If you're a performing guitarist or bass player, it is critical that you have a dependable instrument — one that is easy to play, sounds good, and plays in tune. But is your instrument really living up to its full potential? Without the proper adjustment, or setup, it may not be.
Even if you never do any of the work yourself and would rather leave it to a qualified repairperson, it's still important to understand what goes on in the setup process. My aim is to demystify that process by offering an overview of what takes place and addressing some underlying problems and inherent compromises. Although I will generally refer only to guitars, almost all of the information applies equally to electric bass.
GAUGE YOUR AXE
The first point to make is that you shouldn't necessarily expect your guitar or bass to be correctly set up “out of the box.” Manufacturers often do an inadequate job of setting up even very expensive instruments, typically allowing 20 minutes or less for the entire adjustment process. Also, the manufacturer must choose one particular set of strings to install as original equipment on a given model of instrument — for example, most Stratocaster models are shipped with a .009 to .042 gauge set — and the instrument is adjusted for these strings. If you prefer a set of strings with different gauges, the factory adjustment will be incorrect for you.
What is the desired end result of a setup? The adjustments should culminate in the instrument producing the most pleasing sounds while being as comfortable to play as possible. Of course, the intonation must be adjusted so that the instrument plays in tune.
FIRST STRINGS FIRST
There are several factors inherent in the guitar's design that physically interfere with the free acoustic vibration of its strings and thus distort its intonation. A guitar cannot be adjusted to match standard equal temperament (standard modern piano tuning) as precisely as a piano, but by compensating the guitar's intonation (through adjusting the individual lengths of each string), these factors can be minimized, and its intonation can match a piano's surprisingly closely — much more closely than most musicians expect.
Every aspect of the way an instrument sounds and plays is influenced by the characteristics of its strings, but surprisingly few players spend any time experimenting with different string types and gauges. Before I work on an instrument, I find out enough about the player's technical requirements and preferences to be able to recommend a particular type and gauge of string. This is a critical decision because the chosen strings' characteristics affect all of the subsequent adjustments. Initially, I examine the instrument to see how it's set up and discuss the existing setup with the player to find out what he or she thinks of the instrument's sound and feel. Once I learn something about the player's preferences, I'm in a better position to recommend a particular type and gauge of string. With that in mind, I'm going to start by discussing the ways that an instrument's strings affect its tone, intonation, and playability.
Three major factors affect the sound and feel of a guitar string: its thickness or gauge, its design or level of tension, and the materials from which it is made. (For a detailed discussion of string tension see the sidebar “Extremely Technical String Information” at www.onstagemag.com.)
STRING THEORY
Most guitarists are familiar with the effect of changing the gauge of a plain (unwound) string — for example, changing the guitar's first (high E) string from a .010 gauge to a .009 or an .011. The thinner-gauge .009 string will be both easier to fret and to bend, will have lower output, will have less sustain, and will sound more twangy — that is, it will have a weaker fundamental note, with louder, more pronounced harmonic overtones. The thicker .011 string will be harder to fret and to bend, will have higher output and more sustain, and will produce a more “solid” note — that is, it will have a stronger fundamental, with a less twangy harmonic content.
The design of a wound string has a similar effect on its behavior: a relatively thin core wire, with a thicker wrap-wire layer (or layers), will result in a more flexible string than one with a thicker core wire. Flatwound strings are wound using a metal ribbon rather than a round wire for their outer layer. Typically, they are much higher tension than a round-wound string of the same gauge.
There are several materials used as wrap wire for wound electric-guitar strings; pure nickel, nickel-plated steel, stainless steel, and some other nickel-iron alloys are all widely used, with nickel-plated steel being by far the most common. Stainless-steel wrap wire tends to produce the brightest (most treble) sounds, whereas pure nickel produces the darkest. Pure nickel round-wound strings were in widespread use from the earliest days of the electric guitar up until the early '70s, and their characteristic sound is associated with vintage equipment and with both retro music, such as rockabilly and new swing, and with classic-rock sounds, such as music by Jimi Hendrix.
Unless the new strings that have been chosen for the instrument are radically different from those already on the instrument, I make my initial adjustment to the action using the existing strings to save wear and tear on the new ones. The goal of the initial work is to find the action on the instrument that best suits the player's technique. After we agree on an initial action setting, I change the strings and fine-tune the action a bit more while stretching the new strings. All the subsequent adjustments are to produce the best possible intonation and tone from the instrument, given the chosen strings and action (see the sidebar “One Step at a Time”).
THIS IS A PICKUP
The most overlooked problem with an electric instrument's setup is, without a doubt, the correct adjustment of its pickups — they are routinely adjusted much too close to the instrument's strings. When that is the case, the magnets in the instrument's pickups interfere with the free vibration of the strings. (This is one of the mysterious intonation distorting factors that I mentioned.) The magnetic interference will adversely affect all of the subsequent adjustments, so before proceeding I lower the pickups until I know that they can't significantly affect the free vibration of the strings.
The stronger a pickup's magnetic field is, the farther away it will have to be from the strings. Also, the neck pickup has to be farther from the strings than the bridge pickup (assuming that it has the same magnetic field intensity as the bridge pickup), because it is easier for the magnetic field of the neck pickup to influence the strings. The reason for this is that the strings vibrate more freely over the neck pickup than they do over the bridge pickup (which is closer to the bridge where the strings don't vibrate at all). Pickups that are too close can even cause the strings to rattle more against the frets — a common yet generally unrecognized problem with electric basses.
When an instrument's pickups are too close to its strings, attempts to fine-tune the adjustment of the pickups produces little audible difference because not much room is left to maneuver. When the pickups are initially adjusted so that they aren't too close to the strings, subsequent fine-tuning of a pickup produces clear, obvious changes in the pickup's tone and balance.
STRATS AND PAULS
At this point, I can recommend some optimal pickup distances that produce the best results. On a regular, garden-variety Stratocaster, the neck pickup should be initially adjusted so that its face is more or less flush with the pickguard. I'm not exaggerating. On many Strats, the pickup mounting screws aren't long enough to allow the pickup to be adjusted this low, so check first or be prepared to replace them before attempting this. Strat middle pickups can be only slightly (.04 to .10 inches) higher, and Strat bridge pickups can typically be raised to where the magnets are around .20 to .25 inches from the strings. Note that those distances vary greatly from Fender's factory-recommended pickup adjustments.
Les Pauls as well as other humbucking-equipped guitars typically need to be adjusted so that the neck pickup on the instrument is around .30 (or 5/16) inches from the strings — flush with or slightly recessed into the pickup mounting ring. The bridge humbucking pickup can typically be adjusted so that it is around .15 (or 5/32) inches from the strings. Those recommended pickup adjustments will provide a starting point for learning to spot magnetic interference and for noticing the effect that pickup adjustment has on the instrument's tone. Once the instrument's pickups are set far enough from the strings, I begin to fine-tune the instrument's action.
WHERE THE ACTION IS
The process of setting an instrument's action involves three adjustments: the height of the bridge saddles, the neck's truss rod, and the distance between the strings and the first fret, which is determined by the depth of the slots in the nut (see Fig. 1). On many guitars, setting the bridge's overall height is a separate adjustment, which must be made before setting the height of the string saddles. For example, most Fender-style guitars using a Strat-style vibrato bridge will need to have the range of movement and neutral point for the vibrato set before adjusting the individual heights of the saddles. Many Gibson-style instruments have bridges that don't have individual string action adjustments and can be adjusted for overall action only on the treble and bass sides.
Initially, I adjust the saddles (or bridge) to approximate the desired action. Most players prefer the overall action on the treble strings set as low as possible as long as the strings can still be bent without “fretting out.” Once the action of the treble strings is determined, the action of the bass strings will follow naturally. Most players prefer to have somewhat higher action on the bass strings. The action of the individual strings, when viewed across the upper end of the fingerboard, should form an arc that follows the arc of the fingerboard.
After I initially set the action, I examine the neck before making my first truss-rod adjustment. Proper truss-rod adjustment is a (very) minor art — that of finding the best compromise for the peculiarities of a given neck. Generally, the optimum neck adjustment for most players will leave the fingerboard basically dead straight under the first (high E) string, but with a slight, progressive “bow” (as though the string were the bow string of a bow-and-arrow-type bow) under the sixth (low E) string. This slight bias with more bow, or relief, on the bass side is not adjustable with a normal, single truss rod; it is entirely determined by the player's chosen strings and the idiosyncrasies of the neck in question.
Even when the neck has dual truss rods, usually other imperfections in the neck's shape determine the best compromise for the adjustment. Musicians who play more forcefully with their picking hand often prefer neck adjustments with more relief.
There are various ways to measure a neck's relief. The traditional technique is to just sight, or look down the length of one edge of the neck. Because that method takes quite a lot of practice, fret the sixth string at the first fret by the nut, either with a finger or with a capo; that temporarily eliminates the issue of the nut's adjustment. Simultaneously, fret the same string at the top fret by the body (see Fig. 2). This will leave the string lying along the frets, for the entire length of the neck. If the neck is fully straight, or if it has an actual back-bow (the opposite of a bow), then the strings will simply seem to be lying on the frets along the entire length of the neck.
If, however, the neck has any relief on the bass side, there will be a slight gap between the string and the frets, primarily in the central area of the neck (say, from the 4th fret to the 14th fret). That gap should exist (on the bass side, anyway) and can be as little as .01 inches or as much as .05 inches and still be appropriate, depending on the player's technique. After checking the relief on the bass side of the neck, use the same method to compare the relief on the treble side. Unfortunately, many necks have as much or more relief on their treble side, though ideally they should have less than half as much as on the bass side.
ADDITIONAL ACTION
Once I have the truss rod adjusted and the action set about right at the bridge (it doesn't have to be precisely finalized, but it does have to be pretty close), I check the height of each string above the first fret. The distance is critical, and it is frequently set incorrectly by the manufacturer. If the distance is left even slightly too high, the notes fingered at the first fret will be noticeably sharp, and the action in the lower third of the fingerboard will be compromised.
It's possible to determine the correct distance by first fretting the string being adjusted at the first fret and then measuring (or observing) the distance between the string and the second fret. Next, release the string at the first fret and then measure or observe the distance between the string and the first fret. The distance between the string and the first fret should be .002 to .003 inches higher than what was observed at the second fret.
When recutting the nut, it is also necessary to shape the floor, or bottom, of the slot correctly, or the string will be unable to slide through it freely. If the slot isn't correctly shaped, it will prevent smooth tuning and will hamper the instrument's ability to return to tune after using a vibrato. When the string binds in the nut slot, it makes a pinging or creaking sound when it breaks free of the slot. Most people have heard that, but they often assume that the sound is produced by the tuning machines or by the vibrato mechanism. In fact, friction between the strings and the nut slots is the main reason why using a guitar's vibrato can put the guitar out of tune, and the degree to which that friction is eliminated determines how well the instrument will return to tune.
A couple of caveats are in order. It is not possible to recut the slots in the instrument's nut correctly without the appropriate sizes of blind files — specialized files specifically made for this job. These files are readily available through the major repair-parts suppliers, but a reasonably complete set of them will be fairly expensive. Also, the errors that I'm talking about correcting are pretty small; changes as small as .005 inches are certainly worth making. You may want to leave this one to a pro, though you should certainly examine the action at the first fret and have a clear idea of the changes that you want made. If the repairperson you approach doesn't understand what you're talking about, I suggest leaving — promptly!
JUST INTONATION?
I'd like to make a few points about adjusting (or, technically, compensating) an instrument's intonation. The intervals of the major scale are based on the harmonic overtones of the note that is the root pitch of the scale. The modern equal-tempered scale is not just an assembly of these natural harmonic intervals: these intervals have been retuned (tempered) to allow the instrument to be played in any key. I'm not talking about particularly subtle retuning, either. For example, the equal-tempered major-third interval is 14 cents sharp when compared with the harmonic major third. That is one-sixth of the way to the next note!
Therefore, anyone trying to tune his or her guitar using chords that contain either major- or minor-third intervals is likely to tune the string that is producing the third interval somewhat flat: that is, closer to the actual harmonic third. Then, when the player switches to another chord to check the tuning, the string that was tuned flat will now produce a different interval, also flat. Unless the player has had sufficient ear training to be able to precisely hear the tempered intervals as correct, it is necessary to tune using chords that contain only root, fifth, and octave intervals — so-called power chords.
Additionally, bear in mind that bending a string away from its rest position stretches the string, which raises its pitch. Bending the string farther raises its pitch more. Because the action on a guitar gets steadily higher as you go up the instrument's fingerboard, you must push a string farther away from its rest position when fretting the string farther up the fingerboard. That means that it is impossible to intone a guitar equally well in all registers (regions) of its fingerboard. So if the guitar is adjusted to play mostly in tune in the central register (from the 5th to the 10th frets), the low register (from the 5th fret to the nut) will be intoned slightly flat and the high register (above the 12th fret) will be slightly sharp. For most players, that is the most useful compromise, though it is a compromise.
Most players are familiar with the method of adjusting a guitar's intonation by fretting each string at the 12th fret and then comparing a given string's fretted pitch with the pitch produced by that string when a harmonic is struck on that string at the 12th fret. The string is then either lengthened (if the fretted note is sharp) or shortened (if it's flat) to make the fretted note sound in unison with the harmonic (see Fig. 3). This method is crude because it leaves the instrument intoned flat. It is also hard to get the adjustments accurate, and the results will vary depending on string wear. (For a detailed account of my method for adjusting intonation, see the sidebar “Adjusting Intonation” at www.onstagemag.com.)
WINDING DOWN
I hope that the information contained in this article has been useful and has brought your attention to some of the most critical considerations regarding setting up guitars and basses. Additionally, you can find detailed information about another interesting topic, the wound G string, in the sidebar “The Wound G String” at www.onstagemag.com.
Finally, I wish to credit an author whose work has been invaluable to my understanding of this subject: John R. Pierce, the author of The Science of Musical Sound, published by W. H. Freeman and Company. This book is an amazing distillation of a staggering amount of research on (among many other things) acoustics, psychoacoustics (the way humans interpret what they hear), and the mathematical basis for the harmonic intervals of the Western 12-tone scales, presented in a clear, understandable form.
