Product Details:
DIY Kit: You need to weld and assemble by yourself.
Power 25W
Voltage: about ±23V
PC size: 260*45MM (manual measurement, slight error)
Quasi-mirror layout, 99% of the original machine wiring.
2SK370 and 2SJ108 differential tube input, high power tube IRF240 and IRF9240 tube output.
P2 adjusts the midpoint, and P1 adjusts the current.
When the single tube current is 450mA, each channel outputs 25 watts of class A power (8 ohms).
3 pairs of large tubes per channel.
Distortion @ 1 watt .05% @ 1 KHz
Input Impedance 47 Kohm
Damping Factor 40
Output power stereo 8 ohms 25 watts @ 0.5% THD, 1KHz
Voltage Gain -0.3 dB
Maximum unclipped output +/-20 Volts
Maximum output current 5 amps
Frequency response - .5 dB @ 0.1 Hz, 200 KHz
Noise 50 uV unweighted, 20-20 KHz
Debug instructions:
First install a pair of high-power tubes, check the components for welding and installation errors, especially the directional components, and then power on the test.
Measure the midpoint voltage, use the voltage gear of the multimeter, and clamp the test leads between OUT and GND. The midpoint voltage is within 1V, which is basically normal.
Then adjust P2 to make the midpoint zero, then measure the current of the large tube, clamp the test leads to both ends of the high-power resistor in front of the large tube, and adjust P1 to make the voltage at 0.2V.
After the thermal engine is stable, adjust the midpoint voltage again. Adjustment of the midpoint voltage may be required multiple times! If you encounter the situation that the adjustable resistance remains unchanged, please power off and check, please do not exceed the adjustable adjustment range!
