Sixth Chord
A sixth chord adds a major sixth to a major triad. C6 contains C, E, G and A. It shares all four pitch classes with Am7, so bass, harmonic context and phrase destination determine which root and symbol make sense.
- 1-3-5-6
- major triad
- shares notes with relative m7
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Which notes are in C6?
Use the formula 1-3-5-6:
- C: root
- E: major third
- G: perfect fifth
- A: major sixth
The symbol is C6. Cadd6 is possible but uncommon because 6 already means the added sixth without a seventh.
How do you build it?
Start with C major, C-E-G, and add A.
A lies nine semitones above C and one whole step above G.
Transpose the formula. F6 is F-A-C-D; B-flat6 is B flat-D-F-G.
What is the difference between C6 and Cmaj7?
C6 uses A. Cmaj7 uses B.
Both keep the C-major triad. The added note changes available melodic lines and intervals.
Cmaj7 contains B one semitone below the octave C. C6 contains A, which can remain, move to G or continue to B depending on the progression.
Are C6 and Am7 the same chord?
They contain the same pitch classes:
- C6: C-E-G-A
- Am7: A-C-E-G
If C is the bass and the progression resolves to C, C6 is usually the clearer name. If A is the bass and A functions as root, Am7 is clearer.
An inversion label alone cannot decide harmonic root. Use the bass, preceding chord, melody and tonal center together.
Where does C6 occur in a key?
C6 uses degrees 1, 3, 5 and 6 of C major.
It can extend the tonic without adding the major seventh. Jazz, swing, bossa nova, country and popular arrangements use major-sixth tonic voicings.
The same pitch collection also represents vi7 in first inversion when A is the harmonic root.
What is the difference between C6 and C13?
C6 is a major triad plus A and has no required seventh.
C13 normally implies C-E-G-B flat plus upper extensions, especially A as the thirteenth. The guide-tone tritone E-B flat makes it a dominant structure.
The same pitch A is called sixth in C6 and thirteenth when a seventh-based extension stack is implied.
What is C6/9?
C6/9 adds both degree 6 and degree 9 to the major triad.
C6/9 contains C-E-G-A-D. It normally omits a seventh.
The slash in 6/9 belongs to the chord-quality label and does not specify a bass note. This differs from C/E.
How do inversions work?
C6 has four bass positions using C, E, G or A.
With A in the bass, the notes can sound and function as Am7. Notation should follow the harmonic role.
Voice leading may favor E or G in the bass inside a stepwise line while C remains the chord root.
Which notes can you omit?
Keep E for major quality and A for the sixth.
The fifth G is often optional. A bassist may supply C.
A compact shell C-E-A clearly states the chord, while E-A over a C bass provides the essential third and sixth.
How should you practice it?
Build C, C6 and Cmaj7 by adding A or B.
Play C6-Am7 with C and A in the bass while keeping the upper notes close. Identify when your hearing of the root changes.
Then compare C6 with C13 and locate the extra B flat that creates dominant structure.