C9 guitar chord
The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped.
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- Fingers, notes or intervals
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About C9 — drop 3 voicings
C9 is C, E, G, Bb and D — C7 with the ninth stacked on top.
It sounds bright and full, still clearly pulling. The ninth adds height without softening the tritone underneath it, which is why funk and soul comp on this rather than on a plain 7.
C9 notes and formula
| C | E | G | Bb | D |
|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | 9 |
Dominant — the same pull as a 7, with more colour.
Also written Cdom9 or C dominant 9. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play C9
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.
C9 has 10 of them, on strings 6-4-3-2 and strings 5-3-2-1, from open position up to the 12th — every inversion the chord has: C in the bass, E in the bass, Bb in the bass and D in the bass. The one to learn first is the E 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 x32030 — no barre and 2 open strings. 1 of the 10 shapes here sits in open position. 6 of the 10 need a barre. Together they cover the neck from the 2nd fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x32030 | open position | C, root position | E | 2 open strings |
| x32333 | 2nd fret | C, root position | G | barred |
| x55556 | 5th fret | D, 9th in the bass | Bb | barred |
| 855756 | 5th fret | C, root position | Bb | barred |
| 8787xx | 7th fret | C, root position | D | all fretted |
| 8-10-8-7-8-10 | 7th fret | C, root position | D | barred |
| 8-10-8-9-8-10 | 8th fret | C, root position | D | barred |
| x-x-10-9-11-10 | 9th fret | C, root position | D | all fretted |
| 12-x-10-12-11-10 | 10th fret | E, 1st inversion | D | all fretted |
| x-15-14-15-15-15 | 14th fret | C, root position | G | barred |
The same notes rebuilt from scratch give 4 shell, 15 drop 2, 15 rootless and 6 open string voicings, each on its own page.
Tensions. A shell of C9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (F#), the b13 (Ab) and the 13 (A).
How to use C9
C9 is the V of F, and that is where it goes if it goes anywhere: the third and the flat seventh are a tritone apart, and both resolve by a semitone into F.
Voice by voice, C9 → F. 2 voices move by a semitone, and one note is common to both chords.
| In C9 | Moves | In F |
|---|---|---|
| C, the root | stays where it is | C, the fifth |
| E, the major third | rises a semitone | F, the root |
| G, the fifth | falls a whole tone | F, the root |
| Bb, the flat seventh | falls a semitone | A, the major third |
| D, the ninth | falls a whole tone | C, the fifth |
In which keys. Every note of C9 belongs to D minor (the ♭VII) and F major (the V, the dominant).
What to play over C9
Every note of C9 is in C mixolydian and C lydian dominant.
Chords near C9
Change one note of C9 and you have Cmaj9 (the flat seventh becomes a major seventh), Cm9 (the major third becomes a minor third), Cadd9 (drop the flat seventh), C69 (the flat seventh becomes a sixth), C7 (drop the ninth) or C7/G (drop the ninth).
C9 is a dominant chord — root, major third, fifth, minor seventh. Dominant seventh chords on every root.
On C9’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.