Understand and Play the C7b9 Guitar Chord
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The flat ninth gives C7(b9) (C seventh flat nine) its edge. The notes are C, E, G, Bb and Db: a dominant seventh plus a Db, a half step above the root. The sound is tied to minor-key dominants and to the Spanish colour of the phrygian dominant scale.
Between fret 2 and fret 9, this page holds five voicings, and none of them uses an open string. The C Half-Whole scale, the eight-note scale built from alternating half steps and whole steps, lines up with C7(b9), because it contains all five chord tones. To see the distances between its notes on the neck, read intervals on the fretboard.
Strum the shape in front of your microphone and the chord player at the top shows which strings ring and which are muted.
C 7th with flat 9th guitar chord is also written as C7(b9), C7b9 or C7-9.
Notes in the C 7(b9) chord:
Chord Structure:
Formula: 1 3 5 b7 b9
C 7(B9) Guitar Chord Diagrams
Position 1 Barre Movable
Finger Positions
- Mute the low E string
- Mute the high E string
- Place your index finger (1) on the fret 2 of the D and B strings at the same time
- Place your middle finger (2) on the fret 3 of the A string
- Place your ring finger (3) on the fret 3 of the G string
Position 2 Movable
Finger Positions
- Mute the B string
- Mute the high E string
- Place your index finger (1) on the fret 6 of the G string
- Place your middle finger (2) on the fret 7 of the A string
- Place your ring finger (3) on the fret 8 of the low E string
- Place your pinky finger (4) on the fret 8 of the D string
Position 3 Barre Movable
Finger Positions
- Mute the A string
- Place your index finger (1) on the fret 8 of the low E, D and B strings at the same time
- Place your middle finger (2) on the fret 9 of the G string
- Place your ring finger (3) on the fret 9 of the high E string
Position 4 Barre Movable
Finger Positions
- Mute the low E string
- Place your index finger (1) on the fret 2 of the D and B strings at the same time
- Place your middle finger (2) on the fret 3 of the A string
- Place your ring finger (3) on the fret 3 of the G string
- Place your pinky finger (4) on the fret 3 of the high E string
Position 5 Movable
Finger Positions
- Mute the A string
- Mute the high E string
- Place your index finger (1) on the fret 2 of the D string
- Place your middle finger (2) on the fret 2 of the B string
- Place your ring finger (3) on the fret 3 of the low E string
- Place your pinky finger (4) on the fret 3 of the G string
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Created by
Giancarlo is a musician (teaching guitar since 2000), software engineer, AI consultant and published researcher
FAQ
What notes does C7(b9) contain?
C, E, G, Bb and Db. The root, major third, perfect fifth and minor seventh make a C seventh chord, and the Db is the flat ninth, a half step higher than C one octave up.
What makes C7(b9) sound so tense?
Two things: the E and Bb in the chord are a tritone apart, and the flat ninth Db rubs against the root C by a half step. Together they ask strongly for resolution.
Which scale fits the C seventh flat nine chord?
The C Phrygian Dominant scale, spelled C, Db, E, F, G, Ab and Bb, contains all five chord tones. It is the fifth mode of harmonic minor.
How many voicings does C7(b9) have?
Five voicings are listed, from the second fret to the ninth fret. Three of them are barre voicings, and none uses open strings.
Where does C7(b9) often resolve?
A dominant seventh tends to resolve up a fourth, so C7(b9) leads to F. With the flat ninth, F minor is the most natural target.
