Tuesday, September 15, 2009

Diatonic Symmetry


Fretography focuses on the symmetrical distribution of tones on the guitar fretboard. This symmetry is not some graphic trick. It's not an accident that the notes line up the way they do. The symmetry is inherent in the Diatonic system itself. Out of the twelve tones which comprise the diatonic system (which is the basis of western music), a set seven tones make up each key. The interval relationships within each key are the same (see "Tetrachords" in this blog).

The whole-steps and half-steps are sequenced symmetrically in a repeating pattern. Strangely, this symmetry is obscured in the major scale;




W-W-H-W-W-W-H

However, if we look at the Dorian mode, which begins on the second scale degree, we can see a clear mirror symmetry around a central whole-step;




W-H-W-W-W-H-W

This mode is central to the Diatonic system, and the underlying element of the symmetry of the fretboard.

In the key of C, D becomes the fulcrum around which the entire system revolves;

--------------------------------------------------------------------------
D W E H F W G W A W B H C W D W E H F W G W A W B H C W D
---------------------------------------------------------------------------

If you study the line above you'll see that the whole-steps and half-steps are symmetrically arrayed around the D. There is no other tone in the key which can function as the fulcrum. Place any other tone at the center and you will have asymmetry.

Notice that, except for D, all the other tones are paired symmetrically; C&E, G&A, B&F are each paired. They are three sets of symmetrical counterparts on either side of the fulcrum, while D is its own 'partner'. This arrangement is precisely what we see on the guitar fretboard in the Fretography system.

From the open strings to the 10th fret, within the four top strings as a set (D-G-B-E low to high), and within the three bottom strings as a set (E-A-D low to high) the tones are found in symmetrical opposition to each other in the same pairs as we've just laid out. Where C appears on the 1st fret of the 2nd string, E is found on the 9th fret of the 3rd string. At the center of the span, C is on the 3rd string 5th fret, E is on the 2nd string 5th fret, and so on.

Study the diagram at the top of this post, and those in the previous posts and you will see how this method will enable you to achieve a greater awareness of the relative positions of all the notes on the fretboard, not simply as linear progressions, but connected over the entire grid in every direction and across wide distances.


All contents of this blog are © Mark Newstetter

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