Bb9

General info

Full name

Bb 9th

Symbol

Bb9

Root

Bb

Quality

9th

Chord notes

Functions & resolutions

Typical function in key

VDominant (V)Eb major

Stability / tension

High tension — requires resolution

Most common resolutions

EbEb MajorCmC Minor

Unstable degrees

3D

4Eb

resolves up to the resolution tonic

6G

b7Ab

resolves down to the tonic 3rd

Main resolution

Bb9source

EbEb Major

Dominant 7th Bb7 naturally resolves up a 4th to Eb. It is the tritone between the chord's 3rd and 7th that creates this pull.

Other resolutions

Bb9source

Deceptive resolution

CmC Minor

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

Bb9source

Modal resolution

AbAb Major

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

Bb9source

Jazz reharmonization

E7E Dominant 7

Tritone substitution: Bb7 can be replaced by E7 (a tritone away). Both chords share the same tritone between the 3rd and 7th, resolving to the same tonic.

Bb9source

Functional resolution

Bbsus4Bb 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

E7E Dominant 7

Features

Character

Dominant, with a minor 7th and major 9th

Characteristic interval

9th

Description

The major 3rd and minor 7th form a dominant core, while the major 9th adds a diatonic extension. The dominant tritone preserves directed tension toward resolution.

Application

• V9–I in jazz
• Funk and soul
• Blues harmony

Voicing & structure

Harmony

Compatible scales

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