C7♯9
C Dominant 7th Sharp 9 — major and minor thirds colliding in one chord — gritty, electric, built for emphatic moments.
The keys
C – E – G – B♭ – D♯
What's inside C7♯9
| Note | Interval from root | Degree |
|---|---|---|
| C | Root | 1 |
| E | Major 3rd | 3 |
| G | Perfect 5th | 5 |
| B♭ | Minor 7th | b7 |
| D♯ | Sharp 9th | #9 |
A working voicing
Split the chord between two hands the way working players do — a solid shell low down, the colour tones up top:
| Hand | Keys |
|---|---|
| Left (shell) | C2 – B♭2 |
| Right (colour) | E4 – E♭5 |
Where C7♯9 lives
Hard resolution
C7♯9 → Fm9
Altered dominants resolve with maximum drama — especially into minor.
Chromatic approach
Gm7 → C7♯9 → F
The alteration sharpens the pull of the standard two-five.
Put C7♯9 under your fingers
Hear every voicing, see the keys light up, and drill it in the interactive Chord & Voicing Lab.
Open the Chord & Voicing Lab →