Jack Cable

Jack connectors are popular for musical instruments. they are available as 2 pole or 3 pole versions. (TS or TRS). 3 pole (TRS) versions are sometimes used to transmit stereo audio (a left and right channel with a common ground) but in pro audio it is more common that the TRS type jack is used as a balanced connection.

Jack connectors are often used as Insert Points on Mixing Desks where the send and return of an insert point are made on the tip and ring (T and R) of the jack. This connection shares the common ground (Sleeve (S)).

Jack to XLR3, Jack to Phono, Jack to Jack socket are frequently found.

Standard jacks are 6.35 mm jacks.
Mini jacks are 3.5mm and 2.5mm versions are available.

Jack plugs are sometimes used for speaker connections in some smaller setups. Again this is often frowned upon due to the male connectors having live terminal showing. In larger applications there can be several amps transmitted through a Speaker Cable.

Polarity (Phase) Reverse

The Tip and Ring on a balanced jack are reversed. Some mixing consoles have a switch on inputs and sometimes outputs which will do this job. Otherwise this type of lead is needed.

A microphone on the bottom of the snare would normally need to be the inverted polarity of the one on the top of the snare. If no switch is available then this type of lead would be useful here.