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.
Ab13 is Ab, C, Eb, Gb, Bb and F — Ab9 with the thirteenth added on top.
It sounds big and open. Six notes will not fit under four fingers: the fifth goes first, then the ninth, and the third, flat seventh and thirteenth stay.

| Ab | C | Eb | Gb | Bb | F |
|---|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | 9 | 13 |
Dominant — the full V chord.
Also written Abdom13 or Ab dominant 13. The same chord either way; which spelling you meet depends on who wrote the chart.
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.
Ab13 has 2 of them, on strings 6-4-3-2 and strings 5-3-2-1, from the 4th fret up to the 11th — all in one inversion, so the bass note never moves. The one to learn first is the Ab shape at the 4th fret.
Start with x-11-10-11-13-13 — no barre. None of the shapes for Ab13 uses an open string, so every one of them is movable; the lowest sits at the 1st fret. 6 of the 7 need a barre. Together they cover the neck from the 1st fret to the 13th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 413112 | 1st fret | Ab, root position | Gb | barred |
| 433342 | 2nd fret | Ab, root position | Gb | barred |
| 444566 | 4th fret | Ab, root position | Bb | barred |
| 464564 | 4th fret | Ab, root position | Ab | barred |
| x-11-10-11-13-13 | 10th fret | Ab, root position | F | all fretted |
| x-11-10-11-11-13 | 10th fret | Ab, root position | F | barred |
| 11-11-11-11-13-13 | 11th fret | Eb, 2nd inversion | F | barred |
The same notes rebuilt from scratch give 14 drop 2, 9 drop 3 and 22 rootless voicings, each on its own page.
Tensions. A shell of Ab13, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (D).
Ab13 is the V of Db, and that is where it goes if it goes anywhere: the third and the flat seventh are a tritone apart, and both resolve by a semitone into Db.
In which keys. Every note of Ab13 belongs to C# major (the V, the dominant) and Bb minor (the ♭VII).
Every note of Ab13 is in Ab mixolydian and Ab lydian dominant.
Change one note of Ab13 and you have Abmaj13 (the flat seventh becomes a major seventh), Ab69 (drop the flat seventh), Ab9 (drop the sixth) or Ab9#11 (the sixth becomes a flat fifth).
Ab13 is a dominant chord — root, major third, fifth, minor seventh. Dominant seventh chords on every root.
On Ab13’s sound and use this page follows Ted Pease & Ken Pullig, Modern Jazz Voicings (Berklee Press, 2001). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.