A7#9

A7#9 is A, C#, E, G and B#, a seven sharp nine. The shape this page opens on is written x32223, lowest string first.

Also written A7(#9), A7+9 or A7♯9. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 9 common shapes for A7#9 on the guitar, and 43 derived voicings in 5 families.

The common shapes, written lowest string first: x32223, 5455xx, x45555, 575688, 575658, xx7688, x77688, x-0-10-9-8-9, x-12-11-12-13-x.

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. A7#9 has 5455xx, xx7688, x-12-11-12-13-x.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. A7#9 has 5455xx, xx7688, x-12-11-12-13-x, x3522x, xx5525, x4758x, 8-10-7-6-x-x, x-10-10-6-10-x.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. A7#9 has x3x223, 5x552x, x4x585, 8x768x, x-10-x-6-10-8, x-12-x-12-13-9, 9-x-10-12-10-x, 15-x-11-14-13-x.

Rootless. The root left to the bass player. Frees a finger for a tension. A7#9 has x3202x, x4555x, x-x-10-9-8-9, x-x-11-12-13-12, x3x020, xx2523, x4x553, xx5658.

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. A7#9 has x02523, 5x5520, 03522x, x35220, 005525.

Tensions. A shell of A7#9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (D#), the b13 (F) 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.