The A 7♭5♯9 chord is a five-note chord made up of A, C♯, E♭, G, and B♯. It is built from a root, major third, diminished fifth, minor seventh, and augmented ninth.
Construction
A 7♭5♯9 = Root + Major 3rd + Diminished 5th + Minor 7th + Minor 3rd = A · C♯ · E♭ · G · B♯
| Note | Interval | Degree |
|---|---|---|
| A | Root | 1 |
| C♯ | Major 3rd | 3 |
| E♭ | Diminished 5th | ♭5 |
| G | Minor 7th | ♭7 |
| B♯ | Minor 3rd | ♭3 |
Key Signature
A chord has no key signature of its own, but the A 7♭5♯9 is the tonic (I) chord of A Major, whose key signature has 3 sharps (F♯, C♯, G♯).
F♯C♯G♯
Order of sharps
Sharps are added to a key signature in a fixed order. Each new sharp key adds the next sharp on the list.
F♯C♯G♯D♯A♯E♯B♯
Mnemonic: Father Charles Goes Down And Ends Battle
Chords in the Key of A Major
These are the triads built on each degree of the A major scale:
A 7♭5♯9 — Frequently Asked Questions
What is the A 7♭5♯9 chord on piano?
The A 7♭5♯9 chord contains the notes A – C♯ – E♭ – G – B♯. On piano, play these notes together to sound the chord.
What notes are in the A 7♭5♯9 chord?
The A 7♭5♯9 chord (A7♭5♯9) contains 5 notes: A, C#, Eb, G, C. Formula: R-M3-d5-m7-A9.
How is A7♭5♯9 used in music?
A7♭5♯9 is used in jazz, fusion, and contemporary music to add harmonic color. It appears as a dominant or tonic chord depending on context.
What is the scale degree formula for A7♭5♯9?
A7♭5♯9 uses scale degrees 1-3-b5-b7-#9, giving it its distinctive sound.