C♯7
C# Dominant 7th — the engine of harmonic motion — the tritone between its third and seventh drives resolution down a fifth.
The keys
C♯ – E♯ – G♯ – B
What's inside C♯7
| Note | Interval from root | Degree |
|---|---|---|
| C♯ | Root | 1 |
| E♯ | Major 3rd | 3 |
| G♯ | Perfect 5th | 5 |
| B | Minor 7th | b7 |
Inversions
| Position | Keys (low → high) |
|---|---|
| Root position | D♭4 – F4 – A♭4 – B4 |
| 1st inversion | F4 – A♭4 – B4 – D♭5 |
| 2nd inversion | A♭4 – B4 – D♭5 – F5 |
| 3rd inversion | B4 – D♭5 – F5 – A♭5 |
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 – A♭4 |
Where C♯7 lives
Resolving down a fifth
C♯7 → G♭
The defining dominant move: the tritone inside this chord releases onto the chord a fifth below.
In a ii–V–I
A♭m7 → C♯7 → G♭maj7
This chord as the V — the engine of the most-used cadence in music.
Put C♯7 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 →