Ab9

Ab9 is Ab, C, Eb, Gb and Bb, a dominant ninth. The shape this page opens on is written x11112, lowest string first.

Also written Abdom9 or Ab dominant 9. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 8 common shapes for Ab9 on the guitar, and 39 derived voicings in 5 families.

In which keys. Every note of Ab9 belongs to C# major (the V) and Bb minor (the ♭VII).

The common shapes, written lowest string first: x11112, 411312, 4343xx, 464346, 464546, xx6576, 8x6876, x-11-10-11-11-11.

Shell. 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. Ab9 has 4343xx, xx6576, x-11-10-11-11-x.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. Ab9 has 4343xx, xx6576, x-11-10-11-11-x, x1411x, xx4314, x3637x, 6965xx, x9859x.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. Ab9 has x1x112, 4x431x, x3x374, 6x657x, x9x596, x-11-x-11-11-8, 8-x-8-11-9-x, 14-x-10-13-11-x.

Rootless. The root left to the bass player. Frees a finger for a tension. Ab9 has xx1312, x3434x, xx4546, xx8878, x-x-10-11-11-11, x-13-13-11-13-x, x-x-13-15-13-14, x3x342.

Open string. 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. Ab9 has x34340, 6x6570.

Tensions. A shell of Ab9, 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).

The common shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.