Ab7b5 guitar chord
An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful.
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- Fingers, notes or intervals
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About Ab7b5 — open string 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
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
Ab7b5 has 6 of them, on strings 6-5-4-3-2-1, strings 6-4-3-2-1, strings 5-4-3-2-1, strings 6-5-4-3-2 and the top four strings, from the 2nd fret up to the 5th — every inversion the chord has: Ab in the bass, Ebb in the bass and Gb in the bass. The one to learn first is the Ab shape at the 4th fret, which is the easiest grip here.
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, 14 drop 2 and 10 drop 3 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.