Taking the Guitar Beyond Equal Temperament

by Don Musser

Originally published in American Lutherie #30, 1991 and Big Red Book of American Lutherie Volume Three, 2004



If someone were to tell you that the simple C chord you just played on your perfectly intonated, handmade guitar was in fact significantly out of tune with itself, you might have a few doubts and perhaps some curiosity about just what he was talking about. If that person were Mark Rankin and he happened to have his little Martin set up with the just intonation, key-of-C fretboard, and you compared a C chord on that guitar to the C chord on your guitar, instead of doubts and curiosity you would have something else: the beginning of a revelation, a revelation not only about the guitar itself, but about the foundation of the music we play on it.

Back in 1987, David Ouellette, a Eugene, Oregon musician for whom I had built several guitars in the early 1980s called and wanted a new, unconventional instrument built. It was to be a special guitar with magnetic interchangeable fretboards having staggered frets set up for alternative tunings of the scale steps within the octave. The standard guitar fretboard we all play on is based on the equal-tempered scale where the octave is divided into twelve equal half-step intervals. This equal division of the octave is good in that it allows modulation from key to key without intolerable dissonance. Its drawback, though, is that the scale intervals are tempered, i.e., harmonically inaccurate and slightly out of tune with one another.