·         The whole-tone scale on G (Example [16.1]) is the parent of G+.  It also fits to G7 5b.  Might there be an augmented cycle of substitutions along the lines of the diminished cycle described in Step 15?

·         The answer is yes.  The chords of G7 5b, B7 5b and Eb7 5b are all made of notes in the whole-tone scale of G.  But the interchangability of chords from this parent scale extends further.

·         Any 7 5b chord with, as its root, any note of the whole-tone scale will substitute for any other.

·         Thus G7 5b, A7 5b, B7 5b, C#7 5b, Eb7 5b and F7 5b are completely equivalent when set against the whole-tone scale of G.

·         Chords of the dominant seventh series thus offer enormous scope for the construction of corresponding improvised themes.  By drawing on lydian dominant, HW diminished and whole-tone scale materials, lines of great freedom and flexibility can be created.

·         Choose a key and work out the notes of the relevant lydian dominant, HW diminished and whole-tone scales.  You should find that only two of the twelve possible notes are not included in any of these scales.  What are they?*

·         Play the simple root-position tertian seventh shell of your key in the left hand and with the right construct some improvised lines that either include or avoid these two notes.  What does this tell you about the limitations on absolute freedom when building a solo over seventh chords? 

* The 4th and the major 7th.  Sometimes notes like these that don't occur in any of the scales related to a particular chord are called avoid notes. Ordinarily your improvised lines over that chord should omit the avoid notes.  The bad sound of F against the extended chord of C major discussed in Step 7 is another example of an avoid note - dealt with, in this case, by sharpening it.