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GMC Forum _ GEAR & PRODUCTION _ Difference Between A Class A And Class Ab Tube Amp?

Posted by: Goliath Dec 5 2007, 07:05 PM

I often see reference to Class A and class AB when looking at amps... what's the difference? Usually smaller tube amps boast as being class A. My guess is 1 channel vs. multi channel?

Posted by: Twibeard Dec 5 2007, 10:14 PM

QUOTE (Goliath @ Dec 5 2007, 07:05 PM)

I often see reference to Class A and class AB when looking at amps... what's the difference? Usually smaller tube amps boast as being class A. My guess is 1 channel vs. multi channel?

Class A amps are the cleanest amps, but output is like 25-50% of the power applied.
Class AB amps are more unlinear, but output are something like 70-80% of the power applied.

Posted by: Milenkovic Ivan Dec 6 2007, 03:02 PM

ALso AB is actually two class B working together in a push-pull relationship, each working on one half of the sine wave, thus combining both you get somewhat something that resembles on a class A. Advantage of AB amps is that they do not disipate the power as much as class A, but they do not have quality sound, since they quickly distort. Class A is usually used for high end tube hi-fi amps since it gives the most purest sound. CLass AB usually in mainstream audio equipment where power comsuption is important and sound quality is important (important only on small levels).

THis is all not expert knowlegde, so if someone who is in the filed can explain it that would be great.