C9sus(#4) Suspended
The C9sus(#4) chord is built from the notes C – F – G – Bb – D – F#.
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Also known as
Chord tones, one by one
Root
The fundamental note the chord is built on — C.
Suspended 4th
A perfect 4th replaces the third — tense, wants to resolve (sus4).
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).
Ninth (9)
A 9th — colorful extension a whole step above the octave.
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

