25W Power Amplifier with MOSFET IRF530/IRF9530

This is a MOSFET powered amplifier circuit. The circuit output will be 25 Watt RMS @ 8 Ohm (1KHz sine wave) with frequency response of 30Hz to 20KHz -1dB.

Components Part:

R1, R4 = 47K R2 = 4K7 R3 = 1K5 R5 = 390R R6 = 470R R7 = 33K R8 = 150K R9 = 15K R10 = 27R R11 = 500R R12, R13, R16 = 10R R14, R15 = 220R R17 = 8R2 - 2W Resistor R18 = R22 - 4W Resistor (wirewound)

C1 = 470nF/63V C2 = 330pF/63V C3, C5 = 470µF/63V C4, C6, C8, C11 = 100nF/63V C7 = 100µF/25V C9 = 10pF/63V C10 = 1µF/63V Q1-Q5 = BC560C Q6 = BD140 Q7 = BD139 Q8 = IRF530 Q9 = IRF9530

Circuit Notes:

• This circuit dual polarity power supply to supply the amplifier.
  
• This audio amplifier can be directly connected to CD players, tuners and tape recorders. Just add a 10K Log potentiometer (dual gang for stereo) along with a switch to cope using the different sources you need.
• Q6 and Q7 must have a small U-shaped heatsink.
• Q8 and Q9 must be mounted on heatsink.
• Adjust R11 to set quiescent current at 100mA (best measured with an multimeter connected in series to Q8 Drain) with no input signal.
• A correct grounding is very important to eliminate hum and ground loops. Connect to the same point the ground sides of R1, R4, R9, C3 to C8. Connect C11 to output ground. Then connect separately the input and output grounds to power supply ground.