Why does this work?

What g chord? If you are talking about the second chord (A-G-E-A) that would simply be an inversion of the A dominant chord. It works because the A-D chord can be seen as an inversion of the D5, we'll call that the I or tonic chord. In D major (f and c sharped) the dominant chord is the A, spelled A-C#-E-G.

Did this help you?

Those are four separate major chords, xdamnablex.

Olive, the choice of this chord makes that line sound a bit more bluesy, and I think that's the bottom line - they used it because they liked it, and they made it fit.

That doesn't mean there isn't a theoretical explanation, of course :)

A lot of the 'psychadelic rock' (Grateful Dead, Jefferson Airplane, etc) songs are written in Mixolydian mode. That lowers the 7th of the scale, giving you this harmony:

I - Major
ii - minor
iii - diminished OR minor*
IV - Major
V - Major OR minor*
vi - minor
bVII - Major OR vii diminished*

* the choice of which chord depends on whether the melody is in mixolydian or major at this point

Because the melody line of the vocals has the b7, the bVII chord works. The range of the vocals doesn't have a b7 at the E-A change, allowing for the more conventional V-I cadence.

Thanks, Noteboat. It kinda-sorta makes sense now. :wink:

I seem to recall one of David's lessons referring to the IV of IV of I working well within a progression. In this case D is IV of A, and G is the IV of D, so G is the IV of IV.

I find it's kind of fun to play around with this in different keys when I just messing around.

In this case, the "x of..." analysis doesn't really work. That approach to viewing chords is called the 'secondary dominant principle', because it's most often done with dominant chords, as in:

C-D7-G7-C

The above progression works, even though D7 isn't in the key of C, because D7 is the 'V of V' - G is the V in C, so D is the V of V. Progressions of that sort leave the home key temporarily, and the secondary dominant principle is the analysis of how the get neatly back where they belong.

To call the G the 'IV of IV' means that G will resolve down a fourth (in a plagal cadence) to a D chord, which will then resolve down a fourth (in another plagal cadence) to an A chord:

G-D-A

but that's not the progression we're talking about - the G goes to E, not D. (Please note that the 'x of...' doesn't indicate a substitution, it indicates a progression of two chords - although G is indeed the IV of IV of A, if the IV of A isn't present, so you can't look at the progression in those terms)

G is the bIII of E, or the III in Em... but you wouldn't say it's the III of IV, because that implies the progression has modulated through the key of Em - and it's really a stretch to say you've gone through a minor key when there are no minor chords in the phrase.

Man, and I thought I had it all figured out... :?

I've been playing "Sugar Magnolia" recently. The song is in the key of A, but there is a random G chord in the verse. It sounds fine, but I can't figure out why it works.

The verse chords are:

A-D
A-G-E-A
A-C#m-F#m
E-D-A

So, why the G chord?

Why the G chord? Because it sounds good. It expresses emotion. But it's out of "key" isn't it. This causes alot of confusion to beginners. When we speak of key in a "classical" or "tonal" piece of music we are speaking of the tonal center and mode. However, most music is not strictly "tonal" in nature. Especially American popular music.

Folk, Blues, Jazz and rock music are also influenced by modal music (not to be confused with the "modes" in tonal music) and polyphonic music from various cultures around the world to varying degrees. Most modern music is a hybrid of different types of music. So when we speak of a "key" in this song it is not to be taken as strictly as a classical song. It dosen't follow the same rules. But there is a method to the madness.

I was about to say it changes modes , but in a music theory forum I would get lynched, have my fingers chopped off and burned at the stake for that. That's an oversimplification. The tonal center is obviously A. So I'll just call it a polyphonic modal melody. Everyone from the Beatles to Clapton to Metallica uses this technique extensively in their compositions.

And before anyone grabs the gasoline can, when I say modal I mean it is influenced by modal music, not that it changes modes. This same polyphonic melody is a staple of some traditional African modal music. Only they usually do it with perfect 4ths and 5ths.

What I'm trying to get at is that most modern music is a hybrid. It's not strictly tonal in nature like classical music. However most teachers ignore this fact and it causes alot of confusion among students. I always encourage beginners to study the history and roots of their music. It' gives them a better understanding. You have to look at it from different perspectives.