Finger Positions

Root Note C

Name C dominant ninth over A#

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

Relative Minor Am

Notes A#, C, E, G, Bb, D

Aliases C9

How to play the C9/A# Chord

The C9/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 C dominant ninth over A# is built using the 1P, 3M, 5P, 7m, 9M intervals. In the key of C Major, this chord functions as the I chord.

Common Progressions

In music composition, the C9/A# chord is often used to create tension or resolution.

I-V-vi-IV

C → G → Am → F

vi-IV-I-V

Am → F → C → G

The Diatonic Family

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

Triads

C Dm Em F G Am Bdim

7ths

Cmaj7 Dm7 Em7 Fmaj7 G7 Am7 Bm7b5

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#, C, E, G, Bb, D.

Acoustic & Digital Analysis

Digital footprint of the C9/A# chord for MIDI programming and synthesizer sound design.

MIDI Numbers 70, 60, 64, 67, 70, 62

Frequencies (Hz)

466.1637615180899, 261.6255653005986, 329.6275569128699, 391.99543598174927, 466.1637615180899, 293.6647679174076