Euroack Power

Besides the mechanical size standard of Eurorack modules, there is also a power standard. A Eurorack case usually provides two power rails:

• ±12 V – the most important rail, used by almost all modules. This is a practical compromise that supplies enough energy for most integrated circuits while providing sufficient headroom for classic audio and CV signals.

• +5 V – mainly intended for digital modules. This rail is less commonly used today, because most modern digital chips run on 3.3 V or less, and most designers include onboard voltage regulators to generate the required voltage locally.

Power is delivered via an IDC ribbon cable connector. There are two standard sizes:  

• 10-pin – provides only ±12 V and ground. 

• 16-pin – adds +5 V, as well as bus connections for CV and Gate signals. 

The red (or otherwise marked) edge of the ribbon cable indicates the –12 V side. On most designs, this is located at the bottom of the connector (and should be clearly marked on the PCB if it’s different). This becomes especially important if the IDC socket is replaced with a 0.1″ (2.54 mm) pin header to save space or cost.