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Transducers

Transducers

by Reagan Cole

Originally published as Guild of American Luthiers Data Sheet #54, 1977



The purpose of this particular article is to project one man’s opinion about the theoretical whys and wherefores of the transducer for acoustic instruments. This is not a consumer’s report analysis of commercially available products. Anyone interested in this information may consult the series which is currently running in Mugwumps Instrument Herald. A full market report and commentary has been promised. I have never had the money to run out and A-B all the stuff that crops up in the pages of Guitar Player; anyway, I have never used any of the commercial units since I build my own systems.

There seems to be several major camps regarding the amplification of acoustic instruments. These I would categorise as follows: (1) Only microphones should be used. These devices are, after all, an electrical analogue to the human ear, so if the mike is good all will be well. Absolutely nothing should be attached to an existing acoustic instrument. (2) Transducers are a necessary evil. They do allow musicians playing acoustic instruments to compete in an electric or an electronic ensemble. At any rate, if they are used they should be easily removable, leaving no trace. (3) The acoustic-electric is yet another evolutionary phase. The performance of the instrument transducer system is of paramount importance; It may be necessary to modify the instrument or even to design a new type for acoustic-electric use. I don’t believe that there are grounds for a serious feud lurking in any of these arguments; all are correct from their own frames of reference.

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Conical Radius Fretboard Formula

Conical Radius Fretboard Formula

by Elaine Hartstein

Originally published in American Lutherie #34, 1993 and Big Red Book of American Lutherie Volume Three, 2004



As a follow-up to Tim Earls’ article “In Search of the Perfect Cone” in American Lutherie #30, I’ve come up with a formula for finding the hypothetically-ideal radius for the fingerboard at any distance from the nut. Since a set of nonparallel strings cannot lie flat on a cylindrical fretboard, we wish to discover the geometry of the cone described by the strings. As Tim Olsen suggested, the outside strings (as opposed to the edges of the fingerboard) should define the cone. The cone defined by the fingerboard edge would give results with a smaller radius.

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Questions: Significance of Q

Questions: Significance of Q

by Brian Burns

Originally published in American Lutherie #86, 2006



John Belluci of Baltimore, MD asks:

Please explain what “Q” is when referring to wood or instruments. The definition I’ve seen is, “internal damping.”


Brian Burns of Fort Bragg, CA responds:

“Q” is one of the basic qualities of the materials we use to make stringed instruments. The traditional low-tech Q test is to listen to the tap tone of a piece of wood and hear how long it takes for the sound to die away. The longer the tap tone lasts, the higher the Q, and the greater the potential of that piece of wood to make a loud instrument with long sustain. The design and construction of the instrument of course determine the ultimate result; the Q test just gives you an idea of the potential of that particular piece of wood.

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Questions: String Tension and Purity of Tone

Questions: String Tension and Purity of Tone

by Alan Carruth

Originally published in American Lutherie #99, 2009

See also, Questions: String Tension and Pure Tone by R.M. Mottola



Alan Carruth from Newport, New Hampshire writes in response to Pat Bowen’s question in AL#98 about the relationship between string tension and purity of tone:

While there is some truth in the equation higher tension=purer tone, it is, as the editor said, not as simple as that. A lot depends on how you get the higher tension.

When you pluck a string, it vibrates at a set of different, but related, frequencies. For ideal strings, the kind that you only find in physics books, these frequencies form a harmonic series; each one is an exact whole-number multiple of the lowest (or fundamental) pitch that the string makes. Real strings don’t do this, and that affects the way they sound.

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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. —