Power Supply for Hi-Fi Audio Amplifier – Symmetrical Output Including +/-15V DC Output

The power supply has been designed to use for audio power amplifiers. This power supply uses a transformer, a bridge rectifier, various rail capacitors, fuse for protection, also supply has separate dual regulators for +/-15 V DC output.  Maximum output for main audio amplifier +/-42V DC, high voltage output possible by altering bus capacitor voltage. The power supply also provides +/-15 V DC to power up pre-amplifier or other support circuit required symmetrical low regulated voltage. Replace LM7815/LM7915 IC with LM7812/LM7912 if need +/-12V regulated output. NTC used for inrush current at power on. All inputs and outputs provided with Screw terminals for easy connections. Project can provide Load current up to 10Amps for amplifier and +/-15V 500mA for pre-amplifier. R2 and R3 resistor used to discharge the capacitor at power off.

Note 1 : Default Bus capacitor value used for 30-0-30V AC Transformer, For higher voltage output use appropriate capacitor voltage. 

Note 2 : Short the EMI transformer T1 terminal using jumper wire as shown in circuit  (Transformer not required for Audio amplifier)

Note 3 : Advisable to use Chassis earth connection, Tie ETH terminal to amplifier chassis


  • AC Input 30-0-30V AC 10Amps Center Tape Transformer
  • AC Input 12-0-12V 500mA
  • +/-42V, 10Amps DC Output ( Unregulated)
  • +/-15V , 500mA DC Output ( Regulated) for Pre-Amplifier and Biasing Circuit