A compendium of useful audio amplifier circuits for the experimental constructor.

Whatever their particular area of interest, most electronics enthusiasts encounter the need to amplify and reproduce audio signals. The final stages of radio receivers, intercom units, security and surveillance installations, or just a hankering for a big sound from a Walkman or portable CD player, all involve audio amplification and a speaker system. And the amplification usually goes hand-in-hand with some form of signal processing.

Music reproduction calls for a wide frequency response and tone-control circuitry. Speech communication, especially under difficult conditions, is greatly clarified if the frequency response is curtailed.

This short series of articles describes simple, but effective, ways of meeting these different requirements. Although the circuits are capable of a good standard of reproduction, they will particularly interest the constructor who looks for plenty of performance per pound or dollar.

We begin with the power amplifier. Six alternatives are given and, with the requirement of maximum performance for minimum cost and effort, they are all based on widely available integrated circuits (ICs).