Ab7b5 guitar chord
A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings.
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About Ab7b5 — drop 2 voicings
Ab7b5 is Ab, C, D and Gb — Ab7 with the fifth lowered a semitone.
It sounds symmetrical and slightly unreal. The same four notes spell a 7♭5 a tritone away, which is exactly why one can stand in for the other.
Ab7b5 notes and formula
| Ab | C | D | Gb |
|---|---|---|---|
| 1 | 3 | ♭5 | ♭7 |
Altered dominant — and the chord that makes the tritone substitution work.
Also written Ab7(b5), Ab7-5 or Ab7♭5. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play Ab7b5
Take the four notes stacked as close together as they go, then drop the second voice from the top an octave. The gap it opens is what makes the chord sound like a chord rather than a cluster.
It lands on four adjacent strings, which is why it is the workhorse voicing on guitar.
Ab7b5 has 14 of them, on the top four strings, the bottom four strings and the middle four strings, from open position up to the 12th — every inversion the chord has: Ab in the bass, C in the bass, Ebb in the bass and Gb in the bass. The one to learn first is the Ebb shape at the nut, which is the easiest grip here.
5 of them sit on the top four strings, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with 4x453x — low, at the 3rd fret. None of the shapes for Ab7b5 uses an open string, so every one of them is movable; the lowest sits at the 3rd fret. None of them needs a barre. Together they cover the neck from the 3rd fret to the 13th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 4x453x | 3rd fret | Ab, root position | D | all fretted |
| xx6778 | 6th fret | Ab, root position | C | all fretted |
| x-9-10-11-9-10 | 9th fret | Gb, 3rd inversion | D | all fretted |
| x-x-10-11-9-10 | 9th fret | C, 1st inversion | D | all fretted |
| x-11-12-11-13-x | 11th fret | Ab, root position | C | all fretted |
The same notes rebuilt from scratch give 5 shell, 10 drop 3 and 6 open string voicings, each on its own page.
Tensions. A shell of Ab7b5, root, third and seventh, leaves a string free, and the tones that belong over it are the b9 (Bbb), the 9 (Bb), the #9 (B), the b13 (Fb) and the 13 (F).
How to use Ab7b5
Ab7b5 is a dominant with its tension raised, so it still points at Db — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.
What to play over Ab7b5
Every note of Ab7b5 is in Ab whole tone, Ab lydian dominant, Ab altered and Ab half-whole diminished.
Chords near Ab7b5
Change one note of Ab7b5 and you have Abmaj7b5 (the flat seventh becomes a major seventh), Abm7b5 (the major third becomes a minor third), Ab7 (the flat fifth becomes a fifth), Abaug7 (the flat fifth becomes a sharp fifth) or Ab9b5 (add the ninth).
Ab7b5 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On Ab7b5’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.