This HiFi headphone amplifier circuit is a series that has been designed specifically to drive headphones that have not too high impedance. Headphone amplifier consists of a High quality op-amp and two transistors as an additional amplifier.
The signal input from the source will enter the low pass filter circuit consisting of C1 and R1. Use of Op-Amp IC LF356 will benefit the generated signal has a very low distortion.
The standby current is set by the diodes D1-D4, R7 and R8. R3 and R4 will serve as feedback that will generate gains of 15dB. Frequency response of the amplifier circuit is the range of 10Hz to 30KHz.
Because the headphone amplifier circuit is used to drive the headphones, it does not require great power to operate. This amplifier is capable of producing 1 watt at 8ohm loudspeaker load, with the input sensitivity of 500mV. This amplifier circuit can also produce sound with very well with headphones has an impedance of 32ohm.
The voltage necessary for the circuit to operate is 6-8VDC. To prevent the transistor from damage, it is recommended to use a heatsink on the second transistor so that the heat can be channeled.