Formula
- Degrees: 1 2 3 4 #5 6 7.
- Steps: W W H 1½ H W H (2 2 1 3 1 2 1 semitones).
- Parent scale: 3rd mode of harmonic minor. C Ionian #5 = notes of A harmonic minor from C: C D E F G# A B.
- On Eb: Eb F G Ab B C D (from C harmonic minor). On G: G A B C D# E F# (from E harmonic minor).
Alternative names: Ionian augmented, “major #5”.
Characteristic note and color
The augmented 5th (#5) over a major scale with the perfect 4th: compared with Lydian augmented (which has the #4) it is more “earthy” and less suspended. The augmented 2nd falls between the 4 and the #5 (F – G#). Color: tense major, bright but restless, with a dramatic-romantic flavor.
Diatonic chords (C Ionian #5)
| Degree | Triad | Seventh |
|---|---|---|
| I+ | C+ | Cmaj7#5 |
| ii | Dm | Dm7 |
| III | E | E7 |
| IV | F | Fmaj7 |
| #v° | G#° | G#°7 |
| vi | Am | Am(maj7) |
| vii° | B° | Bø7 |
Where it is used (chord-scale)
- bIII+maj7 in a minor key: in A minor the chord Cmaj7#5 (C E G# B) comes from harmonic minor: over it the “key” scale is exactly C Ionian #5. It is typical of line clichés and Baroque progressions (i – bIII+ – iv).
- Imaj7#5 in major, when you want a tonic chord with the perfect 4th in the melody: the choice between Lydian augmented (with the #4) and Ionian #5 (with the 4) depends on the melody.
- Passing augmented chord C – C+ – F (I – I+ – IV): over C+ the C Ionian #5 scale keeps F as the arrival note.
Use in genres
- Romantic classical: passages over augmented tonic triads as a transition to the IV or the vi (Liszt, Wagner, Tchaikovsky).
- Pop and musicals: the chromatic line on the tonic (C – C+ – C6 – C7, or C – C+ – F) is a cliché of Broadway musicals and of the Beatles (“Oh! Darling” and “Fixing a Hole” use passing augmented triads).
- Jazz: as the scale of the bIII+ in the minor and in ballads.
- Neoclassical metal: augmented arpeggios on the 3rd degree of harmonic minor.
Melodies
- The #5 rising to the 6 (G# – A) is the most natural movement: it anticipates the vi or the IV6.
- The phrase 3 – 4 – #5 – 6 (E F G# A) is the exotic “leap” of the augmented 2nd.
Common mistakes
- Using the perfect 5th and the #5 in the same chord.
- Confusing it with Lydian augmented when the melody has the #4.
- Using it as the mode of an entire piece: it is mainly a passing color over an augmented chord.
Exercise
- Progression Am – Cmaj7#5 – Dm – E7 – Am: improvise over Cmaj7#5 with C D E F G# A B.
- Write the line C – C+ – C6 – C7 – F on a pad and a melody that rises G – G# – A – Bb – A.
- Compare over the same Cmaj7#5 a phrase with F (Ionian #5) and one with F# (Lydian augmented).
Connections
Harmonic minor and its modes; Lydian augmented; Altered chords (augmented triad); Augmented scale; Chord-scale theory.