Guitar Setup
Some Thoughts on the Basics of Guitar Setup
Repair shops make their income by doing what we cant or wont do for ourselves. A good repairman knows that setting up a guitar is a very subjective process, what pleases one player may well irk another. So the starting point, in my opinion, is in knowing what is possible and knowing what you (the player) want.
Acoustic Properties of All Guitars
Every guitar has acoustic properties whether it is a huge acoustic archtop or a thin solid body. Another way to look at this is to say that when you pick up a solid body guitar the sound you hear unplugged has a big effect on the sound you here amplified. The sound comes from the pressure of the vibrating strings being transmitted through the bridge and through the nut. The angle at which the strings break over the bridge and the nut has a big effect on the sound quality and sustain of the instrument.
Here is the first problem with guitar setup, the easier the strings are to push down the less pressure is be exerted over the nut and bridge so there is a balance point. If you could handle very high effort for holding down strings you would get great sound but most of us want at least some ease of playing. So a compromise has to be reached, tone and string tension are related so you will sacrifice tone for ease in playing.
The next compromise is in neck relief, the amount of bow in the neck. A perfect fret job will allow you to have a very straight neck while a little bit of bow in the neck will cover for minor imperfections in the frets. As you add more and more neck relief you will quickly pass a point of diminishing returns and start to experience problems with intonation and possibly buzzing on the upper frets. The amount of effort to push the strings down will increase quickly as well.
Finding a Starting Point
The first thing to do is an inspection of your guitar. Is the neck to body joint sound? Are the frets in good condition and reasonably leveled? Is the bridge properly centered on the guitar? All of these items must be in order if you want to achieve a useable setup. Assuming that the guitar itself is in sound condition I would advise starting with two measurements. The action height as measured at the 12th fret should be written down for each string. A six inch steel ruler works well. Remember to measure from the bottom of the string to the top of the fret. Neck relief will require either a capo or a friends assistance. Simply pin the strings at the first fret and the highest fret and measure the gap at its greatest point using a thickness gauge (feeler gauge). You will want to record the number for both the first and sixth strings plus the fret that had the greatest gap. Keeping these numbers in a safe place will give you a fallback position in case you dont like the results of your setup.
I wont suggest figures for string height or neck relief but many manufacturers publish these as part of their specifications. Once you have determined the amount of neck relief you desire you can adjust the truss rod if you feel confident of your ability to do so safely. If you over-tighten the truss rod you can reverse bow or even split the neck and quite possibly ruin the guitar. If you over loosen the truss rod there is a danger that you will disengage the rod from the nut that it is threaded into. This is best left to a pro unless you have experience. If you do decide to do this yourself remember that as with all adjustments if you are making big changes there is a good chance that you are making a mistake. Make all changes incrementally and gradually over time. A severely warped neck shouldnt be straightened in one session.
Once the neck adjustments have been made the string height and intonation will need to be set. This will vary by the type of bridge but I will use a Fender style bridge as an example. If you are working with a Stratocaster with a tremolo type bridge you will save yourself many headaches by getting a good spring claw and a matching set of springs and tightening the springs enough to prevent the bridge from floating. Blocking the tremolo is another viable option.
To set the string height start with the sixth string and play that string at every fret checking for buzzes. If there are no buzzes and you are satisfied with the string height you can move on to the intonation. An accurate electric tuner helps at this stage. Tune the string to its correct pitch and then carefully push the string down at the 12th fret. If the fretted note is sharp the bridge element for that string must me moved away from the nut, if it is flat the bridge element must be moved closer to the nut. Repeat this step for all strings and then go back and start over again, checking that your settings didnt change as the guitar adjusted to its new setup. Normally, I dont have to redo anything but it is good to check anyhow, sometimes you get a nasty surprise when you recheck.
Setting Pickup Height
The pickups on an electric guitar are actually small generators. The pickups create a magnetic field that project upwards towards the strings. The strings vibrate within these fields as you play creating a tiny current in the coils that are wound around the magnets in the pickups. This tiny current is fed into the amplifier and increased to a high power signal which the speakers convert to sound. The stronger the magnetic field the stronger the signal but it is not that simple. If the magnetic field is too strong the strings will be impeded in their movement and there will be a resultant loss of sustain. If the field is very weak the signal will require more amplification bringing extraneous noise with it. Dramatic changes in pickup height can put you on the wrong side of one of these problems so I would advise not getting too extreme in these adjustments. Mainly, I just go for a balanced volume between the bass and treble strings. Balance between pickups is a bit dodgier because the physical characteristics of the strings vibration vary at different points on the string. It is also possible that the neck, bridge and middle pickups are all of differing strengths. As the recipes state "season to taste".
