Bb-alt7b13 Half-Diminished
The Bb-alt7b13 chord is built from the notes Bb – Db – Fb – Ab – E.
Piano sound loads on first tap.
Also known as
Bbm7(b5)#11Bbm7b5(#4)
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).
EExtension
Sharp eleventh (♯11)
A ♯11 — the bright, floating Lydian color.
🎼 Related scales
🎹 Modal analysis
This chord implies the Locrian scale; its characteristic note is the unstable ♭5.
🎸 Genres
Modern jazz · Post-bop · Fusion