25 Watt MOSFET Audio Amplifier Circuit

This high quality 25 Watt audio amp can be connected directly to CD players, MiniDisc Players, Tuners, Cassette players, etc. without the need for a preamplifier.

The page also features the circuit diagram for an ideal dual-rail power supply, with +33 VDC and -33VDC power outputs.

The main transistors in this audio amplifier circuit are:

• Q1-Q5 - BC560C 45V 100mA Low noise High gain PNP Transistors
• Q6 - BD140 80V 1.5A PNP Transistor
• Q7 - BD139 80V 1.5A NPN Transistor
• Q8 - IRF530 100V 14A N-Channel Hexfet Transistor
• Q9 - IRF9530 100V 12A P-Channel Hexfet Transistor

• Output power: Well in excess of 25 Watt RMS @ 8 Ohm (1KHz sine wave)
• Sensitivity: 200mV input for 25W output
• Frequency response: 30Hz to 20KHz -1dB
• Total harmonic distortion @ 1KHz: 0.1W 0.014%, 1W 0.006%, 10W 0.006%, 20W 0.007%, 25W 0.01%
• Total harmonic distortion @10KHz: 0.1W 0.024%, 1W 0.016%, 10W 0.02%, 20W 0.045%, 25W 0.07%
• Unconditionally stable on capacitive loads