FRENCH SIXTH CHORD

A French sixth chord is the chord built as a stack of the major third, diminished third and major third, with the chord root on the second scale degree. It follows from the above: the French sixth chord is the dominant seventh flat five chord on the second scale degree. This is shown in the next figure.

Figure: The French sixth chord in the C major key

Annotating French sixth chord

The harmony annotation for the French sixth chord is Fr+6 no matter of a position in which it occurs. The next figure shows an example of the annotated French sixth chord in the position where it appears most often.

Figure: Annotating the French sixth chord

French sixth chord in major and minor key

The French sixth chord is the same in a major key and its parallel minor key, thus having the same note names, chord annotations and harmony annotations. This is illustrated in the next figure.

Figure: The French sixth chord in the C major key and its parallel C minor key

We see that if the current key is a minor key, the French sixth chord needs only one altered scale degree, the raised fourth scale degree. However, if the current key is a major key, then the French sixth chord needs two altered scale degrees: the raised fourth scale degree and the lowered sixth scale degree. This is the reason why the French sixth chord appears more often in music written in minor keys.

French sixth chord usage

The French sixth chord most often resolves to a chord with the root on the dominant (the fifth scale degree). The raised fourth scale degree resolves up to the fifth scale degree while the sixth scale degree resolves down to the fifth scale degree. This is illustrated in the next figure.

Figure: Resolving the French sixth chord in the C minor key

Chopin’s Prelude No. 20 in C minor

In chapter Chord analysis we determined and annotated the chords in Chopin’s Prelude No. 20 in C minor. Now it is time to complete the harmony analysis by determining and annotating the harmony.

The next figure shows the results of the harmony analysis. We see that the whole composition is written in the C minor key. The only exception is measure 2, where we find the chord progression I – IV – V7 – I in the Ab major key, which is very similar to the chord progression in the C minor key in measure 1.

The alternative is to write measure 2 as the chord progression on the sixth scale degree of the C minor key by the using secondary chords, which is VI – IV/VI – V7/VI - VI in the C minor key.

The harmony annotations of the two chords are given in both keys (the C minor key and the Ab major key). The reason for this will be explained in chapter Common chord modulation. 

We see the French sixth chord in measure 6 (which is also repeated in measure 10). The French sixth chord resolves to a chord with the root on the dominant.

We see the Neapolitan chord in measure 8 (which is also repeated in measure 12). The Neapolitan chord resolves to a chord with the root on the dominant. 

Figure: Harmony analysis of Chopin's Prelude No. 20 in C minor