C#11#9 Dominant 7th
The C#11#9 chord is built from the notes C# – E# – G# – B – D## – F# – F##.
Piano sound loads on first tap.
Chord tones, one by one
Root
The fundamental note the chord is built on — C#.
Major third
Four semitones — makes the chord major (brighter, happier).
Perfect fifth
Seven semitones — the most stable interval, reinforces the root.
Minor seventh (♭7)
Ten semitones — the dominant/minor seventh. Adds bluesy tension (7, m7).
Sharp ninth (♯9)
A ♯9 — the gritty 'Hendrix' tension over a dominant chord.
Eleventh (11)
An 11th — a suspended, airy color on top of the chord.
Sharp eleventh (♯11)
A ♯11 — the bright, floating Lydian color.
🎹 Modal analysis
This chord is so rich it doesn't fit a single scale: it's a polychord (an “upper structure”) that stacks tensions from several scales at once. It doesn't work like a dominant that “wants” to resolve — it's pure color: picture one triad floating over an unrelated bass, the kind of sound used in reharmonization and modal passages. To make sense of it, follow the note-by-note breakdown above.
🎸 Genres
Modern jazz · Fusion · Film & TV scoring · Impressionism