Connectors

In the UK, the terms jack plug and jack socket are commonly used for the respective male and female connectors. In the US the more fixed connector is called a jack.

Patching
The jacks and plugs commonly used for creating synthesizer patches are the 1/4" (exactly 6.35 mm), the 3.5mm (approx 1/8"), the banana and the 0.141" (3.58mm) Tini-Jax, these are all monophonic.

Midi
MIDI cables terminate in a five pin 180° DIN connector. Standard applications use only three of the five conductors: a ground wire, and a balanced pair of conductors that carry a +5 Volt signal. Some proprietary applications, such as phantom-powered footswitch controllers, use the spare pins for DC power. Opto-isolators keep MIDI devices electrically separated from their connectors, which prevents ground loops from occurring.

External DC connector
The coaxial power connector is the miniature power connector used for attaching extra-low voltage devices such as consumer electronics to external power supplies. Also known as barrel connectors, concentric barrel connectors or tip connectors, these small cylindrical connectors come in a variety of sizes.

3U
For internal power distribution, a Eurorack case typically has a distribution board with 10-pin IDC headers. The 16 pin IDC used by Doepfer includes +5 Volts, Gate and CV as used by a few modules to pass these signals between modules without needing extra patch cables. The power cable is typically a length of ribbon cable with a female 16-pin IDC connector on one end and a 10-pin on the other. Incorrectly connecting one of these connectors can damage the module. The stripe on the ribbon cable indicates the -12V side of the connectors.

See also Comparison of 3U modules

5U
To distribute DC from the power supply to the modules MOTM and Oakley implement a power bus with 4 way MTA-156 headers or 4 way Molex KK 0.156" headers. Synthesizers.com implements a DC cable harness. The harness connects to the power supply by a 4 pin .093 Molex connector while six pin keyed MTA-100 connectors on the harness connect to male headers on the modules, with +/-15V, +5V and a ground shared between these.

See also Comparison of 5U modules