Seventh Chords – Inversions

To review:

The quality of a 7th chord is determined by the quality of the triad and the quality of the seventh (i.e., the interval between the root and the note a 7th above the root).

There are many types of seventh chords, but five are most common:

Inversions

Just like triads, any note of the 7ths chord can be in the bass.

If the root is in the bass, then the chord is in root position.
If the third is in the bass, then the chord is in first inversion.
If the fifth is in the bass, the the chord is in second inversion.
If the 7th is in the bass, then the chord is in third inversion.

Jazz/pop designations

As with triads, to show the note in the bass using jazz/pop symbols, just add a / and then the name of the note to the chord designation.

The first chord above has the C, the root, in hte bass. In this case, nothing more than the chord designation needs to be indicated.

In the second chord above, the E (the third) is in the bass. The chord is marked as C7/E indicating the chord is in first inversion.

In the third chord above, the G (the fifth) is in the bass. The chord is marked as C7/G indicating the chord is in second inversion.

In the fourth chord above, the Bb (the 7th) is in the bass. The chord is marked as C7/Bb indicating the chord is in third inversion.

Figured Bass

In classical music, we use figured bass to indicate the intervals above the bass (in closed position). These numbers and the usual abbreviations are:

For a root position 7th chord (i.e., the root is in the bass), the figured bass contains 7, 5, and 3 indicating intervals of a 3rd, 5th, and 7th above the bass. It can be abbreviated with just the 7.

For a first inversion 7th chord (i.e., the third is in the bass), the figured bass contains 6, 5, and 3 indicating intervals of a 3rd, 5th, and 6th above the bass. It can abbreviated with just 6 and 5.

For a second inversion 7th chord (i.e., the fifth is in the bass), the figured bass contains 6, 4, and 3 indicating intervals of a 3rd, 4th, and 6th above the bass. It can abbreviated with just 4 and 3.

For a third inversion 7th chord (i.e., the 7th is in the bass), the figured bass contains 6, 4, and 2 indicating intervals of a 2nd, 4th, and 6th above the bass. It can abbreviated with just 4 and 2.

Only the bass matters

Even though all the intervals above the bass are marked in the figured bass (or abbreviations of them with assumptions of some of them), it is really only the bass that matters.

If the root is in the bass, the chord is in root position and the 7 designation is used.
If the 3rd is in the bass, the chord is in first inversion and the 6/5 designation is used.
If the 5th is in the bass, the chord is in second inversion and the 4/3 designation is used.
If the 7th is in the bass, the chord is in third inversion and the 4/2 designation is used.

Remember, when using jazz/pop symbols, just indicate what note is in the bass.