18W音频放大器电路

18W音频放大器电路

Amplifier parts:

P1 = 22K Log.Potentiometer (Dual-gang for stereo)

Notes:

Can be directly connected to CD players, tuners and tape recorders.

Don't exceed 23 + 23V supply.

Q3 and Q4 must be mounted on heatsink.

D1 must be in thermal contact with Q1.

Quiescent current (best measured with an Avo-meter in series with Q3 Emitter) is not critical.

Adjust R3 to read a current between 20 to 30 mA with no input signal.

To facilitate current setting add R8 (optional).

A correct grounding is very important to eliminate hum and ground loops. Connect in the same point the ground sides of J1, P1, C2, C3 C4. Connect C6 at the output ground.

Then connect separately the input and output grounds at the power supply ground.

Technical data:

Output power: 18 Watt RMS @ 8 Ohm (1KHz sinewave)

Sensitivity: 150mV input for 18W output

Frequency response: 30Hz to 20KHz -1dB

Total harmonic distortion @ 1KHz: 0.1W 0.02% 1W 0.01% 5W 0.01% 10W 0.03%
Total harmonic distortion @10KHz: 0.1W 0.04% 1W 0.05% 5W 0.06% 10W 0.15%

Unconditionally stable on capacitive loads