5

I'm messing around with number sequences and harmony to produce chord progressions.

I've ended up with a progression I really like:

Amin7 - F#min7 - D#min7 - Cmin7

The root notes of each chord outline a diminished scale if you start with F# (F#, A, C, D#).

After noodling around trying to find a melody, I found that Cmin pentatonic works really well with everything.

Can anyone tell me why?

7

This descent by minor third is pretty common, and these four chords actually combine to create an octatonic collection:

A B♭ C D♭ E♭ E F♯ G

(If you aren't familiar with octatonic scales, it's just alternating half and whole steps.)

C minor pentatonic works okay, because C E♭ G B♭ are in that octatonic collection. F, however, is not, but F♯ is.

You can continue using C minor pentatonic, but using the above octatonic scale gives you more (and more accurate) options.

Furthermore, you can use that same scale over a different chord progression. Keep the roots the same, but change the qualities to dominant seventh, major triad, minor triad, half-diminished seventh, fully-diminished seventh, or mix and match. No matter what you do, as long as you keep the roots, it'll still create the same octatonic scale.

(Come on, that's cool!)

  • Would this tonality be associated with a particular style? I know of the octatonic scale from jazz theory. – Michael Curtis Jun 7 '17 at 19:45
  • I would say jazz would be the best home for it. The Coltrane changes, for instance, emphasize movement by major third, whereas your progression is by minor third. – Richard Jun 7 '17 at 20:11
  • Chick Corea uses minor third chordal movement a lot in his compositions. One example that comes to mind quickly is Humpty Dumpty, but there are definitely many others. The recording from his album Mad Hatter is on YouTube. Check out measures 11-14 here: guitarcats.com/images/JazzStandardCharts/… – jdjazz Jun 9 '17 at 23:40
  • Relatedly, octatonic scales are often played over diminished chords, and the roots of your chords (C E♭ G B♭) spell out a diminished chord. – jdjazz Jun 10 '17 at 1:25
  • I can't speak to other genres, but I definitely agree with Richard that jazz is a home for this progression. Anecdotally, it feels to me like this progression became more popular and more common after the bebop era, maybe in the 70s. (But that's a guess.) – jdjazz Jun 10 '17 at 1:40

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