C7b9 guitar chord
The standard grips this chord is usually shown with.
- Tap a note to hear it
- Arrows change position
- Fingers, notes or intervals
- Play the chord
About C7b9 — 3rd inversion
C7b9 is C, E, G, Bb and Db — C9 with the ninth lowered a semitone.
It sounds dark and urgent. The flat ninth comes from the harmonic minor, so this is the V of a minor key rather than a major one.
Altered dominant — it points at a minor chord.
C7b9 notes and formula
| C | E | G | Bb | Db |
|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | ♭9 |
Also written C7(b9), C7-9 or C7♭9. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play C7b9
C7b9 in 3rd inversion puts Bb in the bass instead of C, the 7th of the chord. The notes are the same; what changes is what the bass line does, which is most of why you would reach for it — it lets the lowest voice move by step where the root would have jumped.
One of C7b9’s 6 common shapes does this:xx8989
Play C7b9 as a shell — root, third and seventh — and the spare string takes the #11 (F#), the b13 (Ab) or the 13 (A).
All 6 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
- x32323, 2nd fret, C, root position, top note G, barred
- 8786xx, 6th fret, C, root position, top note Db, all fretted
- xx8989, 8th fret, Bb, 3rd inversion, top note Db, all fretted
- 8-10-8-9-8-9, 8th fret, C, root position, top note Db, barred
- x-x-10-9-11-9, 9th fret, C, root position, top note Db, all fretted
- x-15-14-15-14-15, 14th fret, C, root position, top note G, barred
How to use C7b9
C7b9 is a dominant with its tension raised, so it still points at F — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.
In a phrase:Gm7b5→C7b9→Fm7— the minor ii–V–i of F.
Voice by voice, C7b9 → Fm. 3 voices move by a semitone, and one note is common to both chords.
| In C7b9 | Moves | In Fm |
|---|---|---|
| C, the root | stays where it is | C, the fifth |
| E, the major third | rises a semitone | F, the root |
| G, the fifth | rises a semitone | Ab, the minor third |
| Bb, the flat seventh | falls a whole tone | Ab, the minor third |
| Db, the flat ninth | falls a semitone | C, the fifth |
What to play over C7b9
Every note of C7b9 is in C half-whole diminished.
Chords near C7b9
Change one note of C7b9 and you have C7 (drop the flat ninth), C7/G (drop the flat ninth), Calt (the fifth becomes the sharp fifth), C9 (the flat ninth becomes the ninth) or C7#9 (the flat ninth becomes the sharp ninth).
C7b9 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.