Six-three chord

The third at the bottom

A triad can appear in three positions. In root position the root lies at the bottom. If the third is in the bass it is the six-three chord. In C major E is in the bass, with G and C above it. The sixth C above the bass E gives the chord its name. In figured bass the numeral for it is 6, in German functional theory a small 3 below the function symbol.

In the glossary: Chord inversion · Root position · Six-four chord

Sound and use

In sound the six-three chord feels lighter and less fixed than root position. It does not rest but presses on, and so is hardly suited as a final chord, but well suited to the course of a passage. Its most important job is bass motion: with six-three chords a bass can be led by step where root positions would make it leap, and the chords connect more smoothly. Unlike the six-four chord, whose fourth above the bass counts as a dissonance, the six-three chord can be used freely in a passage.

What to watch in four-part writing

The school rule teaches not to double the third in the bass and to double the root or fifth instead. It is compulsory only when the third is the leading tone, because two resolved leading tones give octave parallels. This is the case with the G/B in the listening example: the B in the bass is the leading tone of C major. Otherwise doubling of the bass note is certainly found in the literature, for example in sequences of several six-three chords.

Special cases with the name

Historically the six-three chord has a special status. In the fauxbourdon of the 15th century the writing rests on chains of parallel six-three chords that only end in octave and fifth at the closes. Several fixed harmonic formations carry its name although they are special cases: the Neapolitan sixth chord is a major triad on the lowered second degree in first inversion, the augmented sixth chord an altered formation with an augmented sixth above the bass.