I was reading some of Ivor Darreg’s writings and a really interesting idea jumped out.
“Try this: Move the bridge down until the 13th (instead of the 12th) fret sounds the octave of the open string. This will give an approximation of the 13-tone equal temperament.”
Here’s how it works. If you have a guitar with a movable bridge, then you can move it down such that the 13th fret gives you a perfect octave. This gives you a 13 tone scale to play on your guitar!
While its approximation to 13-edo is far from perfect (you’d need to completely move the frets for that) this should offer plenty of new tonal resources to the experimenting microtonal guitarist. Compared to 13-edo, the error is largest in the middle of the scale.
You can reverse this and push the bridge up such that the octave lies on the 11th fret, giving you a brand new 11-tone scale to experiment with. Again, it poorly approximates 11-edo but don’t worry about that, there are plenty of new sounds available through this method.
The idea can be pushed further:
“I fretted a guitar to 18-tone (Busoni’s proposed third-tones) and can use this guitar as a 17 or a 19 without the theoretical errors from moving the bridge spoiling any performances. So you can have three systems for the price of one.”
This really is “one weird trick that luthiers don’t want you to know!” Bwaha… ok I’ll see myself out the door.
For something a little different, check out 9 Alternative Tunings NOT for Guitar.