AB Class Live Power Amplifiers

Buckle in, class: it takes a bit of an amp history lesson to get a good feel for where AB-class live power amplifiers fit into the pro audio landscape. It all started with the simplest and earliest style, which many pros still consider the best-sounding: A-class amps. Their circuits are based on a single transistor, and that creates a special challenge. In order to get the speaker to sit at rest when there's no voltage going into the amp, it needs to bias its transistor, which means it's using power all the time - even when it's silent! A-class amplifiers have the lowest efficiency of all types, with as much as three-quarters of the power they draw being lost as heat.

To create an amp that wouldn't bake itself from the inside out, engineers developed a two-transistor design that became the B-class amplifier. It uses one transistor for positive voltages (the peaks of the soundwave) and a second one for negative (the troughs), which puts the neutral point right in the middle. But this isn't perfect, either: the lag between transistors creates an effect called "crossover distortion". Fortunately, there's a simple solution - by injecting a little bit of bias back into the circuit, we can eliminate the distortion while giving up only a small amount of efficiency. The result is an AB-class amplifier, delivering almost all the sound quality of A-class with almost all the efficiency of B-class.

Amps in this category are the most common overall, so it's only natural there would be plenty of choices designed for live sound. There are AB-class live power amplifiers here for systems of all scales, from the typical outputs of the QSC RMX850a Power Amplifier and the Cerwin-Vega CV-900 Power Amplifier to the blistering power levels of the QSC RMX850a Power Amplifier and the Behringer EP2000 EUROPOWER Power Amp. Looking for a happy medium? Check out the QSC RMX1450a Power Amplifier. No matter which AB-class amp turns out to be the right fit for you, it's safe to say you can find it here - just take as much time as you need to weigh your options!