Extending Diminished 7th Chords with Dominant 7th Arpeggios

The diminished 7th chord is one of those chords that seems to give many of us fits when improvising. One of the problems is that the diminished chord is built symmetrically. This can lead to a very mechanical, pattern-oriented line that is more of a lick than a melodic phrase.


One way I find to be an effective approach in improvising or writing over a diminished 7th chord is to think of its' extensions. I've been writing about extensions over the other 7th chord types, which you can view here.

But the diminished 7th chord is a little different from the other types because of the symmetrical build. So, for this chord, I like to think of the 9th, 11th, b13th, and the natural 7th as an extension. You wouldn't normally include the natural 7th as an extension, but for a diminished 7th chord, it functions like one to my ear.

In the excerpt below, I've written out four different examples of how to build the extensions into a diminished 7th chord. The trick is to use a dominant 7th arpeggio a half-step below the root of the diminished 7th chord you're playing.

For an Adim7 chord, the first line below shows the combination of an Adim7 arpeggio with an Ab7 arpeggio. The result puts emphasis on the natural 7th (G#/Ab) of the Adim7 chord. Lines two, three, and four then follow the same logic; the Adim7 chord is now shown from the inversions. As you'll see after working through what's below, you get four different dominant 7th chords from which to choose notes. Each of the dominant 7th chords (Ab7, B7, D7, and F7) are also built a minor 3rd apart, like the diminished 7th chord.  

As each dominant 7th arpeggio is applied, another extension of the chord is emphasized. You can see in the diagram which extension is being featured with the corresponding number above the second part of the arpeggio.

---

As with pretty much everything I write about here, give yourself some time to let your ears wrap around these different sounds. The idea is to have these different options as a melodic choice when you play or write.

If you have other ideas about this concept, let me know about it! Share your ideas below!