F7b9

F7b9 is F, A, C, Eb and Gb, a seven flat nine. The shape this page opens on is written xx1212, lowest string first.

Note by note. F is the root, A is the major third, C is the fifth, Eb is the flat seventh and Gb is the flat ninth.

Also written F7(b9), F7-9 or F7♭9. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 6 common shapes for F7b9 on the guitar, and 34 derived voicings in 4 families.

One note away. Change a single note of F7b9 and you have F7 (with one note taken away), Falt (with one note moved), F9 (with one note moved), F7#9 (with one note moved) or F/D# (with one note taken away).

The common shapes, written lowest string first: xx1212, 131212, xx3242, x87878, 13-12-13-11-x-x, 13-x-13-14-13-14.

Under the hand. None of the shapes for F7b9 uses an open string, so every one of them is movable; the lowest sits at the 1st fret. 3 of the 6 need a barre. Together they cover the neck from the 1st fret to the 14th.

Where it goes. F7b9 is a dominant with its tension raised, so it still points at Bb — 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. F7b9 has xx3242, x8787x, 13-12-13-11-x-x.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. F7b9 has xx3242, x8787x, 13-12-13-11-x-x, 2632xx, x6426x, 5848xx, xx4865, x-x-7-10-7-11.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. F7b9 has 2x324x, x6x262, 5x486x, x8x875, 11-x-7-10-7-x, x-9-x-10-10-11, 13-x-13-11-10-x.

Rootless. The root left to the bass player. Frees a finger for a tension. F7b9 has xx1212, x3424x, xx4545, x6757x, xx7878, x-9-10-8-10-x, x-x-10-11-10-11, x-12-13-11-13-x.

Tensions. A shell of F7b9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (B), the b13 (Db) and the 13 (D).

What kind of chord this is. F7b9 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.