Jackson 7-String 11-Limit Split-Fret (2022)
This seven-string uses a fixed Otonal tuning of harmonics 2-3-4-5-7-9-11 of a 30Hz fundamental. This aligns within 150 cents of the standard tuning, allowing string gauges and saddles to be relatively untouched.
Scroll down to see the full pitch-map of the fretting.
7-String Split-Fret Scale
The "split-frets" (partial frets) are chosen for each of the strings with a preference for simple 11-Limit pitches.
For example, many of the X/11 frets appear on the highest string (tuned to harmonic 11) where the resulting pitch is a simple harmonic on that string [e.g., 14/11 on the 11-string = 14th harmonic].
The pitch map below chows each fret (on the rows), each string (the column-groups) as HEJI pitches, ratios from the 30Hz fundamental, and frequencies.