Running the length of the neck there is a simple truss rod, and at the end a hexagonal M5 (8mm) nut. This assembly allows customization of the neck position. Some players prefer a straight neck, but for an aggressive bluegrass picking style a slightly curved profile can be more advantageous. The curve reduces string buzz and rattle against the frets, especially when the player is „chopping“ chords.
With a new mandolin, it’s best to begin with the nut only slightly tightened. During the first few weeks monitor the neck curvature by pressing the strings against the fretboard at the first and fifteenth fret. The ideal curvature will leave a slight gap between the strings and the level of the frets. To attain this shape, gently tighten the nut. To return the neck to its original shape, it’s best to carefully pull the neck back with one hand while adjusting the nut with the other. Don’t use force!