Two meanings of “altered”
- In classical theory an altered chord is a chromatic chord, containing notes foreign to the key for a functional reason: secondary dominants, Neapolitan sixth, augmented sixths, borrowed chords, dominants with an altered fifth.
- In jazz theory “altered” mainly means the dominant with altered tensions: b9, #9, #11 (= b5), b13 (= #5). The “7alt” chord includes them all. This card focuses on the alterations of the dominant and on triads with an altered fifth.
Catalog on G (V of C)
| Symbol | Notes | Altered notes | Associated scale |
|---|---|---|---|
| G7b5 | G B Db F | Db (b5) | whole-tone, Lydian dominant (as #11) |
| G7#5 / G+7 | G B D# F | D# (#5) | whole-tone, altered |
| G7b9 | G B D F Ab | Ab | half-whole diminished, Phrygian dominant |
| G7#9 | G B D F A# | A# (Bb) | altered, blues |
| G7#11 | G B D F A C# | C# | Lydian dominant |
| G7b13 | G B D F Eb (± A) | Eb | Mixolydian b6, altered, Phrygian dominant |
| G7b9b13 | G B F Ab Eb | Ab, Eb | Phrygian dominant (dominant of the minor) |
| G13b9 | G B F Ab E | Ab | half-whole diminished |
| G7alt | G B F + b9/#9 + b5/#5 | Ab, A#, Db, D# | Super Locrian (altered scale) |
In practice G7alt is often played as G7#9b13 (G B F A# Eb), or with an upper structure: the Eb major triad (Eb G Bb) over the tritone B–F supplies the b13 (Eb) and the #9 (Bb = A#). See “Upper structure triads”.
Altered triads
- Augmented (C+ = C E G#): symmetrical, divides the octave into three major thirds; three inversions sound the same. It works as a dominant (G+ → C: the D# rises to E) or as a passing chord (C – C+ – C6 – C7: the line G – G# – A – Bb).
- Major with a diminished fifth (C(b5) = C E Gb): it is part of C7b5 and of the French sixth.
How the alterations resolve
Every altered note tends toward the nearest semitone in the chord of arrival. G7alt → C:
- b9 (Ab) → G (5th of C) by descending semitone.
- #9 (A#, often written Bb) → usually falls to A (6th/13th of C); read as A# it can rise to B if the arrival is Cmaj7.
- b5 (Db) → C (root).
- #5 / b13 (D#/Eb) → E (3rd of C) by ascending semitone, or D (9th).
- 3rd (B) → C, 7th (F) → E: the tritone resolves as always.
The alterations “double” the leading tones: nearly every voice moves by a semitone, which is why the altered cadence sounds so conclusive.
Augmented sixths as classical altered chords
The French sixth (Ab C D F#, in C minor toward G) sounds like a D7b5 with Ab in the bass: it is the same family as the jazz 7b5. The German sixth coincides with a dominant seventh chord (see Enharmony). The tritone substitution (Db7 in place of G7) contains the same notes as a G7alt: Db7 = Db F Ab Cb, that is b5, 7, b9, 3 of G.
Examples in real songs
- “Purple Haze” (Jimi Hendrix, 1967): E7#9, the “Hendrix chord”.
- “Taxman” (The Beatles, 1966): D7#9 in the main riff.
- “Oh! Darling” (The Beatles) and a lot of doo-wop: the augmented triad as a passing dominant (E+ → A).
- In bebop and hard bop (Horace Silver, Wayne Shorter) almost every V7 going to a minor tonic is altered (G7b9b13 → Cm).
- In gospel and soul ballads the dominant with #5 (G7#5 → C) is a classic move into the chorus.
Common mistakes
- Putting a b9 on a chord that is not a dominant (e.g. on Imaj7): it is a real clash.
- Doubling natural 9 and b9 together in the same voicing without intention.
- Leaving the perfect 5th in a chord with #5: the #5 replaces the fifth.
- Playing the altered chord with the bass playing the altered 5th: the bass must stay on the root (or on the tritone, if you use the substitution).
Exercise
- Play ii–V–i in C minor: Dø7 – G7b9b13 – Cm(maj7). Then in C major: Dm7 – G7alt – Cmaj7.
- Build G7alt as an Eb triad over the tritone B–F (B F Eb G Bb): hear the “upper structure” color.
- In one of your songs, replace the dominant before the chorus with a V7#5: feel the push of the fifth rising to the third.
Related topics
Altered scale (Super Locrian); Upper structure triads; Tritone substitution; Augmented sixth chords; Ninth chords; Diminished scale.