US 3494241 A
Description (OCR text may contain errors)
e 10,, 1970 R. s. JONES, SR 3,494,241
FRETTED INSTRUMENT SOUNDING BOARD PROCESS AND PRODUCT Filed Nov. 1, 1967 5 Sheets-Sheet 1 BY semmes $2 semmes ATTORNEYS Feb. 10, 1970 R. s. JQNES, SR 3,494,241
FRETTED INSTRUMENT SOUNDING BOARD PROCESS AND PRODUCT Filed Nov. 1, 1967 5 Sheets-Sheet 2 INVENTOR flay/Av 5. 74/2255? BY Semmes $2 Semmes ATTORNEY Feb. 10, 1970 R 5, ES, 5R 3,494,241
FRETTED INSTRUMENT SOUNDING BOARD PROCESS AND PRODUCT Filed Nov. 1. 1967 5 Sheets-Sheet 3 I F/a x 76? y INVENTOR Iii/47s 74022:, 5/9:
81! Se'mmes & 8mm
ATTORNEYS United States Patent 3,494,241 FRETTED INSTRUMENT SOUNDING BOARD PROCESS AND PRODUCT Ralph S. Jones, Sr., Hyattstown, Md. 20734 Filed Nov. 1, 1967, Ser. No. 679,897 Int. Cl. Gd 3/02 U.S. Cl. 84-307 2 Claims ABSTRACT OF THE DISCLOSURE In the art of fretted and bowed musical instruments, an effort is made herein to provide, in wooden instruments, resonance and volume with clear tone and power whereby to carry the sound created at greater distances without distortion or loss of tone quality. The process in its most explicit terms resides in circularly shaping correspondng boards to delineate opposed circular diaphragms which are of exquisite uniformity from circumference to center thereof, the uniformity of thicknesses resulting in precision quality control in the manufacture of corresponding instruments. The instrument when assembled provides hereby an oval shaped air chamber.
Description of the prior art In the prior art, the design and shape of the diaphragm forming the sounding board varies with the exterior pattern of each instrument, most such instruments having been made of very thin selected woods having proven volume characteristics and given interior bracing, sufficient to support the thin structure against the stress of string tension. In such instruments, variation in depth of acoustic chamber yields progressively deeper or higher pitchedtones, as is known. Among the more popular instruments are those having arched tops and backs which are generally considered thicker in the center adjacent the bridge area tapering to the outer edge, thus yielding improved tone resonance and power, the arch created by the construction providing thereby an oval shaped air chamber. Conventionally, sound posts have been provided contiguous the bridge to transmit vibrations from front to back, Whereas others rely upon air transmission and yet in the manufacture of succeeding instruments purporting to have the same qualities, uniform tolerances as between diaphragm elements becomes practically impossible. Moreover, such instrumentation does not lend itself to variation in ovenall pattern or design of the instrument and/or improved acoustics brought about by variation in exterior design. Additionally, cracking and warping are brought about by the angular relation of supporting woods to supported, where imperfect sealing occurs or as inordinate stresses may be applied.
Field of the invention The field of the invention is such as to encompass both acoustic and acoustic-electric or electronic fretted instruments as well as bowed musical instruments, wherein uniformity in the creation of the acoustic chamber is of importance in the manufacture of multiple instruments each having the same precision quality control in the transmission of energy from the string. An effort is made herein to maintain the natural frequency of the instrument low, as for example only, under 360 c.p.s. avoiding thereby the range of harmonic frequencies which ultimately yield feedback, currently prevalent in electronic and electric instrument.
Description of the drawings In the drawings: FIGURE 1 is a plan view showing one-half of a circular, diaphragm sounding board acoustic chamber prepared in accordance with the first step of manufacture thereof;
FIGURE 2 is a vertical sectional view of the invention shown in FIGURE 1, taken along the lines 2-2 of FIG- URE 1;
FIGURE 3 is a showing of corresponding halves manufactured initially in accordance with the FIGURE 1 and FIGURE 2 showings, whereby the final step of shaping the respective opposed sounding boards has been applied;
FIGURE 4 is a modification of invention whereby the two assembled halves containing the sounding board of a fretted instrument have been shaped initially in accordance with the principles established under FIG- URES 1 and 2 inclusive and finished in accordance with the principles illustrated in FIGURE 3;
FIGURE 5 is a sectional view of invention showing enlarged portions of the respective sounding boards of FIGURE 1 in the pre-assembled condition;
FIGURE 6 is a view of the means for securing shown in FIGURE 5, fully assembled;
FIGURE 7 is a plan view of the assembled FIGURE 3 modification showing string anchor and individual bridges set in place; and
FIGURE 8 is a vertical sectional View of the FIGURE 7 device taken along the lines 88 thereof.
Description of invention To yield better tone and preserve the power of the energy created by string vibration and to maintain the natural frequency of the instrument low are among the objectives of invention. These are achieved by tapering the diaphragm sounding board elements, yielding a controlled tone, power of resonance and changing of frequency from center to rim of the respective diaphragms. Naturally, varying thicknesses of diaphragm will be used according to the density of the particular wood employed in the manufacture of the instrument, to achieve precision quality control, from instrument to instrument, to avoid feedback, to maintain natural frequency low, to preserve power of resonance, and to control tone. The instruments shown herein (FIGS. 1-6 inclusive) are especially adapted to electric-acoustic systems; nonetheless, it will be appreciated that for plain acoustic use, sound holes shall be appropriately cut in the top, back or rim of the instrument. Moreover, whereas the showings herein involve two-piece diaphragm construction to comprise the entire body of the instrument with rim, the application of separate rim with either front and/or back diaphragm attached thereto is within the spirit of the invention.
The process and product involve the steps illustrated in FIGS. 1-3 inclusive wherein it Will be noted with respect to FIG. 1 that a solid blank of material 100, configured to external design requirement has been placed on a lathe and accurately centered whereby the instrument half having fret board base 112, interior surface 114 and locking grooves 116 defines as well the outer surface 118. By graduated lathing the surfaces of the diaphragm 120, 122, 124, 126 and 128 are formed progressing in thickness from the center of the diaphragm to the outer rim thereof. In finishing by rotary shaving or sanding, one provides the diaphragm surfaces 140 and 140' of FIG. 3 wherein the halves and 120' have been assembled. My micrometric setting of the cutting tool of the lathe, a duplication of the same instrument may be made substantially automatically and without resort to fallibility of human error. In the particular FIG. 3 construction, the circular diaphragm sounding boards comprising the acoustic chamber are of convex configuration, the opposed and thickest surfaces of the respective sounding boards 118 and 118' providing a suitable base for a sound post, not shown.
A related arched top and back construction is shown in FIG. 4 wherein the modification 200 is provided with convex surfaces 240 and 240" yielding a substantially stronger acoustic chamber than is provided in the FIGS. 1 and 3 concepts. Obviously, different thicknesses of diaphragms will be used according to the density of the particular wood, conforming thereby to a pre-selected frequency, established by electronic visual testing at interval diameters of the diaphragm to control thereby tone, power of resonance and frequency change from center to rim.
In assembly, it is proposed that the diaphragm half is circularly machined of the varying thicknesses and finished by shaving and sanding as indicated; that subsequently, the machine diaphragms are respectively treated with a moisture resistant lacquer both externally and internally of the respective surfaces and that sequentially, the two halves are brought together under spring tension in the manner illustrated in FIGS. 5 and 6 by means of the opposed spring tension assemblies 150 and 150 which are fastened to the instrument halves 110 and 110' by means of the screws 152 and locked in position as in FIG. 6. This fastener construction is a tension type yielding a vibration free overall construction.
The results achieved hereby are to avoid cracking of joints as between the components forming the diaphragm sounding boards, which may be due to expansion and contraction of counteracting grains in the wood. Accordingly, in practice, it is desired that the respective halves delineating the acoustic chamber are aligned grain for grain, precedent to tension locking thereof.
This controlled thickness controls feedback and yields perfect reproduction with uniform response in view of the asymmetric formation of the respective halves comprising the sounding board and of the opportunity to duplicate same faithfully from instrument to instrument depending on the setting of the machine tools involved.
With reference now to FIGS. 7 and 8, the instrument having top is provided with suitable string anchor 150, the respective strings being anchored by posts 152, said strings being adapted to pass over individual bridges mounted as indicated at upon a transversely extending base 162462 through which the respective adjustable uprights 164- having adjustment nut 166 with bevelled edge 168 is seated to secure the rearmost bifurcated portion of the respective string bridges '170. The bridges 170 are, as indicated in FIG. 7,' bifurcated at 172 and provided with transverse corrugations 174, for seating with the bevelled edge 168 of the adjustment nut 166. At the forward portion of each cantilever bridge construction 170- there is found the bridge slope 176 having appropriate grooves 178 disposed for securing each string against transverse displacement. Said bridge includes cavity 180 having appropriate corrugations to securely seat the bevelled edge 182 of the fulcrum member 184, said fulcrum member being movably adjustable longitudinally of the instrument and vertically to Vary the pitch of the respective strings in critical sounding board area which is normally located immediately adjacent the center of the sounding board, per se.
1. In fretted musical instruments having strings secured in adjustable relation to a diaphragm sounding board, the improvement comprising:
(A) a floating bridge for at least one of each of said strings;
(B) a bridge anchor secured to the diaphragm of the sounding board, said bridge being in movable contact with the bridge anchor at one end and having a string supporting projection at the other end,
(C) a movable bridge fulcrum on the diaphragm detached from the bridge, the point of maximum string tension support being regulated by the fulcrum location on the diaphragm, intermediate ends of the bridge.
2. The improvement according to claim 1 in which the fulcrum member is disposed substantially immediately adjacent the center of the diaphragm for horizontal adjustment relative thereto and for vertical adjustment of the cantilever bridge to increase and decrease the pressure on the diaphragm as the increase in string tension may be adjusted.
References fited UNITED STATES PATENTS 906,612 12/1908 Cayton 84-291 1,001,302 8/1911 Ranch 84-291 1,361,182 12/1920 Reams et al. 84-291 1,649,559 11/1927 Bacon 84-291 3,181,409 5/1965 Burns et al 84-307 3,302,507 2/1967 Fender 84-291 OTHER REFERENCES Music Trade Review, Oct. 8, 1921.
RICHARD B. WILKINSON, Primary Examiner L. R. FRANKLIN, Assistant Examiner US. Cl. X.R. 84-291, 294