Upsidedown & Backwards
Explorations in 13-tone Equal Temperament
by David Finnamore
13 EDO is one of the wierdest, least harmonic, most counter-intuitive tunings I've ever come across. Generally, almost everything you can play in it seems broken, distorted, stubbornly wrong. I suspect that if one were depressed to begin with, and persisted in playing music in this tuning every day, he would probably commit suicide within a few weeks. It's just wretchedly out of sync with humanness.
Thus, it's nearly perfect for expressing the dreadful effects of Enlightenment philosophy that continue to plague Western society, splintering us into smaller and smaller fragments until we are all coming apart at the seams (and, via relativism, at the seems), from each other and from our selves. For me, 13 EDO music tends to convey the Cartesian crack in the human mind that has widened into a gaping, bottomless chasm.
The foregoing is only true when using acoustic music instruments, or instruments that use similarly harmonic overtone structures. By artificially (electronically) creating tones that use overtone structures matching the inharmonic dis-tonality of the scale, pleasant and even joyful sounding music can be made, although it still sounds like there's something awry somewhere that you can't quite put your finger on.
The mp3 examples below are very roughly played and recorded ideas, no more than sketches for future reference. But they should give an idea of some of the kinds of musical identities that 13 EDO can take on. They were played on an old electric guitar that was crudely modified by moving the bridge back until an octave sounded at the 13th fret instead of at the 12th. That technique yields something relatively close to 13 equal in the first octave of frest; close enough for getting the feel of it anyway.