Finger Positions

Root Note C#

Name C# major ninth over A

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

Relative Minor A#m

Notes A, C#, F, G#, C, D#

Aliases C#maj9, C#Δ9, C#^9

How to play the C#maj9/A Chord

The C#maj9/A is a fundamental major 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# major 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 C#maj9/A chord is often used to create tension or resolution.

I-V-vi-IV

C# → G# → A#m → F#

vi-IV-I-V

A#m → F# → C# → G#

The Diatonic Family

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

Triads

C# D#m Fm F# G# A#m Cdim

7ths

C#maj7 D#m7 Fm7 F#maj7 G#7 A#m7 Cm7b5

Scale Compatibility

View All Scales

Major Bebop Lydian Harmonic Major Bebop Major Ichikosucho Messiaen's Mode #3 Chromatic

* 8 scales found containing the notes A, C#, F, G#, C, D#.

Acoustic & Digital Analysis

Digital footprint of the C#maj9/A chord for MIDI programming and synthesizer sound design.

MIDI Numbers 69, 61, 65, 68, 60, 63

Frequencies (Hz)

440, 277.1826309768721, 349.2282314330039, 415.3046975799451, 261.6255653005986, 311.1269837220809