A7b9#5

A 7b9#5

Octaves

Musical context

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

Theory

General info

Full name
A 7b9#5
Symbol
A7b9#5
Root
A
Quality
7b9#5

Chord notes

1Aroot
3C#major 3rd
#5E#aug 5th
b7Gminor 7th
b2Bbminor 2nd

Functions & resolutions

Stability / tension
Stable — can serve as major tonic
Most common resolutions
Unstable degrees
#5F
6F#
resolves up to the 6th
4D
b7G
resolves down to the resolution tonic
Main resolution
A7b9#5source
EE Major
Major chord A is a stable tonic. As tonic it doesn't require resolution, but in a progression context typically moves to IV or V.
Other resolutions
A7b9#5source
Deceptive resolution
F#mF# Minor
As the V degree, a major chord can defy expectations by moving to vi instead of I (deceptive cadence).
A7b9#5source
Modal resolution
GG Major
In modal context, a major chord can freely move to bVII, bIII, or bVI — characteristic of Mixolydian mode.
A7b9#5source
Jazz reharmonization
Amaj7A 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).
A7b9#5source
Functional resolution
EE Major
As the IV degree (subdominant), a major chord can resolve to V or directly to I (plagal cadence).

Substitutions

Tritone substitution

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

Root position

v1A(A4)Bass
root
v2C#(C#5)M3from A
v3E#(E#5)M3from C#
v4G(G5)M2from E#
v5Bb(Bb5)m3from G

Harmony

Compatible scales

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

This chord on guitar 🎸

See how A7b9#5 looks on guitar.

Explore

Circle of fifths

Highlighted major keys contain this chord among their diatonic harmonies.

CAmGEmDBmAF#mEC#mBG#mF#D#mDbBbmAbFmEbCmBbGmFDmAmajor
Relative key
Dominant
Subdominant
Key signature
3 sharps (F#, C#, G#)

Practice

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Frequently Asked Questions