Getting Strung Up
A guitar must be properly set up before it can do its player justice and nowhere is this more important than in the studio. H&SR shows you how.
Getting a good guitar sound on to tape depends largely on the instrument itself. This month we look at setting up an electric guitar for the studio.
With so much of the business of generating and recording music being handled by sophisticated electronics, perfect tuning and accurately defined signal levels tend to get taken for granted. However, a guitar, even an electric guitar depends heavily on mechanics rather than electronics, and how well the mechanics are adjusted has a great deal of influence on its playability and the accuracy of its intonation. Put simply, a guitar that's badly set up can be a pig to play and impossible to tune, rendering all the recording gear in the world totally helpless to improve matters. This all sounds pretty depressing, but one evenings work can bring about a dramatic improvement. First, let's define the problem areas.
The action of a guitar is always a compromise; if the strings are set too high the instrument will be difficult to play and if too low, it will buzz or rattle.
In order to set the lowest possible action, the frets need to be of even height, the neck must not be twisted, and the truss rod tension should be set to match the gauge of strings being used. A twisted neck is really beyond the scope of home based first aid but the other two problems can be attended to if a little care is exercised. Sighting along the neck will tell you if the neck is twisted or not so if all is well, take off the strings and check the neck with the edge of a steel rule placed along the frets to see if it is straight, (see Figure 1). With no string tension it is unlikely to be straight, so if it is concave, tighten the truss rod nut; if convex, slacken it. Truss rods only require fairly small adjustments so try a quarter of a turn at a time and allow the neck a few minutes to settle before making further adjustments. When the neck is as straight as you can get it, you can test for uneven frets by colouring the tops of the frets with indelible marker and then using a fine flat carborundum stone held firmly against the frets, abrade away a small amount of material by sliding the stone along the length of the fingerboard and back, working your way across the full width of the frets, (see Figure 2).
As you might imagine, the highest frets will be the first to lose their markings whilst the lowest ones may remain untouched. If there is no excessive fret wear, the frets can be levelled up using only the stone, but badly worn frets will need the attention of an experienced guitar repairman. If in any doubt about your ability to perform this task, practice on an old copy or your little brother's acoustic before vandalising your best guitar.
When the frets are level, finish off by rubbing the stone across the width of the fingerboard a few times to remove any tiny grooves in the frets which might otherwise cause a rough action when bending strings.
If you haven't had to remove much material from the frets, the chances are that there will be no sharp edges and so reprofiling using a fret file will not be necessary. This is just as well, as correctly profiled fret files are difficult to obtain and even more difficult to use properly.
So now the frets are level and the next job is to fit new strings and sort out the truss rod. With the strings fitted and tuned to pitch, hold the bottom E string down onto both the first and last frets of the neck and observe the gap between the string and the eighth fret. Because we have previously adjusted the truss rod for a straight neck, the string tension will cause the neck to become bowed or concave. The truss rod should now be adjusted so that the gap between the string and the eighth fret is about the thickness of a piece of cigarette packet; a dead straight neck is undesirable as the strings vibrate most near the middle of their length and so need a little extra clearance in this area. Remember though that any truss rod adjustments should be made cautiously, leaving the neck to settle down before making any subsequent re-adjustments.
The string height should now be adjusted to give a comfortably low action without buzzes, and this is done by adjusting the bridge saddles (or the whole bridge in the case of bridge with fixed saddles). Once you are satisfied that you have optimised the action, use a tuner, if one is available, to check that the notes on the twelfth fret are exactly one octave above the open string pitches. If the octave is flat, move the bridge saddle towards the neck and if it is sharp, move it away from the neck; after each adjustment, retune the open string before checking the octave. The easiest way of checking this is to compare the harmonic at the twelfth fret with the note fretted at the twelfth fret - they should sound identical in pitch. If you have a tuner, it makes this task very much easier.
There is now one more problem that is often overlooked and that is the nut.
The nut as you probably know is that slotted piece of plastic, bone or metal that supports and separates the strings at the headstock end of the neck. Most guitars have no 'zero fret' and so the pitch of the open string is determined by amongst other things, the nut position. Fortunately, very few nuts are fitted in the wrong position but they are very often badly cut. The main fault is that the nut slots are not deep enough, and this causes the string to 'sit' too high above the fingerboard. This not only makes fretting hard work but it also causes tuning problems, because when you do fret a string, you stretch it causing the pitch to go sharp. If you then tune your guitar so that a certain chord sounds correct, the open strings may well sound flat. So what is the correct slot depth? Well, if you hold down a string at the first fret and see by how much it clears the second fret, this is a fair indication of by how much the open string should clear the first fret. Using a junior hacksaw, carefully deepen the slot and keep checking, because it's much easier to cut a slot deeper than to fill it in if you go too far.
Another problem often encountered is the syndrome of the sticking string, cured in some modern guitars by the use of graphite compound nuts. The usual problem is that you bend a string and it jams in the nut causing it to sound flat. My solution to this is to place a piece of PTFE or Teflon plumbers tape over the nut before fitting the new strings. This material has a very low co-efficient of friction and is of negligible thickness, so it will cure your sticking problems without affecting the action or tone of your guitar.
A final word about pick-ups. They don't normally affect the action of a guitar, but pick-ups with strong bar magnets such as Strats can cause the higher notes on the bottom couple of strings to sound out of tune. This happens when the pick-up is mounted too close to the strings and the magnetic field interferes with the string vibrations. The only cure is to lower the pick-ups until the problem goes away.
Electronics might be an easy way of producing accurate musical sounds, but there's still a lot of mileage left in the heathen plank of wood and metal that constitutes the electric guitar. Anyone with even a slight aptitude for things mechanical can do the few simple adjustments required to keep the guitar working at its best, and the tools required are minimal. With a little care and attention, the singing tree will be with us for many years to come.
Feature by Paul White
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