Root, third and seventh: the guide tones fix the quality, so the fifth is dropped. That is what leaves a string free, so pick a tension to put on top.
C69 is C, E, G, A and D — C6 with the ninth added as well.
It sounds wide and entirely at rest. The modern way to voice a tonic when a triad is too bare and a maj7 too pointed.

| C | E | G | A | D |
|---|---|---|---|---|
| 1 | 3 | 5 | 6 | 9 |
Tonic — it commits to nothing.
Also written C6/9, C6add9 or C six nine. The same chord either way; which spelling you meet depends on who wrote the chart.
Root, third and seventh. The third and seventh, the guide tones, are what make the chord major, minor or dominant, so the fifth can go: it says nothing the symbol needs.
Three notes means a spare string, which is the real point. Put a tension on it.
C69 has 4 of them, on the middle four strings, the bottom four strings and the top four strings, from the 2nd fret up to the 14th — all in one inversion, so the bass note never moves. The one to learn first is the C shape at the 2nd fret, which is the easiest grip here.
Start with x30055 — no barre and 2 open strings. 1 of the 9 shapes here sits in open position. 7 of the 9 need a barre. Together they cover the neck from the 2nd fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x32233 | 2nd fret | C, root position | G | barred |
| x30055 | open position | C, root position | A | 2 open strings |
| x55555 | 5th fret | D, 9th in the bass | A | barred |
| 877788 | 7th fret | C, root position | C | barred |
| x-x-10-9-10-10 | 9th fret | C, root position | D | barred |
| x-10-10-9-10-10 | 9th fret | G, 2nd inversion | D | barred |
| x-12-12-12-13-12 | 12th fret | A, 6th in the bass | E | barred |
| x-15-12-14-13-12 | 12th fret | C, root position | E | all fretted |
| x-15-14-14-15-15 | 14th fret | C, root position | G | barred |
The same notes rebuilt from scratch give 15 drop 2, 10 drop 3, 15 rootless and 6 open string voicings, each on its own page.
Tensions. A shell of C69, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (F#).
How you get to it. The turn that lands on C69 is Dm7 to G7 — the ii and the V of C — and G7 shares its third and seventh with Dm7, so the hand barely moves between them.
In which keys. Every note of C69 belongs to C major (the I), D minor (the ♭VII), E minor (the ♭VI), F major (the V), G major (the IV) and A minor (the ♭III).
C69 is every note of the C major pentatonic, and nothing else. It also sits inside C major, C lydian, C mixolydian and C lydian dominant.
Change one note of C69 and you have Cmaj9 (the sixth becomes a major seventh), Cmaj13 (add the major seventh), Cm69 (the major third becomes a minor third), Cadd9 (drop the sixth), C6 (drop the ninth) or C9 (the sixth becomes a flat seventh).
C69 is a major chord — root, major third, fifth. Major chords on every root.
On C69’s sound and use this page follows Mark Levine, The Jazz Piano Book (Sher Music, 1989). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.