D Dominant 9th
9
0 - 4 - 7 - 10 - 14Dom7 + major 9th
About D Dominant 9th
D9 is a dominant ninth built on D — D, F♯, A, C and E — and on guitar it is one of those chords learned as a single movable grip. Slide the shape along the neck and it becomes E9, F9, G9; that portability is why funk and blues rhythm playing leans on it so heavily.
The notes
D, F♯, A, C, E. The C is the flat seventh and provides the pull; the E is the ninth and provides the colour. In practice the A is dropped — five notes rarely fit comfortably, and the fifth is the least missed.
Compared with D7, the ninth softens the chord without weakening its direction. In the key of G both resolve the same way, but D9 sounds urban where D7 sounds rural.
The shape
Root on the A string at the fifth fret, with the remaining notes on the middle strings and the index finger acting as a partial barre. Nothing is open, so the grip moves without alteration.
Played with the palm damping the strings between strums, it produces the percussive rhythm figure that defines a great deal of soul and funk. The chord and the technique arrived together.
Where it shows up
As the V of G major, and as the tonic of a blues in D. In the second role it never resolves — the whole form is built on unresolved dominants, and the ninth simply makes them richer.
In jazz it appears in the ii–V–I as a substitute for the plain dominant, especially when the melody sits on the ninth and the harmony needs to accommodate it.