C♯9
C# Dominant 9th — a dominant seventh widened with the ninth — fuller, funkier movement toward the resolution.
The keys
C♯ – E♯ – G♯ – B – D♯
What's inside C♯9
| Note | Interval from root | Degree |
|---|---|---|
| C♯ | Root | 1 |
| E♯ | Major 3rd | 3 |
| G♯ | Perfect 5th | 5 |
| B | Minor 7th | b7 |
| D♯ | Major 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) | D♭2 – B2 |
| Right (colour) | F4 – E♭5 |
Where C♯9 lives
As the I chord
C♯9 → G♭ → A♭ → C♯9
The classic I–IV–V–I motion with this chord as home.
In a ii–V–I
E♭m7 → A♭7 → C♯9
The strongest cadence in harmony, resolving onto this chord.
Put C♯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 →