Schematic Drawing
Some modifications are recommended to improve this amplifier's performance.
Alternate Schematic Drawing (same circuit with mods[rev2])
With a +/- 30v dual power supply you get 64 watts output into a 4 ohm load. This test includes the above modifications and the test was done with the smaller (TIP142, TIP147) TO-220 80 watt power transistors. Most darlinton power transistors will work for the output. You can parallel output transistors, but it is best to add another pair of 0.33 Ohm resistors into the circuit.
Consider using the Current Limited Split Power Supply for Audio Amplifier
The following is a Circuit board designed for this circuit.
This layout employs PCB pattern that supports both the 80 watt and 125 watt output transistors.
Photo of actual circuit board of the 100 to 150 Watt Amplifier.
Some modifications are recommended to improve this amplifier's performance.
- Change R5 and R3 to 3.3k ohm to center the clipping point.
- Add C4 and C5 to reduce high frequency instability.
- Add C6 and C7 for power supply rail bypassing.
- Change R2 to 2K to reduce gain and increase stability.
Alternate Schematic Drawing (same circuit with mods[rev2])
With a +/- 30v dual power supply you get 64 watts output into a 4 ohm load. This test includes the above modifications and the test was done with the smaller (TIP142, TIP147) TO-220 80 watt power transistors. Most darlinton power transistors will work for the output. You can parallel output transistors, but it is best to add another pair of 0.33 Ohm resistors into the circuit.
Consider using the Current Limited Split Power Supply for Audio Amplifier
The following is a Circuit board designed for this circuit.
This layout employs PCB pattern that supports both the 80 watt and 125 watt output transistors.
Photo of actual circuit board of the 100 to 150 Watt Amplifier.
