35W power audio amplifier circuit based on LM391

Here is a 35W power audio amplifier circuit based on LM391. The inductor L1 consists of 20 coils with a line thickness of 0.9mm and a round resistor R16. Transistors Q3-4 are the final amplification part, which should be placed on the heat sink. If Q3-4 is used in the package TIPxxxx, they can be placed directly above the PCB. However, if the transistors are used in the package TO-3, it is assumed that they are connected with short cables at the corresponding positions on the PCB.

Schematic diagram, schematic diagram:

Parts List:

PCB Layout:

Component placement:

Note that this amplifier requires a bipolar power supply. Build the supply using a center tapped transformer with a minimum output current of 2A and an output voltage of 30V, using about 6800uF - 10000uF electrolytic capacitors (elco).