◪ 1. Too large noise.
◪2. The speaker input line is not connected with ground line but directly connect to the 100V and 70V.
◪3. The bass volume is too large.
◪4. The MIC volume is too large.
◪5. Impedance speaker connect to the voltage terminal of the amplifier.
◪6. The amplifier is not connected with COM terminal but connect to the 100V and 70V.
◪7. Signal is too large.
◪8. Amplifier is not match with the speaker.
