Stereo audio power amplifier

How it works

This circuit raises a low-level stereo signal to a level suitable for driving loudspeakers. Each channel needs a stable supply and a suitable speaker load. Keep the input wiring away from the high-current supply and output wiring to reduce hum and feedback.

The original description calls this a 22 W amplifier and estimates a 5 A supply requirement at full output. Treat these as design notes, not measured specifications: actual output depends on supply voltage, load impedance, distortion, and cooling.

On the bench

Fit the amplifier IC to an adequately rated heatsink before applying power. Start with a current-limited supply and low input level; check idle current and temperature before connecting speakers.

Resources & provenance

Rewritten from the original circuits/aum/lj3on1t_aum001.php page. Component values and historical performance claims have not been independently bench-tested. The circuit figures have had their watermarks removed.