Construction
B♭ 9♯11 = Root + Major 3rd + Perfect 5th + Minor 7th + Major 2nd + Diminished 5th = B♭, D, F, A♭, C, E
| Note | Interval | Degree |
|---|---|---|
| B♭ | Root | 1 |
| D | Major 3rd | 3 |
| F | Perfect 5th | 5 |
| A♭ | Minor 7th | ♭7 |
| C | Major 2nd | 9 |
| E | Diminished 5th | ♭5 |
Key Signature
A chord has no key signature of its own, but the B♭ 9♯11 is the tonic (I) chord of B♭ Major, whose key signature has 2 flats (B♭, E♭).
B♭E♭
Order of flats
Flats are added in a fixed order — the reverse of the sharp order. Each new flat key adds the next flat on the list.
B♭E♭A♭D♭G♭C♭F♭
Mnemonic: Battle Ends And Down Goes Charles’ Father
Chords in the Key of B♭ Major
These are the triads built on each degree of B♭ Major:
B♭ 9♯11 : Frequently Asked Questions
What is the B♭ 9♯11 chord on piano?
The B♭ 9♯11 chord contains the notes B♭ – D – F – A♭ – C – E. On piano, play these notes together to sound the chord.