Chord · Bb Dominant 7♯9 (Hendrix)
B♭7♯9 Chord
B♭7♯9 is Bb, D, F, Ab and C# — the Hendrix chord. Bluesy and aggressive.
B♭7♯9 on every instrument
The same 5 notes, 2 sets of hands. Open a diagram for alternate shapes, audio and the mistakes to avoid.
What B♭7♯9 is made of
Bb Dominant 7♯9 (Hendrix) (Bb dominant 7♯9 (hendrix)) is built from the notes Bb, D, F, Ab, C#, with the interval pattern 1, 3, 5, b7, #9. A common dominant 7♯9 (hendrix) chord across many styles.
Stack 1, 3, 5, b7 and #9 on a root of B♭ and you get Bb, D, F, Ab and C#. That interval recipe is what makes the chord a seventh sharp nine chord — move the same shape to another root and the character travels with it, which is why C7♯9 sounds like a transposed B♭7♯9.
Dominant 7♯9 (Hendrix): The Hendrix chord. Bluesy and aggressive.
Spelling: the notes above are written the way a score would write them, not simplified to the nearest piano key. That is why this chord is spelled with B♭ rather than its enharmonic equivalent.
Keys that contain B♭7♯9
No major or natural-minor key contains all 5 of these notes — this one gets borrowed.
Chords like this one sit outside the diatonic set — they arrive as secondary dominants, borrowed chords or passing harmony. Browse every key to see which progressions pull it in.
Other chords on B♭
Same root, different colour.
The same seventh sharp nine shape, moved
The identical interval recipe, built on other roots.
Questions people ask about Bb7#9
- What notes are in the Bb7#9 chord?
- Bb7#9 is made of Bb, D, F, Ab and C# — the 1, 3, 5, b7 and #9 degrees of a seventh sharp nine chord built on Bb.
- What keys use the Bb7#9 chord?
- No major or natural-minor key contains all 5 notes of Bb7#9. Chords like this arrive as borrowed harmony — secondary dominants, harmonic-minor colour, or chromatic passing chords — rather than as one of a key's native chords.
- How do you play Bb7#9 on guitar and piano?
- This page shows Bb7#9 on guitar and piano — 5 voicings in total. Each diagram links to the full instrument page with alternate shapes, audio and common mistakes.
- Is Bb7#9 the same as A#7#9?
- Yes. Bb7#9 and A#7#9 are enharmonic — identical pitches written two different ways. Which spelling you use depends on the key you are in; Bb7#9 is the spelling this site treats as canonical.
Learn the theory behind it
Why B♭7♯9 behaves the way it does — the guides that explain the chord instead of just spelling it.