Half Whole Diminished Scale Tutorial
The half-whole diminished scale is an 8 note symmetrical scale. The scale alternates half and whole steps until the scale starts again. This is why we refer to it as a symmetrical scale, because the repeating interval pattern takes you back to the note that you started on.
Due to the repeating interval pattern of half and whole steps, there are only 3 different half-whole diminished scales to learn for all 12 keys. The following 3 groups share the same half-whole diminished scale:
Group 1 : C, Eb, Gb,A
Group 2 : C#, E, G, Bb
Group 3 : D, F, Ab, B
If you look closely you will see that the notes in each group make up 4 different diminished chords. Diminished chords also have a symmetrical interval structure so Cdim7, Ebdim7, Gbdim7 and Adim7 all contain the same notes but are simply different inversions.
In the context of the half-whole diminished scale, you only need to learn one scale for each of these 3 groups (each scale starts on a different note but contains the exact same notes and intervals).