C7b5

C7b5 is C, E, Gb and Bb, a seven flat five. The shape this page opens on is written x12312, lowest string first.

Also written C7(b5), C7-5 or C7♭5. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 5 common shapes for C7b5 on the guitar, and 30 derived voicings in 4 families.

The common shapes, written lowest string first: x12312, xx2312, x3435x, 8x8970, x-x-10-11-11-12.

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. C7b5 has x3x352, 8x897x, 8-7-8-11-x-x, x3237x, x-x-10-9-11-14.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. C7b5 has xx2312, 2323xx, x3435x, xx4556, xx8978, 8989xx, x-9-10-9-11-x, x-x-10-11-11-12.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. C7b5 has 2x231x, x3x352, 6x455x, x7x576, 8x897x, x-9-x-9-11-8, 12-x-10-11-11-x, x-13-x-11-13-12.

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. C7b5 has 004556, 070576.

Tensions. A shell of C7b5, root, third and seventh, leaves a string free, and the tones that belong over it are the b9 (Db), the 9 (D), the #9 (D#), 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.