Bb7b9#5

General info

Full name

Bb 7b9#5

Symbol

Bb7b9#5

Root

Bb

Quality

7b9#5

Chord notes

Functions & resolutions

Stability / tension

Stable — can serve as major tonic

Most common resolutions

EbEb MajorFF MajorGmG Minor

Unstable degrees

#5Gb

6G

resolves up to the 6th

4Eb

b7Ab

resolves down to the resolution tonic

Main resolution

Bb7b9#5source

FF Major

Major chord Bb is a stable tonic. As tonic it doesn't require resolution, but in a progression context typically moves to IV or V.

Other resolutions

Bb7b9#5source

Deceptive resolution

GmG Minor

As the V degree, a major chord can defy expectations by moving to vi instead of I (deceptive cadence).

Bb7b9#5source

Modal resolution

AbAb Major

In modal context, a major chord can freely move to bVII, bIII, or bVI — characteristic of Mixolydian mode.

Bb7b9#5source

Jazz reharmonization

Bbmaj7Bb Major 7

In jazz, a major chord is enriched to maj7, 6/9, or add9 and can smoothly transition into a ii-V of another key (modulation).

Bb7b9#5source

Functional resolution

FF Major

As the IV degree (subdominant), a major chord can resolve to V or directly to I (plagal cadence).

Substitutions

Tritone substitution

E7E Dominant 7

Features

Character

Dominant, with b9 and #5

Characteristic interval

Augmented 5th (#5), Minor 9th (b9)

Description

The augmented 5th and minor 9th alter two tones of a dominant seventh chord. Both allow semitone voice leading into the next chord, giving the sonority sharp, directed tension.

Application

• Jazz cadences V → i
• Altered dominant
• Harmonic minor

Voicing & structure

Harmony

Compatible scales

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