Guitar Chord A#7b9: Structure, Notes and Theory

A#7b9 — a chord built on the note “A#” with an energetic sound and a strong pull toward resolution. A classic element of jazz and blues progressions, adding drive and a sense of phrase completion. The chord includes alterations: b9 — a rich dominant tone that should be applied carefully in arrangements.

Formula and Structure of the A#7b9 Chord

Interval formula from the root note: 1 — 3 — 5 — b7 — b9. The chord consists of the following notes:

• Bb — unison and the main tonal anchor.
• D — major third with a bright major quality and clear stability above the tonic.
• F — perfect fifth, stabilizing the triad and adding tonal grounding.
• Ab — minor seventh with dominant pull toward the tonic.
• B — flat ninth with a dominant bite, best kept high and away from the bass.

Together, these notes form the harmonic foundation of the A#7b9 chord, defining its sound and role in the musical context.

Alternative Names for the A#7b9 Chord

There are no alternative names for this chord.

Using the A#7b9 Chord

Build a stable frame from the 3 and b7, keeping them in fixed positions. Add colors (#9, b9, #11, b13) sparingly to preserve clarity. Classic usage is II–V–I, but it can also work in bebop runs. It’s useful to omit the fifth temporarily to make room for color tones.

Conclusion

A#7b9 is an expressive and versatile chord. Learn several fingerings, experiment with different positions and voice spacing, then try weaving it into your own playing — this will help you quickly find your unique tone.