Actually difference between class A and AB?

Mithch2: "If I were to generalize based on my experience, in an attempt to answer your question, I would say well designed Class A amps, when compared to well designed AB amps, offer “sweeter” sounding high frequencies with less tendency towards grain or harshness, seductive midranges that are generally full and rich sounding with excellent harmonics, as well as being more dimensional..."

TY, Mitch--I could not have written it better nor agreed more. To my 67-year-old (non-Golden) ears, the really good Class-A amps sound just a little bit smoother--less edgy, grainy--but still highy detailed.

I've had (and LOVED) Vandersteen 5As for months. Altho they're relatively insensitive at c. 87dB, a few weeks ago I bought and started using on the 5As two pairs of twenty-year-old Marantz MA-24s.

http://www.dutchaudioclassics.nl/Marantz_MA-24_Music_Link_power_amplifier/

They're rated at 30 into 8 and 60 into 4, and with 4 amps driving the 5As' 6-to-4-Ohm impedance, combined maximum continuous power is around 200. That's plenty enough for me, even in my largish--c. 3200CF--room. These amps never sound gritty, edgy, grainy--and are always detailed and musical. They are indeed full-Class-A and do get hot, but that's certainly manageable in my room.

Class-A is a design tool that I appreciate and can afford, and my Class-A amps sound fabulous to me. Other amps sound great, too, and I don't argue with anyone who chooses not to buy Class-A amps. We're blessed with LOTS of fine-sounding amp to choose from.
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I find that class A amplifiers play bass better as well as being smoother in the mids and highs. They can also be more detailed as they make less distortion.

BTW/FWIW there is no such thing as A/AB. That would simply be an AB amplifier. If you see such designations they are marketing terms, not technical terms.

Athmosphere,

Not quite, the nomenclature A/AB simply denotes that the amplifier operates in Class A up to a certain power level then switches over to Class B. This switch point is determined by the bias.

http://www.passlabs.com/pdfs/articles/leaving_class_a.pdf

Liguy, I have to disagree, despite Nelson's paper. The designation of 'AB' **already** "denotes that the amplifier operates in Class A up to a certain power level then switches over to Class B. This switch point is determined by the bias.", as you put it above.

IOW, Class AB already meant this; it could be class A to 0.5 watts or class A to 35 watts with clipping at 40 watts, either way that is what AB is... Putting another 'A' in front of it thus has no meaning, and is not found in the textbooks. That's why I say its a marketing term.

The Latest issue of The Absolute Sound has an artical that goes through all the different types of amps.
Just got it yesterday, have not read the whole artical yet. Looks like it has some good infromation in it.
Joe Nies