Circuit Diagram of 24 Watt Class A Linear Audio Amplifier

This is a circuit diagram for a 24 Watt Class A Linear Audio Amplifier, built and tested by Marc Klynhans from South Africa. The supply voltage can be between 34V and 46V, and the quiescent current measured through R25 should be set to 1.7A (for a quiescent current just under 1.7A, a voltage of 0.75V must be measured across R25). R23 is a trimmer and must be set to maximum resistance (10kOhm) when powered up. The resistance of R23 must then be reduced until the quiescent current is reached. Amplifiers are very safe from thermal runaway if they are mounted on a large enough heat sink (0.6K/W maximum). Intelligence must be used when selecting the power and voltage ratings of resistors and capacitors.

24W Audio Amplifier (Class A) Specifications:

Class 24WA to 8 ohms

100mHz–100kHz flat

305mV input, 24W into 8 ohms (33dB gain)