C9#11 guitar chord
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About C9#11 — uncommon voicings
C9#11 is C, E, G, Bb, D and F# — 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.
Dominant — the lydian dominant sound.
Also written C9(#11), C9+11 or C9♯11.
What these less common shapes are
How to use C9#11
C9#11 is a dominant with its tension raised, so it still points at — harder than a plain seventh does. A plain dominant has two voices a semitone from home; an altered one has four, because every altered tone is also sitting a semitone from a note of F. More voices leaning the same way is all "more tension" means here.
In a phrase:→→
The ii–V–I of F.
Voice by voice, C9#11 → . 3 voices move by a semitone, and one note is common to both chords. Those semitones are what the ear follows; the rest is the chord rearranging itself underneath.
| 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.
Each of those is a page: the scale across the neck, and the chords it harmonises into — which is where C9#11 sits in it. Every scale.
Chords near C9#11
Change one note of C9#11 and you have (drop the sharp eleventh), (drop the fifth) or (the sharp eleventh becomes the thirteenth).
C9#11 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.