About the B flat major seven sharp five chord
The B flat major seven sharp five chord is a B flat major seventh sharp five built from B flat, D, F sharp, A. You will most often meet it as the I+ chord in B flat Lydian Augmented.
It is also written A sharp major seven sharp five , which spells the same notes enharmonically.
In shorthand it is commonly written Bbmaj7#5.
Positions
(root position)
Notes and intervals
| 1 | B flat | Root |
| 2 | D | Major 3rd |
| 3 | F sharp | Augmented 5th |
| 4 | A | Major 7th |
Shapes
Chromatic
Circle of Fifths
Keys that use B flat major seven sharp five
B flat major seven sharp five is diatonic to these keys, where it acts as the chord shown.
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 stands in for this chord's dominant with a dominant seventh a half step above the root, which slides down by a half step to resolve here.
