MIDI Out For A Korg CX-3 Organ


[Michael] loves this old organ of his, but recently he wondered if it would be possible to add MIDI out without altering its original functionality. With a bit of research and more than a bit of hard work he accomplished his goal.

The nice thing about working on a quality piece of hardware like this is the resources you can find regarding how they work (which we bet is tailored for how to repair them when they break). [Michael] found a website with plenty of info on the circuit boards and how they work. From this he was able to locate a few chips which stream serial data regarding which keys have been pressed. Bingo!

Once he located the three signals he was after he built a board to translate them to the MIDI protocol. His circuit is based around an ATtiny2313. It is supported by a liner voltage regulator circuit as well as a buffer chip which converts the incoming signals to the 5V levels needed. His home etched board is clean and well mounted, and the success of the project can be heard in the clip after the jump.


5 thoughts on “MIDI Out For A Korg CX-3 Organ

  1. I assume that it would be either or both. Nothing disables the normal path of sound, just an additional source of note data.
    Next question. Can he send drawbar data to external engine, Leslie state. Next hack.
    Congratulations on putting midi on a mux’ed organ. There are kits, they are made for DC voltage per note, This is useful on church organs as a means of expanding sound palate. The mechanical action of most new keyboards is poor compared to even the mux’ed stuff of the 80’s. Fatar etc. yet alone a good full console 32 pedal organ.

    1. @echodelta Can you recommend a kit or two? I have a friend that has been bugging me with his organ for something similar. I had looked at a couple of newer models, but never pulled the trigger. The organ is a Bontempi portable and it is indeed muxed and would be easy to tap off of at any number of areas. It has the dead wire paperclip style keys iirc. Originally, he was just getting it running again so I merely had to clean decades of grime from the wire contacts (one of the easiest key cleans ever lol btw). Anyhoo, if ya can recommend a kit I would greatly appreciate it as you seem to be the resident organ guru :)

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