Ben Hjertmann
Music Composition, Teaching, Recording, Instrument Building
HP43 (#2): Full 43-Tone Partch Tuning
Completed in July 2026. This and #1 are the first guitars in history to contain all of Partch's 43-tone tuning!
That is, as far as I or anyone I've asked knows, correct me if I'm wrong. HP43 (#2) is a custom fretted Alvarez acoustic guitar with slim body, cutaway, and electronics designed to perform the complete 43-tone Just Intonation system developed by Harry Partch. The instrument’s fretboard has a new custom fret layout that contains all 43 pitches of the scale across three octaves and a perfect 4th. Compared to #1, it has an additional 4th at the high end allowed by the cutaway profile,
The full explanatory details of the fretting, scale, and chord possibilities can be found on the HP43 #1 page.
Please check out that page for the deep dive into the design of these instruments. Rather than restate all of the info from that page here, below you'll find specific info about #2's fret layout and HEJI inlays (combo glyphs of my design).
Inlays and Glyphs
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Open and Familiar Chord Shapes
Because the instrument retains a familiar intervallic layout, many conventional guitar shapes remain recognizable. Major chords, minor chords, dominant sevenths, major sevenths, minor sevenths, suspended chords, diminished chords, augmented chords, and extended harmonies can all be performed using fingerings closely related to those used on a standard guitar. At the same time, the expanded fret system allows access to the numerous additional intervals and harmonic relationships found within Partch’s 43-tone scale.
One essential design element is that each Otontality (rooted on each Udentity 1/1,3,5,7,9,11) are located where the 1/X is on the fretboard. So, if you want to play an Otonal 8-16/11 (no 13 of course) you go to the 16//11 location (fret 6.5) and there are all the pitches you need within reach. Many are located elsewhere too. This element is
