Diminished Responsibility

Ah, be honest – how often have you wanted to “do a Harpo” to a piano?

Jazz musicians don’t use the harmonic minor scale, right? Wrong.

Of course, everyone would admit there are occasions where the harmonic minor is specifically called for, to evoke a sort of “Eastern promise” sound (a lot of people use it on Nardis and Caravan, for instance). But actually this scale is commonly used in all sorts of “non-ethnic” situations as well.

Here’s a clue. People who think that you don’t use the harmonic minor scale in jazz often struggle (though they’ll probably not admit it) when playing over diminished chords… We’ll start by looking at the sort of places diminished chords appear in functional harmony.

As so often with me, we’ll be using “kitchen sink” science to look at practical ways of dealing with what strict theorists refer to as leading-tone functions.

DIMINISHED CHORDS AS DOMINANT SUBSTITUTIONS

Diminished chords are very often just substitutes for dominants, which imply the use of a diminished scale and allow for chromatic bass motion. For instance:

  • Bo   CΔ
  • G7b9/B   CΔ

are the same thing, and you could play the G half-step whole-step diminished scale over the first chord in both situations:

G Ab A# B C# D E F

(note that this is the same thing as the B whole-step half-step diminished scale.)

DIMINISHED CHORDS FOR PASSING CHROMATICISM

There are other uses of diminished chords that you tend to find in older standards (Body & Soul, Night & Day, Here’s That Rainy Day, for instance) and some bossas (How Insensitive, Corcovado). Typically, they are used to add extra chromatic steps when ascending or descending in the lower reaches of the tonic scale. For instance, in the key of C:

  • Em7 Ebo Dm7 G7 C
  • C Dm7 Ebo Em7

That sort of thing. These figures were sometimes substituted on the fly by pianists, to add interest when the harmony rests on the tonic for a bar or more.

DIMINISHED CHORDS ON THE TONIC

Io was a fairly common harmonic usage during the Tin Pan Alley era – in modern times these diminished tonic chords are usually substituted as #IVm7b5 VII7b9 instead. The classic example here is Stella by Starlight, which originally began Bbo but is usually played today as Em7b5 A7b9.

You can play the whole-step half-step diminished scale over any of these diminished chords. But you can also play harmonic minors – even though they’re theoretically a bit “off”, they’re very idiomatic.

There are a few simple rules to remember to determine which harmonic minor to play:

RULE ONE

Over a diminished chord on the root, b3rd or b5th, play the harmonic minor of the 3rd degree of the scale. For instance, in the key of C:

Over Co, Ebo and F#o play E harmonic minor:

E F# G A B C D#

RULE TWO

But, if the diminished chord moves up a semitone, play the harmonic minor scale of the note you’re resolving to instead. So, over C#o going to Dm7 play D harmonic minor:

D E F G A Bb C#

Actually, rule two gives us another way of playing over dominants resolving down a fifth. Since C#o Dm7 can also be seen as a bassline substitution for A7b9 Dm7, we could play D harmonic minor over A7b9 as well. Pick any Parker solo you like, and you’ll find this kind of scale sound in it somewhere.

So we can restate rule two as a sort of rule three…

RULE THREE

Over a minor V-I, play the harmonic minor of the I over the V chord.

Actually this harmonic minor scale can be used over the whole of a minor II-V (the half diminished chord as well) – a useful simplified gloss, particularly when the chords are whipping past at speed. So, over a minor II-V-I in C, for instance:

(Dm7b5) G7b9 | Cm

you can play C harmonic minor then C melodic minor (or Dorian, whatever takes your fancy).

This harmonic minor scale can also be used where you have a minor II-V resolving to a major I (eg Night & Day, What Is This Thing). Remember too that you can play 7b9 on any dominant (as long as it doesn’t clash with the melody).

Try this stuff out and let me know what you think.

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Posted in a) Soloing Scales & Modes, b) Harmony & Comping
2 comments on “Diminished Responsibility
  1. simon says:

    Good stuff !! C harmonic minor is also G mixolydien b9b13 (G F Eb D C B Ab G). If you play G mixolydien b9b13 you can use the passing tone like : G F# F Eb D C B Ab G and it sound more bebop. Thanks for your website ! (sorry for my english)

    • Jason says:

      Thanks for getting involved Simon. Your comment has given me an idea to write something about passing tones in all scales. That’ll be a long one!

      No need to apologise for your English. Where are you from?

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