A 6/9 chord is a major chord or a minor chord with an added sixth interval and an added ninth interval. In both cases, with the major and minor chord, the sixth is a major sixth and the ninth corresponds to a major second.
The chord C6/9 is the chord composed of C, E, G, A, and D. The notes C, E, and G form the C major chord and the notes A and D are the added sixth and ninth respectively.
The chord Cm6/9 is the chord composed of C, Eb, G, A, and D. The notes C, Eb, and G form the C minor chord and the notes A and D are the added sixth and ninth respectively. (The sixth note A is the sixth on the Dorian scale in C, in which the Cm chord is the chord on the root (the tonic).
Both the major and minor 6/9 chords do not require resolution and can be used to substitute chords on the root of the scale.
Examples of scales with 6/9 chords
The following are examples of where the major 6/9 chord occurs in common heptatonic scales.
- On the first note (the tonic), second note (the supertonic), and fourth note (the subdominant) of the major scale. That is, if a major 6/9 chord is composed over the first, second, or fourth note on the major scale, then all notes in that chord will also be on the major scale.
- On the third note (the mediant), fourth note (subdominant), and sixth note (the submediant) of the minor scale.
- On the fifth note (the dominant) of the altered scale.
The following are examples of where the minor 6/9 chord occurs in common heptatonic scales.