All phono plugs have three wires just as you described. So my question would be is it OK to use a common ground? By the way, the speakers are not marked + and - and they are mounted 180 opposite each other. In other words + may be on the top of one speaker but on the bottom of the other. I...

Hi, a friend of mine gave me a set of Koss Pro/4AAA headphones to repair. He tried to solder a loose / open connection and made a mess with splatter etc. When I got them three of the five wires in the input ear piece where not attached and he can’t tell me which wire goes where. Three wires from...