C#7#9

General info

Full name

C# 7#9

Symbol

C#7#9

Root

C#

Quality

7#9

Chord notes

Functions & resolutions

Typical function in key

viRelative tonic (vi)E major

Stability / tension

High tension — requires resolution

Most common resolutions

F#F# MajorD#mD# Minor

Unstable degrees

3F

4F#

resolves up to the resolution tonic

6A#

b7B

resolves down to the tonic 3rd

#2E

4F#

resolves to the resolution tonic

Main resolution

C#7#9source

F#F# Major

Dominant 7th C#7 naturally resolves up a 4th to F#. It is the tritone between the chord's 3rd and 7th that creates this pull.

Other resolutions

C#7#9source

Deceptive resolution

D#mD# Minor

Instead of the tonic, the dominant resolves to the vi degree. Creates surprise and is often used to extend a musical phrase.

C#7#9source

Modal resolution

BB Major

In rock and blues, the dominant often moves to bVII or IV instead of the tonic, creating a modal flavor.

C#7#9source

Jazz reharmonization

G7G Dominant 7

Tritone substitution: C#7 can be replaced by G7 (a tritone away). Both chords share the same tritone between the 3rd and 7th, resolving to the same tonic.

C#7#9source

Functional resolution

C#sus4C# Sus4

The dominant can resolve beyond the tonic: moving to IV (subdominant) or to a suspension (sus4) are common alternatives in pop and folk music.

Substitutions

Tritone substitution

G7G Dominant 7

Features

Character

Dominant, with an augmented 9th

Characteristic interval

Minor 7th (b7), Augmented 9th (#9)

Description

The augmented 9th is enharmonically equivalent to a minor 3rd and sounds alongside the chord’s major 3rd. Their chromatic clash creates sharp tension characteristic of blues and rock.

Application

• Blues rock (Jimi Hendrix "Purple Haze")
• Funk
• Jazz fusion

Voicing & structure

Harmony

Compatible scales

All chord tones are contained in these scales — use them for improvisation.