Posted on April 21, 2023May 18, 2023 by Dale Phillips Battery-Powered Instrument Amplifiers Battery-Powered Instrument Amplifiers by Joseph Ennis Originally published in American Lutherie #69, 2002 and Big Red Book of American Lutherie Volume Six, 2013 After reading Francis Kosheleff’s description of building speaker enclosures which resemble instrument bodies, I thought I would offer my experience of what has worked for me. I have added battery-powered amplifiers and speakers inside instrument bodies to either augment the sound of a weak instrument like a harp or mandolin, or just to act as stage monitors. The thing left unspoken in Mr. Kosheleff’s article is that not just any speaker will work well. The speaker should be chosen to match the instrument body resonance. The first air resonance of a hollow body instrument is essentially the same as the Helmholtz resonance of a tuned speaker cabinet. The same math applies. The formula is given below. 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, 2023April 24, 2023 by Dale Phillips Calculating Soundbox Volume Calculating Soundbox Volume by Dave Raley Originally published in American Lutherie #70, 2002 and Big Red Book of American Lutherie Volume Six, 2013 Want to design a new guitar shape and maintain an equal volume of enclosed air by adjusting the height of the sides? Here’s how to calculate volumes. Accuracy is a function of how long you want to spend measuring and calculating. Consider two bodies: Figs. 1a and 2a. The body in Fig. 1 is 18" on the X axis and 4" on the Z axis. Suppose that you wish to make the body in Fig. 2 have the same volume as the body in Fig. 1 while maintaining the same X axis. Fig. 3 defines the axes regardless of the way the figures are turned. 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 11, 2023 by Dale Phillips Questions: Rusty Instrument Odors Questions: Rusty Instrument Odors by Ed Pastor Originally published in American Lutherie #66, 2001 Kelly Johnston from Cleveland, OH asks: Is there a safe way to get a musty smell out of an old and valuable guitar? Ed Pastor of Hemphill, TX answers: Make a sachet of cedar shavings (Western red or Tennessee cedar should work) in a piece of panty hose or fine gauze, place inside of soundhole if one is present; if f-holes are present, squeeze the sachet into one of the holes and suspend for several days to a week. If there is a case with the instrument, place it in direct sunlight outdoors for at least four hours and then place a small sachet of cedar shavings in the case.
Posted on April 21, 2023April 24, 2023 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 April 21, 2023April 24, 2023 by Dale Phillips Letter: Vacuum Clamp Letter: Vacuum Clamp by David Haxton Originally published in American Lutherie #67, 2001 GAL: I share Jon Calkin’s enthusiasm for the dished workboard (see AL#65). I know it’s made my guitars better. But he could trade all his clamps and dedicated workstations for a much simpler and, I would say better, solution: the use of a vacuum pump. You get absolutely even clamping pressure across the entire face of the plate and no dents from over-tightened clamps. In fact, I preshape and sand all my braces before gluing, lessening the need for chisel work after glue-up, and the whole procedure is quicker. I’ve also used my vacuum pump to make radiused sanding blocks for fretwork and laminated linings, and they make great hold-downs. My pump came from a mail-order surplus supply company for about $80.
