Bb7#9

Q: What notes are in the Bb7#9 chord?

The Bb7#9 chord (Bb 7#9) contains: Bb, D, F, Ab, C#. Its interval structure is shown above in the Theory section.

Q: How do I build Bb7#9 on the keyboard?

Take the root and add the remaining chord tones following the interval formula. The highlight shows chord content, while the inversion control changes which chord tone is in the bass.

Q: Which keys is Bb7#9 found in?

The chord acts as a diatonic degree in several keys — they are marked on the circle of fifths in the "Harmonic context" block.

Q: What can I substitute for Bb7#9?

A substitution depends on harmonic function and voice leading, not only on shared tones. Computed options appear in the "Substitutions" block and should be checked in context.

Bb 7#9

Octaves

Musical context

ChordBb majorTriad

ChordBb7#9Bb 7#9

ArpeggioBb majorBroken triad

ScaleBb major7 notes

KeyBb majorMajor key

ProgressionPop axisSequence

How the chord relates to the scale, mode, key and progression.

Theory

General info

Full name: Bb 7#9
Symbol: Bb7#9
Root: Bb
Quality: 7#9

Chord notes

1Bbroot

3Dmajor 3rd

5Fperfect 5th

b7Abminor 7th

#2C#aug 2nd

Functions & resolutions

Stability / tension: High tension — requires resolution
Most common resolutions: EbEb Major CmC Minor
Unstable degrees: 3D
4Eb
resolves up to the resolution tonic
6G
b7Ab
resolves down to the tonic 3rd
#2Db
4Eb
resolves to the resolution tonic
Main resolution: Bb7#9source
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: Bb7#9source
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.
Bb7#9source
Modal resolution
AbAb Major
In rock and blues, the dominant often moves to bVII or IV instead of the tonic, creating a modal flavor.
Bb7#9source
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.
Bb7#9source
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 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

Root position

v1Bb(Bb4)Bass

root

v2D(D5)M3from Bb

v3F(F5)m3from D

v4Ab(Ab5)m3from F

v5C#(C#6)P4from Ab

Harmony

Compatible scales

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

ScaleD Hungarian minor ScaleF# Harmonic major ScaleA Double harmonic ScaleA Persian scale ScaleA Byzantine ScaleC# Diminished (half–whole)ScaleD Diminished scale ScaleF Diminished scale ScaleF Bebop melodic minor ScaleG# Diminished scale

This chord on guitar 🎸

See how Bb7#9 looks on guitar.

Explore

Circle of fifths

Highlighted major keys contain this chord among their diatonic harmonies.

Relative key: GmG minor
Dominant: FF major
Subdominant: EbEb major
Key signature: 2 flats (Bb, Eb)

What to learn next

ScaleBb Chromatic scaleScale to improvise over this chord PracticeChord trainerLock the fingering into muscle memory ProgressionChord progressionsHow this chord works inside real progressions

Recommended for you

Bb Chromatic scaleA scale related to this chord

Practice

Keyboard Trainer

Reinforce it in practice — play and name notes on the interactive keyboard.

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Test yourself

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What notes are in the Bb7#9 chord?

How do I build Bb7#9 on the keyboard?

Which keys is Bb7#9 found in?

What can I substitute for Bb7#9?