C#7b9 C# dominant seventh flat nine chord
- Notes
- C# E# G# B D
- Formula
- 1 3 5 b7 b9
- Semitones
- 0 4 7 10 13 above the root
- Also written
- Db7b9 (Db F Ab Cb Ebb)
- Other symbols
- C#7(b9), C#7-9
C# to E# is a major third (4 semitones), E# to G# is a minor third (3 semitones), G# to B is a minor third (3 semitones), B to D is a minor third (3 semitones). A dominant seventh with a flattened ninth, D, a half step (plus an octave) above the root. It is the sharpest-sounding of the common dominant chords and pulls hard towards a minor tonic.
C#7b9 on the piano
Root position from C#4: C#4, E#4, G#4, B4, D5. Middle C is C4.
C#7b9 on the guitar
Standard tuning (E A D G B E). Strings run low E on the left to high e on the right, frets downwards; × is a muted string, ○ an open string, and each dot shows the note it sounds, with the root in blue-green. Every shape below has C# as its lowest note.
x 4 3 4 3 x (low E to high e)
Sounds C#3 E#3 B3 D4, fifth left out
9 x 9 10 9 10 (low E to high e)
Sounds C#3 B3 E#4 G#4 D5
The E-shape and A-shape grips are movable: an E-shape chord's root is the note under your first finger on the low E string, an A-shape chord's root is the note on the A string. Slide the same grip up or down to play dominant seventh flat nine chords on other roots.
Inversions of C#7b9
An inversion puts a note other than the root in the bass. The name is what semicord's chord finder calls those notes played bottom to top; a slash name like C/E means a C chord with E in the bass.
| Position | Notes, bass first | Named | Listen |
|---|---|---|---|
| Root position | C# E# G# B D | C#7b9 | |
| 1st inversion | E# G# B D C# | C#7b9/F | |
| 2nd inversion | G# B D C# E# | C#7b9/G# | |
| 3rd inversion | B D C# E# G# | C#7b9/B | |
| 4th inversion | D C# E# G# B | C#7/D (also read as C#7b9/D) |
Where C#7b9 fits
C#7b9 is V7b9 in F# minor. Its upper four notes E# G# B D are Fdim7, so C#7b9 and that diminished seventh are interchangeable over a C# bass. The flat ninth D falls a half step to the fifth of F#m.