Today’s Tech Tip, while being guitar oriented, is going to deal specifically with the unique Tremolo and Stoptail bridge design of Paul Reed Smith guitars. As far as adjusting the intonation goes, this is a universal concept to be applied to all guitars. However, before we start, I would like to issue the following warning: DANGER! DANGER! If you’re not familiar with making these adjustments, I highly recommend that the guitar be taken to a qualified repair center. (Much like the one you find here, at Sweetwater.)
PRS Tremolo Bridge
Paul Reed Smith was granted a patent on his tremolo system in 1984. The design elements are simple and resemble the traditional fulcrum tremolo but with important differences that result in much greater tuning stability than traditional designs.
Tuning and Setup Hints
If the guitar is returning sharp after using the tremolo arm, put a little lightweight machine oil under the head of each screw (do not loosen the screws). This will effectively oil the knife-edge of the tremolo. The correct adjustment of the six brass screws, which act as a pivot and anchor the tremolo system, is level with each other so the bridge floats 1/16″ off the body. These 6 screws are factory adjusted and you really should not have to adjust them at all. If it becomes necessary to adjust the 6 notched screws, make sure the guitar is detuned or you will ruin the knife-edge. Adjust the screws incrementally so the notches under the screw heads are fitted with the corresponding hole in the bridge. These holes serve as the knife-edge on which the tremolo unit rocks. Again, this is a very tricky adjustment and could ruin the knife-edge if done improperly.
The bridge saddles should be low in the range of adjustment to keep the action low and leverage of the bridge in good working order. They should be adjusted so that the height of the string at the top of the 12th fret to the bottom of the string is 2/32″. If the tremolo bridge is not floating 1/16″ off the body, remove the tremolo back plate. Adjust the claw screws about 1/4 turn at a time until the bridge floats perpendicular to and about 1/16th off the body. Tune to pitch and check, re-adjust until the bridge sits properly. When the tremolo is adjusted properly and the guitar is in tune, the tremolo arm will raise the low E string pitch to F#: no more, no less. The intonation may be adjusted by moving the (6) Phillips-head screws facing the tail end of the guitar in and out with a Phillips-head screwdriver. Match the octave (fretted) note of all six strings with their corresponding 12th fret open harmonics by shortening or lengthening the strings with the adjusting screws. Remember to tune and retune until the process is complete.
PRS Stoptail Bridge
Designed to take full advantage of the resonant properties of their guitars, the PRS Stoptail Bridge provides direct transmission of string vibration to the guitar body and makes set-up a breeze. First used in 1991 on the PRS Dragon | guitar, it now appears on almost half of all PRS guitars sold. This bridge features slots that recess the strings comfortably as they pass over the top, in a gentle curve. Although it is pre-compensated for modern string gauges, fine-tuning is possible by adjusting the setscrews at each end of the bridge.
Tuning and Setup Hints
Action height is adjustable by raising or lowering the studs the bridge sits on. To adjust the mounting bolts, first detune the instrument to relieve the tension on the bridge. Then using a Quarter, make the necessary adjustments and retune. Intonation can be adjusted using the two Allen set screws facing the tail end of the guitar. A strobe tuner or other electronic tuning device should be used. Match the octave (fretted) note of the first and sixth strings with their corresponding 12th fret open harmonics by shortening or lengthening the strings with the adjusting screws using the Allen wrench provided. Start with the treble side and then go to the bass side, return to the treble side for one last check. The other four strings are present and will intonate correctly provided a conventionally gauged string set with a plain third (G) string is used. Use of a wound third string is not recommended with this bridge. Remember to tune and retune until the process is complete.
Adjustable Stoptail Tuning and Setup Hints
Action height is adjustable by raising or lowering the studs the bridge sits on. To adjust the mounting bolts, first detune the instrument to relieve the tension on the bridge. Then using a Quarter, make the necessary adjustments and retune. The intonation may be adjusted by moving the Phillips head screws on the inside edge of the bridge (facing the treble pickup) in and out with a Phillips head screwdriver. Match the octave (fretted) note of all six strings with their corresponding 12th fret open harmonics by shortening or lengthening the strings with the adjusting screws. Additional minor adjustments to the intonation may also be made by moving the setscrews facing the tail end of the guitar in and out with the Allen wrench provided. Remember to tune and retune until the process is complete.