#1
In reading the many threads that come up involving how to analyze a piece of music, I notice that tonal center tends to be at the crux of the argument. Obviously sense certain progressions have chords that all fit into several keys, it is necessary to find the tonal center so that the melody does not fight the chord progression. As an example of what I mean.

Am - G - C - G

Techniquely this chord progression could be in C major, of G major. However, sense C is the fifth of G, and the C leads into the G, the classic V I perfect cadence, it would be more correct to view this piece as G major, as oppose to Em, Am, or C, for the purposes of writing a melody. So, if I did that right, the tonal center is G, and beyond not writting a melody in Em or Am, it is impossible because the tonal center dictates that the piece is in G major? Is that a correct understanding of how tonal center works, and if not what am i screwing up?
#2
C is the 4th of G. G is the 5th of C.

Tbh, that chord progression is quite ambiguous. An obvious Am progression would usually have an E7 or G#dim in it, Em would usually have a B7 or an Ebdim in it. A typical C major progression would end on a G and start on a C, while a typical G major progression would end on a D and start on a G (though of course it doesn't have to).

Since the chord progression is obviously not in any harmonic minor, and since it contains no D chord, I'd say it's in C.
#3
Quote by gt4068
and the C leads into the G, the classic V I perfect cadence
Wrong way around. The perfect cadence is G-C.
If you wanted a perfect cadence to G you would want D-G.
404: Sig not found.
#4
Indeed, my mistake. So my question remains, what is the tonal center of that progression, or could you write the melody to resolve to different notes?
#5
C Major.

Yes, you could say as the first chord is Am, and the fact you'd probably finish the song with a final Am, that it is in Am.

That would be fine if the sequence went something like Am-G-F-G.
But as soon as you put the C in there it pulls towards C Major.

Just play it through and end on an Am, then play it through and end on a C. It just sounds more complete going to the C Major.


Edit: I rambled a bit.
404: Sig not found.
#7
A plagal cadence is IV-I. In the key of C that would be F-C.


Edit: The C-G would be an imperfect cadence.
404: Sig not found.
Last edited by ChrisN at Feb 4, 2009,
#8
^a plagal cadence in the key of G is C-G, which is what I think blueriver was getting at.

TS. When finding the tonal centre, some will say look at the first chord some will say look at the last chord, some will say look for a perfect movement (root movement down a fifth or up a fourth). These are all clues but none of them are fool proof.

The best way is to listen and determine the tonal centre by ear. You listen to the progression and consider what each chord does. Ask yourself does this chord provide tension or movement, does it feel like it wants to move somewhere, or does this chord sound stable and at rest?
Si
#9
Quote by 20Tigers
^a plagal cadence in the key of G is C-G, which is what I think blueriver was getting at.
Ah yea, you're probably right. I'd got my mind tuned in to C
404: Sig not found.