The system switching circuit of the 12-channel audio switcher adopts high-reliability electromechanical relays to maintain the integrity of the signal source and the input signals of the tested equipment. This series of products have excellent crosstalk characteristics, and the balance mode at 20KHZ is less than -150db. The signal interface control and switching operation of the audio switcher are integrated into ATC control software, and fast switching between corresponding channels can be observed from LED indicator lights.