supose, a separate class, but rather a combination, and their output devices are on more than 1/2 but less than always on.

Then to cloud the issue even more is the class G and H amps. Of course these are not really classes by themselves. Instaead, they use some sort of sliding bias or other means to make their power ratings appear higher than they really are. This is not necessarily a bad thing, I've owned such amps. Soundcraftsmen and Parasound are two such amps and I am sure there are many others. What about amps with switching power supplies? I think these are called class D and I am sure these are not normaly used in audio.

Jim

I sort of misunderstood your original question about classes of amps. I personally take with a very large grain of salt the Stereophile class ratings. I understand their attempt to rate components, but to think that a class A versus class B component will have a quantifiable difference in sound quality is, in my opinion, not going to happen.

Of course, if I could afford some of the A rated components I would probably own them if for no other reason than pride of ownership.

Jim