Class A amps

<< I've read a few articles on class A amps but still don't have a good understanding of how it affects sound quality. I've even seen amps which can be swithced into class A mode or AB. Does anyone have experience with this type of unit? Does class A have a true audible advantage or can it be detected only by test instruments? If it is audible, in what resepects? Thanks, Rick M. >> Class A amp will usually give you more detail and smoother midrange but less punch and dynamics. It all depends on what speakers you use and what type of music you like. I am so sure about that because I used to have a Gryphon Antileon power amp from Denmark. This monster amp has adjustable 50%, 75% and 100% class A knob which can be set during play.

Generally, the differences between single ended (class A) amps and push-pull units are very audible: the former have a much wider and more true-to-life soundstage. On the other hand, they tend to dissipate more energy as heat and are therefore usually less powerful than the latter units using the same output tubes or transistors. Tom

The sonic difference between Class A and AB is mostly because the Class A amps usually have better power supplies and regulation, and are also better built (they have to, as they run very hot). However, I have heard Class AB amps that sounded better than most of Class A amps. The switching noise is not hearable in any way with a good Class AB amp. Usually it is easier to make good sound with Class A, but again it only depends upon how well is the AB one designed. In my experience good class AB push-pull transistor amps usually sound better than SE units. The same is true with tube amplifiers: Class A is not necessarily better than class AB. Even when using the same topology or the same tubes, one amp can be world-class and can be mid-fi. As a conclusion: usually class A amps sound good, but not necessarily _very_ good. Speaker-cable-amp interaction is more important than the class of the amp.

In class a amp's amplification is don by just one transistor in the output stage, where class b amp's have two transistors sharing the job. One transistors handles the plus, the other the negative part of the sinus. There is, however, a small area where they both work. This can cause cross-over distortion. A class a amp will be cleaner, without this distortion. Dis-advantages are that they run very hot, do not have a high output (generally speaking) and are expensive. The difference between a good class a and a good class b amp should be quit audible though.