The French Augmented Sixth Chord

Hello there, intelligent and wonderful music lovers! It is time once again for me to talk about music composition and give you a brief glimpse into how I approach it. So if you’re interested in writing music and want to pick up a new tool you can use, get ready! I’m going to show you a chord I use in my music quite often and demonstrate its use in a piece of music I wrote for a video game called Selatria.

Today’s topic is the French augmented sixth chord. There are also German and Italian sixth chords, but the French one is the one I like the most. It’s one of my absolute favorite chord voicings, one that I use especially frequently as a transitional mechanism between sections.

If you’re not familiar with this chord, here’s the basic info. It contains the scale degrees 6124. (For instance, in C, that would be A♭-C-D-F♯. Note that A♭-F♯ is an augmented sixth, which is where the name of the chord comes from. A♭-F♭ is a minor sixth, A♭-F is a major sixth, A♭-F♯ is an augmented sixth.)

The standard usage of the chord is to use these specific scale degrees and then, typically, resolve to the dominant chord of the key. The 6 and 4 both usually step to 5, the 1 steps to 7, and the 2 doesn’t move. So in C, we’d resolve the French sixth to G. The A♭ and F♯ both step to G, the C steps down to B, and the D stays where it is. I’d encourage you to play around with the chord form on whatever instrument you’re comfortable with and get used to how this transition works.

Another way to think about the chord form is as the combination of two major thirds separated by a tritone, or as the combination of two tritones separated by a major third. (Either way gives you the same chord.) For instance, C-E is a major third. A tritone up or down from C is F♯, so then another major third up is A♯, and that gives us the form of the French augmented sixth chord: C-E-F♯-A♯. (This is the standard French sixth in the key of E.)

Yet another way to think about the chord is that it’s like a seventh chord (e.g., C-E-G-B♭) but with the fifth of the chord lowered by a semitone (e.g., C-E-F♯-B♭). Of course, it is traditionally written with an augmented sixth rather than the enharmonically equivalent minor seventh, which is why it’s C-E-F♯-A♯ instead of C-E-F♯-B♭.

Now as mentioned above, the standard usage of the chord is to resolve to the dominant. My personal preference is to forget about that and use the chord wherever I want to and built up on whatever scale degrees I like, essentially borrowing the chord from other keys for use in whatever key I’m in. It’s a striking way to prepare the ear for other chords using chromatic pitches or to set up modulations to other keys.

Let’s get to some music already! Here’s an example that includes the chord. It’s the transitional turnaround that occurs right before the repetition of the whole piece. These kinds of chords are useful for transitions like this because they’re so colorful. They add a lot of dramatic tension that’s useful when leading back into the more straightforward parts of the music.

Listen to the example:

There are four chords here, two of which have the form of the French augmented sixth (the chords labelled 1 and 3). The chord labelled 2 is E7, and the chord labelled 4 is Am. Everything between 2 and 3 is merely several repetitions going back and forth between chords 1 and 2.

The melodic bass line was constructed entirely by moving through the chord tones. Take a look. Every bass note is one of the pitches in the chord on the treble staff. There are no extra pitches here.

So take a look at chord 1. The notes in this chord are F, A, B, and D#. This is the standard French augmented sixth chord in the key of A. Of course, this piece is actually written in D, so I’m technically borrowing the chord from the dominant key of A to prepare the ear for the E.

Then chord 3 is B♭-D-E-G♯, the French sixth from the key of D, so this is our standard French augmented sixth chord. As expected, it resolves to the dominant of the key. (The observant reader may wonder why it’s Am rather than A. The reason is that the passage that follows is modal. All the C’s are natural, so technically we’re in D Mixolydian, but you really don’t need to worry about that.)

It’s also worth noting that E7 and this second French augmented sixth differ by only one pitch being moved a semitone. In fact, some theorists analyze the French sixth as a secondary dominant with a diminished fifth. In our case, an E7 chord with a B♭ instead of a B. In a sense, we’re kind of treating the B♭ as a passing tone stepping down between the B in the E7 and the A in the Am. I personally don’t concern myself much with theoretical analysis, and I certainly don’t stress over which interpretation is correct. My approach to music is to concern myself primarily with whether it sounds good.

Below you can listen to a full version of the entire piece the example is taken from. The example occurs right at the beginning and at about the middle. I also wouldn’t be able to forgive myself if I didn’t credit Christopher Nuño for writing one of the melodies in this piece. It’s quoted from Selatria’s main theme, written by Chris.

To wrap up, the key concepts I’d encourage you to take away from this entry are the form of the French augmented sixth and the idea that you can shift this chord form around in order to add drama to the approach to other chords. I could have written a transition that simply used the E7 by itself to approach Am, but by preceding the E7 with the French sixth that standardly resolves to E (that is, F-A-B-D♯), and then between E7 and Am including the French sixth in D (again, B♭-D-E-G♯), I added dramatic tension and color, which lends character to the transition.

Thanks for joining me, and I’ll see you next time! If you find this article interesting or helpful, please let me know. Any other feedback is also welcome. Thanks!

Relevant links:

Whim Independent Studios – Creators of the RPG Selatria
H2O Music Entertainment – Chris Nuño’s website
Wikipedia Entry on Augmented Sixth Chords – For further reading

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