Abstract: A stringed instrument having a fretboard with a sawtooth surface profile with the crests of the teeth in the normal fret positions.Optionally the instrument may have a rotatable nut of generally cylindrical form having a plurality of annular grooves therein, one groove for each string of the instrument. The nut is so mounted or the grooves are so shaped that on rotation of the nut, the heights of the strings from the surface of the fretboard are varied simultaneously.