Finger Positions

Root Note A

Name A dominant ninth over A#

Intervals 1P-3M-5P-7m-9M

Relative Minor F#m

Notes A#, A, C#, E, G, B

Aliases A9

How to play the A9/A# Chord

The A9/A# is a fundamental dominant chord in guitar music. To play this chord correctly, ensure your fingers are placed precisely on the frets indicated in the diagram above.

Music Theory Analysis

From a theoretical perspective, the A dominant ninth over A# is built using the 1P, 3M, 5P, 7m, 9M intervals. In the key of A Major, this chord functions as the I chord.

Common Progressions

In music composition, the A9/A# chord is often used to create tension or resolution.

I-V-vi-IV

A → E → F#m → D

vi-IV-I-V

F#m → D → A → E

The Diatonic Family

Understanding the "family" of chords that belong to A helps with transposition and ear training.

Triads

A Bm C#m D E F#m G#dim

7ths

Amaj7 Bm7 C#m7 Dmaj7 E7 F#m7 G#m7b5

Scale Compatibility

View All Scales

Bebop Mixolydian Mixolydian B6 Lydian Dominant Lydian Minor Bebop Minor Composite Blues Messiaen's Mode #3 Chromatic

* 9 scales found containing the notes A#, A, C#, E, G, B.

Acoustic & Digital Analysis

Digital footprint of the A9/A# chord for MIDI programming and synthesizer sound design.

MIDI Numbers 70, 69, 61, 64, 67, 71

Frequencies (Hz)

466.1637615180899, 440, 277.1826309768721, 329.6275569128699, 391.99543598174927, 493.8833012561241