Open source electronic musical instruments designed in London.
DIY Eurorack Module

Supply: 75mA
Size: 4 HP
Depth: 40mm

Modular Grid
License: CC-BY-SA
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Full kits from Thonk

10 things to know about the Chord Organ

  1. It’s perfectly possible to create chords on a modular synth, but it’s a pain — lots of tuning and messing about. I wanted to create something as simple as a home organ with chord buttons. Chord Organ is exactly that; the top knob chooses a chord shape, the bottom a root note.
  2. Chord Organ and Radio Music are identical modules; you can convert one to the other by installing new firmware over USB - details on how to install the firmware - and go back just as easily.
  3. This video shows what you can do with a Chord Organ in a simple little case. Here the chord shape and root note are sequenced by an expanded turing machine and filtered through a God's Box Humpback Filter:
  4. The full story of Chord Organ, including how it was inspired by a Bontempi Organ found in the street, is in this article over on Medium.
  5. The top knob chooses the chord shape (Major, Minor, Drop 3 9th). The bottom knob chooses the root note. Both can be CV controlled.
  6. The latest firmware now includes:
    • A choice of 12 waveforms (the original just had four)
    • Program chords by uploading MIDI files
    • Easy to use configuration page.
    • Alternative tuning support by dropping standard Scala files onto the SD card (installation details).
  7. There’s a long history of press-button-to-get-chord instruments; accordions, the Suzuki Omnichord, the Autoharp, or all those auto-accompaniment electronic keyboards that you used to see.
  8. Here's a great video from Synth DIY Guy that shows making and using a Chord Organ module:
  9. Here's Ebcidic getting deep dubby sounds from his Chord Organ:
  10. Here's Voltage Control Lab on programming custom chords into the module: