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Hjertmann Instruments

Below are the instruments I've built or modified, mostly into Just Intonation, with the most recent appearing at the top.  Click the images to see more about each instrument's design and tuning.


Please use the contact form on this site to inquire about purchasing or designing microtonal/Just Intonation guitars and guitar necks.

This is a 23-Limit Guitar with a fixed tuning of B-E-B-E-B-E

It contains 23-Prime-Limit harmonics between 24 & 48.

24-25-26-27-28-30-32-33-34-35-36-38-39-40-42-44-45-46 | 48

Click the image to learn more.


The Gigantar is a 6-foot guitar with more than twice the scale length of your average guitar.  It features a fretting with harmonics 4-32 with frets ranging from 1/4-inch to one foot!  Why?  How?  Click the image to learn more.


I made a new fretboard for this Republic Tricone after the Lou Harrison National Resonators that were commissioned to perform his final piece, Scenes from Nek Chand.  Since then, other composers have written for this instrument.  I believe this is now one of only eight in the world.  Unlike the other instruments here, I did not design this fretting.  It was developed by William Slye and Bill Alves.  Click the image for more.

I retuned this pump organ to an 11-Limit tuning by filing the brass reeds.  Afterward, I was delightful contacted by Kraig Grady, of Anaphoria, who identified it as identical to his "Centaura" scaleClick image to learn more.


The "Bifur" is an original instrument of my own design.  It is similar to a hammered dulcimer or santoor in concept.  It contains 12-strings in groups of 2 (6 "courses"), like a 12 string guitar, but with "chessman bridges" with divide (or bifurcate) the strings into two parts creating natural Just Intonation relationships (string length ratios, inversely proportional to JI frequency ratios).

Click the image to learn more.

This is my first completely handmade guitar.  I handcarved it from a reclaimed antique hardwood door.  It is an extra-long baritone guitar (30.8-inch scale length compared to the 25.5-inch standard or the 27-inch baritone. The extra length accommodates more closely-spaced fret.

Of course it's nickname is a pun combining door and Dorian, a mode which is found in 5-Limit and 7-Limit JI this fretting.


This seven-string contains my most complex fretting to-date, "split-frets" (partial frets) covering 1-6 of the strings allow for hand-picking pitches on each string and repeating pitches rather than frets.  Unlike my other guitar designs which have flexible tunings, this guitar's fretting is based on a consistent 30Hz Fundamental with strings tuned to harmonics 2-3-4-5-7-9-11.

Click image to see more info.

I built the Kitele from parts in Telecaster-style.  The fretting is including 3, 7, 11-related overtones and /3, /11 undertones.  This allows for modulation between A440-land and my 60Hz-related tonics (X/11's).

The Kitele has quickly become my most-used JI guitar for it's playability, timbre, and recursive fret-logic.


This short-scale classical guitar is an 11-limit mixed fretting, designed for open tunings such as "Open-D" (harmonics 2-3-4-5-6-8).  It features the numinous 11/10 fret, a personal favorite.  It uses gold frets for the overtones (X/2) and silver frets for the other denominators.

My first JI re-fret was this Rogue Strat from my childhood.
The frets are equally-spaced and exactly the same size.  This creates a 47-limit Utonal scale with a mix of familiar JI intervals (16/15, 8/7, 6/5, 4/3, 3/2, 8/5, 16/9) and otherworldly undertones (48/47, 48/43, 48/41, 48/37, 48/31, 48/29), and some gorgeous possibilities in between.

Click the image to see tuning charts & building process.

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