MIDI Connections Have A New, Smaller Standard

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.

28 thoughts on “MIDI Connections Have A New, Smaller Standard

  1. I acknowledge that several manufacturers have been using this style and so this is codification of an existing practice.

    However, it is a terrible terrible idea.

    MIDI signals are not electrically compatible with stereo audio signals. Using the exact same jack and cable for both is a bad design practice, a bad engineering practice, and will be the source of countless problems. It’s just bad all around.

    1. But if I understand this, manufacturers are already doing this, so it just standardizes the wiring so it will work.

      But yea, it would make sense to use a different type of small connector that couldn’t be mistaken in a rush or dark room situation. If they could make one that is robust.

      It’s a little ironic that Apple starts getting rid of 3.5mm stereo jacks for various “issues” while some manufacturers embrace it as a small format MIDI connector.

      I like headphone jacks, though I have had a few problems with them over the MANY years. I like MIDI din jacks, but I can see how they are too big for tiny devices.

    2. Eurorack systems use 3.5 mm connectors for audio, control voltage and gate. None of these are theoretically compatible, but people work it out.

      For years synths have used 1/4” connectors for audio, sync trigger pulses, TRS volume pedals, momentary footswitches, CV/gate and headphones.

      Somehow we trudge onward.

      I think you’re overreacting.

    3. Well the original MIDI connector was also the same plug as an already existing audio connector, the 5-pin DIN plug. Widely used for audio, at least in Europe. And that worked fine.

        1. yeah… I’ve got a DIN-wired HiFi, and the connectors are identical. Also, I don’t think mixing up the connectors is too much of an issue; voltage levels are all low enough not to cause issue with each other, and MIDI is opto-isolated on the input too, pinout is the same RE signal/gnd etc. Not sure what would happen if you plugged output to output, but that can happen on both audio and midi anyway, so I doubt it’d release the magic smoke.

    4. Can you elaborate on some of the “countless problems” you’re predicting? My only experience with such a setup is my Chase Bliss pedal but I’ve had zero problems with it recognizing the midi signal from my controller.

      I’d argue that using TRS jacks has advantages such as smaller footprint, removing the pain of lining up the pins, zero chance of bent pins when there are zero pins, good quality TRS cables are relatively cheap and practically ubiquitous in any studio, club, TRS cables/jacks have proven to be very durable and (as long as a manufacturer doesn’t block access) replacing bad jacks on equipment isn’t terribly difficult.

    1. There’s nothing stopping companies from using USB – but today’s announcement has absolutely nothing to do with that.

      Today’s announcement is just about standardizing how connectors are put on the ends of a wire. Standardizing this means that you can connect a modern device to 30 year old synth with a cheap MIDI wire and that you can make cheap cables and adapters to handle this.

      USB is completely different – it doesn’t natively send MIDI, it connects two computing devices.

    2. USB-C seems like it would be fine in a studio but in a live rig I wouldn’t trust the jacks and thin cables to be plugged/unplugged frequently. Current USB MIDI implementations always seems to require a computer or special box to make the connections between gear.

      1. USB is a hub-and-spoke network. The hub is always a USB host device, connecting to devices at the end of the spokes. Note that you can’t connect two hosts via USB nor can you daisy chain the connection. USB as a MIDI carrier is just for convenience, it’s like having an interface built in.

        Regular MIDI is more akin to plumbing because the signals go in specific directions (in/out) and can be split (thru), and like a telephone trunk wire with individual channels…

  2. this has been sorely needed for a while. It seems like the MMA is a few years late with this but I guess better late than never

  3. The strength of MIDI is it’s backwards compatibility. The power of a data connection between gear from the 80’s into something some maunufacturer released last week. Always keep that in mind.

  4. Makes sense to me. My own MIDI projects (Open Theremin and Breath controller) use 3.5mm wiring to this spec as it’s just so convenient and compact. I *think* Arturia Beatstep pro uses an alternative wiring, as I had to make my own 3.5mm to 5-pin DIN adapters.

  5. If this means more “midi” (read: usb) controllers will have ACTUAL midi ports, then I’m all for it. No more plausible, but totally fake excuses that, “there was no room for full midi ports.”

      1. I appreciate your statement, as I too like my hearty DIN midi connections. I wouldn’t go so far as to not purchase something (Beatstep Pro, Electribe 2, Circuit, etc.) because they decide to scale down their connections. I think that rationale is short-sighted.
        Plus, I like the option to use a standard 3.5mm headphone jack splitter as a MIDI signal splitter.

  6. MIDI din plugs are appalling. The standard originally called for 3 pin cannon plugs, only octave plateau used them in the voyetra8. Now a new standard to try to solve the current mess. Now we have 4 midi connections, cannon, din, USB and stereo mini jack, what next????

    1. What exactly are you complaining about?

      MIDI isn’t a cable type, it’s a standardized format for serial data.

      We have completely cable-less MIDI-over-WiFi and MIDI-over-Bluetooth, we could send MIDI using IR, or tightly timed laser pulses, or gravity waves…. we could send MIDI (slowly) using Morse Code, semaphore or smoke signals if we really wanted to.

      Cable types are really about practicality and convenience.

      XLR was recommended, but as you yourself noted, only one synth (a vanishingly rare one, at that) ever used it. I’m guessing people thought it wasn’t really a good idea to have cables that could potentially be confused with a different type, for fear of frying their gear.

      5-pin DIN far and away is still the leading standard.

      USB isn’t really for connecting MIDI devices between each other, it’s just a practical way to avoid having to use a USB-to-MIDI interface in between an end device and a computer. Its network topology is not a daisy chain like MIDI, it’s hub-and-spoke, so it can’t really be used ‘freeform’ like regular MIDI cables can be. It’s a popular adaptation but it merely complements the existing standard.

      Stereo minijack is just a practical accommodation of the plug size, for devices too small to support a full-size DIN port. Those kinds of cables are inexpensive and common, so that makes it good for musicians; it isn’t hard to splice one to a regular MIDI cable if you need to make an adapter, now that the pinouts are standardized.

      You claim there is a “mess?” I disagree. I see one big standard that dominates, that is getting an official blessing for a miniature plug type, after 35 years. Hardly appalling, more appealing.

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