A# Dominant Thirteen Sharp Ninth Guitar Chord (A#13(#9)) | Easy Ways to Play It
The A#13(#9) chord, also read as A# thirteenth sharp nine, is spelled A#, C##, E#, G#, B##, D# and F##: a root, a major third, a perfect fifth, a minor seventh, a sharp ninth, an eleventh and a thirteenth.
The double sharps come from stacking thirds on A#. The same pitches are spelled Bb13(#9), so the two names sound identical. The A# Half-Whole scale, built from alternating half and whole steps, has every chord tone except the eleventh.
As a dominant chord it usually resolves to the chord a fourth above A#, and the sharp ninth B## adds tension that a plain thirteenth chord does not have.
A# 13th with sharp 9th guitar chord is also written as A#13(#9), A#13#9 or A#13+9.
Notes in the A# 13(#9) chord:
Chord Structure:
Formula: 1 3 5 b7 #9 11 13
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Giancarlo is a musician (teaching guitar since 2000), software engineer, AI consultant and published researcher
FAQ
What notes make up A#13(#9)?
A#13(#9) is spelled A#, C##, E#, G#, B##, D# and F##. That is the root, major third, perfect fifth, minor seventh, sharp ninth, eleventh and thirteenth.
Can A#13(#9) be written as Bb13(#9)?
Yes, both names mean the same seven pitches. Bb13(#9) spells them Bb, D, F, Ab, C#, Eb and G, which avoids the three double sharps in A#13(#9).
Why is the sharp ninth of A#13(#9) written B##?
The ninth is counted by letter, so from A# it falls on B. The major ninth is B#, and raising it by one more half step gives B##.
Which scale suits A#13(#9)?
The A# half-whole scale contains every chord tone except the eleventh, D#. Its alternating half and whole steps supply the sharp ninth and the thirteenth.
