Cm7b5 guitar chord
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About Cm7b5 — 2nd inversion
Cm7b5 is C, Eb, Gb and Bb — Cm7 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.
Cm7b5 notes and formula
| C | Eb | Gb | Bb |
|---|---|---|---|
| 1 | ♭3 | ♭5 | ♭7 |
Pre-dominant — the ii of a minor key.
Also written Cø, Cø7, Cm7-5, Cm7(b5) or C half diminished. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play Cm7b5
Cm7b5 in 2nd inversion puts Gb in the bass instead of C, the 5th of the chord. The notes are the same; what changes is what the bass line does, which is most of why you would reach for it — it lets the lowest voice move by step where the root would have jumped.
One of Cm7b5’s 7 common shapes does this: xx4546.
Start with x3434x — no barre and low, at the 3rd fret. None of the shapes for Cm7b5 uses an open string, so every one of them is movable; the lowest sits at the 1st fret. 3 of the 7 need a barre. Together they cover the neck from the 1st fret to the 11th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x31312 | 1st fret | C, root position | Gb | all fretted |
| x3434x | 3rd fret | C, root position | Eb | all fretted |
| xx4546 | 4th fret | Gb, 2nd inversion | Bb | all fretted |
| 8xx876 | 6th fret | C, root position | Bb | all fretted |
| 8x887x | 7th fret | C, root position | Gb | barred |
| 8-9-10-8-11-8 | 8th fret | C, root position | C | barred |
| x-x-10-11-11-11 | 10th fret | C, root position | Eb | barred |
The same notes rebuilt from scratch give 5 shell, 14 drop 2 and 9 drop 3 voicings, each on its own page.
Tensions. A shell of Cm7b5, root, third and seventh, leaves a string free, and the tones that belong over it are the 11 (F) and the b13 (Ab).
How to use Cm7b5
Cm7b5 is the ii of Bb 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 Cm7b5 belongs to C# major (the vii°, the leading tone) and Bb minor (the ii°, the supertonic).
What to play over Cm7b5
Every note of Cm7b5 is in C blues, C locrian, C altered and C half-whole diminished.
Chords near Cm7b5
Change one note of Cm7b5 and you have Cdim (drop the flat seventh), Cdim7 (the flat seventh becomes a sixth), Cm7 (the flat fifth becomes a fifth), CmMaj7b5 (the flat seventh becomes a major seventh) or C7b5 (the minor third becomes a major third).
Cm7b5 is a diminished chord — root, minor third, flat fifth. Diminished and half-diminished chords on every root.
On Cm7b5’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.