C#9b5

General info

Full name

C# 9b5

Symbol

C#9b5

Root

C#

Quality

9b5

Chord notes

Functions & resolutions

Stability / tension

High tension — requires resolution

Most common resolutions

F#F# MajorD#mD# Minor

Unstable degrees

3F

4F#

resolves up to the resolution tonic

4F#

b5G

resolves inward to the resolution tonic

6A#

b7B

resolves down to the tonic 3rd

Main resolution

C#9b5source

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#9b5source

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#9b5source

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#9b5source

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#9b5source

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 9th and diminished 5th

Characteristic interval

Diminished 5th (b5), 9th

Description

The minor 7th establishes the dominant structure, the 9th extends it, and the diminished 5th adds a second tritone against the root. The chord is more dissonant than a regular 9.

Application

• Tritone sub with ninth
• Jazz and fusion
• Improvising over Lydian dominant

Voicing & structure

Harmony

Compatible scales

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