What notes are in C#7b9?

C#7b9 contains C# · E# · G# · B · D. Name any set of notes with the chord identifier.

When do you use a ♭9?

Most naturally on the V of a minor key, where the flattened ninth is diatonic. It also works as an altered colour on any dominant.

What scale fits a 7♭9 chord?

The half-whole diminished scale, and the harmonic minor of the key it resolves to.

What notes are in the C# Dominant flat ninth chord?

The C# Dominant flat ninth chord contains the notes C# · E# · G# · B · D: the root C# with the intervals 1P, 3M, 5P, 7m, 9m stacked above it. Play them together for the chord or one after another for an arpeggio. The lowest note is normally C#, but any chord tone can take the bass in an inversion.

What intervals make up the C# Dominant flat ninth chord?

Measured from C#, the C# Dominant flat ninth chord stacks the intervals 1P, 3M, 5P, 7m, 9m. The quality of the third and of the seventh, if there is one, is what gives the chord its character; the rest of the notes colour it. Every interval in the formula links to its own page, with its sound.

C# Dominant Flat Ninth Chord (C#7b9): Notes, Piano & Guitar

Play it on your instrument

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Voicings on the piano

Voicing	Notes	Play it on your instrument
Closed, root position	C#3 · E#3 · G#3 · B3 · D4
Open (drop 2)	B2 · C#3 · E#3 · G#3 · D4
Shell	C#3 · E#3 · B3
Rootless	E#3 · A3 · B3 · D4

Tap a key or a fret to hear it.

Anatomy

C# Dominant flat ninth (C#7b9) contains the notes C# · E# · G# · B · D, each with a role measured as an interval from the root.

Read on: how triads are built · seventh chords · extensions

Inversions

An inversion of C# Dominant flat ninth puts a chord tone other than C# in the bass; the name after the slash is that bass note.

Where it lives

The keys and the scales C# Dominant flat ninth belongs to.

In which keys

C# Dominant flat ninth is diatonic to 1 key; the numeral is its degree and the label its harmonic function.

F# minorV7b9Dominant

Extensions beyond the seventh count when every note sits in the key.

Scales that contain it

C# Dominant flat ninth fits inside these scales, each built on C#.

C# Phrygian DominantC# · D · E# · F# · G# · A · B
C# Spanish HeptatonicC# · D · E · E# · F# · G# · A · B

Related chords

Chords that share most of their notes with C# Dominant flat ninth: simpler and richer stacks of the same notes, and the substitutes a chart would accept.

Simpler

C#7C# · E# · G# · B
C#alt7C# · E# · B · D
C#majaddb9C# · E# · G# · D
C#C# · E# · G#
C#7no5C# · E# · B
C#5C# · G#

Richer

C#13b9C# · E# · G# · B · D · A#
C#7b9b13C# · E# · G# · B · D · A

Common substitutions

G7b9G · B · D · F · Ab
G7b9 shares the third and seventh of C#7b9 a tritone away, so it can replace it as a dominant.
G#m7G# · B · D# · F#
G#m7 is the ii chord that leads into C#7b9 in a ii–V.

Dominant flat ninth on every root

C7b9 D7b9 Eb7b9 E7b9 F7b9 F#7b9 G7b9 G#7b9 A7b9 Bb7b9 B7b9

Open it in a tool

Understanding the C# Dominant flat ninth chord

Names and symbols

C#7b9 is the chord symbol for C# Dominant flat ninth.

How it is built

On C# it is C# · E# · G# · B · D, stacking 1P · 3M · 5P · 7m · 9m. The ♭9 sits a semitone above the root, which is a deliberate clash.

How it is used

It is the standard dominant of a minor ii–V–i, where the flattened ninth belongs to the key rather than being an import. Its upper four notes form a diminished seventh chord, which is why diminished vocabulary works so well over it.

Learn this properly

Chapter 17: Theory in Styles

Common questions

What notes are in C#7b9?: C#7b9 contains C# · E# · G# · B · D. Name any set of notes with the chord identifier.
When do you use a ♭9?: Most naturally on the V of a minor key, where the flattened ninth is diatonic. It also works as an altered colour on any dominant.
What scale fits a 7♭9 chord?: The half-whole diminished scale, and the harmonic minor of the key it resolves to.
What notes are in the C# Dominant flat ninth chord?: The C# Dominant flat ninth chord contains the notes C# · E# · G# · B · D: the root C# with the intervals 1P, 3M, 5P, 7m, 9m stacked above it. Play them together for the chord or one after another for an arpeggio. The lowest note is normally C#, but any chord tone can take the bass in an inversion.
What intervals make up the C# Dominant flat ninth chord?: Measured from C#, the C# Dominant flat ninth chord stacks the intervals 1P, 3M, 5P, 7m, 9m. The quality of the third and of the seventh, if there is one, is what gives the chord its character; the rest of the notes colour it. Every interval in the formula links to its own page, with its sound.