Many electronic circuits dealing with audio amplifier circuits have been published here. This is just another one and here we use the TDA 1514 high-performance hi-fi amplifier from Philips. The IC has a bunch of useful features like thermal protection, mute-standby facility, low harmonic distortion etc. The amplifier operates from a dual +25/-25 V DC power supply and can deliver 40Watts output power to an 8-ohm speaker.
The audio signal to be amplified is fed to pin 1 of the IC and the capacitor C2 acts as a DC de-coupler. The resistors R3 and R4 determine the closed loop gain and it can be varied between 20 and 64 dB. Resistor R2 and capacitor C4 form a Zobel network which corrects the loudspeaker impedance and improves the frequency response. Resistors R7, R6, and capacitor C5 are the boot-strap elements. If bootstrapping is not needed then these components can be omitted and the pin7 can be connected to pin 6, but the output power will be reduced by some 10%. R1 is the input bias resistor and it has an effect on the input impedance.
- Assembling the circuit on a good quality PCB will improve the sound quality.
- Use a +25/-25V DC, 4A dual power supply for powering the circuit.
- K1 can be an 8 ohm, 50W loudspeaker.
- IC1 must be fitted with a proper heat sink.