Jack plugs are a standardised, cylindrical plug and socket system used in a wide range of electronics applications. These include low voltage power connections, remote accessories and telephone connectors. The most common use for jack plugs is in audio connections, however, and the 3.5mm plug and socket are the standard connection for headphones. The plug consists of a tip, ring and sleeve connections, which provide stereo audio connectors for a variety of music players.
Solder the positive wire from the left headphone speaker to the tip connection in the body of the jack plug. The tip is the "arrowhead" part of the plug on the very end. It uses the smallest solder tag inside the body of the plug, at the centre of the connections.
Solder the positive wire from the right headphone speaker to the ring connector. The ring is the middle band on the jack plug and uses the solder tag inside the body of the plug that is slightly longer than the tip connection.
Solder the negative wires from both the left and right headphone speakers to the sleeve connection. The sleeve is the largest connection at the base of the plug, and has a long solder tag that reaches the full length of the jack plug's body.
Twist the negative wires from the two headphone speakers together before soldering them to the sleeve. The sleeve is sometimes referred to as the barrel. The ring is sometimes referred to as the collar. Mixing up the left and right channel connections won't do any harm, but will reverse the stereo effect when listening. It's good practice to individually insulate the solder tags inside the body of the jack plug with electrical tape after the wires have been soldered.