LM4903/4905 high gain audio amplifier circuit

As shown in the figure, this is the LM4903/4905 high-gain audio amplifier circuit. J1 is a jumper. When J1 is disconnected, pin 1 is connected to VDD and the amplifier works at full power. When J1 is connected, pin 1 is grounded and the amplifier is shut down at micro-power. J2 is also a jumper. When J2 is disconnected, the amplifier IN terminal is suspended and cannot be biased, so the amplifier does not work. When J2 is connected, the amplifier IN terminal is biased and the amplifier works.