About Fm7b5 — drop 3 voicings
Fm7b5 is F, Ab, Cb and Eb — Fm7 with the fifth lowered a semitone.
It sounds hollow, and unmistakably going somewhere. Almost always the first chord of a minor ii–V–i, so it walks straight into an altered dominant.
Fm7b5 notes and formula
| F | Ab | Cb | Eb |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭7 |
Pre-dominant — the ii of a minor key.
Also written Fø, Fø7, Fm7-5, Fm7(b5) or F half diminished. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play Fm7b5
The same operation one voice further down: the third voice from the top falls an octave and becomes the bass.
That leaves a bigger hole under the top three notes, so a string gets skipped: the muted string in the middle is the shape, not a mistake.
Fm7b5 has 9 of them, on strings 5-3-2-1 and strings 6-4-3-2, from open position up to the 12th — every inversion the chord has: F in the bass, Ab in the bass, Cb in the bass and Eb in the bass. The one to learn first is the Cb shape at the nut.
5 of them sit on strings 6-4-3-2, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with x8989x — no barre. 1 of the 9 shapes here sits in open position. 5 of the 9 need a barre. Together they cover the neck from the 1st fret to the 13th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 1x110x | open position | F, root position | Cb | barred |
| 123141 | 1st fret | F, root position | F | barred |
| xx3444 | 3rd fret | F, root position | Ab | barred |
| x86867 | 6th fret | F, root position | Cb | all fretted |
| x8989x | 8th fret | F, root position | Ab | all fretted |
| x-x-9-10-9-11 | 9th fret | Cb, 2nd inversion | Eb | all fretted |
| 13-11-13-13-0-x | 11th fret | F, root position | Ab | barred |
| 13-x-x-13-12-11 | 11th fret | F, root position | Eb | all fretted |
| 13-x-13-13-12-x | 12th fret | F, root position | Cb | barred |
The same notes rebuilt from scratch give 5 shell and 14 drop 2 voicings, each on its own page.
Tensions. A shell of Fm7b5, root, third and seventh, leaves a string free, and the tones that belong over it are the 11 (Bb) and the b13 (Db).
How to use Fm7b5
Fm7b5 is the ii of Eb minor, which is where it is nearly always found: half-diminished, then an altered dominant, then the minor tonic.
In which keys. Every note of Fm7b5 belongs to Eb minor (the ii°, the supertonic) and F# major (the vii°, the leading tone).
What to play over Fm7b5
Every note of Fm7b5 is in F blues, F locrian, F altered and F half-whole diminished.
Chords near Fm7b5
Change one note of Fm7b5 and you have Fdim (drop the flat seventh), Fdim7 (the flat seventh becomes a sixth), Fm7 (the flat fifth becomes a fifth), FmMaj7b5 (the flat seventh becomes a major seventh) or F7b5 (the minor third becomes a major third).
Fm7b5 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On Fm7b5’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.