MidiThru is an active MIDI splitter useful for distributing MIDI clock and powering MIDI devices through MIDI connector.

There are two variants available: original 1 to 5 and MidiThru x2 which is two 1 to 5 MidiThru combined.

MidiThru_v02_built (small)


Both are easy to build, inexpensive and very useful MIDI gadgets. A must have for any non trivial MIDI setup.

42 thoughts on “MidiThru

  1. Pingback: MidiThru | Futuredraht

  2. Hey Peter,
    I love this kit, but do you have a solution for a midi merge situation? It appears that this is a 1 to 5 out but I would love to construct a 4, or 5 into 1 output format. I can’t seem to locate any projects online, maybe you know of a source for a DIY kit? thanks!

  3. This is a nice and compact solution, good work! Will it be difficult for a beginner to build this with just 3 MIDI outs? Will I just have to drop 2 of the MIDI out connectors and their corresponding resistors and inv Hex Schmitt Triggers? Or would I have to change the supply voltage or something?

  4. Thanks for your instant reply! Excuse my slurry wording, sure the triggers are part of the IC which I just have to leave unconnected…

  5. Hey, would this work for note data? I’d like to utilize more midi synths with out buying equally more midi keyboards (I already have one nice one I paid to much for to begin with). I’m already planning on making one for my drum machines, but I’d love to make 2 if it works for note data as well!

  6. …to anyone considering ordering this board and building the midi thru โ€” the components are easy to find and inexpensive, its easy to build, and the finished unit works flawlessly. Highly recommended!

    • Agreed! This was my first build where I just bought the PCB and sourced all the parts myself so I was a bit out of my comfort zone but I had absolutely no problem getting this up and running in about an hour tonight! Thanks Peter! Excellent work!

      • Any plans to produce this case? I’d love to build this but I’m terrible with cases and don’t have access to a laser cutter for the acrylic. The cases on your other kits look great! Thanks!

      • At this point i don’t have a case for MidiThru. Even if i’ll come up with one, it’s not going to be a full box case. The plan is to use a “sandwich” case with only top and bottom plates.

  7. Do you think the existing regulator and the first trigger could drive 20 outs of I just continued to attach triggers in parallel? I only ask because you might have the network values worked out already, save me some time and brain power ๐Ÿ™‚

    • I did not try this, however it should be possible, because connecting 4 inputs to 74LS output is not a problem, and 78L05 has enough current capability to power 5 ICs.

  8. This midithru will be my first attempt at building a real through hole project, I’ve practiced my soldering technique on a handful of beginner soldering kits. Any suggestion on which components to install first? I plan in building Midirex after this .

  9. Hey,
    Just wondering, why would you put SN74LS14N (which is an inverter) to revert midi in and then revert it again afterward?
    I don’t really get this part logicwise, eventhough I guess it’s about electronical matter that I don’t really understand. Could we only use an AOP in all midi input ?

      • I guess AOP is the french word for operational amplifier. I do understand why do you need the schmitt trigger, I was thinking that it was only an inverter.
        Anyway thanks for the schematic, I think I will have the use for it very soon :p!

  10. Hi,
    I’m interested into building a thrubox kit but I would better have it 1->8 minimum.
    Ive read I could use 2x hexinverter To do so.
    Could I somehow make it with your pcb ?
    Do you have any schematics or pcb files to make it happen ?


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