6/9

Notes and formula

The formula is 1 – 3 – 5 – 6 – 9, or 0 – 4 – 7 – 9 – 14 in semitones. The absence of the seventh is not an omission but the definition — add one and the chord becomes a thirteenth or a major ninth.

Without a seventh there is no tritone and no semitone friction anywhere in the chord. Every interval in it is a consonance, which is why it can be held indefinitely and why it sounds closed rather than open.

How to play it

On guitar the standard form is x–3–2–2–3–3, sounding C–E–A–D–G. It sits comfortably, moves anywhere on the neck, and is one of the first grips taught in any jazz-guitar method.

On piano the chord is often voiced in fourths — a stack of D, G, C, E, A produces the same notes and the same effect with a distinctly modern sound.

What it is for

Ending things. Before major sevenths became the default jazz tonic, this was the chord that closed an arrangement, and it never lost the job: a big band that finishes on a plain triad sounds abrupt, and one that finishes on a major seventh sounds like it might continue.

It also works as a standing tonic in bossa nova and in guitar-led writing, where the added sixth keeps a long chord from flattening out.

Where you hear it

The last bar of a great many jazz standards. The rhythm-guitar sound of western swing and gypsy jazz. The opening chord of much Brazilian repertoire, where the six-nine and the major seventh are used almost interchangeably.

In pop it appears as a substitute for a plain major chord whenever an arrangement wants warmth without implying a key change.

Six-nine or thirteenth

C6/9 has no seventh and rests. C13 has a flattened seventh, contains a tritone, and pulls toward F. Cmaj13 has a major seventh and sits between the two.

The same sixth appears in all three, which is why they can be confused on paper, and the seventh is what the ear is actually judging.

Scales that contain it

Ionian, Lydian and Mixolydian all fit, since the chord says nothing about the seventh degree and nothing about the fourth. That is unusually permissive.

The major pentatonic contains every note of the chord exactly — root, second, third, fifth and sixth — which is the cleanest correspondence between a scale and a chord anywhere in the catalogue.

Frequently asked questions