Ab7b9 guitar chord
Root, third and seventh: the guide tones fix the quality, so the fifth is dropped. That is what leaves a string free, so pick a tension to put on top.
- Tap a note to hear it
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- Fingers, notes or intervals
- Play the chord
About Ab7b9 — shell voicings
Ab7b9 is Ab, C, Eb, Gb and A — Ab9 with the ninth lowered a semitone.
It sounds dark and urgent. The flat ninth comes from the harmonic minor, so this is the V of a minor key rather than a major one.
Ab7b9 notes and formula
| Ab | C | Eb | Gb | A |
|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | ♭9 |
Altered dominant — it points at a minor chord.
Also written Ab7(b9), Ab7-9 or Ab7♭9. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play Ab7b9
Root, third and seventh. The third and seventh, the guide tones, are what make the chord major, minor or dominant, so the fifth can go: it says nothing the symbol needs.
Three notes means a spare string, which is the real point. Put a tension on it.
Ab7b9 has 3 of them, on the bottom four strings, the top four strings and the middle four strings, from the 2nd fret up to the 10th — all in one inversion, so the bass note never moves. The one to learn first is the Ab shape at the 2nd fret, which is the easiest grip here.
Start with 4342xx — no barre and down at the nut. 1 of the 6 shapes here sits in open position. 3 of the 6 need a barre. Together they cover the neck from the 1st fret to the 11th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x01112 | open position | Bbb, 9th in the bass | Gb | barred |
| 4342xx | 2nd fret | Ab, root position | A | all fretted |
| xx4545 | 4th fret | Gb, 3rd inversion | A | all fretted |
| 464545 | 4th fret | Ab, root position | A | barred |
| xx6575 | 5th fret | Ab, root position | A | all fretted |
| x-11-10-11-10-11 | 10th fret | Ab, root position | Eb | barred |
The same notes rebuilt from scratch give 12 drop 2, 9 drop 3, 13 rootless and 4 open string voicings, each on its own page.
Tensions. A shell of Ab7b9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (D), the b13 (Fb) and the 13 (F).
How to use Ab7b9
Ab7b9 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 Ab7b9
Every note of Ab7b9 is in Ab half-whole diminished.
Chords near Ab7b9
Change one note of Ab7b9 and you have Ab7 (drop the flat ninth), Abalt (the fifth becomes a sharp fifth), Ab9 (the flat ninth becomes a ninth) or Ab7#9 (the flat ninth becomes a minor third).
Ab7b9 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On Ab7b9’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.