About the B flat seven sharp five chord
B flat seven sharp five sits outside the plain diatonic set, so it is borrowed to add color and tension. Think of it as a B♭ seventh sharp five chord.
Its notes are B♭, D, F♯, and A♭. The intervals are a major third, an augmented fifth, and a minor seventh.
Also called augmented seventh and +7. A sharp seven sharp five spells the same notes enharmonically.
Positions
Notes and intervals
| 1 | BbB♭ | Root |
|---|---|---|
| 2 | DD | Major 3rd |
| 3 | F#F♯ | Augmented 5th |
| 4 | AbA♭ | Minor 7th |
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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