#4. The Diminished Scale and its Harmony

I've been thoroughly enjoying the 8-tone, dominant diminished scale lately. It's also called the "half-whole" (HW) diminished scale. Here's how it's built:

root-H-W-H-W-H-W-H-W or
1 b2 b3 3 #4 5 6 b7

What's cool is that it's a symmetrical scale and all kinds of weird parallel harmonies can be found in it:

1. Diminished Seventh chords can be found on every chord tone.
2. Dominant Seventh chords (with tensions: b9, #9, #11, 13) can be found on the root, b3, b5, and 6th scale degrees.
3. Minor Seventh (or Half Diminished) chords can be found on the root, b3, b5, and 6th scale degrees.

I find this mind-boggling, that both major and minor chords are found on the main chord tones of the scale!

This is a mode of limited transposition (thanks Messaien) so there are only 3 unique diminished scales!

There are some crazy harmony tricks you can use to add a diminished sound to your compositions/improvisations. Here's my favorite: A very wacky set of triads can work over a C7 chord if you use the dominant diminished scale. Each triad will resolve to a chord tone in F major.

• C major triad
• Eb major triad (#9, 5, b7)
• Gb major triad (tritone substitution! #11, b7, b9)
• A major triad (13, b9, 3)

...bizarre, but awesome.
http://www.guitar9.com/columnist331.html
http://scraggo.blogspot.com/