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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.

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Travel Lute

Travel Lute

by Ben Cohen

Originally published in American Lutherie #101, 2010



I am an amateur luthier and a lutenist. I recently attended a reunion of sorts with a number of singers from my old early music ensemble at Oberlin College, and I regretted not having a lute handy to be able to accompany some friends on lute songs. I travel with a mandolin because it fits in the airplane overhead bin and allows me to play Bach suites and choros while my flight is delayed. Lutes aren’t good for air travel. The funny shape makes them hard to fit in the overhead bin. While there are some small 6-course instruments that might squeeze into an overhead bin, most lutenists would prefer to travel with an 8-course instrument to cover as much repertoire as possible. Lutes are also delicate and expensive. Flying with a lute usually requires some kind of super-protective flight case, awkward and expensive.

Guitars do not make decent lute substitutes. The guitar has only six strings, and they are not spaced at all like a lute. The world needs a good travel lute.

A banjo approach struck me as the way to go, since the lute has such a thin top that it sounds more like a banjo than any other wooden plucked string instrument. I used a Remo 12" pretuned hand drum that I had on hand.

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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.

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