How to make a simple and powerful 500 W amplifier

The circuit of this audio frequency power amplifier is very attractive in that it does not contain any microcircuits, is entirely built on transistors, and yet is quite simple and has a minimum of parts. Thanks to several negative feedbacks in the circuit, the coefficient of harmonic distortion at an output power of 500 W does not exceed 0.1%.

Will need

• Power output transistors 2SC5200 and 2SA1943 -
  
• Transistors BD140 and BD139 -
  
• Transistors BC557 and BC548 -
  
• Resistors 0.22 Ohm 5 W -
  
• Capacitors 4700 µF / 50 V -
  
• All resistors -
  
• All capacitors -

500 W amplifier circuit

Almost classic class AB amplifier circuit.

A push-pull amplifier with negative feedback is built on 6 transistors. But a little later, 2 more output transistors will be added for efficient operation and reduced heat transfer.

Rectifier circuit:

The power supply is bipolar, built according to a classic bridge circuit with a tap from the middle point of the transformer.

The transformer produces 32 V on the shoulder; as a result, after rectification, a bipolar power supply of 40 Volts is obtained.

How to make a powerful 500 W audio amplifier

First, let's assemble the amplifier by hanging it and check its operation.Solder resistors to the output transistors.

We assemble the mounted mounting of the entire amplifier.


We solder the rectifier and connect it to the transformer.

Radiators are small; for maximum efficiency, we immerse them in water. This life hack will definitely prevent the output stages from overheating if something happens.

Install a sound generator application on your smartphone. We feed sound from it to the amplifier.

We supply power to the amplifier circuit and check the operation.

The dynamic head moved so much that it could not stand it, began to smoke and failed.
It was decided to move the amplifier to the board and add two output stages in parallel to those available on the same parts.
Solder the transistors to the universal board.

We install the output stages of the transistors on the radiators.

We assemble the entire amplifier according to the diagram.

We connect it to a powerful speaker and check the operation.

This amplifier does not have any protection, so you need to be very careful when connecting, to avoid short-circuiting or overloading the speaker systems.

Watch the video