Bb-7(b5b9) Half-Diminished
The Bb-7(b5b9) chord is built from the notes Bb – Db – Fb – Ab – Cb.
Piano sound loads on first tap.
Also known as
Bb-alt7b9Bbm11b5b9b13Bbm7(b5)b9Bbm7b5b9Bbmi7(b5b9)
Chord tones, one by one
BbRoot
Root
The fundamental note the chord is built on — Bb.
DbThird
Minor third
Three semitones — makes the chord minor (darker, sadder).
FbFifth
Diminished fifth (♭5)
Six semitones — a flat fifth. Creates instability, typical of m7♭5 and diminished chords.
AbSeventh
Minor seventh (♭7)
Ten semitones — the dominant/minor seventh. Adds bluesy tension (7, m7).
CbExtension
Flat ninth (♭9)
A ♭9 — sharp, dissonant tension typical of altered dominant chords.
🎼 Related scales
🎹 Modal analysis
This chord implies the Locrian scale; its characteristic note is the unstable ♭5.
🎸 Genres
Modern jazz · Post-bop · Fusion