Hiya, I have a Yamaha FG-413S-12 and really rate it highly. Try one if you get a chance. The spacing at the head end on the "thin strings" is 2mm and 2.25mm to 3mm on the others (graduating with thickness of string). There is 5mm between each pair of strings at the head end (nut?) and this gives an overall here of 40mm between string extremeties (head end again). This dimension is 53mm at the bridge.
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