CAS Journal
November 2000
Volume 4, No. 2 (Series II)


To Our Readers

This issue has "Wood" as its theme, though not exclusively so. In order to provide a starting point, Daniel Haines has updated his earlier CAS Journal articles on the mechanical properties of different types of wood; the underlying data are the same but the commentary has been expanded. The article by Voichita Bucur on inorganic compounds in the cellular wall is a useful complement, as is Hajo Meyer's paper on changes in mode frequencies. An interesting couterpoint is made by Knut Guettler in his discussion of the HagetrÝ Violin, which is made of plywood, and even more so by Charles Besnainou in his review of the use of composite materials in the construction of stringed instruments. Gregg Alf's call for the formulation of a Tonewood Study Group within the Catgut Acoustical Society suggests that there is still a lot to be learned.

For the first time we are including a special section "From the Contributing Editors." It provides a forum for the somewhat more speculative discussio of findings and areas in need of further research which characterized the early years of the Catgut Acoustical Society. These contributions are not peer-reviewed; however, their authors are eminent in their field. Hopefully, their thoughts will stimulate further discussion.

The Catgut Acoustical Society serves several constituencies, notably stringed instrument makers and acoustical scientists. Oliver Rodgers' paper could well be described as the manifesto of a third group, those of an engineering bent. It is a refreshing approach, and will no doubt strike a chord amon the many engineers (and hopefully others) in our membership.

Talking about constituencies, we have an interesting article by Tom Rossing on mandolins which ought to be relevant especially to those of you who are interested in plucked string instruments. And the violinmakers among you will be interested in the description of a new bowing machine John McLennan and of a soundpost cutting jig by Bill Atwood & Tom Croen.

The range of topics addressed in this issue is proof of the need for a Journal such as this. I wish to thank the various authors in this issue for their contribution; they are setting a fine example.

J. Maurits Hudig

Table of Contents with Abstracts

3 - Letter to the Editor - Audibility of Tonal Qualities in Old and New Violins by Daniel Ling

8 - From the Contributing Editors

A Next Step in the Advancement of Violinmaking: Announcing the CAS Tone-wood Study Group by Greg Alf

Introduction to the Use of Composite Materials in Musical Instruments by Charles Besnainou

The HagetrÝ Violin by Knut Guettler

A patented novel design enables quality instruments to be made from thin plywood.

13 - An Engineering Approach to the Violinmaking Problem by Oliver E. Rodgers and Pamela J. Anderson

An approach to violin making is described which emphasizes collecting and using data about wood properties, dimensions, and a crude electronic acoustical analysis of sound output and then making adjustments after an instrument is first assembled. Details of the required equipment and setup are described. This cause and effect approach to violin making is strongly recommended.

20 - The Essential Mechanical Properties of Wood Prepared for Musical Instruments by Daniel W. Haines

This article presents an update of reports originally published in the CAS Newsletter (#31, 1979 and #33, 1980). The earlier articles represented a study of 87 samples from 25 species of woods that had been selected for the primary components of high quality musical instrument wood, including violins, guitars and pianos. The properties studied were density, stiffness (including Young's moduli and shear moduli) and damping. More recently obtained results enabled the addition of the in-plane shear stiffness for this article. I offer the rationale for selecting these properties and the test procedures, and the numerical values of the properties are given in tabular form. Means and standard deviations are given for species with sufficient samples to justify such analysis. The data is then used as the basis for offering an explanation of certain traditions in the making of violins and other string instruments.

33 - Thinning Behavior of Normal-Mode Frequencies of Arched Biolin and Viola Top Plates by Hajo G. Meyer

Discussions on recommendable plate-mode tuning schemes are well covered in the literature. The way, however, in which the frequencies are lowered during the thinning process has received little attention. The same holds for the relation between the final thickness achieved and the acoustical properties of the wood used. In this paper a semi-empirical theory will be presented in which the violin plate is no longer modelled as a flat plate. It can better be compared to a curved thin shell and the by no means negligible consequences of this are presented.

39 - Relationships between the Inorganic Component of the Cellular Wall and the Acoustic Properties of Wood for Violins by Voichita Bucur, A. Clement, and D. Thomas

The wood species analayzed in this article are Picea spp and Acer spp, for the top and back of violins. The specimens were collected from different sites and different countries. The mineral components (Ca, Mg, Mn P) of the cellular wall were identified qualitatively using scanning electron microscopy - X-ray spectra and quantitatively with ICP spectroscopy. The acoustical properties were studied using ultrasonic direct transmission technique. Regression analysis was used to establish relationships between mineral components and acoustical properties.

48 - Normal Modes of Vibration in Mandolins by David Cohen and Thomas D. Rossing

Using electronic TV holography, we have studied the vibrational modes of two mandolins of the Gibson F-type, one with f-holes and the other with an oval sound hole. Although the observed normal modes are moderately similar to those observed in guitars, the coupling between plate modes and air cavity modes appears to be weaker. Plate coupling is greater in the oval hole instrument, and we observe three (0,0) modes as in a guitar. in the f-hole instrument, a doublet (0,0) is observed.

55 - A New Bowing Machine by John E. McLennan

A new bowing machine, weighing 250 g, has been developed so that it can be attached to the violin and enable notes to be stopped with the left hand. It is supported on a wooden shoulder rest and permits the four necessary parameters (string selection, bow position, bow force and bow speed) to be changed.
The bowing machine enables certain expected string behaviour, e.g. the sympathetic excitation of harmonics on strings other than on the one being played, to be demonstrated.
A comparison between machine bowing and hand bowing used in a parallel study employing a modified Saunders Loudness Test gave similar results.

61 - A Simple Soundpost Cutting Jig by William Atwood and Thomas Croen

Authors

2 -

Carleen Maley Hutchins Medallion Awarded to Norman C. Pickering

3 -

Recent Publications of CAS Members

63 -

Meetings, Workshops, Seminars

64 - ISMA 2001 - Perugia, Italy - Sept. 10-13, 2001

New Violin Family Association News

66 -


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