US3325579A - Electrical stringed instrument - Google Patents

Description

June 13, 1967 y, Q CQOKERLY ET AL 3,325,579

ELECTRICAL STRINGED INSTRUMENT Filed March 30, 1965 I2 I3 I4 5 INVENTORS so l JACK c. cooKERLY Fle. BY GEORGE R. HALL ATTORNE S United States Patent O 3,325,579 ELECTRICAL STRINGED INSTRUMENT .laclr C. Cookerly, 7566 Atoll Ave., North Hollywood, Calif. 91695, and George R. Hall, 13613 Huston St.,

Sherman (laks, Calif. 91403 Filed Mar. 30, 1965, Ser. No. 443,958 7 Claims. (Cl. 84-1.16)

ABSTRACT OF THE DISCLOSURE This disclosure relates to an improved electrical guitar wherein a uniquely designed magnet is employed to provide a magnetic iield cutting across the strings over a portion of the length of the strings 4between the guitar nut and bridge. The magnetic field configuration is such that the resulting current induced in the strings as a consequence of vibration will have frequencies and amplitudes proportional to the frequencies and amplitudes of the vibrations themselves and may be passed through suitable wave-shaping circuits and amplifier means to loud speakers. The magnetic field generating arrangement extends a suflicient distance along the length of the strings to result in a long sustaining output signal. In addition, the' electrical circuitry involved together with other features provides for proper dampening of undesired resonances in the neck structure of the guitar. In this respect, the guitar neck includes a laminated conducting plate which serves to dampen resonances in the neck and also serves to provide a current path for current induced in the strings.

This application is a continuation in part of our copending application Serial No. 244,376, now Patent No. 3,297,813, tiled ec. 13, 1962 and entitled, Electrical Instrument.

This invention relates generally to electrical instruments and more particularly to stringed instruments in which an electrical signal is generated in response to string vibrations for reproduction through a loud speaker.

An example of the type of electrical instrument with which the present invention deals is the electric guitar and for purposes of illustrating certain embodiments of the invention, its use in conjunction with an electric guitar will be described.

Conventional electric guitars incorporate some type of transducer means for generating an electrical signal in response to vibration of the strings. Basically, two types of transducers are possible: iirst, an electrostatic transducer wherein a change in capacity, for example, can be effected in response to physical string vibrations, and this resulting change in capacity electrically detected to provide the desired output signal. Second, electromagnetic means wherein one or more coils with magnetic cores are employed in conjunction with a string of ferrous material which varies the coil eld when vibrating in such a manner that the desired output signal is generated in the coil.

The electrostatic transducer system is necessarily a high impedance device and, therefore, introduces a serious shielding problem in order to eliminate hum. In addition, there is usually required a high D-C polarizing voltage which also necessitates shielding for practical purposes.

The electromagnetic type of pickup employing a coil ICC overcomes the objection of high impedance, but it is very diicult to design in such a manner as to eliminate pickup from adjacent strings on the instrument. This latter problem can become very serious in electrical instruments of the type such as described in our co-pending patent application Ser. No. 153,467, tiled Nov. 20, 1961, for Tone Generation System, wherein the output from each individual string is fed into a trigger circuit to provide signals of double or half frequencies or of particular wave shapes. Such trigger circuits are sensitive and if there is not proper isolation between the various strings, one may serve to trigger the circuit associated with an adjacent string.

Moreover, in coil pickup type instruments, the strings of the instrument must include a ferrous material which restricts the player to the use of predominently iron strings as opposed to phosphor-bronze, beryllium-copper, or metallic coated nylon or gut type strings.

In addition to the above, in many present day transducer systems, the transduced signal is different when the string is plucked towards rather than away from the pickup. This lack of symmetry diminishes the fidelity of the system.

Other problems relateto undesirable resonances generated in the body portion of the instrument upon which the strings are mounted. With presently available transducing systems, such undesirable resonant conditions are detected along with the desired string movements from the artists playing of the strings. It would be highly advantageous to incorporate in a transducer system means for minimizing or eliminating such undesirable resonant conditions. i To avoid general bulkiness, present day transducer systems of -both the electrostatic and electromagnetic type are miniaturized as much as posible. As a consequence, only a very small portion of the string is employed to provide the ,movement to be transduced. As a result, traveling harmonics in the string tend to be accentuated. Stated differently, when only a small portion of the string is employed, any traveling harmonic constitutes a relatively large percentage of the string movement that is trans. duced. Further, the sustaining power of the string in present dav transducer systems is somewhat limited. Thus, even lthough the string may still vbe vibrating, the sound appears to drop off relatively quickly rather than be sustained as is the case when the instrument is employed as aconventional sound instrument.

With all of the foregoing in mind, it is a primary object of the present invention to provide a greatly improved electrical instrument incorporating novel transducer means in which the foregoing problems are substantially eliminated. t

MoreA particularly, it is an object to provide in an electrical instrument a low impedance transducer means to the end that shielding may be substantially eliminated.

Another Object is to provide a low impedance transducer for a stringed instrument in which pickup from adjacent strings is substantially eliminated.

Another object is to provide a transducer for a stringed instrument in which the strings are not restricted to a ferrous material.

Another important object of this invention is to provide a transducer which may be polarized to the extent that undesirable resonances resulting Ifrom vibrations in the strings in .given planes are automatically eliminated.

Another object is to provide an improved transducer for a stringed instrument which is compact, simple in construction, and avoids any bulky structure which might otherwise interfere with an artists attack on the strings.

Still another object is to provide a transducer in which the percentage content of traveling harmonics is greatly reduced and which has a relatively long sustaining power as compared to transducers presently available.

Another important object of this invention is to provide a novel transducer means in combination with a neck structure and string anchoring means in which undesirable resonances `are substantially `damped or broadened in such a manner as to result in an improved output tone.

Briefly, these and many other objects and advantages of this invention are attained by utilizing the strings of the instrument themselves 'as part of the electrical pickup means. More particularly, the instrument is provided with a magnetic field passing in a given direction across the strings in such a manner that vibration of the strings in the field induces currents in the strings themselves. The current in each string is individually passed through an associated wave shaping and amplifier circuit to an audio output.

`Since only a string that is moved will have a current induced therein, there is substantially no interference from adjacent strings so that excellent isolation between the individual strings is realized. In addition, by providing the magnetic field in a -given direction, only movement of the strings in planes cutting across or forming an angle with this direction will result in the inducing of current in the strings so that vibrations in undesirable planes as might result from resonances, for example, will have substantially no effect on the output signal.

In the preferred embodiment of the invention, the magnetic field is established by a single elongated rectangularly shaped permanent magnet `cooperating with an L- shaped channel member. The arrangement is such that the top surface of the magnet constitutes one pole of the magnetic field and the top edge portion of the vertical part of the L-shaped channel constitutes the other pole.

The structure is positioned beneath the strings close to the point at which the neck intercepts the body portion of the instrument and preferably includes elongated strip members of magnetic material which effectively extend the inuence of the magnetic field to cover a substantial length portion of the strings. As a consequence, the fundamental signal induced at any one instance is large compared to any traveling harmonics along the string. Further, a desired sustaining power is realized.

These foregoing lfeatures in combination with further mechanical features in the structure of the instrument for damping undesirable resonances results in a greatly improved electrical stringed instrument.

A better understanding of the invention will be had by now referring to a preferred embodiment thereof -as illustrated in the accompanying drawings, in which:

lFIGURE 1 is a perspective view, partly schematic in form and partly broken away, illustrating the basic features of the electrical stringed instrument of this invention;

FIGURE 2 is a fragmentary cross-section taken in the direction of the arrows 2--2 of FIGURE 1;

FIGURE 3 is a broken away enlarged perspective view of a portion of the magnetic field generating means incorporated in the instrument of FIGURE l; and

FIGURE 4 is a `cross-section taken generally in the direction of the arrows 4-4 of FIGURE 1 useful in eX- plainin-g certain features of the invention.

Referring first to FIGURE 1, there is shown a stringed instrument in the form of a guitar designed in accordance with the present invention. The guitar includes a body having an elongated neck portion 11. The guitar strings are illustrated at 12, 13, 14, 15, 16, and 17 and have first ends passing over the conventional nut 18 and secured to suitable tuning pegs 19. A shunting bar `20 of electrically conducting material is bridged across the strings beyond the nut and serves to electrically connect the first ends of all of the ystrings together.

The peg board portion of the neck also includes an enlargement indicated 4at 21, the purpose for which will be described in ygreater detail as the description proceeds.

Still referring to FIGURE 1, the second ends of the strings pass over a suitable bridge designated generally by the numeral 22 and are anchored as by pegs 23 to the gui-tar body. The bridge structure 22 and anchoring means 23 .are preferably as described and claimed in our copending patent application Ser. No. 308,870, filed Sept. 13, 1963 and entitled Stringed Instrument Bridge and Anchoring Means.

A-t the anchoring means 23, the strings are respectively connected to a corresponding number of conductors passing from the body 10 as indicated at 24. These conductors, in turn, respectively connect to individual wave shaping and amplifier circuits `designated generately at 25. T-he individual outputs from each of these circuits, in turn, are passed to a suitable speaker system 26.

With particular reference now to FIGURE 2, it will be noted that the first ends of the strings which are shunted by the shunting bar 20 electrically connect to an elongated conducting strip 27, preferably aluminum, and incorporated in the neck of the guitar as part of a laminated structure. The speed of sound in the strip 27 is different from the speed of sound in the surrounding material-s of the lamination and as a consequence, the resonance curve for the neck is damped. Further, the resonant curve is broadened by the provision of the enlargement 21 described in FIGURE 1 and as shown in FIG- URE 2.

The feature of la laminated neck and the manner in which the enlargement effects a desired broadening of the resonance curve to shift the nodal point to correspond to the area of the nut with resultant improvement in the guitar construction lis fully set forth in our copending application Ser. No. 308,871, vfiled Sept. 13, 1963 and entitled, Guitar Neck Construction. In view of the elimination of spurious -signals resulting from resonance and the like in the instrument body itself, the combination of the neck structure shown in FIGURE 2 with the novel electrical transducer means of the present invention constitutes an important overall combination, as each feature contributes to the other in providing an improved electrical signal output.

With respect to the foregoing, the strip 27 serves as a conducting medium for grounding the shunting bar 20 at a point 28 so that all of the wires for the instrument may be brought out at a desired single point in the body and it is not necessary to run a special wire up to the shunting bar 20. The str-ip 27 thus serves the dual function of providing a desired damping of the resonance in the neck as well as a conductor for the shunting bar 20.

Referring now to FIGURE 3, the actual means for generating a magnetic field to induce currents in the various strings 12-17 is shown. This magnetic field generating means comprises an elongated generally rectangularly shaped magnet 29 cooperating with an L-shaped channel member 30. The magnet is disposed along an edge portion of the horizontal part of the L-shaped channel as at 31. The magnet 29 has its top surface of one polarity and its bottom surface of the opposite polarity as indicated by the letters N and S. The L-shaped channel member 30 is of magnetic material and serves to eX- tend the south pole over to the left as viewed in FIG- URE 3 and up to the top edge of the vertical part 32 of the channel.

In addition tothe magnet and L-:shaped channel, there are provided elongated strips 33 and 34 which respectively overlie the top surface of the magnet 29 and the upper edge of the vertical part 32 as shown. The orientation of the strips can be seen in the broken away portion of FIGURE 1. These strips are of magnetic material and extend beyond the far ends of the magnet and L-shaped channel structure to effectively function as pole pieces and extend the infiuence of the magnet field passing between the top surface at the magnet 29 and vertical part 32 of the channel 30. By this arrangement., a substantial portion of the length yof the strings are within the magnetic field and thus the signal induced in each of the strings in cutting the magnetic field is predominently due to the fundamental motion of the string, the harmonics having considerably less effect as a result of the length of string Within the field.

FIGURE 4 illustrates schematically by the arrow 35 the Idirection of the magnetic field as generally parallel to the plane of the strings 12-17. However, when the strings are plucked or played, their directioinal motion is generally in the direction of the double headed arrow 36 which is substantially at right angles to the magnetic field so that -a maximum signal is induced in the strings.

In the overall operation of the electrical stringed instrument of this invention, wherever one or .more strings are played, the resulting vibration will cause the string to cut the magnetic field as illustrated in FIGURE 4.. As a consequence, there will be a current induced directly in the moving string, which current will be conducted by the string itself through one of the leads 24 to the correspondingly connected Wave shaping and amplifying circuit. By way of specific example, each of the wave shaping and amplifier circuits 26 may be of the type shown and described in our co-pending application Ser. No. 153,467, filed Nov. 20, 1961, and entitled, Tone Generation System. In this prior application, the transducing means employed is different from the instant transducing means in that the signal is induced in a coil as a consequence of the moving string. However, the output signal from the string itself as is the case in the present invention co-uld be fed into :amplifier and wave shaping circuits such as shown and described in said co-pending application.

In addition, the wave shaping and amplifier circuits may include suitable tone level control circuits such as shown and described in our co-pending `application Ser. No. 198,642, filed May 29, 1962 and entitled, Tone Level Control Circuit.

The electrical signal induced and carried by each of the strings results in an eventual out-put which is far superior than is afffforded by conventional pickup means such yas the capacitive or inductive types described heretofore.

Furthermore, the only restriction on the strings is that they be conductive so that strings of the phosphorbronze or beryllium copper type, or metallic wrapped nylon 0r gut found on classical acoustic guitars may be used. This latter feature is important lin that the elimination of ferrous strings heretofore thought necessary in electric guitars also eliminates various -undesirable characteristics of ferrous strings; for example, lack of good vibrating character-ictics at the higher tones, high tension `required in the strings, and discomfort to a players fingers.

From the foregoing description it will thus `be evident that the present invention has provided a greatly improved electrical stringed instrument. Not only are the Various advantages and objects of this invention as set forth heretofore fully realized rby the novel electrical pickup means in which the strings themselves are employed as part of the conducting circuit, but this feature in combination with the improved bridge and anchoring means and laminated neck construction and Weight means as described in the various referred to co-pending applications results in an electrical instrument vastly superior to any that has been available heretofore.

What is claimed is:

1. In a musical instrument including a body and a plurality of strings stretched across a portion of said body, means for providing a magnetic field in a given direction transverse to said strings; and electrical means connected to said strings for converting current induced in said strings as a consequence of vi-brational movement in said magnetic field into electrical signals of magnitudes and frequencies constituting functions of the magnitudes and frequencies of vibration of said strings, said means for providing a magnetic field comprising an elongated rectangularly shaped magnet having its top surfacel of one polarity and its bottom surface of an opposite polarity; an L-shaped channel member of magnetic material, said magnet being positioned along the free edge portion of the horizontal part of said L-shaped channel, the vertical part of said channel defining a pole corresponding to the polarity of the bottom surface of said magnet so that the given direction of said field is from the top surface of said magnet to the upper edge of the vertical part of said L-shaped channel; and elongated strips of magnetic material overlying said magnet and top edge of said L-shaped channel, respectively, in positions on either side of said strings to extend the lengths of said strings intercepting said magnetic field.

2. An electrical instrument comprising, in combination: a body having a neck portion extending from one end thereof and terminating in tuning stops; a plurality of strings stretched over said body and secured to said tuning stops; a nut adjacent to said tuning stops over which portions of said strings pass; a bridge secured to said body; said strings passing over said bridge and being secured to said body at points adjacent to said bridge; means for providing a magnetic field in a given direction disposed adjacent to said strings between said nut and bridge; means electrically connecting first ends of said strings to ground; and a plurality of individual wave shaping circuits and `amplifier means connected respectively to second ends -of said strings, each of said strings including electrically conducting material so that movements of said strings in planes at an angle to said given direction to cut said magnetic field generates electrical currents in said strings, said currents being modified and ampified by said Wave shaping circuits and ampifier means, respectively, to provide electrical signals constituting functions of the frequencies and amplitudes of said movements of said strings.

3. An instrument according to claim 2, in which said given `direction is oriented in a position substantially parallel to the direction of movement of said strings resulting from resonant conditions in said body and neck and substantially at right angles to the direction of movement of said strings resulting from playing of said strings, whereby currents responsive to movement of said strings resulting from resonant conditions in said body and neck are substantially reduced.

4. An instrument according to claim 2, in which said neck portion includes an enlargement adjacent said tuning stops to broaden the resonant curve of said neck portion the same as though said neck portion extended an increased distance beyond said nut.

5. An instrument according to claim 2, in which said means for generating a magnetic field includes an elongated rectangular shaped magnet having a top surface of one polarity and a bottom surface of an opposite polarity; an L-shaped channel member of magnetic material, said magnet being positioned along the free edge portion of the horizontal part of said L-shaped channel, the vertical part of said channel defining a pole corresponding to the polarity of the bottom surface of said magnet so that said given direction of said field is from the top surface of said magnet to the upper edge of the vertical part of said L-shaped channel; and elongated strips of magnetic material overlying said magnet and top edge of said L- shaped channel, respectively, said magnet and L-shaped channel being positioned beneath said strings with said strips extending adjacent to either side of said strings lalong a substantial length of said strings.

6. An instrument according to claim 2, in which said neck is of a laminated construction, one of the laminations constituting a metallic strip, said means connecting said ends of said strings to ground including, in part, said metallic strip, said metallic strip serving the additional function of dampening resonant conditions in said neck portion as a consequence of the difference in acoustic speed of sound in said strip as compared to the acoustic speed of soun-d in the remaining portion of said neck.

7. An instrument according to claim 2, in which said plurality of strings include a non-ferrous electrically conducting material.

References Cited UNITED STATES PATENTS ARTHUR GAUSS, Primary Examiner.

B. P. DAVIS, Assistant Examiner.

Claims (1)

1. IN A MUSICAL INSTRUMENT INCLUDING A BODY AND A PLURALITY OF STRINGS STRETCHED ACROSS A PORTION OF SAID BODY, MEANS FOR PROVIDING A MAGNETIC FIELD IN A GIVEN DIRECTION TRANSVERSE TO SAID STRINGS; AND ELECTRICAL MEANS CONNECTED TO SAID STRINGS FOR CONVERTING CURRENT INDUCED IN SAID STRINGS AS A CONSEQUENCE OF VIBRATIONAL MOVEMENT IN SAID MAGNETIC FIELD INTO ELECTRICAL SIGNALS OF MAGNITUDES AND FREQUENCIES CONSITUTING FUNCTIONS OF THE MAGNITUDES AND FREQUENCIES OF VIBRATION OF SAID STRINGS, SAID MEANS FOR PROVIDING A MAGNETIC FIELD COMPRISING AN ELONGATED RECTANGULARLY SHAPED MAGNET HAVING ITS TOP SURFACE OF ONE POLARITY AND ITS BOTTOM SURFACE OF AN OPPOSITE POLARITY; AN L-SHAPED CHANNEL MEMBER OF MAGNETIC MATERIAL, SAID MAGNET BEING POSITIONED ALONG THE FREE EDGE PORTION OF THE HORIZONTAL PART OF SAID L-SHAPED CHANNEL, THE VERTICAL PART OF SAID CHANNEL DEFINING A POLE CORRESPONDING TO THE POLARITY OF THE BOTTOM SURFACE OF SAID MAGNET SO THAT THE GIVEN DIRECTION OF SAID FIELD IS FROM THE TOP SURFACE OF SAID MAGNET TO THE UPPER EDGE OF THE VERTICAL PART OF SAID L-SHAPED CHANNEL; AND ELONGATED STRIPS OF MAGNETIC MATERIAL OVERLYING SAID MAGNET AND TOP EDGE OF SAID L-SHAPED CHANNEL, RESPECTIVELY, IN POSITIONS ON EITHER SIDE OF SAID STRINGS TO EXTEND THE LENGTHS OF SAID STRINGS INTERCEPTING SAID MAGNETIC FIELD.

Images