When is the best time to use this scale? The truth is, there are many situations where this scale could be useful but we will talk about my favorite situations. First off, let’s consider what scale degrees we have available.
In the Half whole Diminished Scale we have:
1 - b2 - #2/b3 - 3 - #4/b5 - 5 - 6 - b7
The first thing I notice is that we have a Dominant 7 chord in there.
1 - 3 - 5 - b7
So let’s make that our base chord for this tutorial.
So we can play an A half whole diminished scale over an A7.
Let’s take that a few steps further by considering the tensions we have within the scale:
b9(b2) - #9#2) - b5 - 13(6)
These tensions could be implied if we were to just be playing over an A7 chord. We could call the A half whole diminished scale a substitution scale.
We could be implying the following chords:
A13, A7b5, A7b9, A7#9, A13b9
Or we could play the A half whole diminished scale over these chords if they exist within a progression.