Multipin metallic audio connector. (3 pin for normal sound use, 5 pin for DMX, Colour Scrollers etc.). Sometimes called Cannons after the original manufacturer. See balanced line. The UK standard for wiring the 3 pin connector is as follows: Pin 1 (Screen), Pin 2 (+ve / “hot”), Pin 3 (-ve, “cold”). (Xternal, Live, Return).