Secondary Augmented 6th chords

So far we have looked at all augmented 6th chords – German, Italian, and French – whose bass is the note a half-step above dominant and the same chords with a bass note a half-step above tonic.

However, augmented 6th chords can appear a half step above other scale degrees as well. These are analyzed as secondary augmented 6th chords.

Let’s look at an example of a secondary augmented 6th chord.

Schubert Moment Musicale in Ab major, Op. 96, No. 6

Schubert’s Moment Musicales No. 6 in Ab major is one of six short pieces for solo piano written from 1823 to 1828. We will look at only the first part of No. 6 – mm. 1-28 (see below).

An analysis of all the chords that we know how to analyze are marked in the following example. The non-diatonic chords that are not known are marked in purple and blue below.

Measure 16-17 and 24-25

Let’s look at the chords mark in purple first (those in m. 16-17 and m. 24-25).

These are the same chords – an Fb7 chord but spelled as Fb-Ab-Cb-D natural which is a German 6 in the key of Ab.

The German 6 resolves like the augmented 6 that it is: the Fb and the D resolve out to the Eb which is the fifth of an Ab minor chord in second inversion.

Therefore, the chord is analyzed below as a German in both mm. 16-17 and 24-25 (marked in purple below).

Measures 10-12

Finally, let’s look at the chords in measures 10-12.

The chord in Measures 10-11 is a Db7b5 – a Db-F-Abb-Cb chord which can be enharmonically spelled as Db-F-G-B — a French 6 chord. Spelled as a French 6, it esolves correctly; the Db and B resolves out to C and the chord resolves to a C chord.

However, in the key of Ab, a C major chord is not V or I – the traditional resolutions of an augmented 6th chord. Instead C major is III in the key of Ab.

Therefore, this French 6 chord is a secondary augmented 6 chord. It is a French/III (since the augmented 6th interval should and does resolve to the note that is the 3rd scale degree in the key) and is marked as such below.

Summary

In summary, a secondary augmented 6 chord is an augmented 6th chord that appears on a note other than the note a half-step above dominant or tonic. It is usually marked as an augmented 6th of (/) that chord it resolves to.