Audio Amp Schematic — 2n3055

as these transistors generate significant heat during operation. emitter resistors to provide thermal stability. Feedback Loop A resistor (typically ) connects the output back to the input stage.

They boost the signal enough to "drive" the heavy-duty 2N3055s. 2n3055 Audio Amp Schematic

A small-signal transistor (like a BC547 or 2N2222) acts as the initial pre-amp/differential pair. The BD139 and BD140 transistors form a complementary pair. 2n3055 Audio Amp Schematic