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.
Ab69 is Ab, C, Eb, F and Bb — Ab6 with the ninth added as well.
It sounds wide and entirely at rest. The modern way to voice a tonic when a triad is too bare and a maj7 too pointed.

| Ab | C | Eb | F | Bb |
|---|---|---|---|---|
| 1 | 3 | 5 | 6 | 9 |
Tonic — it commits to nothing.
Also written Ab6/9, Ab6add9 or Ab six nine. 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.
Ab69 has 3 of them, on the bottom four strings, the top four strings and the middle four strings, from the 3rd 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 3rd fret, which is the easiest grip here.
Start with x-11-8-10-9-8 — no barre. None of the shapes for Ab69 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 11th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x11111 | 1st fret | Bb, 9th in the bass | F | barred |
| 433344 | 3rd fret | Ab, root position | Ab | barred |
| xx6566 | 5th fret | Ab, root position | Bb | barred |
| x66566 | 5th fret | Eb, 2nd inversion | Bb | barred |
| x88898 | 8th fret | F, 6th in the bass | C | barred |
| x-11-8-10-9-8 | 8th fret | Ab, root position | C | all fretted |
| x-11-10-10-11-11 | 10th fret | Ab, root position | Eb | barred |
The same notes rebuilt from scratch give 13 drop 2, 9 drop 3 and 13 rootless voicings, each on its own page.
Tensions. A shell of Ab69, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (D).
How you get to it. The turn that lands on Ab69 is Bbm7 to Eb7 — the ii and the V of Ab — and Eb7 shares its third and seventh with Bbm7, so the hand barely moves between them.
In which keys. Every note of Ab69 belongs to C minor (the ♭VI), C# major (the V), Eb major (the IV), F minor (the ♭III), Ab major (the I) and Bb minor (the ♭VII).
Ab69 is every note of the Ab major pentatonic, and nothing else. It also sits inside Ab major, Ab lydian, Ab mixolydian and Ab lydian dominant.
Change one note of Ab69 and you have Abmaj9 (the sixth becomes a major seventh), Abmaj13 (add the major seventh), Abm69 (the major third becomes a minor third), Abadd9 (drop the sixth), Ab6 (drop the ninth) or Ab9 (the sixth becomes a flat seventh).
Ab69 is a major chord — root, major third, fifth. Major chords on every root.
On Ab69’s sound and use this page follows Mark Levine, The Jazz Piano Book (Sher Music, 1989). 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.