About the B flat nine sharp five chord
B flat nine sharp five sits outside the plain diatonic set, so it is borrowed to add color and tension. Think of it as a B♭ dominant ninth chord with a raised fifth.
Its notes are B♭, D, F♯, A♭, and C. The intervals are a major third, an augmented fifth, a minor seventh, and a major ninth.
Also called aug9 and +9. A sharp nine sharp five spells the same notes enharmonically.
Inversions
B flat nine sharp five (root position)
Notes and intervals
| 1 | BbB♭ | Root |
|---|---|---|
| 2 | DD | Major 3rd |
| 3 | F#F♯ | Augmented 5th |
| 4 | AbA♭ | Minor 7th |
| 5 | CC | Major 9th |
Shapes
Chromatic
Circle of Fifths
Other B flat chords
Simpler triads
Suspended
Sixths and sevenths
Extensions
Altered
Functional relationships
These chords are where this one most naturally comes from and resolves to inside a key.
Relative minor
The relative minor uses the same notes and key signature, so it works as a calmer, darker home base.
Parallel minor
The parallel minor keeps the same root note but lowers the third, giving the same key a darker, sadder sound.
Dominant
The dominant is a fifth above the root, and it builds tension that pulls strongly back to this chord.
Subdominant
The subdominant is a fourth above the root (a fifth below), and it usually leads on to the dominant or back home.
Tritone substitution
The tritone substitution is a dominant chord a tritone away that shares the same tension, so it can stand in for this chord and resolve the same way.
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