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Class A amplifiers amplify over the whole of the input cycle such that the output signal is an exact scaled-up replica of the input with no clipping. Class A amplifiers are the usual means of implementing small-signal amplifiers. They are not very efficient — a theoretical maximum of 50% is obtainable, but for small signals, this waste of power is still extremely small, and can be easily tolerated.

Class A designs have largely been superseded for audio power amplifiers, though some audiophiles believe that Class A gives the best sound quality, due to it being operated in as linear a manner as possible. In addition, some aficionados prefer thermionic valve (or "tube") designs over transistors, for a number of reasons: Tubes are more commonly used in class A designs, which have an asymmetrical transfer function. This means that distortion of a sine wave creates both odd- and even-numbered harmonics. They claim that this sounds more "musical" than the purely odd harmonics produced by a symmetrical push-pull amplifier.

Historically, valve amplifiers often used a Class A power amplifier simply because valves are large and expensive; Many Class A designs uses only a single device. Transistors are much cheaper, and so more elaborate designs that give greater efficiency but use more parts are still cost effective.

JungSon has produced V-88D Valve Class A amplifier, this High End amplifier has all the Class A characteristic and is on sale for Introduction Special for the months of April/May 2007.

For more information, visit V-88D [0]

Photo V-88 inside