Digital Violin


makers . vintage

The Violin is Dead
Eisenberg's Electric Violin Patent Drawing
Long Live the Violin

GEORGE EISENBERG (1929)


Patented Mar. 7, 1933 (1,900,489 )
UNITED STATES PATENT OFFICE
GEORGE EISENBERG, OF BROOKLYN, NEW YORK
MUSICAL INSTRUMENT OF THE VIOLIN TYPE
Application filed April 2, 1929. Serial No. 351,874.

This invention relates to musical instruments and has particular reference to an improvement in a stringed instrument of the violin type. The main object of the invention is to provide a simple and efficient means whereby the bowing of a single stringed instrument of the violin type will result in the reproduction of a volume from such an act of several times the amount of sound which would ordinarily be produced from the single instrument. A further object is to produce this increased volume of tone with absolute clarity and accuracy as to pitch and timbre of the original tone. A still further object is to provide a simple, compact device which can be applied to the stringed instrument and can be quickly and easily adjusted by the musician, after which he can proceed to play it without having to give further thought to the device.

Description of the construction
In the preferred form as at present embodied and illustrated in the drawings, the invention is applied to a musical instrument of the violin type having a frame provided with the usual neck. The usual belly and back are lacking and instead the frame is provided with bars extending from the front to the rear of the frame respectively at the top and the bottom thereof. The upper bar is reinforced with a dependent flange as shown. A cross bar is also provided. The instrument is provided with the usual strings fastened at one end to the tail piece and passing over the bridge mounted on the upper bar. Fastened rigidly to the top of tile bridge by lock nuts is a rod acting as transmitter of vibrations from the strings through the bridge. This rod extends outwardly for a short distance and then downwardly through a hole in the upper bar, clearing this hole without contact therewith. At its lower end it is bent outwardly again and extends rearwardly of the frame and its outer end lies freely within a central bore or opening in a magnet coil. At the lower portion of the rod where it bends outwardly, it is engaged by a flexible member such as a cat-gut string or cord which is wrapped around a shaft. The other end of the shaft has a worm wheel meshing with a worm gear on a shaft to the upper end of which is fastened a thumb piece by turning which the tension and position of the vibration member or rod can be regulated through tightening or loosening the cat-gut.

The electrical unit which is affected by the vibrations of the member or rod comprises a horse-shoe magnet. Beneath the magnet there is disposed a metallic plate of the same general shape and area. Disposed between this plate and the lower face of the magnet is a sheet of fiber or insulation. At its forward edge the plate is provided with upstanding spaced ears formed integrally therewith, and having a gap therebetween at the center of the forward edge of the plate. Disposed back of the ears are a pair of U-shaped pole pieces located with their bases facing away from each other and with their respective legs extending toward each other. The legs of these pole pieces have parallel faces and are spaced apart a given distance back of the gap formed between the ears above mentioned. The other legs of these pole pieces are tapered and their outer ends are small and lie closely adjacent each other but parallel to form a small gap therebetween much smaller than the gap or distance between the legs. These pole pieces are held in position by means of screws passing through the legs and headed into a plate of non-magnetic material lying back of the other side of the face of these legs. The other ends of these screws are engaged by lock nuts lying against the opposite faces of the ears. A shield plate of non-magnetic material is held between the lock nuts and in front of the ears. The plate has a hole in its center in line with the gap between the legs to permit of the passage of the end of the vibrating rod. The outer end of this rod will lie very close to the gap between the legs and because the magnetic field across this gap is very intense the effect of the vibration of the rod thereon is to make the field variations very sensitive. The horse-shoe magnet is held in position against the pole pieces merely by reason of the magnetic pull. Within the pole pieces, the magnetic coil is disposed and lies snugly therein but is not fastened in place. Wires leading from the coil are fastened to an insulating block disposed loosely within the horse-shoe magnet back of the coil. This block has a central screw which passes through holes in the sheets, the plate and the brass container to engage the lower bar and is held by nuts in position on the bar and within the container. A soft pad of rubber lies within the brass container between the ends of the screws connected to the plate and the end wall of the container or box. This pad has a hole therein to permit of the passage of the rod, and acts as a damper of vibrations. The wires connected to terminal clips on the block pass through a hole in the plate and on their other ends are provided with tips to connect to any suitable electrical device such as an audio frequency amplifier.

Operation of the device
When the strings of the instrument are bowed or otherwise vibrated to produce simple melody vibrations or complicated ones representing harmonies, these vibrations are transmitted to the bridge. This in turn is set into vibration and these are transmitted to the transmitting member or rod. The sensitivity of this rod to being vibrated is to some extent dependent upon the tension set up therein by the adjustment through the intermediary of the cat-gut flexible member which can be adjusted in the manner above described. This adjustment also positions the rod with respect to the magnet pole pieces. The magnetic field into which the end of the rod extends is strong but is particularly so near the outer end of the rod and between the legs where the field is very concentrated and the slightest vibration of the end of the rod closely adjacent to the gap between these two legs causes a strong and very sensitive variation in the magnetic field which sets up, in the usual manner, strong and very sensitive variations in the current in the coil which are sent out over the wires to the audio- amplifier and properly magnified to be reproduced on a loud speaker or other device. Thus the vibration of the strings can be strongly and with extreme accuracy amplifies so that the resultant volume is equal to that of several stringed instruments instead of to one. By utilizing this arrangement, a small orchestra of stringed instruments can be amplified to equal a much larger one.
In other words, the stringed instruments not only generate air vibrations as usual but set up very strong and sensitive electrical vibrations which are amplified many times if desired. Several instruments can be connected up to the same audio amplifier so that one loudspeaker can send forth the combined instrumental effects of the several instruments.
It is to be distinctly understood that when we speak of stringed instruments of the violin type we mean to include such instruments as violas, cellos, bass viols, mandolins, banjos, and other stringed-instruments. The device is simple, compact and can be readily adjusted so that the utmost sensitivity of the vibratory parts can be obtained without any trouble on the part of the musician. When the vibrator has once been adjusted, the musician plays as usual and has nothing further to concern him except his playing.
While I have described our improvement in detail and with respect to a preferred form thereof, I do not desire to be limited to such details or form since many changes and modifications may be made and the invention embodied in other forms without departing from the spirit and scope of the invention in its broader aspects. Hence I desire to cover all modifications and forms coming within the language or scope of any one or more of the appended claims.

::: ELECTRIC VIOLIN : MAKERS : VINTAGE :::
BAH

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