Finger Positions

Root Note A

Name A major ninth over C#

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

Relative Minor F#m

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

Aliases Amaj9, AΔ9, A^9

How to play the Amaj9/C# Chord

The Amaj9/C# 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 A major ninth over C# 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 Amaj9/C# 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

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

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

Acoustic & Digital Analysis

Digital footprint of the Amaj9/C# chord for MIDI programming and synthesizer sound design.

MIDI Numbers 69, 61, 64, 68, 71

Frequencies (Hz)

440, 277.1826309768721, 329.6275569128699, 415.3046975799451, 493.8833012561241