C#9b5

C#9b5 is C#, E#, G, B and D#, a nine flat five. The shape this page opens on is written x43443, lowest string first.

Note by note. C# is the root, E# is the major third, G is the flat fifth, B is the flat seventh and D# is the ninth.

Also written C#9(b5), C#9-5 or C#9♭5. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 5 common shapes for C#9b5 on the guitar, and 21 derived voicings in 2 families.

One note away. Change a single note of C#9b5 and you have C#7b5 (with one note taken away), C#9 (with one note moved), C#aug9 (with one note moved) or C#9#11 (with one note added).

The common shapes, written lowest string first: x43443, 989889, 9-10-x-10-0-11, 9-10-9-10-x-11, x-10-11-10-12-11.

Under the hand. None of the shapes for C#9b5 uses an open string, so every one of them is movable; the lowest sits at the 3rd fret. 2 of the 5 need a barre. Together they cover the neck from the 3rd fret to the 12th.

Where it goes. C#9b5 is a dominant with its tension raised, so it still points at F# — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.

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. C#9b5 has x4344x, 9898xx, x-x-11-10-12-11, x4x463, 9-x-9-10-8-x, 9-8-9-12-x-x, x4348x, x-x-11-10-12-15.

Rootless. The root left to the bass player. Frees a finger for a tension. C#9b5 has xx1001, x2304x, xx3443, x6546x, x8988x, x-x-13-12-12-13, x2x041, x6x463.

Tensions. A shell of C#9b5, root, third and seventh, leaves a string free, and the tones that belong over it are the b13 (A) and the 13 (A#).

What kind of chord this is. C#9b5 is an altered chord — a dominant seventh with its fifth or ninth moved. altered dominant chords on every root, and what they are for.

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