This machine is Huang Sheng's old-fashioned combined amplifier, which has been used for many years. The MlC sound of the power amplifier is not loud, and the potentiometer may not be adjusted properly. Small knobs for controlling the volume of MlC ports should all be set in the middle of 12, which should be consistent. There is also a potentiometer behind the power amplifier to control the MlC volume, which is also adjusted to 12. Besides, don't turn the high notes too loud. When the volume is too high, it is easy to produce squeaky and harsh sounds.

After adjusting these items, you can control the volume by operating the MlC master knob. But if the volume is still too low and the music is normal, it may be that the MlC anti-noise board in the power amplifier is broken. This circuit board is used to prevent the microphone from howling and screaming at high volume, and also to control the volume. The fault is not easy to repair. You can find a friend who is familiar with the power amplifier to check it for you.