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·
Recall the diminished scale (Step
9). If you look carefully, you can find
all the notes of four of the twelve possible dominant
seventh chords in each diminished scale.
Example
[15.1] shows G7 in the HW diminished scale
(as we saw before, it is also the diminished scale on
Bb, on Db and on E).
·
In
Step 5
we learned that a diminished chord can behave as a
rootless 7 9b. This relationship between diminished and
dominant series chords arises from their sharing a
parent scale, the diminished. The HW diminished
scale is an excellent source of improvised lines
against an extended dominant chord.
·
Try playing a simple G7 shell in the left hand set
against phrases constructed from the G HW diminished
scale in the right. You should find it's very
effective.
·
Let's explore this relationship between dominant seventh
and the HW diminished further.
Example
[15.2] shows G13 as a quartal shell, F B1
E1. Following the rule of tritone
substitutions (Step
3), we expect Db13 (Example
[15.3]) to be available as an alternative.
·
G
and Db are two notes in the diminished sequence
G Bb Db E. If dominant series chords of G can be
substituted by equivalent chords based on Db, could it
be that Bb and E chords will also substitute? It could
indeed.
·
Example [15.4]
is the quartal shell of Bb13 (Ab D1 G1)
and
Example [15.5] is E13 (D A1b D1b).
Take all the notes of G13, Bb13, Db13 and E13 as given
in Examples [15.2],
[15,3],
[15.4] and
[15.5] and put them in order and you
get G Ab Bb B Db D E F - the G HW diminished
scale.
·
So we can extend the rule about tritone substitution to
state that the dominant seventh series chords on 3b
and 6 may also substitute by virtue of their sharing
a common parent diminished scale.
·
Example [15.6]
presents a nice form of quartal G7 9b 13, followed by
the equivalent structures in the diminished substitution
cycle (Bb7 9b 13, Db7 9b 13, E7 9b 13), all over a
sustained pedal G. Don't you think it makes a
beautiful and mysterious progression?
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