Introduction:

Symasym5-3 Power amplifier is a very well-known circuit on the DIYAudio forum. The number of clicks on the circuit’s posts is still very active. It has ultra-low distortion when fully loaded, and the sound quality can be said to be very good. It has a power of 100W (4 ohms) per channel. It is very suitable for home use, suitable for driving high-power HIFI speakers above 6.5 inches. The circuit works in high partial class A and B, without noise and current sound. The production is simple, and the circuit is stable and reliable. Voltage feedback, suitable for HIFI players to grinder.

Status: Class AB

Output power:

                         200W + 200W 2Ω

                         150W + 150W 4Ω

                         100W + 100W 8Ω

Input voltage: DC +/-35V --- +/-45V (Recommended DC +/-40V)

THD: 0.002% 1 KHz Full power

          0.005% 10 KHz Full power

Power Out transistor: ON NJW0302/NJW0281

Drive tube: Toshiba 2SA1930/2SC5171

Small signal transistor: MPSA18/2N5401/2N5551/BC546

PCB Size: 138mm * 50mm

DIY Kit debugging instructions:

Set the multimeter to the DC mV position, measure the two ends of any white cement resistor with two pen tips, adjust the blue 500R adjustable resistor, and use the white cement resistor with a voltage of 15---22mV at both ends.