C9#11 guitar chord
An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful.
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- Fingers, notes or intervals
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About C9#11 — open string voicings
C9#11 is C, E, G, Bb, D and F# — C9 with the raised eleventh added on top.
It sounds wide and glassy, bright rather than tense. The ♯11 clears the major third by a whole step, so it adds height without the collision a natural eleventh makes.
C9#11 notes and formula
| C | E | G | Bb | D | F# |
|---|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | 9 | ♯11 |
Dominant — the lydian dominant sound.
Also written C9(#11), C9+11 or C9♯11. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play C9#11
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
C9#11 has 4 of them, on strings 6-5-4-3-2-1 and strings 6-4-3-2-1, from the 2nd fret up to the 6th — every inversion the chord has: E in the bass and Bb in the bass. The one to learn first is the E shape at the 2nd fret.
Start with x3435x — no barre and low, at the 3rd fret. None of the shapes for C9#11 uses an open string, so every one of them is movable; the lowest sits at the 2nd fret. 3 of the 6 need a barre. Together they cover the neck from the 2nd fret to the 12th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x32332 | 2nd fret | C, root position | F# | barred |
| x3435x | 3rd fret | C, root position | E | all fretted |
| 878778 | 7th fret | C, root position | C | barred |
| 8x897x | 7th fret | C, root position | F# | all fretted |
| 898988 | 8th fret | C, root position | C | barred |
| x-x-10-11-11-12 | 10th fret | C, root position | E | all fretted |
The same notes rebuilt from scratch give 9 shell and 13 rootless voicings, each on its own page.
Tensions. A shell of C9#11, root, third and seventh, leaves a string free, and the tones that belong over it are the b13 (Ab) and the 13 (A).
How to use C9#11
C9#11 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.
Voice by voice, C9#11 → F. 3 voices move by a semitone, and one note is common to both chords.
| In C9#11 | 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 |
| F#, the sharp eleventh | falls a semitone | F, the root |
What to play over C9#11
Every note of C9#11 is in C lydian dominant.
Chords near C9#11
Change one note of C9#11 and you have C9 (drop the flat fifth), C9b5 (drop the fifth) or C13 (the flat fifth becomes a sixth).
C9#11 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On C9#11’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.