US2130174A

US2130174A - Stringed musical instrument

Info

Publication number: US2130174A
Application number: US59032A
Authority: US
Inventors: George D Beauchamp
Original assignee: ELECTRO STRING INSTR CORP
Current assignee: ELECTRO STRING INSTR CORP; ELECTRO STRING INSTRUMENT Corp
Priority date: 1936-01-14
Filing date: 1936-01-14
Publication date: 1938-09-13
Anticipated expiration: 1955-09-13

Description

Sept. 13, 1938. G. D. BEAUCHAMP STRINGED MUSICAL INSTRUMENT Filed Jan. 14, 1936 2 SheetS-Sheei l wy W L d m ro a m J f UQ a@ Om FTW y @ww W Sept. 13, 1938. G. D. BEAUCHAMP STRINGED MUSICAL INSTRUMENT 2 Sheets-Sheet 2 Filed Jan. 14, 19256 \Y, ...r-:5.5. il

Patented Sept. 13, 1938 PATENT OFFICE s'ramcsn Musical. ms'raum'r George D. Beauchamp, Los

or to Electrol String Angeles, Calif., assignlnstrument Comration,

Los Angeles. Calif., a corporation of California Application January 14, 1988, Serial No. 59.032

'iClalma This invention relates to musical instruments and relates more particularly to electrical musical instruments ot the violin type. A general object oi this invention is to provide a practical, compact and eilective electrical stringed musical instrument.

Stringed musical instruments of various characters have been introduced having electrical pick-up units or electro-magnetic pick-up units for converting the vibrations produced by the strings into modulations in an electrical circuit to be ampliiled and reproduced as music. Ithas been the usual practice to include a pick-up of this character in the instrument in addition to its usual or original sounding board or resonant body; The sounding board or resonant body of a violin or a similar instrument is rather large and cumbersome and renders the instrument diiiicult to handle and play. The embodiment of an electrical pick-up unit in the instrument in addition to its usual sound board or resonant body of course increases the weight and bulk of the instrument.

Another object of this invention is to provide an electrical stringed instrument of the violin type that is extremely light in weight and well balanced, and, therefore very easy to handle and play.

Another object oi' this invention is to provide an electrical stringed instrument of the violin type that has its center of gravity and its greatest mass immediately adjacent its inner end to be supported on the shoulder oi' the player and has a simple, very light stub neck devoid of keys and all other parts, which imposes little or no weight on the fingering hand oi the player, making the instrument very easy to play.

Another object of this invention is to provide an electrical stringed instrument o! the violin type in which the key box portion or peg box portion is at the inner end of the neck to be arranged against the shoulder of the player, as distinguished from the usual form of violin in which the peg box is at the outer end of the neck and must be supported by the ngering hand of the player.

Another object of this invention is to provide an electrical stringed instrument oi' the violin class that is of novel construction, whereby the shoulder engaging portion or the shoulder pad on such portion comfortably rests on the shoulder of the player and the iinger board of the neck is elevated in the proper position for playing.

Another object oi this invention is to provide an electrical stringed instrument ci' the character mentioned that is very simple in construction and light in weight, comprising a one piece casting or body forming the neck, the key box portion or peg box portion, and the shoulder engaging portion of the instrument.

Another object of this invention is to provide a stringed instrument oi.' the violin type that embodies a novel, Vsimplied and improved electromagnetic pick-up unit of the general character i'ully described and claimed in my co-pending application Serial No. 728,717, illed June 2, 1934, which has matured into Patent No. 2,089,171", granted August 10, 1937, for converting the vibrations of the several strings into pulsations or modulations in an amplifying sound reproducing circuit.

Another object of this invention is to provide a stringed musical instrument of the violin type that embodies an electro-magnetic pick-up unit embodying permanent magnets and a coil between the polar parts of the magnets, the magnets and coil being positioned so that the strings pass between the coil and the proper polar parts of the magnets whereby the vibrations of the strings vary the density of the magnetic flux or disturb the magnetic neld and thus produce an induced current in the coil, the arms of the magnet being dampened to prevent sound producing vibrations of the magnets.

Another object of this invention is to provide n an electrical musical instrument of the character mentioned that embodiesv an electro-magnetic pick-up unit in which the magnets are shaped and the core magnets of the coil are proportioned and located to have the proper substantially uniform spaced relationship to the strings which are arranged in a segmental or arcuate series.

Another object of this invention is to provide a stringed musical instrument of the character mentioned in which the pick-up unit is very compact and light in weight and is arranged so that it does not interi'ere with the playing oi' the instrument.

The various objects and features of my invention will be fully understood from the following detailed description of a typical preferred form and application oi' my invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. 1 is a top or plan view o! the instrument provided by the present invention. Fig. 2 is a side elevation of the instrument. Fig. 3 is an enlarged transverse detailed sectional view taken as indicated by line 3 4 on Fig. 1. Fig. 4 is an enlarged transverse detailed sectional view illustrating one of the string tuning units being a view taken as indicated by line 4 4 on Fig. 2. Fig. 5 is an enlarged transverse detailed sectional view taken as indicated by line 5 5 on Fig. l. Fig. 6 is a fragmentary longitudinal detailed sec tional view taken as indicated by line 8-8 on Fig. 5. Fig. 7 is a fragmentary elevation view lof the under side of the key box portion of the instrument showing a part thereof in cross section, being a view taken `as indicated by line 1-1 on Fig. 2 and Fig. 8 is a diagrammatic wiring diagram of the circuits involved in the invention.

The improved electrical stringed musical instrument of the present invention includes, generally, a unitary body A having a neck III, a key box portion or peg box portion II and a portion I2 for engaging the shoulder of the player, tensioned strings B extending over the fingerboard of the neck I 0 and an electro-magnetic pick-up unit C on the neck I0 for converting vibrations oi' the strings B into pulsations or modulations in .an amplifying circuit.

The construction and shape of the body A and the relation between the several parts of the body A are important features of the invention. The body A is preferably formed of metal, or other material that may be cast in the form of a single, integral part or casting. In practice I have found it desirable to form the body A of a synthetic organic substance resulting from the chemical condensation of phenol and formaldev hyde which is relatively light, strong and capable of being attractively finished. In' accordance with the invention the body A is an integral onepiece member and provides or forms all of the principal frame parts and supporting parts of the instrument.

The neck I0 over which the strings B are strung is an elongate part comprising the forward or outer portion of the instrument. The neck Ill is shaped to be readily and properly engaged and held by the players fingering hand. The neck III is preferably tapered both horizontally and vertically toward its outer end to be of less cross sectional dimension adjacent its outer end than at its inner end where it joins the portion Il.

- 'I'he lower or under side of the neck I0 is rounded or provided with a convex surface Il. In the preferred construction the neck I0 is tubular or hollow to be light in weight and easy to handle. A longitudinal groove I 5 is provided in the neck I0 and has the same general contour as the external surface of the neck. The fingerboard I 8 of the neck I 0 closes the upper end of the groove I5. 'I'he ngerboard I6 may be cemented or otherwise fixed in place. The upper side or surface I'I of the finger board i6 is transversely convex throughout the major portion of its length and is shaped and finished so that the strings B may be properly pressed against it.

'Ihe outer end portion I8 of the neck I0 may be slightly enlarged and of ornamental configuration. A curved or concave surface I9 is provided on the under side of the neck I0 adjacent its extreme outer end portion I8 to form a stop or abutment for the hand of the player. The end portion I8 of the neck Iii is shaped and formed to hold the end portions of the strings B as will behereinafter described. In accordance with the invention a projection 20 is provided on the under side of the neck I0 at a point spaced between its opposite ends. 'Ihe projection is intended to form a support or abutment engageable by a part of the players hand as he engages or ngers the violin.. In practice the projection 20 is preierably integral with the neck I0 and is substantially round in transverse cross section. l

'I'he invention provides means for locating the playing hand and the string depressing nngers of the player. A member or part l0 projects laterally from the neck I0 at that side of the neck over which the player extends his lingers to depress the strings B. The part Il preferably projects laterally outwardly from the lower side of the neck III at the projection 20, as illustrated in Figs. 1 and 2 of the drawings. In practice the part l0 may be of substantial width and the part is preferably curvedor bowed, being curved laterally outwardy and in the direction of the body portion Il. The curved surface 8| thus presented by the part forms an eiiective rest or means for locating the players fingers with respect to the strings B and the neck. 'I'he invention contemplates the forming of the part 80 integral with the neck I 0 or as a separable member attached to the neck I0. In the simple case illustrated in the drawings the part 80 has one end attached to the projection 2l by pins or screws l2 and has an arm or lug I3 on its other end secured to the under side of the neck by a pin or screw Il. Where the part GII is a separable member it may be formed of sheet stock such as sheet aluminum and the lug 82 may be twisted to properly engage against the neck I0.

A transverse slot or notch 2i is provided in the upper side of the neck Il to receive or carry the pick-up unit C. The notch 2i is adjacent the inner end of the neck I0 being spaced inwardly a considerable distance from the projection 20. The portion of the neck In provided with the opening or notch 2| may be solid or without the groove I5, as illustrated in Fig. 6 of the drawings and may be thickened as at 22.

The key box portion or the peg box portion II of the body A integrally Joins the inner end of the neck I0 and is provided to carry the keys or pegs 23 for tensioning the strings B. The portion I I of the body A may be substantially rectangular in its general configuration having slightly inwardly converging sides 24. The portion II is preferably hollow and provided with an internal space or'cavity 2l which may be open at the under side of the portion II. A central longitudinal web 28 extends through the interior or cavity 25 of the body portion I I and a transverse bridge or web 21 connects the forward or outer portion of the web 28 with the sides 24. rI'he upper wall 28 of the portion Il is provided with spaced openings or slots 29 for receiving the strings B. It is a feature of the invention that the body portion II just described is angularly related to the neck I Il. 'I'he key box portion or peg box portion II extends downwardy and inwardly from the inner end of the neck III as clearly illustrated in Fig. 2 of the drawings. 'Ihis position or formation of the body portion II provides for the proper positioning of the neck I0 and the easy fingering of the strings B when the body portion I2 is supported against the shoulder of the player. The above described relationship between the neck I0 and the body portion II assures the comfortable engagement of the body portion I2 or the shoulder pad (not shown) on the portion I2 with the shoulder of the player while the neck I0 is properly elevated in playing position.

The invention provides improved means for very accurately tuning the strings B by finely regulating the tension of the strings. Adjustin or regulating units U are provided onthe key box portion IlA of thebody A for eecting the fine accurate adjustment of the tension on the strings B. Fig. 4 of the drawings illustrates one of these units U in detail. Each unit U includes a plate 13 attached to the upper face oi' the body portion II by screws 1I or the like. The plates l 10 of the units U are disposed below and transversely of the strings B. A block 12 is arranged on one end part of each block 10 and screws 13 secure the blocks 12 to the plates 13. The screws 13 project from the upper sides of the blocks 12 and are provided with heads 14. The units U include tiltable or pivotable plates arranged on the blocks 12. The screws 13 freely pass through openings 15 in the plates 15 to pivotally support or retain the plates 15. The heads 14 of the screws 13 limit the pivotal movement of the plates 15 and prevent the displacement of the plates. Each plate 15 carries means for engaging or bearing on a string B. In the simple form of the invention illustrated a slotted screw 11 projects from the upper side of each plate 15 and the string B passes through its slot as clearly illustrated in Fig. 4 of the drawings. An adjusting screw 13 is threaded through an opening in each plate 15 and its inner end is adapted to engage or bear against the fixed plate 10. In practice the ends of the adjusting screws 18 may be suitably rounded and may cooperate with correspondingly shaped recesses 19 in the plates 10. Knurled heads 30 may be provided on the adjusting screws 13 to facilitate the accurate manual adjustment of the screws. Means is provided for preventing swinging or turning of the plates 15. Pins BI project from the plates 15 and extend into openings 32 preventing undesirable lateral swinging of the adjustable plates 15. The plates 15 are positioned or set to exert an upward force on the strings B or to form bridges on which the strings bear. I'he screws 13 may be threaded or turned to react against the fixed plates 10 and thus pivot or adjust the bridge plates 15. By carefully turning or adjusting the screws 15 the tension on the vibratory strings B may be very accurately regulated as desired. The units U are very compact and are light in weight.

The portion I2 is provided on the inner end of the body A for engaging the shoulder and chin of the player or for carrying a suitable shoulder pad (not shown) for engaging the shoulder or for carrying a chin rest (not shown) for cooperating with the chin of the player. The shoulder engaging portion I2 of the body A projects laterally in one direction from the inner end of the portion A. 'I'he rear or inner side 30 of the portion I2 is curved forwardly to join its forward face. The upper and lower faces of the portion I2 may be substantially horizontal or substantially parallel with the plane of the longitudinal axis of the neck III. In accordance with the invention the portion I2 is preferably hollow having an internal cavity 3i. The upper side of the cavity 3I is closed by an integral wall 32 of the body A while the lower side of the cavity 3l is closed by a plate 33 cemented or otherwise fixed in position.

'I'he strings B are strung across the finger board I6 of the neck III between the outer end portion I3 of the neck and the body portion II. In accordance with the usual practice there are four strings B of graduated diameters. lThe strings B are formed of steel or other magnetic material to influence the pick-up unit C. Bpaced openings 35 are provided in the outer end portion .of the body neck Il to receive the end portions of the strings B. Suitable nuts, spools'or the like are provided on the strings B to cooperate with the openings 35 to hold the strings against movement in one direction. The strings B pass over a bridge 35 at the-outer end of the ngerboard I5. A bridge 31 is provided at the inner end oi' the finger board I6 and the strings B extend inwardly over the bridge 31 to be in the proper spaced relation to the finger board I5. The bridge 35 is preferably integral with the one piece body A while the bridge 31 may be inserted in and secured in a notch 35. It is to be understood that bridges of various characters may be employed on the instrument if desired. The upper or active string supporting edges oi' the

bridges

35 and 31 are arcuate and support the strings B in spaced relation in a curved or arcuate series to be in their proper relation to the surface I1 of the finger board I5. The usual notches may be provided in the

bridges

35 and 31 to maintain the strings B in their proper positions. The strings B extend inwardly from the bridge 31 to pass through the slots 23 into the cavity 25 of the body portion II. The end portions of the strings B are wound on the keys or pegs 23 whereby the strings may be tightened and tuned by means of the pegs 23.

The pick-up unit C is operable to convert the actual tone producing vibrations of the strings B into pulsations or modulations in an amplifying circuit 40. The pick-up unit C is such that the intensity, frequency, etc. of the sound producing vibrations of the strings B act through the medium of a magnetic field to modulate the amplifying circuit 40 in a proportional or definite manner so that the amplifying circuit 40 is influenced to faithfully and accurately reproduce the sound. In accordance with the invention the pick-up unit C includes a magnet or a magnet assembly comprising a pair of like opposed magnets 4I. It is a feature of the present invention that the magnets 4I are permanent magnets as distinguished from electro-magnets which might influence the amplifying circuit 4I! to produce a hum or other undesirable sound. The magnets 4I are substantially U-shaped in their general configuration, each having two spaced arms 42 and 43. The magnets 4l are arranged in the opening or notch 2I so that their lower arms 42 rest or bear on the inner wall of the notch. In the preferred construction the magnets 4I are proportioned to project from the opposite sides of the neck I0 to be of sufficient length to insure the proper operation of the unit C. In accordance with the invention the magnets 4I are arranged in opposed relation, that is, the confronting or opposed ends of their arms 42 and 43 have opposite polarity as indicated in Fig. 5 of the drawings. This provides a continuous state of polarity at the opposite sides of the assembly of magnets. It is preferred that the confronting or opposed ends of the arms 42 and 43 of the magnets 4I be in spaced relation.

The upper or outer arms 43 of the magnets 4I are formed or shaped to have the proper relationship to the arcuate series of vibratory strings B. The inner end portions 43'L of the magnet arms 43 are curved upwardly and inwardly to extend over the arcuate series of strings B and be substantially equally spaced from the strings. The several strings BB thus influence or aect the proper zone of the magnetic eld of the magnet assembly 4|-4|. The invention provides a sim- "ple and particularly effective means for securing the pick-up unit C to the body A and for dampening the magnets 4| to prevent vibration of their arms. Screws 44 are passed through openings 45 in the neck I8 and extend through openings 48 in the lower arms 42 of the magnets 4|. The upper ends of the screws 44 engage or bear against the under sides of the inner portions 48' of the magnet arms 43. This engagement of the screws 44 with the arms 48 prevents vibratory movement of the arms which might produce a ringing sound. The screws 44 are preferably of non-magnetic material so that they do not short out or affect the magnets 4| The magnets 4| arranged or mounted as Just described have the portions 48n or their upper arms 48 passing over or above the strings B in spaced relation to the strings. Thus the strings B pass through the lines of force of the magnetic field and when vibrated vary the density of the magnetic flux. The magnets 4| may be carefully adjusted or set when 'assembled on the body A to be in the proper relation to the strings B. The pick-up unit C provides or includes a coil 48 arranged within the magnet assembly 4|-4|. The coil 48 is arranged on the inner or lower arms 42 of the magnets 4| and operates to pick up or receive an electrical current from the field of the magnet assembly. The coil 48 is wound on a coil form or spool 48 of the proper configuration. The coil 48 constitutes a winding of suitable enameled wire of the proper gauge trained or -Wound on the spool 49 between its end flanges. The spool 49 is preferably formed of a suitable non-magnetic insulating material and has openings 49 receiving the screws 44 whereby the screws operate to hold the coil in place. It will be understood that the number of turns on the coil 48 and the gauge of the wire forming the coil depend upon the particular amplifying circuit 40 with which the instrument is to be used. The coil C positioned within the assembly of the magnets 4| is located between the north and south poles of the magnet assembly and is related to the strings B to be ailected by their vibration. The upper side of the coil spool 49 is spaced some distance below the arcuate series of strings B and disturbances in the magnetic field or ux of the magnets 4| resulting from vibration of the strings B induces an electric current in the coil 48.

The pick-up unit C includes a plurality of core members 50 for attracting the lines of magnetic force toward the center of the coil 48. The members 58 are in the nature of pins or posts projecting from the upper side of the coil spool 49. The lower ends of the members 58 preferably engage the lower arms 42 of the magnets 4|. In accordance with the invention the upper ends of the members 50 are spaced below or inwardly from the strings 'B there being one member 5U spaced from each vstring B. The post members 50 of the coil project dill'erent distances from the spool 49 so that the spaces between their upper ends and the strings B are graduated substantially in proportion to the graduation in diameter of the strings. This spacing or relationship between the upper ends of the coil members 5l) and the strings B operates to compensate for differences in the degree of variation of the magnetic reluctance or variation in the magnetic reluctance when the strings are vibrated due to the differences in the diameter of the strings.

One lead or conductor 5| from the amplifying circuit 48 extends through a suitable opening in the neck I0 and is electrically connected with the outer winding of the coil 48. The other lead or conductor 52 extending to the amplifying circuit 40 is electrically connected with one of the magnets 4|., A post or member 58 bearing on the lower arm 42 of this magnet engages-the inner windings of the coil 48 to complete the circuit through the coil. The enamel on the inner windings ofthe coil 48 is removed where they engage the said member 58. 'The posts or members 88 operate to carry the stronger lines of the magnetic force into the center of the field of the coil 48. The strings B pass between the ends of the members 58 and the magnet arms 48 vary the density of or disturb the lines of force of the magnetic assembly and thus set up or induce an electrical circuit in the coll 48 picked up from the magnetic field.

The coil 48 of the pick-up unit C is electrically connected to the amplifying circuit 48 which may also be a speaker or sound reproducing unit. Thus variations in the density oi' the magnetic flux picked up by the field of the coil 48 are converted into sound. This sound reproduced iby the amplifying and sound reproducing circuit 48 is a true reproduction of the sounds or tones produced by the vibratory strings B. It is to be understood that any suitable form of amplifying and sound reproducing device or unit may be employed in connection with the pick-up unit C and that the typical unit 40 illustrated in the drawings is not to be construed as limiting the scope or application of the invention.

The invention includes means for conveniently associating or connecting the coil 48 of the unit ('5v on the portable musical instrument with an amplifying and sound reproducing unit such as the circuit 40. In the preferred structure illustrated in the drawings a socket or jack 53 is arranged in an opening in the forward wall of the inner portion I2 of the body A. The Jack 58 projects into the cavity 3| of the body portion 2. The jack 58 is adapted to receive a plug 54 connected with the leads or conductors 55 from the amplifying circuit 40. The conductors 5| and 52 extend through the opening or cavity 25 of the body portion and pass through an opening 58 in the body to extend into the cavity 8|. 'I'he invention includes means for varying the amplification of the sound. A volume control is provided on the instrument or violin in a position to be conveniently accessible to the artist or player. 'I'he lines or conductors 5| and 52 extend through the cavity 8| to the jack 58, and the amplifying control or volume control may bein the form of a variable resistance element or rheostat 58 arranged in the cavity 8| and interposed or connected in the conductors 5| and 52. The control handle or knob 58 of the volume control or rheostat 58 projects from the curved inner surface 88 of the body portion I2 where it is conveniently accessible to the artist or player.

In playing the instrument the body A is held or positioned with the portion |2 resting or bearing against the shoulder and with the neck I8 engaged by the finger hand of the player. It is to be understood, of course, that the portion'l2 of the instrument body A may be provided with the proper shoulder pad (not shown) and chin rest (not shown). As the center of greatest mass and the center of gravity of the instrument is adjacent its inner end the instrument is readily supported or held in this manner. It is to be particularly noted that the neck I0 is very light in weight and does not carry or support any heavy or cumbersome parts. The neck l0 terminates at its outer end in the portion Il which merely carries tbe dead or ilxed ends of the strings B.v This stub neck I is tubular or hollow and when the instrument is in the proper playing position imposes little or no weight on the artist's hand which fingers the strings B. The arranging or locating of the keys or pegs 28 in the portion I i of the body A removes the weight of the pegs and the necessary relatively heavy body portions for carrying the keys from the outer end of the neck which is the position they usually occupy in a typical violin.

A typical bow is drawn over the strings B between the unit C and the bridge l1 or at any other point adjacent the unit C to cause vibration of the strings. Vibration of the strings by the bow or by plucking results in variations or disturbances in the magnetic eld to induce a current in the coil 4l. The current of the coil Il is amplified by the circuit 40 and converted into a reproduction of the sound of the instrument by the circuit 40 and its associated parts. It will be obvious that the vibratory strings B influencing or disturbing the magnetic flux adjacent or above the post members 50 of the coil 4l induces a current in the coil 48 having the frequencies and other characteristics of the vibrations of the strings to accurately or proportionately influence the circuit 40. The amplifying and sound reproducing circuit 40 receiving these pulsations or modulations faithfully produces the sound produced by the strings B, which sound has all the tonal qualities of the sound of the strings. The volume of the sound produced or reproduced by the circuit lll may be easily and conveniently controlled by the artist or player by turning the knob 49. It is to be noted that the electrical musical instrument of the present invention operata to amplify the true tones produced by the vibratory strings without vibration of any other physical parts of the instrument proper.

The instrument or violin comprising the single one-piece body A formed of light material and provided with the openings and cavities described above is extremely light and is very compact. The instrument does not involve any sounding parts or resonant boxes. The neck I0 and the portions Ii and I2 of the body are proportioned and related so that the instrument may be easily and conveniently handled by the player or artist and the relationship of the parts is such that the neck I0 and ngerboard I8 are properly positioned for playing when the body portion i! is supported on the shoulder.

Having described only a typical preferred form and application of my invention, I do not wish to be limited or restricted to the speciilc details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims:

Having described my invention, I claim:

l. In an electrical stringed instrument a neck having a ringer board, a plurality of spaced tensioned vibratory strings extending over the finger board in spaced relation thereto, a magnet on the neck having its poles at opposite sides of the` strings, the magnet comprising spaced arms, a coil between the poles of the magnet positioned so that the strings pass between it and the adjacent arms of the magnet, the coil being operable to convert the ux of the magnet into a current which is modulated by vibration of the strings, and means for dampening the arms of the magnet to prevent vibration thereof.

2. In an electrical stringed instnunent a neck having a iinger board, a plurality of need tensioned vibratory strings extending overthe' iinger board. in spaced relation thereto, a magnet 'on the neck having its poles at opposite sides of the strings, the magnet comprisingspaced. arms, a coil between the poles of the magnet positioned so that the strings pass between it and the adjacent arms of the magnet, the coil being operable to convert the flux of the magnet into a current which is modulated by vibration of the strings, and means for dampening the arms of the magnet to prevent vibration thereof, said means including securing members engaging said arms and securing the magnet and coil to the neck.

3. In an electrical stringed instrument a neck having a finger board, a plurality of spaced tensioned vibratory strings extending over the nnger board in spaced relation thereto and arranged in an arcuate series, a magnet on the neck having its poles at opposite sides of the strings, the magnet comprising inner arms and outer arms, the outer arms being arcuately curved to follow generally the curvature of the series oi strings, and a coil between the poles of the magnet positioned so that the strings pass between it and the adjacent arms, the coil being operable to convert the flux oi' the magnet into a current which is puisated by vibration of the strings.

4. In an electrical stringed instrumenta neck having a convex ngerboard, a plurality of spaced tensioned vibratory strings extending over the fingerboard in spaced relation thereto and arranged in an arcuate series, a magnet on the neck having its poles at opposite sides of the strings, the magnet comprising inner arms and outer arms, the outer arms being arcuately curved to follow'generally the curvature of the series of strings, a coil between the poles of the magnet positioned so that the strings pass between it and the adjacent arms, and core members projecting from the coil toward the strings, the spacing of the members from the adjacent strings being substantially uniform.

5. In a stringed musical instrument having a body and a plurality of spaced tensioned strings extending across the body in spaced relation thereto, a pick-up unit comprising a pair of opposing magnets on the body, each magnet having an arm above the strings and an arm below the strings, an induction coil in the eld of the magnets operable to convert the flux of the magnets into a current that is modulated by vibration of the strings, and screws passing through openings in the body, the lower arms of the magnets and the coil to secure the magnets and coil to the body and engaging the upper arms of the magnets to prevent vibration of the same.

6. In a stringed musical instrument having a body and a plurality of spaced tensioned strings extending across the body in spaced relation thereto, the strings being graduated in diameter and being arranged in an arcuate series, a pickup unit on the body comprising a pair of magnets each having an arm spaced below the series of strings and an arm spaced above the series of strings, the last mentioned arms being curved to follow generally the curvature oi' the arcuate series of strings, an induction coil between the upper and lower arms of the magnet positioned so that the strings pass between it and the upper magnet arms, and core members projecting from the coil toward the upper magnet arms and each having an upper end spaced from a string, the spaces between the upper ends of the core members and the adjacent strings being substantially uniform but graduated substantially in proportion to the graduation in diameter of the strings to compensate for dinerences in the extent of variation o1 the magnetic ilux by vibration of the graduated strings.

1. In a stringed musical instrument having a body and a plurality of spaced tensioned strings extending across the body in spaced relation thereto the strings being arranged in an arcuate series, a pick-up unit on the body comprising a pair o! opposed U-shaped permanent magnets each having an arm spaced below the series of strings and an arm spaced above the series ot through fields in which the lines o't magnetic 10 force converge toward the outer ends of the cors members.

GEORGE D. BEAUCHAMP.