Dominant 9th #11
9#11
0 - 4 - 7 - 10 - 14 - 18Dom9 + augmented 11th (Lydian dominant)
About Dominant 9th #11
A dominant ninth sharp eleven chord is a dominant ninth with a raised fourth — in C that is C, E, G, B♭, D and F♯, written C9♯11. It is the full Lydian dominant: a chord that pulls toward a resolution and floats while it waits, which is the combination fusion built a language on.
Notes and formula
The formula is 1 – 3 – 5 – ♭7 – 9 – ♯11, or 0 – 4 – 7 – 10 – 14 – 18 in semitones. Six of the seven notes of the Lydian dominant scale.
The perfect fifth is retained, which distinguishes the chord from a flat-five dominant. G and F♯ are both present, and keeping them an octave apart is what makes the voicing work.
Where it comes from
The fourth mode of melodic minor. Every note of the chord belongs to it, and the mode is named after the chord as often as the other way round.
It also appears functionally on the flattened seventh degree of a major key — B♭9♯11 in C major — where the raised eleventh is the tonic of the key still sounding above a borrowed chord.
How to play it
On guitar the practical shape is x–3–2–3–3–2, sounding C–E–B♭–D–F♯. The fifth is left to the bass, which is standard for any six-note dominant.
On piano the reliable voicing is C in the left hand and E–B♭–D–F♯ in the right: third, seventh, ninth, raised eleventh, in ascending order and nothing else.
How it sounds
Wide and unhurried. The tritone between E and B♭ still points toward F, but the raised eleventh softens the urgency by adding a consonance where the ear expects tension.
Held, it sounds like a chord that could stay. Resolved, it works exactly like a plain dominant. That double life is what makes it useful.
Against the other dominants with an altered fifth region
C7♭5 replaces the fifth and is symmetrical. C9♯11 keeps it and is not. C7♯11 is the same chord as this one without the ninth.
The presence of the perfect fifth is the thing to listen for: it is what anchors the chord to a root and keeps the harmony readable.
Scales that contain it
Lydian dominant fits exactly. The whole-tone scale fits every note except the perfect fifth, so it applies only when the voicing omits it.
Mixolydian does not fit at all: its natural fourth is the degree this chord raises.
Frequently asked questions
What notes are in a C9♯11 chord?
C, E, G, B♭, D and F♯. On guitar, x–3–2–3–3–2.
Is it the same as 7♯11?
Almost — this chord adds the ninth. Both belong to Lydian dominant and behave identically.
Why keep the fifth when the eleventh is raised?
Because it anchors the root. Drop it and the chord becomes symmetrical and rootless, which is a different sound and a different symbol: 7♭5.