OK, I understand the basic makeup and function of the Italian, French and German sixths but am not clear where these chords occur. In all the examples I've read, the root of the chord is always the (flattened) submediant. Is this correct, or can augmented sixth chords occur with any note (e.g. supertonic, mediant...) as the root?

Thanks!

They best occur in cadences and modulation. The secret is in the preparation.

I looked up augmented sixths in Piston's "Harmony"(revised edition, p. 278). He makes some categorical statements (in quotes) that clarify their normal use.

"The augmented sixth chords are non-dominant in function. They are strongly tonal since they indicate unmistakably the dominant of the key. The interval of the augmented sixth expands in its normal function to an octave which is the octave on the dominant. ... Only by very uncommon exception is the octave of resolution anything other than the dominant."

The third, somewhat turgid, statement accommodates the case where the final resolution to a dominant chord is via a 6/4 chord (often minor) on the dominant bass, or where the resolution is directly to the tonic.

Piston gives a number of examples of irregular resolution, mostly to the current tonic. In the development section of the first movement of the Brahms Violin Concerto, the work has modulated from its home key of D major to A minor. The first inversion of an A minor chord (no fifth) is decorated by an F and a D#, which resolve onto an E octave, giving the current tonic directly, rather than via the dominant. Although in the key of the movement the augmented sixth is on the flattened mediant, in the current key it becomes the conventional submediant.

A more striking example is the chord preceding the finishing chord of the Schubert C major String Quintet: Db, B, F, G, B resolving to a C major triad. Piston considers this to be more properly described as a dominant chord with an altered fifth, but it certainly looks like a French sixth on the flattened supertonic, and he gives this as an alternative view. A jazz player would just regard this as tritone substitution of the bass note.

My personal answer to your question is that there is no reason to avoid use of augmented sixths in other situations provided you can make them sound good ("If it sounds good, it is good" - Ellington).

[quote name='benjaminja' date='Aug 13 2008, 07:02 AM' post='732557']
OK, I understand the basic makeup and function of the Italian, French and German sixths but am not clear where these chords occur. In all the examples I've read, the root of the chord is always the (flattened) submediant. Is this correct, or can augmented sixth chords occur with any note (e.g. supertonic, mediant...) as the root?
Thanks! [quote]
Gosh I seriously have a lot to learn! What grade /standard of theory is this linked to please?

The (flattened) submediant is the bass note, not the root of the chord.

As someone has pointed out, the augmented sixth chords are usually found in cadences and modulations. They are pre-dominant in function and must therefore resolve to a dominant chord. They are essentially chromatically altered II and IV chords, so it is the most effective to use them as follows:

I or VI or IV or II --> augmented sixth --> V OR
I or VI or IV or II --> augmented sixth --> Ic - V

In the second scenario, the Ic chord is known as the cadential six-four chord, which is a harmonic embellishment to V.

I didn't have to do these until I was working for Grade 8 theory.

but not in the detail that has been discussed in the last few posts.

Agreed; I just needed to know enough to be able to identify them in Questions 4 and 5 of the exam papers. That they are found at cadences and modulations was useful in knowing where to go hunting for them.

Thanks for all the informative replies. You have given me much to mull over! I think I will listen to the pieces kenm has discussed to aid my understanding further!

(For information, I think augmented sixths are on the Grade 8 syllabus.)

Yup, that's what I said

I think there is a tendency to try to study/sit/pass theory exams for their own sake, and to forget why we learn this stuff in the first place, i.e.

1. To compose, arrange, transcribe or improvise music effectively
2. To understand the compositions we are studying and (hence?) play them better

Brahms Violin Concerto, Op 77, Mvt 1, Bar 237; Schubert Quintet Op 163, last movement, Bar 425-6, (five bars back from the end).

I agree with Mad Tom. Find out about these things if you want to use them in a composition, or to understand real music better. I don't recall their being mentioned in my degree course. The lecturers probably thought A-level harmony was enough to know, but I hadn't taken that, so thanks for raising the question: my knowledge of augmented sixths and their uses has increased about five-fold in the last 24 hours.

I've got some vague recollection of using aug 6th chords as a shock modulation device - treating it as a mis-spelt dominant 7th ... works like a handbrake turn sending you off in a completely different direction. So, say, you've got a german 6th chord of Ab C Eb F#, which you expect to go to a 6/4 5/3 in C minor, you treat the F# as a Gb, and you've got a dom 7th (Ab C Eb Gb) in Db. Can't think of any examples, but I'm sure there must be some in classical music, otherwise we wouldn't have done it. We didn't do jazz when I was at university, or if we did, we didn't inhale.

You are absolutely right. Composers loved to exploit the enharmonic spelling of the augmented sixth chords. My favourite example is Beethoven, Rondo Capriccio in G Major, "Rage Over a Lost Penny". I don't have the score with me right now, so can't give you the exact bar numbers. But somewhere near bar 160, Beethoven writes the German sixth chord Eb-G-Bb-C# and resolves it as expected to the V chord. Then he writes that same German sixth chord again, but respells the C# as Db. The chord becomes a dominant seventh chord that leads to a modulation to Ab major.

Of course, it is also possible to achieve a chromatic modulation by doing the reverse, i.e. respelling a dominant seventh chord as an augmented sixth chord. You can take a look at Mozart, String Quartet in D Minor, K. 421, 1st movement. I cannot recall the bar number. If I remember right, early in the development section, the dominant seventh chord F-A-C-Eb does not resolve to a Bb major chord, but to the Ic-V progression in A minor.

100% agree. I think taking that on board I should not to put too much pressure on my self. I want to run before I can walk so to speak. Instead of taking the time, I am trying to whizz through as much as I can in as little time as possible but I'd be far better concentrating on what I already know and need to use practically right now - building slowly!! I am a long way of grade 5 theory.
P.s sorry this is off topic!

This is why I relate the theory a pupil is doing to the pieces they are playing, and to the aural. Theory is often seen by pupils as a totally different subject to the practical with no connection to the music in front of them. With my teenage school pupils (most of whom will be doing GCSE music) I try to emphasis that what they do with me in theory can be applied to the compositions they write, from simple things like knowing which way the stem goes on a written note, through to being able to apply suitable chords to their compositions, and I sometimes ask their school music teacher if they're theory lessons with me are making any difference to their compositions. Also in terms of relating theory to their playing, even understanding what the time signatures mean can make a big difference to their playing.

For myself I actually also enjoy analysis for its own sake, as well as finding it useful in playing, which might be why I scored highly on that style of question for the higher grade exams.

When I taught A-level music several years ago we had a set work to study which was a very modern composition. On the first (and second, and third....)hearing I though it was a totally horrible piece of music and was dreading studying it with my students. But when I sat down and analysed it (with the aid of some useful notes - good ol' Music Teacher magazine) I could see how it had been very cleverly structured which totally changed the way I listened to it.

Thanks for this ... I'm glad my memory has not completely failed me! I'll have a listen to the Mozart later to see if I can spot it without the score ...

Your memory is spot on! Yup, bar 45 (4th bar of devt section) prepares dom 7th on F, but slides onto 2nd inversion A minor, with dominant pedal resolving to A minor in bar 50.

Incidentally, Mozart sets up the Eb start of the devt section by doing a similar chromatic shift: in the first time bar he has a dim 7th on F (F G# B D) going to dim 7th on E followed by dom 7th on A, but in the 2nd time bar he spells the G# in the dim 7th as an Ab, which then becomes the 7th of a dom 7th on Bb, so getting his sudden modulation into the flattened supertonic major (Eb maj). Genius. It works particularly well when the exposition repeat is observed, as the first-time-bar sets up an expectation that is cleverly undermined in the second-time-bar.

I ought to be doing some tidying, but this is much more fun.

PS - I'm quite pleased that my ears were correct in identifying where I thought the aug 6th was, but I have to admit to looking at the score for all the detail given above!