The dom 9 chord is simply the dom 7 chord with the 9th note added.
The 9th note is an octave higher than the 2nd note (2 + 7 = 9).
Let’s use the C dom chord to show this:
C7 (dom 7)
C9 (dom 9)
Dom 9 Chord Formula:
The dom 9 chord formula is 1-3-5-b7-9 (i.e. the Root, 3rd, 5th, b7thand 9th notes).
Important note:
For guitarists especially; extended chords can be more difficult to play as you only have a finite number of fingers and options to position them on the fretboard.
IWe recommend that you play dom 9 chords in root position only
(i.e. the root note being the lowest note in the chord).
You can use MusicWheels™ to discover all the other dominant 9 chords and their notes.