Posted on

Lutherie: Art or Science?

Lutherie: Art or Science?

by R.E. Bruné

Originally published in American Lutherie #1, 1985



Aside from the eternal “How do you bent the sides” question asked by non-makers, the most frequent point of curiosity seems to be that of other makers: “What do you think of the Kasha guitar?” I am somewhat surprised at this.

Firstly, it doesn’t really matter what I think of the Kasha model. I don’t build it, and I would think this fact says enough. The second point is that the Kasha model and theories have been around for enough years (nearly twenty if I’m correct) that, were there merit in the model, it would have been almost universally adopted by makers and players by now. It took less than twenty years for the conservative makers of Spain to adopt the design ideas of Torres, for by the time of his death just before the turn of this century, nearly every Spanish maker with the exception of José Ramírez I was using his model. The reason for this nearly overnight conversion is obvious; the models of Torres were clearly superior to anything else available, and the musicians quickly accepted them. In fact, the makers who didn’t adopt his patterns went out of business.

In contrast, one does not see musicians today playing the Kasha model. I know of no professional classical guitarists playing them, and in the nearly twenty years I have been involved in the guitar world, I have never been to a concert where a Kasha model guitar was played. Yet it seems there has hardly been an issue of the G.A.L. Quarterly without some article or reference to the Kasha model as if it were definitive, and desirable.

Become A Member to Continue Reading This Article

This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

If you are already a member, login for access or contact us to setup your account.
Posted on

Space Bass

Space Bass

by David Riggs

Originally published in American Lutherie #28, 1991



We have all benefited from advances in technology resulting from the exploration of space. Brave Americans, along with those of other nations, have risked their lives to study the effects of weightlessness in the fields of metallurgy, botany, and others of interest to luthiers. It has, therefore, become my mission to pursue a role in which I may participate directly in this arena of endeavor.

One fascinating experiment is conspicuously lacking; the advantages of its execution in a weightless environment are so obvious it is astounding that nobody has yet done it. Yes, you know what I’m thinking — I want to build a bass in space!

They’ve sent teachers, congressmen, and the towel boy from the Y-Not Bath House. They’ve probably even sent lawyers. But have you seen one newspaper headline that read, “Luthier Loops Into Lunar Orbit”? Well, I aim for you to see that little number splash down in your bird bath one of these bright mornings.

Become A Member to Continue Reading This Article

This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

If you are already a member, login for access or contact us to setup your account.
Posted on

Tuning the Guitar

Tuning the Guitar

by Ian Noyce

Originally published Guild of American Luthiers Data Sheet #56, 1977 and Big Red Book of American Lutherie Volume One, 2000



Because the guitar has fixed frets set to an even temperament, tuning it properly is not the cut-and-dried process that many people believe. And due to various factors that we’ll get to shortly, if the guitar’s bridge is placed exactly where the nominal scale length says it should be, the instrument may not play in tune at all.

The two most common methods of tuning are: (1) the 4th- and 5th-fret method and (2) the harmonic method. Both of these methods are often misunderstood through confusion regarding perfect (or Pythagorean) intervals and even-tempered intervals.

The 4th- and 5th-fret method. Theoretically, this is the simplest method as it simply involves tuning unison intervals. The A string can be tuned to an A tuning fork, then the bass E is fretted at the 5th fret and tuned in unison with the open A. The D string is tuned in unison with the 5th fret of the A, the G string is tuned to the 5th fret of the D, the B string is tuned to the fourth fret of the G, and the high E is tuned to the 5th fret of the B. In practice this can be difficult because any errors are cumulative. It’s also true that many guitars tuned this way will not play in tune in all keys.

Become A Member to Continue Reading This Article

This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

If you are already a member, login for access or contact us to setup your account.
Posted on

Finishing Lute Soundboards

Finishing Lute Soundboards

by Lawrence D. Brown

Originally published in Guild of American Luthiers Data Sheet #229, 1982 and Big Red Book of American Lutherie Volume One, 2000



There has been much discussion in early music journals recently about the materials used to finish lute soundboards. It would certainly be to our advantage if we knew exactly what was used on the soundboards of old instruments. Some people suggest that it is a moot point because no one is using exactly the same wood for soundboards that was used on old lutes. The old lute makers were almost certainly working under the same commercial pressures as any 20th-century workshop, and like us, used whatever high-quality timbers they could get ahold of. In addition, different luthiers probably used different materials and techniques to finish their soundboards.

It is well known that old lutes have very little or nothing at all on their soundboards. This would seem to be the most relevant point of all. Modern craftsmen have discovered that even one coat of varnish on a lute soundboard has a deleterious effect on the tone of the instrument.

Become A Member to Continue Reading This Article

This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

If you are already a member, login for access or contact us to setup your account.

Finishing Lute Soundboards

by Lawrence D. Brown

Originally published in Guild of American Luthiers Data Sheet #229, 1982 and Big Red Book of American Lutherie Volume One, 2000



There has been much discussion in early music journals recently about the materials used to finish lute soundboards. It would certainly be to our advantage if we knew exactly what was used on the soundboards of old instruments. Some people suggest that it is a moot point because no one is using exactly the same wood for soundboards that was used on old lutes. The old lute makers were almost certainly working under the same commercial pressures as any 20th-century workshop, and like us, used whatever high-quality timbers they could get ahold of. In addition, different luthiers probably used different materials and techniques to finish their soundboards.

It is well known that old lutes have very little or nothing at all on their soundboards. This would seem to be the most relevant point of all. Modern craftsmen have discovered that even one coat of varnish on a lute soundboard has a deleterious effect on the tone of the instrument.

The main concern of a historical instrument maker is to produce instruments that are acoustically, mechanically, and aesthetically similar to the instruments produced by early makers. This does not, however, preclude the use of any and all modern finishing materials. Modern lute makers must also respond to commercial forces and the demands of their customers, as long as this can be done within historical parameters. Bare wood accumulates sweat and dirt at a rate that is intolerable to musicians who are used to having a protective varnish on their instruments.

Because I build a great many lutes each year, I have been able to experiment with a variety of protective coatings on lute soundboards. Although my main concern has always been acoustical, I cannot ignore cosmetic considerations since lute making is rapidly becoming a very competitive market. For this reason, I have tried and rejected egg white sealers because they turn green — especially where the soundboard comes in contact with skin. Sodium silicate (water glass) also turns green and must be tinted with an orange dye in a lacquer overcoat. Oil finishes penetrate the wood too deeply and remain soft. They also collect dirt and discolor badly.

What is needed is a finishing material that will adhere to the surface but not penetrate it very deeply, a material that will dry to a hard, durable surface resistant to mild solvents; and a material that will go on in an extremely thin layer, so as not to have an adverse effect on the tone of the instrument.

This is the most successful method that I have found so far. It requires the use of a compressor and a spray gun, lacquer sanding sealer, lacquer, and lacquer thinner. I use a touchup gun. It is smaller than a standard gun and holds about a pint of liquid. It also has a smaller spray pattern than a larger gun, which seems about right for spraying a lute-size instrument.

Mix 1 part lacquer sanding sealer with 1 part solvent. This makes an extremely thin solution that dries instantly when sprayed on the soundboard, preventing it from soaking into the wood. (If the spray gun is held too far from the soundboard, the solution will dry in the air and deposit a dusty film on the instrument.) Sand lightly with very fine paper or steel wool. This is followed by two coats of lacquer, also mixed 1/1 with solvent. This makes an extremely thin coating that seems to have no effect on the tone of the instrument, but provides a hard and reasonably durable surface. The lacquer sanding sealer not only seals the wood but makes an excellent bonding coat between the wood and the lacquer coat. The surface may be lightly smoothed with steel wool. The reduces the gloss to a uniformly dull finish.

I have tested the acoustical effects of this finishing technique by playing the instrument in the white and after being finished. I have also compared the tone of finished instruments to identical instruments that have not been finished.

It has been noted that old lute soundboards seem to be somewhat dark in color. This was probably due to the effect of ultraviolet light on the wood. Mask one-half of a newly cut and sanded soundboard with heavy paper and leave it around the shop for a month. It does not have to be in direct sunlight. Notice how dark the exposed side of the wood becomes after such a short time. I have noticed that different types of spruce seem to darken more quickly than others. I really doubt that early lute makers artificially darkened the soundboards of old lutes, since this would mean coating the wood with an additional substance when the tendency seemed to be to put as little as possible on the soundboard.

I regularly get a variety of Middle Eastern stringed instruments, including ouds, in my shop for repair. These instruments normally have bare, untreated soundboards. The older ones (20–60 years old) have turned quite dark and closely resemble the lute soundboards in old paintings. In most instances they are not just UV-light darkened but uniformly dirty. In any case, why should we be trying to build lutes that look 20–60 years old when they are brand new? I, for one, am content to wait a few years. ◆

Posted on

Rule of 18 vs Rule of 17.817

Rule of 18 vs Rule of 17.817

by James Buckland

Published online by Guild of American Luthiers, May 2021

 

 

At the 2014 GAL Convention, I conducted a lecture/presentation entitled “Mythbusting the Rule of 18”. The intent was to explore, and possibly refute, some of the misconceptions concerning the Rule of 18.

As conventional wisdom goes, the old rule of 18 was, at best, an approximation on how to calculate fret positions. In truth, it is a better formula than it’s generally given credit. Unlike many historical predecessors, such as Juan Bermudo’s approaches using Pythagorean ratios, the Rule of 18 is based on the concept of equal temperament, probably before the term existed in the vernacular. But, most importantly, Rule of 18 includes its own compensation factor in regard to the position of the bridge.

Most commonly used today, is the square root of two, or 17.817, as the factor with which to divide string length. The result is believed by many to be more accurate based on the fact that it places the 12th fret at the exact midpoint of the vibrating string length. Since we all know that the 12th fret is the octave above the open string, it makes common sense that it should be in the exact middle of the vibrating string length.

However, it is also well known that a guitar built this way will play out of tune, with intonation problems increasing the further one plays up the neck. The solution is to compensate by increasing the string length slightly, generally by moving the bridge position. But, by how much? Examine enough classical guitars fretted with a “650MM scale”, and you’ll find the actual vibrating string length is generally longer, by 2 to 4MM. There doesn’t seem to be much more than vague empirical evidence in just how much to use. In other words, a little bit of “Kentucky Windage” is considered good enough. (For you non-shooters, Kentucky Windage is the practice of adjusting your aim to compensate for wind, without the use of any mechanical features on the weapon.) To me, this is a seemingly strange attitude considering the derision generally cast upon the good old Rule of 18. Maybe “17.817” just sounds more precise than saying “18”?

So, here’s a practical example of the similarity between the two approaches when bridge compensation is taken into account. I began by calculating a fret scale for a 565MM string length (as might be used for the terz guitar in GAL Instrument Plan 80) using the “Rule of 18”. The results are shown in Table 1. Then, I took the resulting value for the distance between the nut and 12th fret (280.446MM) and multiplied it by two. Next, the resulting value (560.892MM) was used to calculate a fret scale using the contemporary 17.817 factor. The calculations are shown in Table 2.

Table 1
Table 2

Notice the outcome! Although the vibrating string lengths are different (560.892MM vs 565MM) the results for the fret placements are generally from about a tenth of a millimeter at the first fret, approaching one millimeter towards the higher frets. To put that into context, consider real world variabilities typically introduced during fretboard fabrication, from layout, to slot cutting, to fret dressing and crowning. Or, compare this to the guesstimate made by many luthiers when choosing bridge placement compensation.

But, what about the issue of the difference in string lengths? Well, as stated above, most luthiers know that to satisfactorily use the 17.817 approach, one must add their own bridge compensation (hence the “Kentucky Windage” analogy).

So, if you add 2-4MM bridge compensation to the 560.892MM string length, you can see that resulting vibrating string length gets pretty close to 565MM!

But, there is another way of looking at the data that shows even more surprising results. The tables of values reflect the string length from the nut to the respective fret(s). What about the other length of the string, the vibrating string length from the fret to the bridge, the part of the string we actually hear?

The greatest discrepancy between the two tables is found with the 24th fret. In the case of the Rule of 18, the distance from the 24th fret to the bridge is 143.312MM. In the case of the 17.817 factor, the distance is 140.221MM. Add 2MM compensation, and the value increases to 142.221MM. Add 3MM compensation, and the value increases to 143.221MM. Add 4MM compensation, and the value increases to 144.221MM. In other words, the discrepancy between fret placement values calculated with either the Rule of 18 or the Rule of 17.817 is less than the variables introduced through the subjective choice of bridge compensation which must be made when using the latter rule. When comparing the other fret values, the difference between the two table of calculations is even less.

Does the use of the Rule of 18 vs 17.817 result in a significantly discernible difference, given other contributing factors? Maybe the old guys knew more than they’ve been given credit? ◆

Thanks to Nitin Arora for writing the fret calculating program
“Eighteen Rules” found on his website.

At the 2014 GAL Convention, author James Buckland also demonstrated the use of proportional dividers for marking fret positions. Set the big end of the dividers to the scale length. The little end now shows you the distance from the nut to the first fret. Re-set the long end to the distance form the first fret to the bridge. You are off and running. Ron Fernandez tries it. All photos by Tom Harper.