Sixth Chords
Sixth chords add a major sixth to a major or minor triad. They are stable color chords rather than dominant sevenths, and their notes can overlap with relative minor or half-diminished harmony.
Major Sixth
A major sixth chord uses R-M3-P5-M6. C6 contains C-E-G-A. It sounds warm and settled because it has no seventh pulling toward another chord. In jazz, pop, country, and Hawaiian music, a sixth chord can replace a plain tonic major chord without making the harmony feel unfinished.
Minor Sixth
A minor sixth uses R-m3-P5-M6. Cm6 contains C-Eb-G-A. The major sixth adds brightness inside the minor chord, creating the characteristic sound heard in minor-key jazz endings, tango, and film-noir harmony.
Related Chords
C6 and Am7 contain the same four pitch classes, but the bass and musical context determine which note feels like the root. Cm6 contains the same pitch classes as Am7♭5. Chord8 keeps the colors relative to the selected root, so changing the root reveals how one pitch collection can perform two harmonic jobs.
Try It
Compare C, C6, and Cmaj7. Then compare Cm, Cm6, and Am7♭5. Listen for the stable major sixth versus the stronger half-step pull of the major seventh.