Finger Positions

Root Note C#

Name C# over A

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

Relative Minor A#m

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

Aliases C#9b5

How to play the C#9b5/A Chord

The C#9b5/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# over A is built using the 1P, 3M, 5d, 7m, 9M intervals. In the key of C# Major, this chord functions as the I chord.

Common Progressions

In music composition, the C#9b5/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

Prometheus Whole Tone Locrian Major Lydian Dominant Leading Whole Tone Lydian Minor Messiaen's Mode #6 Composite Blues Messiaen's Mode #3 Chromatic

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

Acoustic & Digital Analysis

Digital footprint of the C#9b5/A chord for MIDI programming and synthesizer sound design.

MIDI Numbers 69, 61, 65, 67, 71, 63

Frequencies (Hz)

440, 277.1826309768721, 349.2282314330039, 391.99543598174927, 493.8833012561241, 311.1269837220809