Diminished Scale On Dominant 7 Chords

Using the diminished scale over a dominant 7 chord is a common jazz improvisation technique, particularly in bebop. The best part is there are only 3 diminished scales to learn. So let’s get to it.

Let’s start off by talking a little bit about the diminished scale. There are two versions of it: the first follows the ascending pattern of tone-semitone-tone-semitone-tone-semitone-tone-semitone (e.g. D, E, F, G, G#, A#, B, C#, D) and this would typically be used over a diminished chord (e.g. Ddim); the second follows the ascending pattern of semitone-tone-semitone-tone-semitone-tone-semitone-tone (e.g. G, G#, A#, B, C#, D, E, F, G) and this is the scale we would typically use over a dominant 7 chord (e.g. G7). It’s worth noting at this point that the pattern for both scales is the same, except that the first starts with a tone and continues, and the second starts with a semitone and continues similarly. You’ll also see that the notes of each example are the same, just the starting point is different. But, as we’re only focussing on the diminished scale over dominant 7 chords for this post, let’s move on and see why you’d use it and how.

Using the diminished scale above, you’ll see that when you play it in descending order from G to D (e.g. G, F, E, D) these notes are from the G mixolydian scale as you would use normally over a G7 chord. The second half of the scale, however, switches and you start to play the interesting chord tones of the #11, [3rd], #9 and b9 (C#, B, A#, G#) and these notes are the reason you’d play the diminished scale over a dominant 7 chord: it adds a lot of colour, adds tension, and it really feels like it wants to resolve.

So, aside from simply playing up and down the diminished scale on a dominant 7 chord or playing different diminished patterns, a really easy way to implement the sound of it over a V-I chord progression is to play 5 notes down the scale starting from the #9 of the dominant 7 chord (#9, b9, root, 7th) and the fifth note will be the major 3rd of the I chord that you resolve to. For example, if the chord progression is G7 - Cmaj7, starting on the 3rd beat of the G7 bar you’d play [as quavers] Bb, Ab, G, F, then on the first beat of the Cmaj7 bar you’d play the E (which continues the scale and resolves to the 3rd of Cmaj7 - marvellous!)

There you have it. I hope this post has given you some inspiration and knowledge to go practice and perform. Thanks for checking it out.