Two amps, one pure class A, other A/B

My little Marantz gets just as loud in Class A mode (25 watts) as it does in A/B mode (95 watts) , even though examples have been measured at 105 watts in A/B. Also sounds a heck of a lot better in Class A. Kid Rock sounds better (?) in A/B , Miles Davis sounds better in Class A.

It depends if one's a Carver from the 80's in Class A, and one's a set Marantz Mono's in AB, I'd go with the Marantz. It all depends. A/B is the ultralinear circuit, which has slightly lower losses and higher power. Class A has slightly less efficient power, higher lossyness in the circuit, and a lot of the time still makes better sound through brute force.

A prime example of this is the Forte Model 4a and the Forte model 6. The intended design was the 4a outputing 50w in class A and sounding smooth as silk. The marketing guys at Forte felt is would be easier to market and sell a 250 w amp (125/side class A/B) than a 50 w amp, and demanded the higher wattage version. Both were reviewed in Stereophile, the reviewer prefering the 50w model 4 (the "a" model allows for balanced inputs) to the model 6. Closer matching of the output transisters was needed for the 4 vs the 6, but other than that and the wiring, the parts between the two models were identical. The class A model 4 runs warmer of course. Check out the review. Happy Listening

Sashav I apologize for hijacking your thread .

Can anyone describe the difference , in sound , between class A and class B ?

Thank you .

If you have the same power supply and components I would expect the bass to be similar. Typically an amp biased into Class A will produce about 4 times the power in Class AB. I remember some Forte amps that had the same components but the Class A amp made 50 watts and the AB made 200 watts. I have two different Essence amps, one a pair of monoblocks heavily biased into Class A and the other a stereo amp running much cooler in Class AB. The A amp produces better bass mainly because it has a much bigger power supply. It also is more full-sounding and has better dynamics. The AB amp has more speed and detail.

IMHO, flabby bass is not dependent on power output. IF everything except power output are the same you'd still have flabby bass. With the 50wt'er you might have less bass, on the level of 4 to 5 db, but not tighter bass. And the 50 wt'er might be smoother.