Skip fretting system 87 2 17
One way to play 87edo on a guitar is with frets every 2\87 (43.5edo), tuning each pair of adjacent strings 17\87 apart, or about 234.5 cents, corresponding to the sharp ~8/7 generator of rodan temperament.
This tuning may work better on instruments like the harpejji better than on traditional stringed instruments. However, Ron Sword has built a 46edo guitar and claims it is playable.
Among the possible skip fretting systems for 87-edo, one reason (87,2,17) is special is that every 17-limit interval spans at most 8 frets.
The following table describes where all the primes intervals lie in the (87,2,17) system:
note | fretboard position |
---|---|
0 steps = 1 % 1 | string 0 fret 0 |
87 steps = 2 % 1 | string 5 fret 1 |
51 steps = 3 % 2 | string 3 fret 0 |
28 steps = 5 % 4 | string 2 fret - 3 |
70 steps = 7 % 4 | string 4 fret 1 |
40 steps = 11 % 8 | string 2 fret 3 |
61 steps = 13 % 8 | string 3 fret 5 |
8 steps = 17 % 16 | string 0 fret 4 |
22 steps = 19 % 16 | string 0 fret 11 |
46 steps = 23 % 16 | string 2 fret 6 |
75 steps = 29 % 16 | string 3 fret 12 |
83 steps = 31 % 16 | string 5 fret - 1 |
From these, the location of any compound interval can be added by vector-summing the string-fret positions of the interval's factors. See Skip fretting system 48 2 13 for details on how that's done.