Bb7b9 Bb dominant seventh flat nine chord
- Notes
- Bb D F Ab Cb
- Formula
- 1 3 5 b7 b9
- Semitones
- 0 4 7 10 13 above the root
- Also written
- A#7b9 (A# C## E# G# B)
- Other symbols
- Bb7(b9), Bb7-9
Bb to D is a major third (4 semitones), D to F is a minor third (3 semitones), F to Ab is a minor third (3 semitones), Ab to Cb is a minor third (3 semitones). A dominant seventh with a flattened ninth, Cb, a half step (plus an octave) above the root. It is the sharpest-sounding of the common dominant chords and pulls hard towards a minor tonic.
Bb7b9 on the piano
Root position from Bb4: Bb4, D5, F5, Ab5, Cb6. Middle C is C4.
Bb7b9 on the guitar
Standard tuning (E A D G B E). Strings run low E on the left to high e on the right, frets downwards; × is a muted string, ○ an open string, and each dot shows the note it sounds, with the root in blue-green. Every shape below has Bb as its lowest note.
x 1 0 1 0 x (low E to high e)
Sounds Bb2 D3 Ab3 Cb4, fifth left out
6 x 6 7 6 7 (low E to high e)
Sounds Bb2 Ab3 D4 F4 Cb5
The E-shape and A-shape grips are movable: an E-shape chord's root is the note under your first finger on the low E string, an A-shape chord's root is the note on the A string. Slide the same grip up or down to play dominant seventh flat nine chords on other roots.
Inversions of Bb7b9
An inversion puts a note other than the root in the bass. The name is what semicord's chord finder calls those notes played bottom to top; a slash name like C/E means a C chord with E in the bass.
| Position | Notes, bass first | Named | Listen |
|---|---|---|---|
| Root position | Bb D F Ab Cb | Bb7b9 | |
| 1st inversion | D F Ab Cb Bb | Bb7b9/D | |
| 2nd inversion | F Ab Cb Bb D | Bb7b9/F | |
| 3rd inversion | Ab Cb Bb D F | Bb7b9/Ab | |
| 4th inversion | Cb Bb D F Ab | Bb7/B |
Where Bb7b9 fits
Bb7b9 is V7b9 in Eb minor. Its upper four notes D F Ab Cb are Ddim7, so Bb7b9 and that diminished seventh are interchangeable over a Bb bass. The flat ninth Cb falls a half step to the fifth of Ebm.