The most important feature of Heptatonic Systems is the interval pattern that is present in each mode and the triad, seventh chord and upper voices that are present.
The structure of the Ionian mode (also called major) is R,2,3,4,5,6,7. In C the triad is major, C, the seventh chord is Cmaj7 and the upper voices are 9,11&13. The Harmonic Major mode’s structure is R,2,3,4,5,b6,7. The triad and seventh chord remain the same as in Ionian but the b6 gives us a b13 in the upper voices and the interval of an augmented second/minor third between the sixth and seventh degrees of the mode. This produces a profoundly different color and effects the entire character of a composition.
Juxtaposing Ionian and Lydian modes from the same root reveals a subtle yet distinct color difference. Let’s stretch these modes into extended arpeggios by placing the notes in ascending thirds:
Ionian: R,3,5,7,9,11,13
Lydian: R,3,5,7,9,#11,13
The Altered Scale
In an effort to have linear sources that provided even more upper voice coloration, Charlie Parker, Dizzy Gillespie and their followers used heptatonic modes enharmonically to provide more than one altered ninth on a dominant seventh chord. Let’s look at one of these possibilities first.
The extended arpeggio for the Super Locrian mode looks like this:
R,b3,b5,b7,b9,b11,b13
If viewed enharmonically the b3 becomes #9, the b11 becomes 3, b5 can be #11 or b5 and the b13 can be either #5 or b13.
The result is often referred to as the Altered Scale with the symbol B7alt use if taken from the C Melodic Minor system.
R,3,b5(or #11),#5(or b13),b7,b9 and #9
Symmetrical Scales
Evidence of symmetrical scales and patterns in improvisation began appearing with the infusion of the mixture of intellect and passion that is referred to as BeBop. These same improvisors found that the symmetrical scales used by some early 20th century European classical composers, including Bartok, Ravel and Debussy, provided even more variation on upper voices over certain chords.
A symmetrical scale with intervals of alternating half-steps and whole steps adds not only additional colors, but the resolving tendency of this intervalic pattern pushes the melodic possibilities in non-heptatonic directions.
Here we see how the Half Step/Whole Step Symmetrical Diminished mode affects a dominant seventh chord with G as root:
Mode: R,b2,#2,3,#4,5,6 and b7
As an extended arpeggio: R,3,5,7,b9,#9,#11,13 (G13b9,#9,#11)
So this would apply to any variations of a G7 with those specific voices: G7, G7b9, G7#9, G7#11, G13, etc.
For the very same reason that heptatonic modal names are used, other scalar designations can be applied to define moving harmonies. Below we have Symmetrical Scales and their Modal Symbols.
These are listed as:
Mode (Half Step/Whole Step)
Modal Symbol (C w/h symº)
Symmetrical Diminished Scale
Half Step/Whole Step
C h/w symº
Whole step/Half Step
Db w/h symº
Whole Tone Scale
Whole Tone
C w/t
Symmetrical Augmented Scale
Minor Third/Half Step Symmetrical Augmented
C sym aug
Half Step/Minor Third Symmetrical Augmented
Eb h/min3 sym aug
Next: Chords and slash-chords derived from Symmetrical Scales and a glance at the usefulness of Bartok’s Pole Theory in relation to composing for improvisors.
Copyright © 1993-2010 Jack DeSalvo
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