WH Diminished Scale

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The WH diminished scale alternates whole and half steps starting with a whole step. This scale outlines a fully diminished seventh chord:

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It is therefore used primarily over diminished chords. It should be noted that a HW diminished scale also outlines a fully diminished seventh chord, but it does not tend to be used over these chords. This is because the remaining notes of the HW diminished scale are a half step above the chord tones and are dissonant against the chord:

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Whereas the remaining notes of the WH diminished scale are a whole step above the chord tones and are more consonant against the chord:

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The diminished chord is itself symmetric, in that a diminished seventh chord on any note of the chord is identical to the original chord. So for example, a Bdim7 chord consists of B, D, F, and Ab, and a diminished seventh chord built on any of these notes yields the same chord:

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The WH diminished scales built on these roots are also identical:

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Thus, a diminished chord can be replaced by the diminished chord built on any of its notes. For example, Bdim7 can be replaced by Abdim7, since both the chords and the corresponding scales are identical.

When you see a diminished chord, you are always safe using the corresponding WH diminished scale. However, this is not always your only choice. As was explained in the chapter on harmony, many occurrences of diminished chords are acting as substitutes for dominant seventh chords. For example, in the progression Bdim-Cmaj7, the Bdim is acting as a substitute for G7, since the Bdim chord is contained within the G7 chord:

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Similarly, a Bdim7 chord is contained within a G7b9 chord and therefore can substitute for that chord:

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Since Bdim7, Ddim7. Fdim7, and Abdim7 can be substituted for each other, it follows that any of these chords can be substituted for a G7b9 chord as well. Indeed, note that the WH diminished scale built on B, D, F, or Ab is identical to the HW diminished scale built on G:

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Similarly, these diminished chords can also substitute for Bb7b9, Db7b9, or E7b9, since the same diminished chords are also contained within these chords, and the corresponding scales are all identical:

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When you see a diminished chord, you should consider the possibility that it is acting as a substitute for a dominant seventh chord. To determine if this is the case, first note that chord that the diminished chord is resolving to. Considering this chord as a tonic, determine what dominant seventh chord you would expect to resolve to that chord. Then see if the diminished chord you are analyzing relates to that dominant seventh chord. If this is the case, then you may be better of substituting the dominant seventh chord and choosing a scale on that basis.

For example, if the progression is Bdim7-Am7, then you would expect an E7 chord to resolve to the Am7. Bdim7 does indeed relate to E7, since a Bdim7 chord is contained within an E7b9 chord, and they share the same diminished chord. Therefore, in this situation, you should consider substituting an E7 chord for the Bdim7, and then choosing a scale based on the E7. You may end up choosing the E HW diminished scale, which is the same as the B WH diminished scale that you would have obtained had you not performed the substitution, but you are also free to choose E altered or E lydian dominant or any other scale associated with E7. Some of these scales may seem dissonant against the original Bdim7 chord, but you find that in all likelihood, the accompanists are performing the same substitution. Besides, an E lydian dominant scale leads to Am7 every bit as strongly as the B WH diminished scale would have, so the overall effect is preserved:

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Not all diminished scales are substitutes for dominant seventh chords, however. For example, in a Bbdim7-Am7 progression, the Bbdim7 chord does not relate to E7 and therefore is not simply substituting for it. In cases such as this, the WH diminished scale is still the most appropriate choice.

Copyright 2000 Outside Shore Music
Authored by Marc Sabatella

WH Diminished Scale