I have been experimenting with ways to make a normal 12TET bass guitar microtonal by using a special small-interval tuning (usually thirds) then micro-retuning every odd-numbered (or even-numbered) string.
(No recordings yet though, before you ask).
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My first system allows 24 tone / quartertone music to be played:
The tuning is 3.5 semitone intervals (neutral thirds) instead of fourths. 2 of these intervals equals a fifth, so it is actually 2 interlaced fifths tunings, where one fifths tuning is shifted by a quartertone.
For example F Av C Ev G Bv, where 'v' means 'quarter flat'. This being FCG interlaced with AEB, then AEB is detuned a quartertone.
The smaller intervals means a 6+ string bass guitar is ideal to maintain pitch range.
You play the 'normal' notes on strings 2, 4, 6 and the quartertones on strings 1, 3, 5. This obviously requires more shifting along the string, which is why i use a small-interval tuning of thirds, which results in no more shifting than playing a fifths tuning.
Because the strings are in a thirds tuning, it works well for playing chords, nice chord shapes.
Only 12 frets per octave, so no narrow fret spacing, no special guitar or modification needed, does not even look different.
Trauma Triad independently discovered this system and released an album using it Visceral Defects, by Trauma Triad
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My second system is a small retuning of the first system and allows various Just Intonation (JI) scales to be played:
For playing JI major or minor scales the tuning is alternating JI major thirds (3.86 semitones) and JI minor thirds (3.16 semitones).
In all other ways it is like the first system.
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You can retune a normal fourths tuning in the ways above, but the larger intervals make it more difficult to play.
For both systems above, all you need is custom set of gauges chosen for equal tension in neutral thirds, a cheap and reversible modification.
(No recordings yet though, before you ask).
///////////
My first system allows 24 tone / quartertone music to be played:
The tuning is 3.5 semitone intervals (neutral thirds) instead of fourths. 2 of these intervals equals a fifth, so it is actually 2 interlaced fifths tunings, where one fifths tuning is shifted by a quartertone.
For example F Av C Ev G Bv, where 'v' means 'quarter flat'. This being FCG interlaced with AEB, then AEB is detuned a quartertone.
The smaller intervals means a 6+ string bass guitar is ideal to maintain pitch range.
You play the 'normal' notes on strings 2, 4, 6 and the quartertones on strings 1, 3, 5. This obviously requires more shifting along the string, which is why i use a small-interval tuning of thirds, which results in no more shifting than playing a fifths tuning.
Because the strings are in a thirds tuning, it works well for playing chords, nice chord shapes.
Only 12 frets per octave, so no narrow fret spacing, no special guitar or modification needed, does not even look different.
Trauma Triad independently discovered this system and released an album using it Visceral Defects, by Trauma Triad
///////////
My second system is a small retuning of the first system and allows various Just Intonation (JI) scales to be played:
For playing JI major or minor scales the tuning is alternating JI major thirds (3.86 semitones) and JI minor thirds (3.16 semitones).
In all other ways it is like the first system.
///////////
You can retune a normal fourths tuning in the ways above, but the larger intervals make it more difficult to play.
For both systems above, all you need is custom set of gauges chosen for equal tension in neutral thirds, a cheap and reversible modification.
