The Music Thing Modular Chord Organ is a digital chord player for Eurorack. It is inspired by instruments like the Bontempi Organ where you press a button and get a chord. It’s also one of the cheapest ways to get polyphony in Eurorack.
The default chords didn’t do much for me though because I like jazzy chords! I came up with a quick palette of five-note chords which derive from some common musical scales. So if you’ve got your own Chord Organ and want to get jazzy, copy and paste this into the Chord Organ Config Generator, save it to your SD card and enjoy!
1 [0,4,7,9,14] major 6-9 chord
2 [0,4,7,11,16] major seventh
3 [0,3,7,10,15] minor seventh
4 [0,4,7,10,16] seventh
5 [0,3,6,10,15] minor seventh flat fifth
6 [0,3,7,11,15] minor major seventh
7 [0,3,6,9,15] diminished seventh
8 [0,4,8,11,16] major seventh sharp fifth
9 [0,3,7,9,14] minor 6-9 chord
10 [0,4,8,10,16] seventh sharp fifth
11 [0,4,6,10,16] seventh flat fifth
12 [0,4,8,12,16] augmented triad
13 [0,2,7,10,14] seventh suspended second
14 [0,5,7,10,14] ninth suspended fourth
15 [0,5,7,10,17] seventh suspended fourth
16 [0,7,12,0,7] fifth
If you haven’t got a Chord Organ but you’re a Euroracker and you want one, Thonk sells Chord Organ kits. It’s pretty easy to build too! And if you don’t know the first thing about jazz or music theory, have a play with them anyway. 🙂
The music theory parts for people who aren’t nauseated or enraged by music theory
The scales are the major, natural minor, harmonic minor, melodic minor and whole tone scales. There’s a couple of six-nine chords and suspended sevenths thrown in there to make up the sixteen. Each chord is voiced with five notes with the high note representing the tonality (minor, major or suspended). There’s a fifth right at the end in case the jazziness gets too much.
The relationship between chords and scales is useful to know because of the way chords reveal their originating scales four notes at a time. If you stick with chords 2 to 5, no matter what notes you play, you get a noticeably different harmonic colour from chords 3-10.
Here’s the scales which the chords belong to:
- major and natural minor scale seventh chords: 2 3 4 5 13 14 15harmonic minor scale seventh chords: 4 5 6 7 8 10melodic minor scale seventh chords: 3 4 5 6 8whole tone scale seventh chords: 11 12
And here’s how they derive from those scales:
- major scale: 2 3 3 2 4 3 5 (Ima7 IImi7 IIImi7 IVma7 V7 VImi7 VIImi7b5)
- natural minor scale: 3 5 2 3 3 2 4 (Imi7 IImi7b5 bIIIma7 IVmi7 Vmi7 bVIma7 bVII7)
- harmonic minor scale: 6 5 10 3 4 2 7 (Imi/ma7 IImi7b5 bIII7#5 IVmi7 V7 bVIma7 VIIIdim7)
- melodic minor scale: 6 3 8 4 4 5 (Imi/ma7 IImi7 bIIIma7#5 IV7 V7 VImi7b5 VIImi7b5)
The whole tone scale is symmetrical so chords 10 11 and 12 work fine from any degree of the scale. And there’s probably some other jazz scales those chords fit into as well.