US2489169A - Acoustic skeleton chamber for string instruments - Google Patents

Description

G. VlRZl Nov. 22, 1949 ACOUSTIC SKELETON CHAMBER FOR STRING INSTRUMENTS Filed June 28, 1946 ATTORNEY Patented Nov. 22, 1949 UNITED STATES PATENT OFFICE ACOUSTIC SKELETON CHAMBER FOR STRING INSTRUMENTS Giuseppe Virzi, New York, N. Y.

Application June 28, 1946, Serial No. 680,243

4 Claims. 1

This invention relates to musical string instruments.

One object of the invention is to provide an improved acoustic skeleton chamber for string instruments.

Another object of the invention is the provision of a musical string instrument having improved means for resiliently reenforcing a sounding board or chamber thereof for free vibration in response to sound.

Another object of the invention is to furnish improved means for reenforcing a sound chamber of a violin or the like at the bridge and at the sound openings.

Another object of the invention is to provide improved reenforcing means for a musical string instrument including an improved sound post for the bridge thereof.

Heretofore, the art as exemplified by violins and similar string instruments, has long been troubled by defects arising with frequent use, ageing and occasional abuse of the instrument, especially the sound chamber thereof; cracks in the wood, and opening of a seam or joint would develop, and Warping of the wood frequently occurred even in fairly expensive violins. Sometimes any one of these conditions would cause other weaknesses to develop, as the sound chamber of a violin is a highly coherent unit, in which the parts balance in respect to strains and stresses. Having been engaged for many years in the repair of violins, I perceived the need for an innovation in the art, while preserving the essential, well known character of the violin. Marginal reenforcement was inadequate, and I found that the reenforcement had to extend into or over the delicately vibrating walls of the sound chamber, without interfering with the tonal quality of the instrument. I also found that undue rigidity of the sound post is undesirable where it is desired to obtain superior distribution of stresses as in my skeletonized sound chamber.

It is therefore an object of the invention to provide improved means for accomplishing the advantages referred to.

Other objects and advantages of the invention will become apparent as the specification proceeds.

With the aforesaid objects in view, the invention comprises the novel features, combinations and arrangements of parts hereinafter described in their preferred embodiments, pointed out in the subjoined claims, and illustrated in the annexed drawing wherein like parts are designated by the same reference characters throughout the several views.

In the drawing:

Figure 1 is a plan view of an acoustic skeleton chamber for a string instrument such as a violin, embodying the invention.

Fig. 2 is a horizontal sectional view thereof showing the bottom wall.

Figs. 3, 4, 5, and 6 are sectional views taken respectively on lines 33, 4-4, 55, and 66 of Fig. 1.

Fig. 7 is a sectional view taken on the broken line l-'! of Fig. 1.

The advantages of the invention as here outlined are best realized when all of its features and instrumentalities are combined, but useful embodiments may be produced involving less than the whole.

It will be obvious to those skilled in the art to which the invention appertains, that the same may be incorporated in several different constructions. The accompanying drawing therefore, is submitted merely as showing a preferred exemplification of the invention.

Referring in detail to the drawing, in denotes a device such as a sounding board or chamber for musical string instruments, exemplified in a sound chamber of a violin, from which certain conventional portions have been omitted for clarity in the drawing. This device includes a top wall I I, a bottom wall I 2, and a side wall comprising the sections !3 and I4 and the re-entrant portions l5. These Walls may be interconnected in the usual manner adhesively or otherwise, and along the joints there may extend the usual beadlike strips l6 of triangular cross section for reenforcing the joints between the walls. The front and rear walls I l and I2 may be downwardly convexed, and in the front wall II there may be provided the conventional S-shaped sound openings l7 between which is located the bridge l8 for supporting the strings. Internally of the sound chamber Hi there is provided a sound post 2% hereinafter described, located adjacent to one side of the bridge l8, and adjacent to the opposite side of the latter there is a conventional bass bar 2! which forms no part of the invention and is therefore indicated in dotted lines. As above described, the chamber It may represent the sound box of any well-known violin or other portable musical instrument, except that the sound post 20 in the particular construction thereof is a novel feature of the invention. The sound chamber is made of a finegrade of wood, with the grain running preferably lengthwise of the elongated front and rear walls H and I2 as respectively indicated at 22, 23.

Reenforcing means is provided for the sound board or top wall I I comprising one or more strips 25 of a suitable stiffening material consisting preferably of wood whose fine grain extends generally longitudinally of the strip elements, the grain being indicated at 26. Each of these elements may be interrupted by the sound openings H to provide cooperating strips 21. These strip elements preferably extend substantially through out the length of the top wall up to the adjacent marginal walls as indicated at 28, 29, the bead l6 being interrupted to accommodate the ends of these strips. Each strip element 25, 21 is longitudinally substantially curved for longitudinal elasticity or resilience. Preferably such curvature is of generally S-shape, the strips intersecting each other at 30 so as to form a generally X- shaped reenforcement for the upper portion of the top wall and passing thence toward opposite sides of the bridge I8 and diverging from each other at the lower portion of the top wall. This arrangement has been carefully designed with a view to obtaining the best possible stress distribution. Where the strips are interrupted by the openings l1, reliance is placed upon the elements 2|], 2| for supporting the adjacent portion of the top wall. The strips may vary in mass or cross-section so that the sections 21 thereof may be slightly heavier than those shown at 25 or they may be uniform in cross-section throughout. The mass of the strips is so small as not to interfere with the sound vibrating quality of the top wall. For example, the cross section of each of these strips may be such that its dimensions may be substantially equal or only slightly greater than the thickness of the top wall. These strips are caused to conform to the convexity of the top wall and are preferably continuously secured thereto, adhesively or otherwise in a perfectly secure manner. Because the grain of the strips extends generally lengthwise thereof, they possess ample strength and because the strips extend obliquely to the grain of the top wall, they are adapted to afi'ord ample reenforcement at the critical sections of the top wall.

The bottom wall |2 indicates a sounding board provided with reenforcing means comprising elongated transverse strips 3|, 32 having angular edges at 33, 34 and curved or concave edges at 35, 36, the strips consist of wood with the grain running generally lengthwise thereof, as indicated at 31, 38. These strips may terminate at the beads l6 or the latter may be cut away so that the strips come into direct reenforcing engagement with the walls l3 and IS. The strip 3| extends across the violin chamber adjacent to the upper portion thereof, and the strip 32 is located closely adjacent to the sound post 20. These strips 3 32 are secured andfunction in a manner generally similar to the strips 25, 21. In construc tion the strips 3|, 32 differ from the strips 25, 21 principally in that they have substantially greater width and less angularity or curvature, and thus exercise a substantially greater reenforcing ef feet in a direction crosswise of the wall |2 to which they are continuously bonded, with the grain being approximately at right angles to the grain of the wall I2. It will be perceived that the strips 3|, 32 act adjacent to the re-entrant walls |2 where substantial reenforcement is necessary, and the strip 32 is adjacent to the sound post 20 to assist in taking up the stresses created thereby.

Extending generally lengthwise of the bottom wall |2 there are supplemental reenforcing means in the nature of strips, one comprising the portions 4|), 4|, and the other portions 42, 43, these strips converging downwardly with the portions 4|, 43 intersecting at 44 and thence diverging at 45. These longitudinal forms may or may not extend through the adjacent portions of the bead l6 and they may increase in width as shown, although in thickness they may be substantially equal to the strips 25, 21 and 3 32, and the grain thereof extends longitudinally. It is noted that the portions such as 4|], 4| extend to the strip 3| and are interrupted by th strip 32. These longitudinal strip formations are continuously bonded to the wall H and they have sufiicient longitudinal curvature for resilience lengthwise thereof. They are in other respects similar in function to the strips 25, 21, and. cooperate therewith to assist the sound chamber in taking up the tension caused by the strings of the musical instrument.

It is thus seen that there is provided an acoustic skeleton chamber for a string instrument embodying a novel principle for increasing the life and durability of the sound chamber, and avoiding efiects due to warping and unusual stresses to which the same may be subjected accidentally or otherwise, the several features of reenforcement operating at critical points so as to cooperate with each other to avoid weakening of the sound chamber at any one point which might thereby result in the creation of undue stress at some other point however remote. By constructing the reenforcing elements according to angular or curved formations they possess sufficient longitudinal elasticity to permit free vibration of the sound chamber. Because the strips are narrow and small in mass they will not exercise a dampening effect upon the sound vibrations. By suitable arrangement of the grain of the wood, the reenforcement is at a maximum, whereas the added mass of material is relatively a minimum. It will be appreciated that additional reenforcemerits may be added of varying size and shape and variously located to meet the requirements of a particular sounding board or chamber, those herein illustrated representing basic needs for the instrument.

The sound post 20 includes an angular or curved portion 5%} for longitudinal resilience and is particularly characterized in that the grain 5| of the wood extends obliquely or at an angle of approximately 45 to attain the requisite strength and use of the resilient sound post, the various reen-' forcing strips for the walls II and it! may be made of much smaller mass than otherwise. Nevertheless the sound post 20 has suiiicient stiffness not only for adequately supporting the bridge, but to prevent possible setting and permanent deformation of the sound chamber under the pressure exerted by the musical strings.

It will be understood that the reenforcements herein mentioned, or the sound chamber as a whole, may be made not only of wood, but of any other material, such as a plastic, which may be of fibrous or laminated nature to correspond in general to the grain of wood. Additional corner reenforcements such as strips 55 may be employed, or the element 32 enlarged to integrally include the strips 55, with the latter secured to the rear Wall l2 in the manner hereinabove described. It will also be appreciated that a plurality of sound posts corresponding in principle to that shown at 20 may be employed.

I claim:

1. A musical string instrument having a wooden vibratory sounding board having the grain thereof extending substantially lengthwise and responsive to sound waves generated by strings, and reinforcing longitudinally curved wooden vibratory strip elements spaced from the periphcry of the board along a substantial length thereof and secured in contact with said board, said strips being disposed to extend at an angle to the grain of the board with ends of the element terminating at the periphery of said board.

2. A musical string instrument having a sound chamber comprising wooden vibratory walls interconnected at an angle to each other and responsive to sound vibrations generated by strings, reinforcing means including bead-like strips extending along the periphery of the walls for reinforcing joints between adjoining walls, and elongated spaced Wooden strip elements adhesively united to one of said walls, said elements along a substantial length of each being spaced from the periphery of said first wall and directly connected at an end thereof to the other of said angularly disposed adjoining walls, said bead strips being cut away to permit said element end connection.

3. A musical string instrument having a sound chamber comprising wooden vibratory walls interconnected at an angle to each other and responsive to sound vibrations generated by strings,

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and reinforcing means including spaced elongated wooden strip elements having the grain extending substantially the length thereof and adhesively united to one wall, said elements alon a substantial length thereof each being spaced from the periphery of said first wall and having the ends thereof directly connected to the other angularly disposed adjoining wall, said elements being longitudinally curved for resilience and disposed in symmetrical relation with each other and to the contour of said first wall.

4. A musical string instrument having oppositely positioned sound vibrating walls responsive to sound generated by strings and a bass-bar extending longitudinally along one of said Walls, and reinforcing means for said one wall including elongated strip elements adhesively united to said one wall in spaced relation to the periphery thereof, said elements being longitudinally curved for resilience and having a thickness less than one quarter that of the bass-bar so as to permit vi ration thereof with said one wall.

GIUSEPPE VIRZI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 109,696 White Nov. 29, 1870 224,834 Marx Feb. 24, 1880 420,025 White Jan. 21, 1890 464,157 Hudson et al Dec. 1, 1891 673,949 Gould May 14, 1901 1,383,830 Leighton July 5, 1921 FOREIGN PATENTS Number Country Date 53,303 Austria Apr. 25, 1912 353,019 Germany May 10, 1922 633,516 France Nov. 9, 1928

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