When I want my music to sound mysterious, the diminished scale is a reliable tool in the harmonic toolkit. It worked for John Coltrane and Thelonious Monk, and it can work for you!
The basic concept is simple: take a diminished chord, take another diminished chord a half step higher, combine them, and, voila, you have the diminished scale. Here’s how you do it in C:
- Start with C°7: C, E-flat, G-flat, and A (Yes, pedants, I know it’s supposed to be B-flat-flat rather than A, but music theory is hard enough)
- Add Db°7: D-flat, E, G, and B-flat
- Combine them into a scale: C, D-flat, E-flat, E, G, A, B-flat
Alternatively, you could simply think of the scale as a repeating pattern of intervals: half step, whole step, half step, whole step.
The basic concept of the diminished scale may be simple, but the naming conventions around it are hard. One point of confusion is that there are two different diminished scales. When people say “C diminished scale“, they usually mean this:
There is also the other diminished scale, sometimes called the octatonic scale. Here is C octatonic:
Octatonic is a catchy name, but it’s also problematic, because there are many other scales with eight notes in them other than this one (like, for example, that first diminished scale shown above.) This is why people often refer to the octatonic scale as the whole-half diminished scale: because it starts with a whole step (C to D) followed by a half-step (D to E-flat.) And then for clarity, you can call the other one the half-whole diminished scale, because it starts with a half step (C to D-flat) followed by a whole step (D-flat to E-flat.)
Fun facts: as with diminished chords, there are only three possible diminished scales and only three possible octatonic scales.
- The C diminished scale contains the same pitches as the E-flat, G-flat and A diminished scales.
- The C octatonic scale contains the same pitches as the E-flat, G-flat and A octatonic scales.
The diminished and octatonic scales are also modes of each other: C octatonic contains the same pitches as B diminished and D diminished. Notice also that every pitch in both scales has a complementary pitch a tritone away. That is a lot of tritones! There are many more intriguing symmetries contained within the scales. The best way to explore them is just to play around with them on your instrument or in the piano roll.
All of this symmetry gives the diminished and octatonic scales a kind of vertiginous freefalling feeling. They are like the chromatic and whole tone scales in this way: without the asymmetrical patterns of half steps and whole steps that your ear uses to orient itself in more traditional scales, no particular pitch feels like the center. You can force any diminished or octatonic scale tone to temporarily feel like the center by emphasizing or repeating it, and by playing it in metrically strong positions, but this centrality is tenuous and easily destabilized. This lack of a center makes the diminished and octatonic scales useful if you want to move smoothly from one key to another.
Writing diminished and octatonic scales on the staff is a headache because there is no simple way to handle the accidentals. You’re supposed to write your scales so that each letter name appears once, but in the diminished and octatonic scales, this is impossible. There is also no key signature that works for any of them. The scales are much easier to conceptualize as a pattern on the keyboard or fretboard than on the staff. Naming and notation problems aside, though, the scales sound fantastic, so it’s worth putting in the effort.
Here are some ways to permute C octatonic:
Hear these scale permutations with interspersed samples of real-world diminished sounds:
When you build chords from the scale in thirds (using every alternating scale tone), you get a series of diminished chords. These sound okay, but are too symmetrical to be interesting. However, when you build from the scale in fourths (using every third scale tone), then you get some extremely interesting chords. C octatonic gives you F, Fm, Ab, Abm, B, Bm, D, and Dm. These chords are wild, but they sound excellent together. Diminished/octatonic harmony is a great way to break outside of the cliches, because it’s unfamiliar and strange without sounding random or nonsensical.
The typical use case for the diminished scale in jazz is to play the half-whole scale on dominant seventh chords to imply a thirteen flat ninth sound. John Coltrane had an exceptionally creative approach to this idea. He played endless variants on a lick that runs through the scale in a particular pattern: you start on the root, go down a whole step, go down a major third, go down another whole step, and go up a perfect fourth. Then you repeat this sequence as many times as desired. It sounds fantastic, and it is surprisingly easy to play on the guitar. You should also try playing it backwards.
You can hear Coltrane play the diminished riff during his solo on “Moment’s Notice” from Blue Train, and throughout his mind-boggling live performances with Thelonious Monk at Carnegie Hall. Listen especially to “Epistrophy.”
And speaking of, Thelonious Monk plays some super hip diminished scale passages on his recording of Duke Ellington and Juan Tizol’s “Caravan”. (It also has one of my favorite ever bass solos, by the great Oscar Pettiford.)
Here’s my favorite, from 4:44:
Diminished scale shows up in a lot of late nineteenth and early twentieth century European music. Wikipedia has lots of examples. Stravinsky’s Symphony in Three Movements is a pretty happening one, listen at 0:44.
“Diminished Fifth” from Bartók’s Mikrokosmos is cool too.
I had never heard of Willem Pijper until I read the Wikipedia article on the octatonic scale, but his Sonatina No. 2 is all octatonic.
John Williams likes octatonic sounds too, for example in this scene from Raiders of the Lost Ark (thank you Frank Lehman for pointing this out):
Diminished scale mostly belongs to the more intellectually challenging forms of classical and jazz, but it also has a surprising connection to the blues. In The Lydian Chromatic Concept of Tonal Organization, George Russell calls the half-whole diminished scale “the Auxiliary Diminished Blues Mode.” Aside from its flat second, it is indeed quite a bluesy sounding scale! The whole-half scale contains a lot of great blues licks too. It would sound strange to exclusively play either diminished scale in a blues context, but if you dip in and out of them selectively, you will never run out of strong melodic and harmonic ideas.