Structure
The augmented triad is made of two stacked major thirds: C+ = C E G#. The fifth is augmented (G#). Because three major thirds make an octave, the triad divides the octave into three equal parts: it is symmetrical. C+ = E+ = G#+ (Ab+): there are only 4 different augmented triads (C+, C#+, D+, D#+).
Where it comes from
- In A harmonic minor (A B C D E F G#) the III chord is augmented: C+ (C E G#).
- In A melodic minor (A B C D E F# G#) the III chord is augmented, and the four-note chord is Cmaj7#5 (C E G# B).
- In the whole-tone scale every triad built in thirds is augmented.
Main uses
| Use | Example in C | Function |
|---|---|---|
| Augmented dominant | G+ (G B D#) → C | D# rises to E: leading tone toward the third |
| V7#5 | G7#5 (G B D# F) → C | altered dominant, very jazz |
| Passing tonic (line cliché) | C – C+ – C6 – C7 | G – G# – A – Bb |
| Link to the vi or IV | C – C+ – Am / C – C+ – F | G# rises to A |
| III+ in minor | Am – C+ – F (or Dm) | dark color, “mystery” |
| maj7#5 | Cmaj7#5 (Ebmaj7#5 in C melodic minor) | suspended color, modal jazz |
Real examples
- The Beatles, Oh! Darling (1969, A major): the song opens with an augmented chord (E+ = V+) before arriving at A.
- Liszt, Eine Faust-Symphonie: the opening theme arpeggiates augmented triads and uses all 12 notes: the chord as a symbol of ambiguity.
- Major line clichés in many standards and 1950s songs (C – C+ – C6 – C7 in intros).
- Stairway to Heaven (Led Zeppelin): in the intro, E+/G# is part of the chromatic descent in A minor.
The power of connection
By moving just one note by a semitone, an augmented triad becomes one of six major or minor triads:
| From C+ (C E G#) | Note moved | Result |
|---|---|---|
| G# → G | lowered | C |
| E → Eb | lowered | Ab (Ab C Eb) |
| C → B | lowered | E (E G# B) |
| C → C# | raised | C#m (C# E G#) |
| E → F | raised | Fm (F Ab C) |
| G# → A | raised | Am (A C E) |
The three major triads (C, Ab, E) and the three minor triads (C#m, Fm, Am) form Richard Cohn’s hexatonic system: the augmented triad is the “center” of the PL cycle. This makes it a perfect pivot chord for modulating by major thirds.
Augmented scale (hexatonic)
C D# E G G# B (alternating semitone and minor third): it contains C+ and Eb+ (Eb G B); it is used over Cmaj7#5 and in modern improvisation (Oliver Nelson, 1960s Coltrane).
In sound design and film
The augmented chord is the sound of dreams, mystery, and 1950s “magic.” A pad on C+ with slow chorus and a long reverb (5–8 s) instantly evokes vintage science fiction; a rising arpeggio of augmented chords builds suspense.
Producer exercise
- 2-bar loop: C – C+ – Am – F, piano + strings.
- Make one string voice rise G – G# – A and hear how the augmented chord “pulls” toward the vi.
- Then try the cycle C – C+ – Ab – C+ – E – C+ – C (only one note moves each time).
Related topics
Symmetrical scales (whole-tone and diminished), line cliché, Coltrane changes, neo-Riemannian theory, impressionist harmony.