Augmented scale (symmetrical hexatonic 3-1)

Formula

Degrees: 1 b3 3 5 #5 7.
Steps: 1½ S 1½ S 1½ S (3 1 3 1 3 1 semitones).
On C: C Eb E G G# B. On D: D F F# A A# C#.

There is also the 1-3 rotation (semitone – minor third): C Db E F G# A. The scale is symmetrical by major thirds: transposed by 4 or 8 semitones it remains identical, so there are only four different augmented scales.

Names: augmented scale, symmetrical hexatonic, “hexatonic” in neo-Riemannian theory (Richard Cohn). It should not be confused with Messiaen’s Mode 3, which has nine notes: the augmented scale is a set of its own (prime form 6-20, (014589)).

Structure

The augmented scale is the union of two augmented triads a semitone apart (C E G# + Eb G B) or, read differently, of three major and three minor triads with roots a major third apart: C, E, G# (Ab) major and minor. For this reason it is linked to cycles of major thirds and to the “Coltrane changes” (C – E – Ab).

Color

Lustrous, shimmering, ambiguous between major and minor: the two thirds (b3 and 3) coexist. It is a modern, “cinematic” and jazzy color, less tense than the diminished.

Derivable chords

Cmaj7#5 (C E G# B) and Cm(maj7) (C Eb G B): the augmented scale contains both; it is the scale of modern jazz over these chords.
Major triads C, E, Ab (G#) and minor Cm, Em, G#m.
C+ / Eb+ and Cmaj7(#9) (C E G B D#), often used as a “bright” color.

Use in genres

Post-bop jazz: improvisers such as Michael Brecker and modern pianists use the augmented scale over m(maj7) and maj7#5, and to play “triads a major third apart” over a chord.
Coltrane changes (“Giant Steps”, 1959): the progression leaps by major thirds (B – G – Eb); the three tonal centers form an augmented triad, and the augmented scales sum up its geometry.
Neo-Riemannian theory (Cohn): the “hexatonic cycles” alternate major and minor triads linked by the P and L transformations (C – Cm – Ab – Abm – E – Em), which all lie in one augmented scale. These are the “magical” progressions of modern film music and of many passages by Liszt and Wagner.
Film music: progressions C – Cm – Ab – Abm for a sense of uneasy wonder.

Melodies

Phrases that superimpose two augmented arpeggios (C E G# + Eb G B) or triad arpeggios a major third apart.
The semitone b3 – 3 (Eb – E) recalls the blues; the semitone 5 – #5 (G – G#) the augmented color.

Common mistakes

Confusing it with Messiaen’s Mode 3.
Using it over a simple dominant chord (C7): the scale has no b7.
Using it over diatonic progressions as a “key” scale: it is a color, to be introduced and left.

Exercise

Cm(maj7) pad for 4 bars: improvise with C Eb E G G# B, alternating arpeggios of C, E and Ab.
Write the progression C – Cm – Ab – Abm – E – Em – C with tight voice leading (only one voice moves by a semitone at each step).
Analyze the three keys of “Giant Steps” and verify that they form an augmented triad.

Whole-tone scale; Diminished scale; Lydian augmented; Altered chords; Messiaen’s modes of limited transposition; Set theory (2).