Bbmaj11b5#9 Major 7th
The Bbmaj11b5#9 chord is built from the notes Bb – D – Fb – A – C# – Eb.
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Chord tones, one by one
Root
The fundamental note the chord is built on — Bb.
Major third
Four semitones — makes the chord major (brighter, happier).
Diminished fifth (♭5)
Six semitones — a flat fifth. Creates instability, typical of m7♭5 and diminished chords.
Major seventh
Eleven semitones — a lush, jazzy seventh just below the octave (maj7).
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.
🎹 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