Testing the Class A Preamplifier with Class AB audio amplifier 

Let’s break down each part of this: “class A” is a type of amplifier circuit that reproduces the whole audio signal. This is different than a “class B” amplifier which only produces the top or bottom of the sound wave. class B amplifiers are used two-at-a-time so one reproduces the top while the other reproduces the bottom. Class A has the highest fidelity reproducing both together because there is no “crossover distortion” or, more simply put, imperfections when joining the top and the bottom signal from the class B style circuit. The negative about a class A circuit is that it uses much more power and thus creates more heat. “Discrete” that means that the primary circuit for the mic pre uses individual components that are selected for the best combination from the point of view of the designer (the components are separate, or “discrete”). For example a tube, op-amp, or transistor are examples of a discrete components found in a mic preamplifier. Alternatively an integrated circuit (“IC”), or “microchip”, is a small package that contains a very dense layout of semiconductor components. There is a deeper meaning to whether a mic pre, compressor, or converter is class A and what that means to you, the purchaser: A class-A, discrete piece of gear was most likely designed to be higher-end with less compromise than the average integrated circuit design. Though, a poor design can still be marketed as “class A, discrete” because a popular thought is that to be of a certain quality a microphone preamp must be both class-A and discrete.

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