As published in Nightflying Magazine October, 2009
Frets About Frets
So… You’ve got your guitar, or other fretted instrument, properly humidified… but, STILL, there is a buzz when the strings are strummed in the open position. Very “Sitar like”… OR… You have to press so hard to make a chord you get a hand cramp. As the kids say “What’sup wit Dat?”
Well, here’s the buzz on da’ “Buzz”:
As I have told many of my customers: “A fretted instrument, whether it’s a guitar, mandolin, Banjo or Baakzooki, is a study in compromise.” If it has strings, there is, usually, a method for adjustment. Tuning, intonation and action can all be changed. While not all fretted instruments are EASILY adjusted they all can be altered in some way. Fretted instruments are really a feat of engineering.
Ponder this: Most fretted instruments are devises that are, generally, made of wood, a relatively pliable, imperfect material, quite susceptible to environmental conditions. Now add a number of metal or metal-wound strings stretched from nearly on end to the other. A guitar equipped with a set of .12 gauge, steel strings has over 150 pounds of pressure torqued between the headstock and the bridge. These strings are not all the same diameter and some are wound with more metal. Now for giggles, lets offer some varying gauges in strings for the same instrument. Now lets put on metal frets at a spacing that is definitely a compromise. Pepper in the allowance of playing styles ranging from finger picking to heavy metal thrashing and… well, you get the idea.
A well setup Guitar or other fretted instrument should be a pleasure to play. If you are struggling to make clean chords or properly pitched notes on your instrument, there’s something wrong.
I’ve had many customers tell me that they didn’t even know that their guitar, banjo or mandolin could be adjusted to play better. They thought that if the action was high, they just had to “live with it”. The mindset was that the playability was inherent to each individual instrument. For many, it was only after I convinced them to let me work on their prized possessions, that they truly began to enjoy playing their fretted instrument and started, in earnest, to realize more of their full musical potential.
So… Why do instruments get so “outta whack”?
Well, as I described last month, Humidity can have a drastic effect on your axe… but that’s just ONE cause.
Strings, neck bow, neck pitch, saddle height and intonation make up the playability of a fretted instrument.
Not the folding of space and time upon it self to allow for time travel… I’m talking about guitar strings!
Old strings are a big culprit of poor setup. Keeping fresh strings on your guitar is more than just a matter of tone. While it’s true that your instrument will not sound as bright and resonate with old strings, there are other consequences too.
As a metal string stretches, it’s tinsel strength decreases so you tune up to reach the desired pitch. There will come a time when the string has stretched so far that it will fail at some fault in the string. This can be from some anomaly of metallurgy or the failure can be due to some insult to the string. IF there is an absence of sufficient fault, the string will go “dead”. This means the metal string has begun to reach its limit of elasticity. Once that happens, watch out! If you keep tuning up, the pressure increases on the nut, saddle, wood and hardware of the instrument. Somethin’s gotta give.
I’ve seen crushed nuts (no laughing), crushed saddles, detached bridges, bent and broken tuners and, the inevitable, pitched or bowed neck among a multitude of other symptoms of old and/or over-tightened strings.
If you do change strings on a regular basis, you might be experimenting with varying string brands and gauges. This too can be a source of mal-adjustment.
If your instrument is properly setup for a particular gauge of string and you decide to change to a heavier or lighter gauge, then this can have an adverse affect on your “gitfiddle”
The neck-ed truth
Necks are another adjustment point that can make or break the success of a good setup.
The neck of any fretted instrument is a marvel of mechanical engineering. In the past, necks were constructed of wood… period! No metal rods or other bracing materials. As a matter of consequence, they were more susceptible to warping and bowing.
As a rule, the necks of many modern fretted instruments are re-enforced by metal, carbon fiber or some other strengthening material. To allow for a larger variety of playing techniques, there needs to be a point of adjustment. Enter, the truss rod.
The truss rod is a metal rod that runs along the inside of the neck. It is used to correct changes to the neck’s curvature caused by the neck timbers aging, changes in humidity or to compensate for changes in the tension of strings. The tension of the rod and neck assembly is adjusted by a hex nut or an allen-key bolt on the rod, usually located either at the headstock, sometimes under a cover, or just inside the body of an acoustic instrument and accessible through the sound hole or some other access. On electric instruments, the adjustment is located underneath the fretboard, (hopefully) above the pickguard at the “body” end of the neck. Some truss rods can only be accessed by removing the neck and a few guitar necks have an adjustment located on the SIDE of the neck. This can be particularly confounding for the unsuspecting technician.
The truss rod counteracts the immense amount of tension that the strings place on the neck, bringing the neck back to a straighter position. Turning the truss rod clockwise will tighten it, counteracting the tension of the strings and straightening the neck or creating a backward bow. Turning the truss rod counter-clockwise will loosen it, allowing string tension to act on the neck and creating a forward bow. Adjusting the truss rod affects the intonation of an instrument as well as the height of the strings from the fingerboard, called the action. Some truss rod systems, called “double action” truss systems, tighten both ways, allowing the neck to be pushed both forward and backward (standard truss rods can only be released to a point beyond which the neck will no longer be compressed and pulled backward).
There are always exceptions to any rule. The short scale of the mandolin or the nylon stringed classical guitar do not require truss rods. The strings of these instruments exert a lower tensile force with lesser potential to cause structural problems. However the necks of these instruments are often reinforced with a strip of harder wood, such as an Ebony strip running down the back of a Cedar neck. There is no tension adjustment on this form of reinforcement.
One of the most common fretted instrument issues that I see, as a technician, is the unfortunate classical guitar that is brought in with steel strings on it. Someone unknowingly fitted an instrument made for Nylon strings with these high-tension strings and now the neck has pulled forward, the bridge is ripping from the body and taking the top with it as it bellies outward.
Sometimes these poor guitars are repairable, depending upon the length of time they were strung with steel, but as often as not, they are relegated to a showcase in the living room… or even worse, the hands of a youngster with the desire to see how hard he has to bash a guitar in order to see every piece of the insides explode on the pavement.
The most important part of a fretted instrument is… you guessed it… the fret. The fretboard, along with the string gauge, dictates the intonation of the instrument.
Did you ever wonder why frets spacing gets smaller up the neck? Well, lets start with a few of the basics ‘bout fretboard construction.
Also called the fingerboard, the fretboard on western instruments is a piece of wood embedded with metal frets that comprises the top of the neck. It is flat on classical guitars, dulcimers and banjos. Fretboards are slightly curved crosswise on mandolins, acoustic and electric guitars. The curvature of the fretboard is measured by the fretboard radius. The radius is a hypothetical circle of which the fretboard’s surface constitutes a segment. The smaller the fretboard radius, the more noticeably curved the fretboard is. Most modern guitars feature a 12″ neck radius, while older guitars from the 1960s and 1970s usually feature a 6-8″ neck radius. Pinching a string against the fretboard effectively shortens the vibrating length of the string, producing a higher pitch. Fretboards are most commonly made of Rosewood, Ebony, Maple and sometimes manufactured of composite materials such as resin or even alloys such as Aluminum.
Frets are laid out to a mathematical ratio that results in equal tempered division of the octave. The ratio of the spacing of two consecutive frets is the twelfth root of two. The twelfth fret divides the scale length in two exact halves and the 24th fret position divides the scale length in half yet again. Every twelve frets represent one octave. Each fret represents one semitone in the standard western system where one octave is divided into twelve semitones.
In practice, Luthiers determine fret positions using the constant 17.817, which is derived from the twelfth root of two (21/12). The scale length divided by this value yields the distance from the nut to the first fret. That distance is subtracted from the scale length and the result is divided in two sections by the constant to yield the distance from the first fret to the second fret. Positions for the remainder of the frets are calculated in like manner. Actual fret spacing does not use this exact value; the fret spacing on the fretboard was also done by trial and error (testing) method over the ages.
Many western instruments’ frets are not spaced according to the semitones of equal temperament, including the Appalachian dulcimer with frets in a diatonic scale.
There are several different fret gauges, which can be fitted according to player preference. Among these are “jumbo” frets, which have much thicker gauge, allowing for use of a slight vibrato technique from pushing the string down harder and softer. “Scalloped” Fretboards, where the wood of the fretboard itself is “scooped out” between the frets allows a dramatic vibrato effect. If you have ever been to my shop, you may have seen the Chinese Pei Po which has a wood fret board that is constructed by cutting deep “V” shapes from the neck providing a near infinite range of notes.
Fine frets, much flatter, allow a very low string-action but require other conditions such as curvature of the neck to be well maintained in order to prevent buzz.
This is why you should give proper homage to anyone who can build a fretted instrument neck from scratch. It ain’t easy!
Diagnosing your setup
So back to that buzzing your hearing from you instrument or the high action that’s causing those hand cramps.
A few things could be happening. First sight the neck, that is look down the neck from the headstock and see if the fretboard runs parallel with the strings… Well, of course, it does to a large degree, but if you see the fretboard bows up in the middle of the length of the neck, there’s a large part of your problem. Most of the time a delicate adjustment of the truss rod is all that is needed. If you’ve never done this, then easy does it. As a rule, I will tell my customers to not turn the truss rod more than one quarter of a turn at any one time. Remember – Your guitar is made of wood and wood can take a little time to respond to bending adjustments. In this case you will be loosening the truss rod ever so slightly as to allow for more relief in the neck. This will allow for the strings to vibrate without striking frets on the neck when strummed in the open position. A properly adjusted neck should have a slight bit of relief in the neck but if you are adjusting DOWN, then adjust to a flat position and let the guitar naturally relax over the next few days. If you feel justifiably uncomfortable in making this adjustment, then take it to a qualified tech.
Lets talk about that suspension bridge you call a guitar. The action is so high that it that you could shoot arrows from it.
OK, so it’s not THAT bad, but the action feels a bit high. In most cases, here’s what’s going on:
The instrument’s neck is experiencing a higher string tension than for what the neck is setup. The usual cause is from changing to a heavier gauge string set. Going from a set of .10s to a set of .11s, on a guitar, shouldn’t cause much of a change in your action, but going from .10s to a set of .12s or .13s will, definitely, cause this symptom. The good news is the guitar just needs to be adjusted for the heaver strings using the method described above. One caveat is, if the instrument has been left in this condition for a very long time, the neck may have become warped and can be difficult, if not darn well impossible to adjust out.
If you make a properly pitched “E” chord then make a “G” chord and it sounds like a train wreck… your intonation is out of adjustment.
This can be remedied by adjusting the saddle on the instrument with thumbscrews, a screwdriver, an allen wrench or a file, depending on the instrument.
The sequence of adjustment is important as well. A proper setup must be preformed in this order to be effective: the restring, the truss rod, the saddle height and intonation. If the sequence is altered, or a step is omitted, efficiency will be sacrificed.
So you can see how having a qualified Guitar Tech perform a proper setup on your guitar is a must for the seasoned professional as well as the novice player. I have had customers tell me that having their instrument setup is like taking it to a “Spa”. When they get it back, their axe feels fresh, well adjusted and easy to play.
Now please keep in mind that I have made some general statements and this information should, in no way, take the place of having your instrument professionally setup by a qualified technician.
If you have questions or concerns about fretted instruments that you would like addressed in this column, or if you have questions about setups, in general, please drop me an email or call me and I will be happy to help in any way that I can. Here’s how you can reach me: