Posted on June 6, 2024May 23, 2025 by Dale Phillips Questions: String Tension Questions: String Tension by Thomas Knatt Originally published in American Lutherie #95, 2008 John C. from the Internet asks: String tension will deform an instrument in an elastic manner so that when the tension is removed, the instrument will return to its original shape. But over time the tension will also deform the instrument permanently, often requiring repair work to make it playable again. Is this permanent deformation proportionally related to the amount of time the instrument is under tension? If the instrument is tuned to pitch only when it is played, will the time it takes to deform to the point of unplayability be lengthened in proportion to the amount of time the instrument is not under string tension? Thomas Knatt from Groton, Massachusetts responds: The short answer is yes, detuning every time would probably lengthen the life of the instrument. But.... Let’s do a thought experiment. Suppose we significantly loosen one side of a drum or banjo head. The drum would sound duller when struck on the side with the low tension. The sound of the banjo, when played, would change as well, although I won’t predict exactly how. Carleen Hutchins says that you don’t want a lumpy system, because it doesn’t behave well. I have done a glitter test on a well-tuned kettle drum, and the glitter jumped a foot off the head at one frequency. If I went one cycle above or below the tuned frequency, it only jumped an inch. I went ±2 cycles and it barely moved. That is a good example of low damping. A system becomes lumpy by adding lumps (weight) or changing the stiffness in sections. 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 March 7, 2024May 21, 2024 by Dale Phillips Side Soundports There’s a Hole in the Bucket by Cyndy Burton A Discussion of Sideports, with Contributions from Kenny Hill, Alan Carruth, Roger Thurman, John Monteleone, Mike Doolin, and Robert Ruck previously published in American Lutherie #91, 2007 See also, “Sideways” by John Monteleone “Herr Helmholtz’ Tube” by Mike Doolin “Three Holes are Better than One” Robert Ruck Just in case we become too self-satisfied with our “discovery” of ports, Alain Bieber, in his article on lyra guitars (AL#88, p. 16), points us to the Neapolitan Gennaro Fabricatore’s ported lyras from the early 1800s. (Alain ported his own contemporary lyra guitar, too.) So we know prominent makers were putting holes in the sides of their instruments in the late 1700s, early 1800s. Many of us are also aware of Carleen Hutchins’ groundwork in the early 1980s. Her “Le Greyère” violin, with sixty-five sideports, has provided a wealth of data about violin resonances since it was made in 1982. She donated the violin to the National Music Museum in 2002. See some great photos of Le Greyère and a list of publications reporting on that research at collections.nmmusd.org/Archives/NewViolinFamily/Hutchinscheeseviolin.html. People are sensitive about putting holes in things. Many guitarists — perhaps more classical guitarists than others — find the ports some sort of denigration, a violation of the sanctity of the guitar’s perfect form. In all fairness, we’ve met with very strong feelings on both sides of the port issue. Luckily, our customer was very open to the idea. He’s not a concertizing musician, but he’s a serious player, and occasionally he plays publicly for special events. We wanted to try ports for him because he has a hearing loss, and we thought ports would be a great way for him to hear himself better. At that time, Robert Ruck had made about a hundred ported guitars, so we figured he had worked out the kinks. He kindly advised us on size, location, and so on. We followed his lead. The result is a wonderful instrument that the owner truly appreciates. We love the feedback — the monitor effect for the player — and when we tested it in a small auditorium with an overflowing audience, we could not discern any loss of projection or quality of sound. But was it louder? Our evidence was very meager and inconclusive. Many makers are adamant that it’s louder with the ports open for both the player and the audience. 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 March 6, 2024May 28, 2025 by Dale Phillips Using the Golden Section to Design a Kamanché Using the Golden Section to Design a Kamanché by Ahanali Jahandideh, Mitra Jahandideh, Hadi Abbaszadeh, and Samad Jahandideh Originally published in American Lutherie #98, 2009 The kamanché is a Persian bowed string instrument related to the violin. (See “Building the Kamanché” by Nasser Shirazi, AL#4, p. 27 and BRBAL1, p. 126, and GAL Instrument Plan #9. The kamanché has a long neck and a spheroid sound chamber made from gourd or wooden staves, which is usually covered on the playing side with skin from a lamb, goat, or fish. It is widely played in classical music of Iran, Azerbaijan, Uzbekistan, and Turkmenistan, with slight variations in structure. The Golden Section (also known as the Golden Mean, Ratio, or Proportion) is a ratio defined by the number phi (Φ=1.618033988...). It has been used in designing violins and other musical instruments, but for the first time we used it to design an Iranian 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.
Posted on April 21, 2023May 29, 2025 by Dale Phillips Questions: Guitar Air Cavity Questions: Guitar Air Cavity by Art Davis, Alan Carruth, and Joe D. Franklin Originally published in American Lutherie #63, 2000 and Big Red Book of American Lutherie Volume Six, 2013 Tom Blackshear of San Antonio, Texas asks: Is there a formula for measuring the air cavity of a guitar box, then figuring out how to keep the same amount of air with slightly different box dimensions? Art Davis of San Diego, California responds: Use bird seed. It’s not totally accurate but it’s easy. Pour it in, pour it out, and measure it. Hold the guitar really well because ten or twenty pounds of bird seed is heavy. Also, as per W.D. Allen’s, “Basics of Air Resonances,” in The Big Red Book of American Lutherie Volume 1, changing the air volume doesn’t always do what you think it’s going to. 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 September 2, 2022May 23, 2025 by Dale Phillips A Method for the Design of the Guitar Body Outline A Method for the Design of the Guitar Body Outline by R.M. Mottola Originally published in American Lutherie #97, 2009 See also, Parametric Models of Guitar Cutaways by R.M. Mottola A Method For the Design Of the Guitar Body Outline Part 3: Compound Radius Curves by R.M. Mottola One of the most tedious and time consuming aspects of designing a new guitar for me is the process of designing the body outline. The body outlines of my early instruments were the results of many hours of labor, usually over the course of many weeks. This process was so time consuming that I would often forgo it entirely, opting to reuse an existing body outline as is, or scaling up a guitar outline for use in an acoustic bass guitar. But over the years I’ve settled into a method for guitar body outline design which is far less tedious and consumes far less time than did my original efforts. This method involves the use of a standard model of the guitar outline. Use of this standard model helps to make the process of developing an outline more standard as well, and this in turn has resulted in the development of techniques which save time and frustration. In this article I will be outlining the model and discussing some common guitar body types in the context of this model. In talking about the design method which makes use of the model, I’ll try to touch on some of the generic qualities of guitar body outlines and how they can be quantified in terms of the model. Finally, some of the tools and techniques of the method will be detailed. Please note that what I am discussing here is only the mechanical aspects of a body design. Issues of acoustics or ergonomics are not covered. Also note that this method works equally well with either pencil and paper or CAD drawing tools, although there are some differences in how these tools are used. 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.
