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 forms 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 boot-strapping 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 loud speaker.
- IC1 must be fitted with a proper heat sink.