This is the circuit diagram of 70W OCL power amplifier with output power of 70 watts single channel. It uses power transistor TIP2955 and TIP3055 as main component. The power supply used for this amplifier is a symmetrical / dual polarity power supply with output voltage 25V – 32V. This amplifier dan be used to drive the 4-16 Ohms loudspeaker. For stereo sound system application, you need to make two similar circuit and use 5A transformer for power supply.

What is OCL Amplifier?

An OCL amplifier (output capacitor-less amplifier) is any audio amplifier with direct-coupled capacitorless output. Typically, OCL amplifiers can be any of several amplifier classes, and typically have a push-pull output stage (wikipedia).

Advantages of OCL amplifiers over capacitor-coupled amplifiers include:

1. Avoiding the cost and bulk of an output capacitor
2. better immunity to motorboat oscillation
3. larger output power at very low frequencies and DC

I wish you luck with this 70W OCL power amplifier project.