We’ve talked in previous columns about anchors and pivots occurring primarily on roots and fifths. What do we use for pivots in the case of chord inversions? We often see these inversions and other sorts of alternate bass notes in the form of compound chord symbols:
C/Bb Bb/A Db/F Ebmin/Gb Go/C etc
In these chords, there is a triad over an alternate bass note. The bass note is not the root of the chord; it’s frequently some other chord tone, which would create an “inversion” of the chord; or, the bass note could be a passing tone, or the compound symbol could indicate a modal sound, or a harmonic suspension. In recent decades, these compound symbols have come into wider use, and occasionally constitute the “home” tonality of a song.
Does it always make musical sense to declare the bass note to be the root of the chord and look for a pivot (the primary oppositional tone) a fifth above it?
Let’s look at C/Bb.
This could also be considered to be the “third inversion” of a C7; wherein C7/E would be the “first inversion” (meaning “the third in the bass”),
C7/G would be the “second inversion” (with the fifth of the chord in the bass)
The “third inversion” is the variation with the seventh of the chord in the bass. (This is a nice sound, heard frequently in recent decades, and frequently resolves to F/A – that is, the first inversion of its target.)
I think we might agree that this C/Bb is really a C7. If we’re playing a Bb in the bass, and looking for the strongest alternate note, experience will show that the fifth of the chord is still a good choice – although in this inverted form, this note is no longer a fifth above the bass note, but a sixth – the G. Try some alternates, and see which sound good.
Experience shows that finding a chord tone approximately a fifth away provides a pivot effect, although it might not be the fifth of the chord. In the case of F/A, for example, hanging on the A and using the F as the pivot makes good musical sense:
What about a chord with a major seventh in the bass, like Bb/A? This suggests a modal sound; once again, the fifth of the chord works well. In this case the E can work as well for a darker sounding pivot: