US3908503A

US3908503A - Device in stringed musical instruments

Info

Publication number: US3908503A
Application number: US413301A
Authority: US
Inventors: Gustav Georg Arne Bolin
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-09-28
Filing date: 1973-11-06
Publication date: 1975-09-30
Anticipated expiration: 1992-09-30

Abstract

Apparatus for reproducing and amplifying the sound emitted by a stringed musical instrument in which the individual strings of the instrument are connected to separate microphones and the microphones are connected through an amplifier to sound distributing means having a soundboard with similar tonal characteristics as the musical instrument so that the individual tones are reproduced and amplified.

Description

United States Patent [1 1 Bolin 1 1 DEVICE IN STRINGED MUSICAL INSTRUMENTS Gustav Georg Arne Bolin, 12, Renstiernas Gata, 116 31 Stockholm, Sweden 22 Filed: Nov. 6, 1973 21 Appl.No.:413,301

Related US. Application Data [63] Continuation of Ser. No. 292,690, Sept. 27, 1972,

[76] Inventor:

abandoned.

[30] Foreign Application Priority Data Sept. 28, 1971 Sweden 12274/71 [52] US. Cl. ..84/l.16;84/1.14; 181/173; 179/181 [51] Int. Cl. G10F 1/02 [58] Field of Search 181/148, 157, 160, 155,

181/173;179/115.5 R, 115.5 ES, 115.5 PV, 115 R, 181;84/1.141.l6

[56] References Cited UNITED STATES PATENTS Marriott 181/173 [451 Sept. 30, 1975 1,746,289 2/1930 Simpson 179/115 R 1,756,838 4/1930 Staunton 181/148 1,773,910 8/1930 Lane 181/148 1,849,401 3/1932 Fleck... 181/160 1,884,724 10/1932 Keller 181/148 2,731,101 1/1956 Klipsch 181/148 2,896,736 7/1959 Karlson 181/160 3,073,203 l/1963 Evans 84/1.16

3,111,189 11/1963 Scholl 84/160 3,365,021 l/1968 Transue 181/148 Primary Examiner.loseph W. l-lartary Assistant ExaniinerU. Weldon Attorney, Agent, or Firm-A. Yates Dowell, Jr.

[57] ABSTRACT Apparatus for reproducing and amplifying the sound emitted by a stringed musical instrument in which the individual strings of the instrument are connected to separate microphones and the microphones are connected through an amplifier to sound distributing means having a soundboard with similar tonal characteristics as the musical instrument so that the individual tones are reproduced and amplified.

2 Claims, 13 Drawing Figures U.S.Pat ei1t Sept. 30,1975 Sheet 1 of6 3,908,503

Fig.2

US. Patent Sept. 30,1975 Sheet20f6 3,908,503

U.S. Patent Sept. 30,1975 Sheet 3 of6 3,908,503

Fig.6 5

g 33 m 1v1111r 1111/ ///I/// Sheet 4 0f 6 Sept. 30,1975

U.S. Patent I U.S. Patent Sept. 30,1975 Sheet5 of6 3,908,503

U.S. Patent Sept. 30,1975 Sheet6of6 3,908,503

DEVICE IN STRINGED MUSICAL INSTRUMENTS This is a continuation of application Ser. No. 292,690 filed Sept. 27, 1972 now abandoned.

This invention relates to a device for amplifying the sound emitted from a stringed musical instrument provided with a soundboard by means of a microphone device housed in the instrument, an amplifier connected to said microphone device and an electromagnet and coil connected to the output of said amplifier and actuating the sounding board of an instrument body (sound distributor). The invention shall hereinafter be explained with reference to guitars, although it may be applied to other stringed musical instruments also, such as to violins, pianos etc. Hitherto in the emission of music the guitar sound'has been amplified by means of an amplifier of conventional type, e.g. by connection to loudspeaker in the shape of a radio receiver or radiogramophone, the loudspeaker, however, in a disadvantageous manner more or less suddenly intermixing the emitted sounds. The loudspeaker does not solely emit and amplify the fundamentals but also non-desired overtones and this results in a mostly loud, indeterminable mixture of the different sounds in which mixture the character of the instrument disappears more or less completely.

The main object of the invention is to eliminate this inconvenience so that the sound amplified by the sound distributor does not change its character but retains its proper acoustic quality, and in addition prolongates the resonance inherent to the instrument. This is substantially attained by the individual strings being arranged each to be under the action of its associated pressureresponsive microphone of crystal type which microphone individually is in connection with the amplifier and that the sound distributor is a separate unit relative to' the instrument and has a soundboard or sounding board which is tuned to the soundboard of the stringed instrument and to which the armature of the electromagnet is coupled.

The sound distributor is an instrument body with a sounding board having the same dimensions as the soundboard of the primary instrument for amplifying the natural sound. The sounding board of the loudspeaker separates off non-desired overtones in the same manner as is effected inthe primary instrument. The sound distributor tunes the desired frequency range from the impulses emitted from the crystals of the individual pressure-responsive microphones. This is an effect which is quite different from the effect of the cone made of pasteboard of the convenient loudspeaker which emits all sounds caught by the microphone device.

The invention shall hereinafter be described in more detail with reference to some embodiments shown by way of example in the accompanying drawings, further features characterizing the invention being indicated in this connection also. 1

In the drawings:v

FIG. 1 is a principle diagram illustrating the invention applied to a guitar;

FIG. 2 is a cross-section through'the bridge of the guitar represented on a larger scale;

FIG. 3 is a perspective view of a sound distributor shaped as a foot-stool and with some portion assumed broken away;

FIG. 4 is a sectional view following the line IV-IV of FIG. 3;

FIG. 5 is a lateral view of a sounding board forming part of this embodiment;

FIGS. 6 and 7 are sections following the lines Vl-VI and VIIVII, respectively, in FIG. 5;

FIG. 8 is a perspective view of another embodiment of a sound distributor with parts assumed broken away; FIG. 9 is a view following the direction of the arrows IXIX in FIG. 8;

FIGS. 10 and 11 are perspective views of two additional embodiments of the sound distributor with some portions assumed broken away; and

FIG. 12 is a perspective view of the sounding board associated to FIG. 11 and represented partially cut up.

FIG. 13 is a section on the line l313 of FIG. 4.

In all drawing Figures equivalent parts are denoted by the same reference numerals.

Referring now to the drawings and in particular FIGS. 1 and 2, the soundbox 10 of the guitar supports a number of strings 12 which with their one ends are fixed in a member 14 of the soundbox and from there drawn over a bridge 16 and extend along the neck 18 of the guitar to pegs 20 in conventional manner. Provided in the bridge 16 is for each string 12 a piezoelectric, pressure-responsive microphone 22 of the crystal type which thus individually transmits the vibrations of the associated string through a common leader 26 to an amplifier 24. The amplifier may be an amplifier in a conventional radio set or radio gramophone, the loudspeaker thereof, however, being replaced by a resonance box or sound distributor 28 which has a sounding or resonance board 30 of wood which has the same tonal characteristics as the soundboard 10 of the guitar box 10 and which amplifies the low frequency signals generated by the microphones 22. The sounding board 30 is here actuated by the armature 34 of an electromagnet coil 32 which is in contact with the sounding board 30. The resonance box or sound distributor 28 is tuned in the same manner as the sound box of the primary instrument so as to be capable of mechanically separating or filtering off all non-desired overtones etc.

It is of importance that the guitar player is near the source of the sound so that he is able to control the sound reproduction.

The sound distributor may have more than one electromagnet coil and armature.

In the embodiment shown in FIGS. 3 through 7, the casing of the sound distributor has been given the form of a foot-stool 36 provided with a sitting surface 38 intended to be occupied by the musician playing the stringed instrument. The sounding board 30 or the uncovered main portion thereof inside an external clamped edge portion has an increasing width in the direction from one lateral edge 40 to an opposed lateral edge 42, preferably so as to assume the shape of a parallel trapezoid having the upper lateral edge 40 and the lower lateral edge 42 in mutually parallel relationship, the two lateral edges 44 and 46 therebetween converging in upward direction. In this embodiment the sounding board 30 is located in an upright position between spaced

end walls

48 and 50 of the casing of the footstool and extends far enough to reach and be secured to

side walls

52 and 54 as well as top wall 56 and bottom wall 58.

Side walls

52 and 54 converge in an upward direction and are complementary to the edges 44 and 46 of the sounding board 30. The top wall 56 and the bottom wall 58 of the foot-stool are parallel with one another and follow the

edges

40 and 42, respectively, of the sounding board. The electromagnet 32 and the armature 34 connected therewith are supported by a horizontal, preferably U-profiled beam 60. The armature 34 bears against an elongated vertical strip 62 made of wood and over its entire length rigidly secured onto the sounding board 30. The strip 62 is located centrally and the armature 34 is adjacent to said strip at a place 64 located slightly below the center of the sounding board. The breadth as well as the height of the strip 62 may decrease in both directions towards the ends. The strip is intended to transmit and distribute signals transmitted from the armature of the electromagnet to the sounding board 30. The wood strip 62 may be compared with the bridge of a guitar or the like instrument.

Provided on both sides of the central, strong strip 62 are one or several narrower strips 66 which are in parallel relationship with the adjacent, inclined edges 44 and 46, respectively, of the sounding board and which have for their purpose to stabilize and distribute the vibrations in the board. The thickness of the sounding board has its maximum at the place of contact 64 of the armature and decreases therefrom in all directions, as is indicated by circular level lines 68. Each such circular line represents a change in thickness of e.g. between 0.25 and 0.5 mms. The afore-described shape of the sounding board is applicable to all embodiments where the board is made in a single layer.

The sitting surface 38 is positioned at a predetermined distance above the top wall 56 of the casing as is best seen in FIGS. 3 and 4. Through the interspace formed in this way and an aperture 70 formed in the top wall 56 the interior of the sound distributor is in open communication with the surroundings. The end wall 50 is attached to the top wall 56 and bottom wall 58 but the sides of such end wall are spaced from the

side walls

52 and 54. A baffie or wall panel 51 extends inwardly from each of the side walls and terminates in horizontally spaced overlapping relationship with the end wall 50 (FIG. 13) to provide additional open communication with the surroundings.

In the embodiment according to FIGS. 8 and 9 the casing of the sound distributor has the shape of a small table in which the sounding board 30 is disposed horizontally in a frame 72 which follows the trapezoidal configuration of the table top. The corners of the frame are connected to legs 74 which support the table top 76. The electromagnet 32 and the armature 34 are disposed below the sounding board and supported over the beam 60 by the frame 72.

The embodiment according to FIG. 10 differs from the preceding one mainly by the sounding board 30 being inclined and extending diagonally between two opposite lateral edges of the casing. Said casing has walls which are adapted to the trapezoidal configuration of the board 30.

In the embodiment illustrated in FIGS. 11 and 12 the sounding board 30 has the shape of a box the broad sides of which are constituted by two thin

wooden boards

76, 78 which suitably have increasing width in the direction from the top to the bottom, preferably so as to assume the shape of a parallel trapezoid. The two

boards

76, 78 are fixed to a frame composed of two vertical elements 80 and two horizontal elements 82.

The boards have a vaulted form curved about a vertical axis. For this purpose the top and bottom elements 82 are formed with curved edge portions 84 which are broadest in the central portion which the boards bear against. The edge portions 84 may follow a circular or an elliptical curve. Since the frame elements are equally broad over their entire length, the height of arch is greater at the bottom edge of the board than at the top edge thereof. I-Ioused within the box is an inclined beam 86 which bears against the

boards

76, 78 and occupies the major portion of the vertical dimension of the box. Formed approximately in the centre of the sound distributor are suitably curved slots or so called sound-holes 88. The armature 34 exercises its action centrally between said slots. In this embodiment the sounding board 30 has an upright position inside the casing of the sound distributor. The beam 60 supporting the electromagnet 32 and the armature 34 extends vertically between the bottom and the top along the rear side of the casing which side may be open. In this case the casing has sides placed altogether at right angles to one another, the sounding board 30 being held in the predetermined position by lateral knobs 90.

Obviously, the invention is not limited to the embodiments shown and described, but may be varied in many respects within the scope of the basic idea thereof.

I claim:

1. Apparatus for producing and amplifying musical sound comprising the combination of a musical instrument having a plurality of strings which produce sound by vibration, an independent pressure responsive microphone connected to each of said strings, said microphones transmitting vibrations along a common leader to an amplifier, sound distributing means located in a position remote from said musical instrument, said sound distributing means having substantially similar tonal characteristics as the musical instrument and including a resonance box having wall structure defining an enclosed area of generally trapezoidal configuration, said resonance box having at least one opening, a wooden soundboard mounted within said box, said soundboard having a first pair of generally parallel edges and a second pair of edges disposed at an angle to each other and defining a trapezoid which engages portions of said wall structure, a first elongated strip mounted on said soundboard and having a longitudinal axis disposed generally centrally between the angularly disposed edges of said soundboard, at least two additional elongated strips mounted on said soundboard at opposite sides of said central strip and spaced therefrom, said additional strips having longitudinal axes disposed at an angle to the axis of said first strip, support means located within said resonance box, an electromagnetic coil mounted on said support means and coupled to said first elongated strip, said electromagnetic coil being operatively connected to said amplifier, whereby vibrations produced by said strings are amplified and reproduced at greater volume by said sound distributing means.

2. The structure of claim 1 in which the central portion of said soundboard is of a predetermined thickness and the thickness of the remaining portions of the soundboard decreases in all directions.