C7b9

C7b9 is C, E, G, Bb and Db, a seven flat nine. The shape this page opens on is written x32323, lowest string first.

Also written C7(b9), C7-9 or C7♭9. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 6 common shapes for C7b9 on the guitar, and 42 derived voicings in 5 families.

The common shapes, written lowest string first: x32323, 8786xx, xx8989, 8-10-8-9-8-9, x-x-10-9-11-9, x-15-14-15-14-15.

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. C7b9 has x3232x, 8786xx, x-x-10-9-11-9, x-15-14-15-14-x.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. C7b9 has x3232x, 8786xx, x-x-10-9-11-9, x-15-14-15-14-x, xx2526, 6425xx, x4855x, xx8658.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. C7b9 has 6x252x, x3x320, x4x556, 8x865x, 9-x-10-9-11-x, x-13-x-9-13-9, 12-x-11-15-13-x, x-15-x-15-14-12.

Rootless. The root left to the bass player. Frees a finger for a tension. C7b9 has x1202x, xx2323, x4535x, xx5656, x7868x, xx8989, x-10-11-9-11-x, x-x-11-12-11-12.

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. C7b9 has 005656.

Tensions. A shell of C7b9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (F#), the b13 (Ab) and the 13 (A).

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