Posted on April 21, 2023March 5, 2024 by Dale Phillips Constructing an Under-Saddle Transducer Constructing an Under-Saddle Transducer by R.M. Mottola Originally published in American Lutherie #68, 2001 and Big Red Book of American Lutherie Volume Six, 2013 Piezoelectric transducers or pickups (I use the terms interchangeably) are popularly used to “electrify” acoustic instruments, and are increasingly found embedded in the bridge saddles of electric instruments as well. Manufactured transducers are available from a number of sources, but this article provides instructions for making an undersaddle piezo pickup for a flattop guitar from basic materials. If you know which end of a soldering iron to grab hold of, you can build this pickup. Piezo material will generate an electrical charge when mechanically deformed. There are four types of piezo materials used in the manufacture of instrument transducers: lead zirconate titanate (PZT) ceramic chips, PZT ceramic “bender” disks, polyvinylidene fluoride (PVDF) plastic film, and PVDF coaxial cable. PZT chips find their way into first-generation undersaddle guitar transducers, transducers for various bowed instruments, and manufactured archtop guitar and mandolin bridges. PZT disks consist of PZT material bonded to thin brass disks, and are commonly used for soundboard pickups for flattop guitars and for bridge-mounted pickups for upright basses. PVDF film may be found in all sorts of transducers from undersaddle guitar transducers to under-bridge-foot transducers for bass viols. PVDF coax cable is manufactured just like the single-conductor shielded cable used to make instrument cables, except that instead of an insulating material between the center conductor and the outer shielding braid, we find PVDF material. It is used in manufactured undersaddle pickups for acoustic guitars and is the material that will be used to construct a transducer in this article. 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, 2022March 5, 2024 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.
Posted on September 2, 2022March 5, 2024 by Dale Phillips Parametric Models of Guitar Cutaways Parametric Models of Guitar Cutaways by R.M. Mottola Originally published in American Lutherie #99, 2009 See also, A Method for the Design of the Guitar Body Outline by R.M. Mottola A Method For the Design Of the Guitar Body Outline Part 3: Compound Radius Curves by R.M. Mottola In the article entitled “A Method for the Design of the Guitar Body Outline” in AL#97, I introduced the concept of parametric models for the design of the guitar body outline. That article addressed symmetrical body outlines only. In this article I want to consider parametric models for the body cutaway. Taken together the two articles demonstrate a complete method for the design of typical guitar body outlines. Although it was possible to devise a simple parametric model for the design of the symmetrical guitar body outline that was adequate for most of the “standard” guitar body outline types, things are a bit more complicated where the cutaway is concerned. The basic problem is that, except in the most basic designations, cutaway styles have not yet settled out into a small number of distinct types. Rather than pursue a model that would accommodate all existing cutaway designs, I chose instead to derive basic models for the two primary cutaway types, leaving enough configurability to insure that most existing cutaway outlines could at least be approximated. 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, 2022March 5, 2024 by Dale Phillips A Method For the Design Of the Guitar Body Outline Part 3: Compound Radius Curves A Method For the Design Of the Guitar Body Outline Part 3: Compound Radius Curves by R.M. Mottola Originally published in American Lutherie #103, 2010 See also, A Method for the Design of the Guitar Body Outline by R.M. Mottola Parametric Models of Guitar Cutaways by R.M. Mottola The article “A Method for the Design of the Guitar Body Outline” in AL#97 presented a model for drawing guitar body outline halves based on five circular arcs and three straight line segments, as shown in Fig. 1. Here I will present an enhancement to that model. As the original article pointed out, the five-arc model can be used to draw most but not all guitar body outlines. So it was probably inevitable that the first feedback I received following the publication of that article was from someone trying to draw an outline for one of the instruments for which this model is not ideally suited. There are a couple of common instruments that have outlines which cannot be drawn using this simple five-arc, three-straight-line-segment model. These instruments, the OM and the Maccaferri-style guitars, have a “dropped hips” look to the lower bout that cannot be approximated by a single circular arc (Fig. 2). Fortunately, the lower bouts of these guitars can be accurately drawn with a simple enhancement to the model. The enhancement replaces the single-arc lower bout curve with a compound-radius curve. A compound-radius curve is composed of a series of circular arcs, each tangent to the one succeeding it. Although all manner of complex curves can be built up in this fashion, for the purpose of enhancing the simple guitar body outline model, we really only need to introduce compound-radius curves of two radii. 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 August 1, 2022March 5, 2024 by Dale Phillips Questions: String Tension and Pure Tone Questions: String Tension and Pure Tone by R.M. Mottola Originally published in American Lutherie #98, 2009 See also, Questions: String Tension and Purity of Tone by Alan Carruth Pat Bowen from the Internet asks: A generally accepted fact is that the higher the string tension, the more pure the tone. This causes me grief, since I have to build instruments to support the heaviest strings. Even if I don’t recommend them, someone is going to use them. But is this thing about the high tension and pure tone really true or is it just a folk tale? The Questions Column editor responds: The short answer is yes, it is true, and the short explanation is inharmonicity. The higher the tension, the closer the partials are to true harmonic multiples of the fundamental frequency. On p. 115 of his book Engineering the Guitar — Theory and Practice, Richard Mark French states: “...increasing the radius [of the string] or elastic modulus [i.e., stiffness] makes the deviation from the ideal harmonic series worse, while increasing tension or length makes it better.” This is an interesting topic worthy of an article or at least a longer explanation than I’ve given here, which I hope someone will provide.
