Other Music’s American gamelan was tuned to a fourteen-tone-per-octave, seven-limit scale in just intonation (OMJ14), designed by David B. Doty and Dale S. Soules and depicted in the charts on this page. The tuning is based in Ptolemy’s diatonic syntonon, a five-limit, seven-tone scale that is generally considered to be the just archetype of the Western major scale. Each five-limit scale step of the diatonic syntonon is subdivided by a ratio involving seven as a factor, such that all intervals between adjacent scale degrees are superparticular (x+1/x) ratios. The particular subdivisions were chosen, among other reasons, to include examples of the three classical Greek tetrachordal genera. I am not going to explain the Just Intonation terminology in these descriptions here; those interested in learning the fundamentals of Just Intonation should consult my Just Intonation Primer. For those not versed in this terminology, the fourteen tones of OMJ14 are not the familiar twelve tones of equal temperament with two added; every interval in OMJ14 except the octave differs from the nearest “equivalent” in twelve-equal—sometimes subtly, sometimes radically—in the interests of improved consonance and greater intervallic variety. The resulting tuning contains just versions of a great many interesting scales and modes, historical, ethnic, and novel, including, as it turned out, quite serviceable versions of Indonesian slendro and pelog scales, although these were not deliberately designed for.
Other Music's 14-tone just intonation on the seven-limit lattice. The red links represent Ptolemy's diatonic syntonon; the blue links are the added seven-limit pitches. The sharp 1/flat 2 pitch was later changed from 15/14 to 28/27.
Other Music's 14-tone just intonation in staff notation. The accidentals are from Ben Johnston's system, which I currently use in my compositions, but which were not used by Other Music.