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Side Soundports

There’s a Hole in the Bucket

by Cyndy Burton

A Discussion of Sideports, with Contributions from Kenny Hill, Alan Carruth, Roger Thurman, John Monteleone, Mike Doolin, and Robert Ruck

previously published in American Lutherie #91, 2007

See also,
Sidewaysby John Monteleone
“Herr Helmholtz’ Tube” by Mike Doolin
“Three Holes are Better than One” Robert Ruck



Just in case we become too self-satisfied with our “discovery” of ports, Alain Bieber, in his article on lyra guitars (AL#88, p. 16), points us to the Neapolitan Gennaro Fabricatore’s ported lyras from the early 1800s. (Alain ported his own contemporary lyra guitar, too.) So we know prominent makers were putting holes in the sides of their instruments in the late 1700s, early 1800s. Many of us are also aware of Carleen Hutchins’ groundwork in the early 1980s. Her “Le Greyère” violin, with sixty-five sideports, has provided a wealth of data about violin resonances since it was made in 1982. She donated the violin to the National Music Museum in 2002. See some great photos of Le Greyère and a list of publications reporting on that research at collections.nmmusd.org/Archives/NewViolinFamily/Hutchinscheeseviolin.html.

People are sensitive about putting holes in things. Many guitarists — perhaps more classical guitarists than others — find the ports some sort of denigration, a violation of the sanctity of the guitar’s perfect form. In all fairness, we’ve met with very strong feelings on both sides of the port issue. Luckily, our customer was very open to the idea. He’s not a concertizing musician, but he’s a serious player, and occasionally he plays publicly for special events. We wanted to try ports for him because he has a hearing loss, and we thought ports would be a great way for him to hear himself better. At that time, Robert Ruck had made about a hundred ported guitars, so we figured he had worked out the kinks. He kindly advised us on size, location, and so on. We followed his lead. The result is a wonderful instrument that the owner truly appreciates. We love the feedback — the monitor effect for the player — and when we tested it in a small auditorium with an overflowing audience, we could not discern any loss of projection or quality of sound. But was it louder? Our evidence was very meager and inconclusive. Many makers are adamant that it’s louder with the ports open for both the player and the audience.

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Questions: Guitar Air Cavity

Questions: Guitar Air Cavity

by Art Davis, Alan Carruth, and Joe D. Franklin

Originally published in American Lutherie #63, 2000 and Big Red Book of American Lutherie Volume Six, 2013



Tom Blackshear of San Antonio, Texas asks:

Is there a formula for measuring the air cavity of a guitar box, then figuring out how to keep the same amount of air with slightly different box dimensions?


Art Davis of San Diego, California responds:

Use bird seed. It’s not totally accurate but it’s easy. Pour it in, pour it out, and measure it. Hold the guitar really well because ten or twenty pounds of bird seed is heavy. Also, as per W.D. Allen’s, “Basics of Air Resonances,” in The Big Red Book of American Lutherie Volume 1, changing the air volume doesn’t always do what you think it’s going to.

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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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The Anti-Murphy Concert

The Anti-Murphy Concert

by Alan Carruth

Originally published in American Lutherie #39, 1994



I recently had the privilege of attending a somewhat unusual concert by the Tokyo String Quartet, with some acoustics experiments thrown in. Or maybe it was a physics lecture with live accompaniment? And then there was the quiz show part... I guess I’d better explain.

The whole thing seems to have started with the coming together of a number of good ideas. One of the first was a plan by the Acoustical Society of America to produce an educational video on acoustics for grades K–12. This, of course, would require money to do, and the suggestion was made that a benefit concert be held. The members of the Tokyo String Quartet were contacted, and graciously consented. So far, so simple.

But remember, we’re dealing with acousticians here. Why not use the opportunity to do a little research? For one thing, while the acoustics of empty halls are reasonably well understood, nobody is really sure what happens when you put in the audience. Since the object of most concert promoters is to have as large an audience as possible, and nobody likes to listen to music in an acoustically lousy hall, it seemed like a good subject for an experiment. And how about that violin thing; you know old vs. new and all? And while we’re at it...

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Free Plate Tuning, Part One: Theory

Free Plate Tuning, Part One: Theory

by Alan Carruth

Originally published in American Lutherie #28, 1991 and Big Red Book of American Lutherie Volume 3, 2004

See also,
Free Plate Tuning, Part Two: Violins by Alan Carruth
Free Plate Tuning, Part Three: Guitars by Alan Carruth



I started learning free plate tuning on violins and violas more than ten years ago from Carleen Hutchins. For those who have not had the pleasure of her acquaintance, Carleen is one of the founders of the Catgut Acoustical Society and its permanent secretary. She is an able scientist, a great teacher, a fine luthier, and a self-confessed mediocre violist. While working with physicist Frederick Saunders almost thirty years ago she helped rediscover and update the old Chladni method of visualizing the vibrations of plates. Her subsequent research, using Chladni patterns as a window into the differences between good and poor violins earned her a silver medal from the Acoustical Society of America.

Violin makers have traditionally used some variant of “tap tone” tuning to guide them in working out the final graduations of the top and back plates. Although the technique seems simple and organic on the face of it, it is in fact very complex. It takes a long time, as well as a good ear and a lot of talent, to learn to tune plates by tap tone. Even those who are good at it don’t always succeed. Felix Savart, back in the 19th century, tried to adapt Chladni’s method to research on violin acoustics, but the technology wasn’t there. Now we have the means, and as we gain more understanding of how the instruments work, we also gain more control over the sound.

And it doesn’t only work on violins. Fred Dickens, Graham Caldersmith, and Gila Eban have all done major work in applying the principles of violin acoustics to guitar construction. Of course, there are differences and it takes time and effort to sort them out, but physics is physics, or, as a friend of mine said, “it all comes down to F=mA in the end.” I have found these techniques to be useful, and sharing useful techniques is what the Guild is all about.

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