It's A Setup
More technical material by Stephen White
It's A Setup
More technical material by Stephen White
Extremely Technical String Sidebar
Initially, a few definitions are in order. According to the American Heritage Dictionary, tension is defined as "… a force tending to stretch or elongate something." The degree to which a string is subjected to a stretching force is known as its tensile load, or its tension. This must not be confused with stiffness, which is defined as "…[that which is] difficult to bend: rigid."
In my opinion, there are four essential facts which must be grasped, if one is to develop a working understanding of how strings behave.
Fact One: A string’s stiffness; that is, its resistance to being bent, or mechanical inflexibility, is the source of its problems. A string’s stiffness is most easily evaluated when the string is not installed on an instrument. If you take a string and flex it with your hands, the resistance that you feel is the string’s stiffness. By comparing the respective effort necessary to bend two different strings into a two-to-three inch semi-circle, you will get an idea of their respective stiffness.
Fact Two: A string only performs really well (with clear, "in-tune" harmonics, good pitch stability and sustained harmonic "brightness") when it is stretched almost to its breaking point. Normally, strings are designed so that, when they are tuned to their working pitch, they will be tensioned to around 90% of their breaking load. Basically, the string’s tension, when tuned to its working pitch, is what makes the string behave itself — just think; "Tension–GOOD; Stiffness — BAD." This leads to…
Fact Three: The higher a string’s tension-to-stiffness ratio is (more tension; less stiffness), the better the string will perform. Improving either side of the ratio is effective: the reason that nylon "classical" strings sound so "sweet" is that they have very little stiffness (just try our "flex" test…!): even though they only have around half the tension of steel strings, their tension-to-stiffness ratio is very favorable, when compared to steel strings. Alternatively, increasing a string’s tension will make it perform better: a "plain" (unwound) .017" string, when used as the third ("G") string in a standard "tens"(.010" to .046") set of electric strings, is the worst-performing string in the set, but the same .017" string, when used as the second ("B") string in a standard "medium" (.013" to .056") set of acoustic strings, performs just fine — by tuning it up to "B", its tension has been increased dramatically, while its stiffness is unchanged, so it’s tension-to-stiffness ratio is much improved.
Fact Four: The most important single characteristic of a wound string is the thickness of its core-wire, not its outer diameter. This cannot be over-emphasized — the outer dimension of a wound string is not a good predictor of the string’s characteristics, whether one is considering its tone, its flexibility, or the correct placement of its bridge saddle (to correctly compensate the string's’ intonation). The thickness of the string’s core-wire, however, is a pretty accurate indicator of most of these characteristics.
Everyone understands that increasing or decreasing the thickness of one’s first (high "E") string by .001" will dramatically change its sound and feel. Changing the thickness of a wound string’s core-wire by .001" will produce as dramatic a change in its performance. Let’s compare two different types of strings, from the same manufacturer. In this case, we’ll compare GHS "Boomers" and "PROgressives"; in standard 10-46 gauge. Please keep in mind that GHS, like most manufacturers, use only one type of wire for all of the plain strings in their different electric sets; the differences which I’m discussing are only in the wound strings.
Boomers are a thick core-wire design, specifically marketed as being "hard to break", and as having high output — "the power string". These strings do, indeed, exhibit all of the typical characteristics of thick core-wire designs — very high output, stiff, heavy action (per gauge), "punchy" attack, good sustain, relatively little movement per pick-stroke (hence, relatively little fret-rattle per pick-stroke), relatively poor overall intonation, relatively rapid decline in their brightness and quality of intonation with use, "clanky" (metallic) treble response, etc.
GHS "PROgressives", on the other hand, are a thin core-wire design, with very different characteristics. These strings are lower output, very flexible under the fingers (per gauge), smooth, "legato" (not punchy) attack, very sensitive to pick attack and other playing dynamics, relatively susceptible to fret-rattle, relatively good overall intonation, relatively long lasting, brighter, yet "sweeter" (less "clanky") tone, etc. There is no way to determine any of these differences from comparing these strings respective outer diameters. It is impossible to say that either type of string (high tension vs. low tension) is objectively better, merely that a given player will prefer one or the other type.
Wound G String
As we all know, the third, or "G", string in most "normal" sets of strings for electric guitar is a "plain", or unwound string. This unwound third string normally performs quite badly–typical problems include: poor tone and intonation when brand-new, the rapid deterioration of both qualities as the string ages and radical volume imbalance, to name the most common complaints.
The purpose of this sidebar is to point out the obvious: that the reason that the third string has these problems is because it isn’t engineered correctly. Under any normal circumstances, a guitar string tuned to this pitch would be a wound string, like the fourth through sixth strings!
Just think about it — any steel-string acoustic guitar, for example, would have a wound third string, which would typically be eight or ten thousandths-of-an-inch (.008" or.010") smaller in diameter than it’s fourth, or "D", string. For example, standard "acoustic medium" gauges are (from first to sixth) .013"-.017"-.026"-.036"-.046"-.056", with a wound third string. The third strings on acoustic guitars do not have any of the typical string problems found on electric guitars.
I’ve been told that the adoption of the unwound third string was an historical fluke, being the result of players adding a light, .010" string to a standard acoustic medium gauge set of strings and then discarding the .056" low string. This resulted in the .010"-to-.046" "electric light gauge" set that we know today. The reason that the electric guitar’s standard, unwound third string has all of these problems is because, when tuned to the standard "G" pitch, it is being placed under an insufficient tensile load for its strength; it is just too slack for it to perform correctly (see the "Extremely Technical String Sidebar"). This causes the string’s tonal and intonation problems.
The most common complaint about the unwound third string is its tone; the suckers just don’t sound good. People describe the tone in different ways: "harsh", "clanky", "metallic", "sour", etc. Technically, the reason that an unwound third string sounds "sour" — particularly as it ages — is that the string’s harmonic overtones are out of tune with it’s fundamental note: the string is actually out of tune with itself! Because of this, the string’s poor tone is clearly related to it’s intonation problems: they are both caused by the string’s excessive stiffness. This tone/intonation problem can be heard most clearly when playing with heavy overdrive; instead of a producing a smooth, stable note, holding a sustained note will produce a pulsating, or "beating" warble, similar to playing unison pitches on two strings, while tuning one of the strings to the other. This is the sound of the string’s overtones "beating" against the string’s fundamental pitch, and it’s nasty!
Finally, when playing a vintage instrument, an unwound third string will frequently sound much too loud–this is because the instrument’s pickups were designed for a wound third string, since that was standard before 1960. Since a wound third string is generally the lowest-output string in the set, whereas an unwound third string is the highest-output string in the set, the imbalance is pretty drastic.
Prescription for Tone: the Wound Third String
Whew! What a nightmarish litany of problems, huh? Well, the good news is that the solution — switching to a wound third string — has very few real problems, and is a safe, easy and inexpensive experiment.
Obviously, the first step is to get some appropriate wound third strings for the set of strings that you’re using. As you may remember, I mentioned that a wound third string would typically have a diameter .008" to .010" less than the fourth string in that set; this means that, for a .010" to .046" ("electric light-gauge") set, the appropriate wound third string would be a .016" or a .018", of the same type. Although these gauges are not widely stocked by retailers, most of the major string manufacturers do produce them. For example, GHS makes "Boomer" single strings (called "singles" in the trade) down to .016"; D’Addario makes "XL" singles down to .017"; I’m sure that there are others, as well.
After installing the "test" wound third string, check the string’s fit in the slot in the nut, to make sure that the wound third string won’t bind in the slot — if it binds, it won’t tune well, and the friction will eventually damage both the string and the nut. If the slot in the nut needs widening, I recommend that you have it done by a competent professional repair-person. The third string’s intonation will also need re-adjustment. Whereas an unwound third string typically intones correctly when it’s slightly longer than the second and fourth strings, a wound third string typically intones correctly when it’s slightly (.025" to .050") shorter than the second and fourth strings. Interestingly, most vintage (and vintage-style) bridges that don’t have separate intonation adjustment for each string (like the old Gibson "wraparound" S.G. and Les Paul unit), are designed to intone correctly with a wound third string.
Once you have the guitar re-adjusted to your satisfaction, you should find that all of the problems previously mentioned have just gone away, leaving a couple of minor new ones in their wake: the wound third string is somewhat more fragile than an unwound third string, and the wound third string must be bent substantially farther than an unwound third string, to achieve the same change in pitch.
For most players, the problem of fragility is not significant; violent use of the Strat whammy-bar can cause premature string breakage, but otherwise, it’s generally no big deal. However, the question of bendability is, for most players, rather significant. Many players just assume that a wound third string is out of the question for this reason alone. I’m challenging these players to re-evaluate this assumption — do you really want to put up with the Tonal Disaster that is the unwound third string, just to bend the third string like a Blues-Weenie rattling off an arsenal of recycled cliches? Is it really worth it?
I realize that for many players, an unwound third string will always feel like "home"; that’s fine, but for the rest of us (yes, I use a .018" wound third string on my hopped-up post-modern Strat-thing), the decision to use an unwound third string should not be taken blindly. For example, it is possible to switch to a wound third string for the instrument (or instruments) which you use primarily for rhythm parts, or to switch back to an unwound third string just for recording solos.
Or, you could just learn to live with a real "G" string. Think about it.
Intonation
Most players are familiar with the method of adjusting (technically, "compensating") a guitar's intonation by fretting each string (one at a time) 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. As I mentioned in the article, this method is crude, since it leaves the instrument intoned flat. It is also hard to get the adjustments accurate–the method is extremely sensitive to string wear.
The essential technique of my method is to sound notes on two of the instrument's strings simultaneously, and then compare the pitches of the notes. Using one pitch as a reference, the length of the string producing the other note is adjusted, based on the results of the comparison to that reference pitch.
Here's how it works: Start by tuning the instrument, with the strings set to whatever reference you use (like an electronic tuner). Let's say that you're going to adjust the fifth (A) string's intonation–we'll use the sixth (low E) string to sound the reference pitch, and compare the fifth string to it. Strike the fifth-fret harmonic on the sixth string and the seventh-fret harmonic on the fifth string, and then carefully tune the fifth string to the sixth string, so that there is no phase-shift, or "beating" heard when both strings are sounding. I want to emphasize that the strings must be fresh, they must be free from magnetic interference, and that the string being adjusted must be tuned precisely to the reference string, or none of the subsequent adjustments will come out right.
There are two harmonics which can be struck on the reference string (in this case, the sixth string), which are nominally in unison with notes which can be fretted on the string being adjusted (in this case, the fifth string). The harmonic is used as the reference pitch, and the fretted note is compared to this reference pitch. The harmonic produced by striking the sixth string at the fifth fret generates an "E", two octaves above the open low "E" string–this is in unison with the "E" produced by fretting the fifth string at the 19th fret. So, you must strike (or pluck) the sixth string/fifth fret harmonic (which I'll abbreviate as "6/5 H"), and then carefully fret and play the fifth string at the 19th fret (which I'll abbreviate as "5/19 F") without muting the ringing sixth string. I will refer to this '6/5 H-to-5/19 F' comparison as the "upper unison". Although these two notes are nominally in unison, you will probably hear a slow (or maybe not-so-slow) phase-shift being produced, since the fretted note probably is either somewhat sharp or somewhat flat, when compared with the reference harmonic's pitch.
One useful trick, for making the phase-shift easier to hear, is to run the guitar's signal through a fuzz box, with the box set to serious fuzz: this will really emphasize the phase-shift. Sometimes it can be hard to tell whether the fretted note is slightly sharp, or slightly flat of the reference pitch By gently pulling back on the fretted string with the fretting fingertip, you will raise the pitch of the fretted string slightly–this will cause the phase-shift to either speed up (if the fretted note was initially slightly sharp), or slow down and possibly stop (if the fretted note was initially slightly flat). Once you can clearly hear the phase-shift between the reference harmonic and the fretted note, notice the rate, or speed of the phase-shift 'beats'.
Once you have determined, after having conducted the 'upper unison' comparison test, whether the fretted note is sharp or flat when compared with the reference harmonic's pitch, and noticed the speed of the phase-shift 'beats' produced by the procedure, you are going to conduct a similar comparison procedure, using the harmonic produced by striking the sixth string at the seventh fret, which generates a "B", which is in unison with the "B" produced by fretting the fifth string at the 14th fret. I will refer to this '6/7 H to 5/14 F' comparison as the "lower unison". You will notice that you are getting a somewhat different result from this lower unison–the fretted note will be slightly lower in pitch, relative to its reference harmonic's pitch, when the results of the 'lower unison' test are compared with the results of the 'upper unison' test.
It is not possible to adjust the length of the string being adjusted (in this case, the fifth, or 'A' string) so that both unisons are precisely in tune, at the same time: if the length of the string being adjusted is set so that the lower unison is precisely in tune, then in the upper unison the fretted note will be slightly sharp. Likewise, if the length of the string being adjusted is set so that the upper unison is precisely in tune, then in the lower unison the fretted note will be slightly flat. So, you distribute the error between the two unisons: that is, you adjust the length of the string being fretted so that in the upper unison the fretted note is slightly sharp, while in the lower unison the fretted note is slightly flat. There is only a very narrow range of string length (around .020") where these two results co-exist. Assuming that you have achieved this precise adjustment, neither of the unisons will 'beat' at more than two Hz (beats per second). Please keep in mind that the strings being compared must be kept precisely tuned to each other, in order for this comparison procedure to be meaningful.
Once you have adjusted the fifth string to your satisfaction, tune the fourth (D) string to the fifth string, and repeat the procedure, using the fifth string as the reference for adjusting the length of the fourth string. This procedure will work for all of the remaining strings, although when adjusting the second (B) string, you will have to fret the string being adjusted one fret higher, since the string is only tuned a major-third higher than the third string.
This leaves only the sixth (low E) string to be adjusted. The method is as follows: after tuning the sixth string to the fifth string, strike the harmonic at the 12th fret on the fifth string. This gives you an "A", which is nominally in unison with the "A" produced by fretting the sixth string at the 17th fret. Adjust the length of the sixth string so that the fretted note is only very slightly sharp–no more than one phase-shift per 2 seconds (1/2 Hz). That's it–you're done.
This method of compensating a guitar's intonation is tedious and difficult. However, of all the methods that I have tried, it produces the most accurate, musically useful results. Remember, the instrument's pickups must be far enough away from its strings to not interfere with the strings free vibrations–afterwards, you can raise the pickups incrementally, and listen for the strings intonation to begin to show signs of magnetic influence, which can be an educational experience. I hope that you find this whole article useful and informative–good luck, and feel free to e-mail me (at guitar_tech@earthlink.net) with questions and comments.