4 Conductor Endpin Jack Socket, Can be Tightened from Outside the Guitar

Typically your output wire will come from the switch if you are wiring the socket into a Fender Strat or Gibson Les Paul. Some other instruments will have the output wire coming from the volume pot. This wire is then sent to the hot or positive tag on the jack socket. The earth wire is connected to the ground / negative tag on the socket and is then soldered to the back metal casing of one of the pots.