Bb13(#9)(#4) Dominant 7th
The Bb13(#9)(#4) chord is built from the notes Bb – D – F – Ab – C# – E – G.
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Chord tones, one by one
BbRoot
Root
The fundamental note the chord is built on — Bb.
DThird
Major third
Four semitones — makes the chord major (brighter, happier).
FFifth
Perfect fifth
Seven semitones — the most stable interval, reinforces the root.
AbSeventh
Minor seventh (♭7)
Ten semitones — the dominant/minor seventh. Adds bluesy tension (7, m7).
C#Extension
Sharp ninth (♯9)
A ♯9 — the gritty 'Hendrix' tension over a dominant chord.
EExtension
Sharp eleventh (♯11)
A ♯11 — the bright, floating Lydian color.
GExtension
Thirteenth (13)
A 13th — full, rich top extension.
🎼 Related scales
🎹 Modal analysis
This chord implies the Half-whole diminished scale; its characteristic note is the ♭9 / ♭2.
🎸 Genres
Bebop jazz · Hard bop · Gypsy jazz