PRS Double Acting Truss Rod Adjustment
The advantage of the PRS double acting truss rod is that provides neck adjustment in both directions. Conventional truss rods can only compensate for forward neck bow. Due to varied climate and other conditions to which your PRS guitar may be exposed during its lifetime, we have made our necks fully adjustable. PRS switched over to the double acting truss rod about halfway through the 1992 production year.
To determine whether your PRS guitar has this system simply examine the adjusting nut. The PRS single acting rods used a brass adjusting nut threaded onto a steel rod. The PRS double acting rods use a steel nut fused to a steel rod. Neck adjustment can be accomplished as before except that a reverse bow can now be fully corrected. The PRS double acting truss rod achieves twice the amount of adjustment as the single acting rod with the same amount of movement of the adjusting nut. Do not over-adjust!
Understanding Truss Rod Adjustments | Tips From The Tech - YouTube