The MIDI Manufacturers Association (MMA) let us know that they’ve adopted a new a Recommended Practice for the use of standard “TRS” connectors with MIDI devices.
As MIDI devices have gotten smaller, manufacturers like Korg and Arturia have have started using small ‘headphone plug’ connections to carry MIDI. There has not been a standard for this, though, so the manufacturers implementations have not been compatible.
The Recommendation defines how to wire “tip-ring-sleeve” connectors and describes the necessary device circuitry and cable specifications to support MIDI 1.0 compliant electrical connections to DIN-MIDI devices. This will let users connect new MIDI devices using standard stereo cables and also will allow for standard adapters from TRS connections to MIDI DIN.
Here’s what the MMA has to say about the new Recommendation:
The inclination towards smaller hardware devices has made it increasingly difficult to make use of DIN connectors for MIDI In/Out in the past few years. Many manufacturers have chosen to use 2.5mm or 3.5mm “TRS” connectors instead. But since there was no specification for wiring a TRS MIDI connection, the situation exists where two devices may not have chosen the same wiring scheme, so compatibility between devices is not known. By specifying the pin-out for the TRS connection, and also the connectors for the adapter cable, we can ensure greater interoperability between TRS and DIN-MIDI equipped devices.
The official Specification for use of TRS Connectors with MIDI Devices [RP-054] is available via the MIDI.org site.