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From: Ross
Remote Name: 76.101.5.120
Date: 12 Nov 2007
Time: 07:13:43 -0500
Luthier’s Weblog 11/12/07 I really don’t feel like discussing frets. I know I said I was going to, but it would to take a huge effort of will to do so. While frets serve an important function, there is very little in their design that I feel needs tweaking. I know that there is the stainless steel school of thought, purported to obviate the need for periodic dressing and refretting. I remain unconvinced. The hardness of stainless frets is such that the decreased string life may more than offset any savings realized from needing less regular fret servicing. The method of attachment for standard frets, tangs being inserted into slots in the fingerboard, is quite simple and lends itself to servicing. There may be improvements to be made, but I would rather direct my focus to other areas of the instruments that present more fertile ground for design revision. Perhaps one day some huge glaring flaw in my thinking about frets will present itself. I’ll let you know. Or, you can let me know. One thing that nags me about flattop instrument design is the bridge. Considered to be the top’s most important brace, it sits amidships and executes it’s various duties in a peripatetic way. It provides the strength to effectively channel string pull. It guides the string ends to their anchor spot at the bridge plate, under the top. It’s saddle precisely determines string length and assures proper intonation. It transforms string energy into a form that the top of the instrument can diffuse in the form of sound waves. It is this last which seems to me to be most susceptible of improvement. When the string is picked or plucked, it’s directional vibration quickly assumes a rotational envelope, round in cross section. It is this energy that most impacts the bridge. Lengthwise, or stretch/recover cycles of the string comprise only a very small percentage of energy transmitted. The rotational energy must be transferred into a form that enables the top to vibrate in a largely up and down manner, generating sound waves. This is difficult to do. So difficult, in fact, that the great majority of string energy (minute as it is to begin with) is lost in the translation. An example would be the relative inefficiency of a shaft drive motorcycle which has to translate the direction of drive from latitudinal to longitudinal and then back, as opposed to the more efficient chain drive, in which no such change need be made. In the latter case, the crankshaft and transmission rotation can mirror the rotational plane of the drive wheel. No translational energy loss. The wasted energy (of motorcycle or guitar) is given off in the form of heat, from friction incurred along the way. The fact that your hands don’t get appreciably hotter as you play the guitar indicates what a small amount of energy this is. The tiny remnant that makes it through to become musical sound waves, though, can seem mighty, indeed. Magical, this transformation, isn’t it? And yet, it seems like the bridge could do the job better. One ponders, as the robot luthier does the same. Ross Teigen 8:47 am