It sounds warm, and considerably richer than an m7. Use it in the same places as m7 when the melody or voicing can include the 9th.
8 moveable shapes. None has an open string in it, so each one plays every root there is; the dots are degrees, and R is the root.
Pick a root and every diagram below moves to it. Nothing about any of the shapes changes — only the fret they start on, and each one starts somewhere different because they are rooted on different strings.
Showing Cm9. Every voicing of it, open strings included, is on its own chord page.
The lowest root available, so these are the fullest-sounding shapes and the ones that carry a band. F at the first fret, G at the third, A at the fifth: the shape is the same and the fret is the whole of the difference.
8-10-8-8-8-10
6 notes · 3 frets
8687xx
4 notes · 3 frets
The other half of the pair. Pair them with the low E shapes and the hand barely moves: the root a fourth up sits at the same fret on the A string, and the root a fifth up two frets higher.
x3133x
4 notes · 3 frets
No bass note under it, which is the point rather than a shortcoming: these sit above a bass player instead of competing with one, and they reach the extensions the lower shapes have no fingers left for.
x-x-10-8-11-10
4 notes · 4 frets
The same chord with something other than the root underneath. You reach for one of these because of what the bass is doing, not because of what the chord is — a bass line that walks while the harmony stays put is made of these.
♭3 in the bass. 2 ways to get it.
♭3 on the low E string, root on the B string
11-13-12-12-13-x
5 notes · 3 frets
♭3 on the A string, root on the high E string
x68788
5 notes · 3 frets
9 in the bass. 2 ways to get it.
9 on the low E string, root on the D string
10-10-10-8-11-x
5 notes · 4 frets
9 on the A string, root on the G string
x55546
5 notes · 3 frets
Every voicing of one particular m9 chord — including the open-string ones that do not move — is on that chord's own page, linked under each shape above. All the moveable shapes for every quality are on the shapes index, and the minor chords as a family are on their own page.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.