Professional MIDI Guide
MIDI Tie Lines
When installing permanent wiring remember to allow for free cables up to two metres each end; this restricts the fixing wiring run to less than 11 metres. Longer distances will require a Long Haul Converter.
Do not connect the screens of cables together, e.g. on the connector panel or at a passive patch field.
Do connect the chassis to to a safety earth, especially if mounted on plastic blanks. Remember that the cable plug shell is not otherwise connected.
The original SCI MIDI proposal allowed for the use of XLR connectors instead of DIN 5 pins, with the provision that the equipment manufacturer should supply the adapter cables, and then neglected to define a pinout. Here is a cable that is compatible with our MIDIZ Long Haul driver for up to 100 metre cable runs (longer runs will require the full system).
Care should be taken to prevent the possibility of connecting MIDI and transformer coupled balanced audio together. A MIDI Out is capable of driving a current through a 600 ohm or less transformer and what that can result in doing to HF voice coil or an expensive microphone capsule doesn't bear thinking about...