US2680986A - Pickup for musical instruments - Google Patents

Description

June 15, 1954 A. COMPANY 2,680,986

' PICKUP FOR MUSICAL INSTRUMENTS Filed Nov. 23, 1951 l N VENTOR A 1 mm Co/v/w/v) BY IQQAW, M f de' ATTORNEYS Patented June 15, 1954 UNITED STATES FATENT OFFICE PICKUP FOR MUSICAL INSTRUMENTS Alvaro Company, Florence, Italy Application November 23, 1951, Serial No. 257,683 Claims priority, application Italy August 6, 1951 (ill. a l-1.15)

7 Claims.

It is known that the stringed instruments, such as guitar and the like, have a rather limited volume of sound, which decreases the possibilities of use, especially in the high sound volume orchectral units.

For this reason some amplifying systems, which however alter the proper original sound of the instrument in question, have been devised.

The system, until now most used, for the amplification of the sound of the stringed instruments and in particular of the guitar, consists in capturing the vibrations directly from the strings or cords, which in said case can only be metallic, and transmit said vibrations to an amplifier and from the latter to a loudspeaker. The resulting sound, amplified with this system, is different respect to the original one of the guitar; in fact, the harmonical case may be eliminated in this instrument and there results to be a metallic sound, deformed respect the original sound. Another method, to which sometimes one recurs for the amplification of the sound of said instruments, is the one consisting in putting a microphone in front of the instrument; but by this method, not only one captures the foreign sounds, but obtains also a constrainedly distorted sound.

The device in question instead makes use of the vibrations of the harmonical plane of the instrument, which are originated from the vibrations of the strings or cords of the same instrument. It results that the metallic cords or strings are no longer an indispensable assumption to obtain the amplification of the same sound and therefore can be also of bowel or catgut or nylon, attaining in this way a satisfactory result, which does not alter the original sound of the instrument. It is therefore possible the use of the guitar also in the orchestras for classic music, until now excluded to said original instrument without amplification, owing to the modest vol ume of sound of said instrument.

The device in question is formed by two groups or sets, each made up of a mechanical means apt to resiliently press the cup or mike, containing the magnet apt to capture the vibrations, in an adjustable way against the inner bottom of the upper plane of the instrument or harmonical plane, with the interposition of a resilient thickness and of an adjusting means; in correspondence of the two ends of the magnet, on said inner bottom of the harmonical plane of the instrument, a thin metallic plaque is applied, said plaque, by means of the adjustment, is more or less brought near to the two ends of the electromagnet.

The vibrations, captured by the magnet, are sent to an amplifier and to a loudspeaker, known per se. Means, apt to avoid that the vibrations be transmitted from the upper plane to the lower on of the instrument, are provided; said means, including, for instance, besides the above-mentioned resilient means, also unelastic thicknesses, such as layers of Chamois leather and the like.

The invention will be better understood follow ing the specification and the accompanying drawing, which shows a schematic form of actuation of the same invention.

In said drawing:

Fig. 1 shows a front View, partially sectioned, of guitar;

Fig. 2 shows a side view of a guitar, partially sectioned along the line II-II of Fig. 1;

Fig. 3 shows, in an enlarged scale, a section of the device according to the line III-III of Fig. 1;

Fig. shows a view according to the line IV-IV of Fig. 3.

Fig. 5 shows a group provided of a tool destined to provide for the application of the metallic plaque to the inner bottom of the harmonical plane.

According to the drawing, the double device is applied to a guitar, of which I indicates the bottom plane of the case, and 2 indicates the upper plane or harmonical plane, provided of theusual opening 3 in correspondence of the cords orstrings 4. The double device in question includes two distinct and equal groups or sets, which are arrangedas it is to be seen in Fig. 1- symmetrically respect the longitudinal plane of symmetry of the instrument and slightly lower respect theopening 3. Each of said groups or sets, forming the double device, comprises (especially see Figs. 3 and 4) abutton 5 shaped as a disc, said button being applied on the inner surface of the lower plane I of the case in a stable way. Said button or bottom centrally shows a recess ii destined to receive the correspondingly shaped lower end I of a threadedpin 7, said pin being thus susceptible of being introduced with itsown appendix 1 into therecess 8 of the disc without any possibility of rotation. Aring 8 destined to operate as a lock nut, besides acylindrical element 9, upperly finishing in a slight shaped enlargement, as in the drawing, are screwed onto thepin 1; thedisc 8 and theelement 9 are both centrally bored with threaded through holes for the reception of thepin 1. Theelement 9 in its upper section shows a cylindrical and coaxial recess in (see especially Fig. 5), in which said threaded hole enters; said recess it is destined to receive a small cylindrical block H, which is mounted in said recess, being surrounded by a thickness l2 of chamols leather or the like. which is destined to absorb the vibrations, transmitted-for what will be hereafter said-to the block I i.

The disc orbutton 5, the pin l, thedisc 8 and theelement 9 are more especially made up of wood, while the block I! is made of bronze or brass or the like.

Thedisc 8 and theelement 9 coact each other in order to constitute a system of nut and lock nut, for the purpose of adjusting the position of the upper surface of the small block it respect the bottom of the wall I, the adjustment taking place by effect of the threading of the pin l, and the fastening by tightening thedisc 8 in function of a lock nut against theelement 9. Aleaf spring 13, is connected, by means of welding or by rivets or by another way, to the small block ii and said spring is also connected in the opposite position to a metallic support M apt to engage the cup or mike iii, altogether similar to a microphone for radio-receivers and the like. Said cup l centrally carries a magnet [5 having a U-shape with the ends turned up wardly (respect Fig. 3); an arm of said magnet it being provided of a coil H which is wound on said arm and which is connected to a bipolar cable It; the cable I8 is connected to an apposite circuit and to an amplifier, of a type known per so, on its turn, connected to a loudspeaker. The cup i5 is surmounted by a threadedring 19 which carries aresilient washer 20, for instance, made of para rubber, saidwasher 20 being pressed, by the action of a leaf spring is against the inner bottom of theupper plane 2 or harmonical plane of the case of the instrument.

In the centre of the cup l5 and in the centre of the zone of the inner surface of theplane 2, restricted by thewasher 20 pressed against said plane, ametallic plaque 2|, having a very thin thickness, is applied stably on said surface;

therefore, theplaque 2| is to be found in correspondence of the arms of the magnet l6 which is centrally located in the cup I5, the distance, between the ends of said arms of the magnet i6 and the metallic plaque 2i, being susceptible to be adjusted screwing, more or less, the ring I9 on thecup 15.

For the location and situation of the specified unit, one determines the position of thebuttons 5 and fasten them on the plane said buttons bear the elements l--8-9; therefore, it is provided for the fastening of the plaque 2i coaxially'to the recess 6 of thedisc 5; for this purpose, thetail 22 of ashaped tool 22, on which upper surface the plaque Z1 is provisionally secured, is inserted in the recess of the element 9 (see Fig. 5); a suitable gluing element is distributed on said plaque; screwing theelement 9 on the pin '3, theplaque 2! lies and presses, through thetool 22, against the inner bottom of theplane 2, theplaque 2| being in said way located in the desired condition. After the drying of the gluing element, which assures the fastening of theplaque 21, thetool 22 is removed, lowering theelement 9; successively the already described and illustrated members of Figs. 3 and i are mounted.

The leaf spring I3 is pressed, more or less, adjusting the position of theelement 9, which is locked by thedisc 8; by this, a determined compression of theresilient washer 20 is obtained against the inner bottom of theplane 2.

The vibrations, which-es usually-are transmitted by the cord or strings, in the known way, to theharmonical plane 2, are captured by the magnet l6, coacting with theplaque 2| and transformed through the winding or coil H, which, by means of thecable 18, energizes the amplifier. Therefore, vibrations, corresponding to those of the sounds produced by the instrument, without deformations or distortions respect the original sound of the same instrument, are transmitted to the amplifier; in fact, the instrument is not modified at all in its harmonical case, nor are its cords or strings l exchanged with necessarily metallic strings, nor are the vibrations, finally, directly taken away from the cords, but from the members, which definitely emit the genuine sonic vibrations of the instrument.

It is intended that the drawing only shows a schematic form of actuation, given only as a practical demonstration of the invention, said invention being in condition to be varied in its forms and executions, without, however, departing from the ambit of the concept which informs the same invention. For instance, the material forming the various members may be different respect that indicated, though being functionally similar; the elements may also assume other shapes and forms, adapted for the purpose.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. A sound amplifier device for stringed instruments provided with a sound box, wherein there are a bottom board and a sound board, made up at least of an unit housed in the inside of the sound box and including a cup containing an U-shaped magnet and a coil combined therewith, adjustable resilient means re-acting between the bottom board and the cup so as adjustably to press said cup against the inner surface of the sound board, positioned in correspondence with the end of the U-shaped magnet, a small thin metallic plate secured to said inner surface of the sound board, and co-operating with said magnet in order to produce an electrical current and a resilient layer interposed between said cup and said inner surface of the sound board.

2. A sound amplifier device for stringed instruments provided with a sound box, wherein there are a bottom board and a sound board, made up at least of an unit housed in the inside of the sound box and including a cup containing an lJ-shaped magnet and combined therewith a coil, a base applied to the bottom board; a threaded stud rising from said base, an element and a disc screwed on said stud and operating as a nut and a locknut connected to said element, a spring pressing said cup against the inner surface of the sound board positioned in correspondence with the end of the U-shaped magnet, a small thin metallic plate secured to said inner surface of the sound board, and co-operating with said magnet in order to produce an electrical current and a resilient layer interposed between said cup and said inner surface of the sound board.

3. A sound amplifier device for stringed instruments provided with a sound box, wherein there are a bottom board and a sound board, made up at least of an unit housed in the inside of the sound box and including a cup containing an U-shaped magnet and combined therewith a coil, a base applied to the bottom board, a threaded stud rising from said base, an element and a disc screwed. on said stud and operating as a nut and a locknut, a small block housed in said element having interposed therebetween a layer capable of absorbing vibrations, a leaf spring connected to said small block and arranged to press said cup against the inner surface of the sound board, positioned in correspondence with the end of the U-shaped magnet, a small thin metallic plate secured to said inner surface of the sound board and co-operating with said magnet in order to produce an electrical current and a resilient layer interposed between said cup and said inner surface of the sound board.

a. A sound amplifier device for stringed instruments provided with a sound box, wherein there are a bottom board and a sound board, made up at least of an unit housed in the inside of the sound box and including a cup containing an U-shaped magnet and combined therewith a coil, adjustable resilient means re-acting between the bottom board and the cup so as adjustably to press said cup against the inner surface of the sound board, positioned in correspondence with the end of the U-shaped magnet, a small thin metallic plate secured on said inner surface of the sound board, and co-operating with said magnet in order to produce an electrical current, a resilient layer interposed between said cup and said inner surface of the sound board and means for the adjustment of the distance between the magnet and said small thin plate.

5. A sound amplifier device for stringed instruments with a sound box, wherein there are a bottom board and a sound board, made up at least of an unit housed in the inside of the sound box and including a cup containing an U-shaped magnet and combined therewith a coil, said cup furthermore including a ring, adjustably threaded to said cup, a base applied to the bottom board, a threaded stud rising from said base, an element and a disc screwed on said stud and operating as a nut and element, a spring arranged to press said ring, screwed onto said cup, against the inner surface a locknut connected to said 4 of the sound board, positioned in correspondence with the end of the U-shaped magnet, a small thin metallic plate secured to said inn r surface of the sound board and co-operating with said magnet in order to produce an electric current and a resilient layer interposed between said ring, screwed onto the cup and said inner surface of the sound board.

6. A sound amplifier device for stringed instruments provided with a sound box, wherein there are a bottom board and a sound board, made up at least of an unit housed in the inside of the sound box and including a cup containing an U-shaped magnet and combined therewith a coil, said cup furthermore, including a ring, adjustably threaded to said cup; at base applied the bottom board; a threaded stud rising from said base; an element and a disc screwed on said stud and operating as a nut and a loclznut, a small block housed in said element, an interposed layer capable of absorbing vibrations, a leaf spring connected to said small block and arranged to press said ring, screwed onto said cup, against the inner surface of the sound board, positioned in correspondence with the end of the ll-shaped magnet, a small thin metallic plate secured to said inner surface of the sound board and cooperating with said magnet in order to produce an electric current and a resilient layer interposed between said ring, screwed onto the cup, and said inner surface of the sound board.

7. A sound amplifier device for a stringed in strunient having a sound box, and an opening therein, according toclaim 4, wherein two units are provided and are symmetrically arranged on the sound box of the instrument in a position below said opening of the sound box of the instrument and in correspondence with the strings of said instrument.

References flirted in the file of this patent UNITED STATES PATENTS Number Name Date 1,838,886 Tuninga Dec. 29, 1931 2,025,875 Loar Dec. 31, 1935 2,486,264 De Armond Oct. 25, 1949

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