Class AB amps ???

[bob412]

If an amp is classified as class AB , and puts out 50 watts per channel how many of these watts will such an amp put out in class A ?

 

[fiddlefye]

If an amp is classified as class AB , and puts out 50 watts per channel how many of these watts will such an amp put out in class A ?

That would vary with the design and biasing done on a particular unit as well.

 

[river25]

Indeed.

For example, the Yamaha A-1020 (120WRMS per channel IIRC) is Auto Class A/B, which means it will run in Class A mode until the output signal goes over 10W RMS and then it reverts to Class B.

It's a design decision.

 

[Baron K Rool]

Zero.

AB does not mean A first, then B. It's its own class.

 

[tygr]

^^What he said. Some Yamahas run (if selected) in class A for the first few watts then switch to class AB.

 

[guiller]

If an amp is classified as class AB , and puts out 50 watts per channel how many of these watts will such an amp put out in class A ?

I find myself without a clue as to why you are asking this. Could you please elaborate on your motivations? Are you having a specific amp in mind?

PS: FWIW, you may infer from this quote that the answer to your question depends a lot on the particular amp you pick:

Its main characteristics are: In fact, many Class AB amps operate in Class A at lower output levels, again giving the best of both worlds The output bias is set so that current flows in a specific output device for more than a half the signal cycle but less than the entire cycle. There is enough current flowing through each device to keep it operating so they respond instantly to input voltage demands. In the push-pull output stage, there is some overlap as each output device assists the other during the short transition, or crossover period from the positive to the negative half of the signal.

There are many implementations of the Class AB design. A benefit is that the inherent non-linearity of Class B designs is almost totally eliminated, while avoiding the heat-generating and wasteful inefficiencies of the Class A design. And as stated before, at some output levels, Class AB amps operate in Class A. It is this combination of good efficiency (around 50) with excellent linearity that makes class AB the most popular audio amplifier design.

http://en.wikibooks.org/wiki/Electronics/Amplifiers