US2207341A - Electrically amplified controlled stringed musical instrument - Google Patents

Description

y9,194 0- M. DICKERS'ON 2 207,341

ELECTRICALLY AMPLIFIED CONTROLLED STRINGED MUSICAL INSTRUMENT Filed June 1, 1957 5 Sheets-Sheet 1 Frq. 1.

Frq. 2.

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18 Inventor. 16 D. J Dickerson \12 14 Hirney y 9, 1940- D. J. DICKEFEESON 07,341

ELECTRICALLY AMPLIFIED CONTROLLE" STRIIIGED MUSICAL INSTRUMENT Fi led June 1, 1957 s Sheets-Sheet 2 Frg. 6. 6

- ii Q Frq. 8.

D. J. Dickerson fliiorzzeys.

y 9, 1940- D. .1. DICKERSON 2,207,341

ELEGTRICALLY AMPLIFIED CONTROLLED STRINGED MUSICAL INSTRUMENT Filed June 1, 1937 S Sheets-Sheet 5 Fig.1]. 163 204 1.9.5 02 1.90

178 198 F q I i I22 Ven 02- 184/ DJ. Dickerson I V A! Hiiornqys Patented July 9, 1940 amcrmcmr am NTBOLLED LIFIED C STRINGED MUSICAL INSTRUMENT Delbert I. Dickerson, West Los Aigeles, CaliL,

signalof one-half Long Beach, Calit.

to Arthur McMahan,

Application June 1, 1931, Serial No. 145,800

'15 Claims. (01. 84l.16)

My invention relates to the control or the electrical amplification of. musical instruments which are held in the hands or possibly resting on the player's knee, such as guitars and similar type of instrument in contradistinetion to large instruments oi. a piano type. In the smaller guitar type of instrument, various arrangements have been employed by which the electrical amplification may be controlled by the player and changed and varied to increase or decrease the amplitude of the sound without materially interrupting with .the playing. However, some'oi these employ a rheostat type of control, the rheostat being built in the instrumentbox or case and having a controlled dial. In most of such instruments it is difllcult for the player to operate such dial while playing the instrument, having either to place the hands in an awkward position to operate the dial and at the same time pluck the strings.

A main object and characteristic of my invention therefore resides in a control for the electrical amplification in which a movable device mounted on the instrument case may be engaged by the arm or wrist and shifted to various positions while the player's hand may be plucking the strings. Thus presuming the player is fingering the strings with the right hand, his right wrist or forearm may operate the movable control element.

My invention also comprehends various ways oi! changing the electric current generated by the vibration of the strings to the particular amplifying unit which varies the input to a loud speaker or the like. My invention therefore includes a rheostat control actuated by the movable device on the instrument case.

standard type of rheostat with a dial for operating the same, which dial may be set by hand and then the auxiliary arm or wrist control may regulate the rheostat in order to change the electric current fed to the electrical amplifier.

My invention also includes changing the relative positions of the electro-magnet assembly in regard to the steel strings in which the permanent magnet having the individual electro-magnets for the various strings may be tilted on a longitudinal axis to vary the distance between the strings and the poles of the individual electromagnets. The position of the magnet assembly may be set to have 'a limit and the change of position varied between these limits. This operation may be controlled by a movable, such as a pivoted, arm or wrist rest on the body of the instrument.

Another characteristic and type of my invention is changing the relative positions of the poles Such case may have a of the electro-magnets in reference to the steel strings of the instrument. In this case the permanent magnet may be held stationary and the the electro-magnetic assembly with its individual poles for each string in reference to the strings. 10 Therefore the poles of the electro-magnets may be shifted laterally in regard to the strings and the permanent magnet.

My invention is illustrated in connection with 2 the accompanying drawings, in which: 16

Fig. 1 shows a plan of a guitar type of instrument showing the form 01 my invention employing a rheostat or an electric resistance device or the like controllable by dial or by a wrist or arm actuated device to vary the electric conductivity 2 or the like of an electric element which may be connected to an electrically actuated amplifying device.

Fig. 2 is an enlarged partial plan similar to Fig. 1 partly broken away to show details of the 25 rheostat or the like control.

Fig. 3- is a transverse section on the line 3& of Fig. 2 in the direction of the arrows.

Fig. 4 is a partial longitudinal section on the line 4-4 01' Fig. 1. 30

Fig. 5 is a partial plan of a guitar type instrument showing a modified construction in which the permanent 'and electro-magnets may be tilted on pinions to vary the distance while maintaining the alignment between the poles of 35 the electro-magnets and the assembly of strings, such section being partly broken away to illustrate the control by a tilting wrist or arm operated element.

Fig. 6 is a detail longitudinal section on the 40 line 66 of Fig. 5 in the direction of the arrows.

Fig. 7 is a transverse section on the line 'l'! of Fig. 5 in the direction of the arrows.

Fig. 8 is a detail transverse section on the line 88 of Fig. 5 in the direction of the arrows 5 through the main pintles of the magnet assembly.

Fig. 9 is a longitudinal section on the line 99 of Fig. 8 through the magnet assembly.

Fig. 10 is a plan of part 01' a guitar assembly 50 showing a modified construction in which the assembly of electro-magnets is shifted laterally to vary the distance between the poles of the magnets and the strings of the instrument.

Fig. 11 is a transverse section taken on the line 55 formed in the top and II-II of Fig. 10 in the direction of the arrows.

Fig. 12 is a longitudinal section on the line I2-I2 of Fig. 10 in the direction of the arrows.

In the construction of Figs. 1, 2, 3 and 4, I illustrate a guitar or similar instrument body II which for the electrically amplified instruments is generally made of a more or less solid block instead of having a resonance chamber as in the ordinary type of guitar or like instruments. In this case at the end of the block there is a recess I2 in which is located the permanent magnet I3, this having a lower pole I4 and an upper pole I5. The magnet is held in place by a set screw I6 threaded in the end of the block, this extending through an ornamental covering material II. The covering material at the top is indicated by the numeral it. A substantial bridge I9 extends across the recess I2 and has the strings 20 of the guitar secured thereto. It will thus be seen that the lower pole i4 and the upper pole I5 are located below and above the strings. A more or less standard electro-magnet assem-- bly 25 has a winding 26 and a series of individual pole pieces 21, there being one pole for each string and positioned directly below its string as illustrated in Fig. 2 held in place by a screw 21' at each end as shown in Fig. 4. Electric leads 28 extend from the coil to a rheostat assembly 36. This may be of a standard type and the interior mechanism is not illustrated. Such assembly is mounted in a cut-out sprocket Si in the block I I. It includes a dialing disk 32 which is attached to the cover 13 by screws 33 or the like. A vertical shaft 34 extends downwardly through the center of the dial and has a finger operating knob 35 connected thereto by a set screw 36 at the top. This knob has a pointer end 31 and may be brought to engage a fixed stop 38 on the dial disk 32. A washer 33 spaces the knob from the top of the disk. A sleeve 43 is relatively rotatable on the shaft 34, this sleeve having a washer 4i thereabove and there being a rubber friction washer 42 between washer 4i and the underside of the dial disk 32. The sleeve is connected to a drum-like housing 43, there being a radial arm 44 connected to the sleeve and a retraction spring 45 connected to this arm and to a fixed attaching device 46 on the inside of the socket 3I. This tends to hold the drum in a fixed position. The shaft 34 extends into the drum and between the shaft and the drum there is a rheostat assembly which is standard equipment and does not form part of my present invention as many different types of rheostats of this nature may be utilized. One of the rheostat assemblies which I use is manufactured by the Central Laboratory and is quite well known on the market, However, as the rheostat itself forms no part of my invention I may employ a rheostat of the type shown in the Stimson Patent No. 1,962,919 as element 51; in the Stimson Patent No. 2,078,350 as element 49 and in the .Beauchamp Patent No. 2,089,171 as element 43.

The control for the rheostat while playing is indicated by the assembly numeral 69. This employs a raised cover piece 6I secured to the ornamental top I6 or extending thereabove, this having an opening 62. A wrist actuated lever 63 is formedofl a plate having a fulcrum or hinge 64 at one side of the opening 62, this being the side remote from the strings. A recess 65 is this has a slot 66 through which extends an operating arm 6i attached'to the bottom of the plate 63. A stop pin 68 is secured to one or both sides of a transverse deep groove 69 extending across the block II and joining the socket 3|. This is to accommodate an actuating link I0 secured at H to the arm 61 and at 12 to the arm 44. One or more coil springs 13 engage the block II, passing through a cut-out section on the ornamental top I8 and normally tends to elevate the outer edge 14 of the plate 63.

The manner of operating the device of Figs. 1 through 4, as above mentioned, is by the spring 45 operating through the amp, the sleeve 40 and the drum or housing 43 holds this housing in one position which may be designated as the initial position. The knob 35 may then be rotated which changes the rheostat until for instance a desired volume of tone is obtained. Should the player desire to change the tone entirely by the knob 35 he may do so provided he does not operate the hinge plate 63. Where however he intends to efiect a further control by such plate, the knob 35 may be turned until a suitable amplitude of sound is developed, this being however preferably the softest or quietest tone desired. Then while the player is playing the instrument with the fingers, for instance the fingers of the right hand being used to pluck the strings, the underside of the wrist may rest lightly on the pivoted plate 63 and the raised section 6| of the ornamental top, Then by increasing the pressure on the plate 63 this is de-' pressed, moving the arm 61 to the left of Fig. 2 and exerting a pull on the link ill which moves the arm 44 against the tension of the spring 45. On account of the friction developed-by the friction washer 42 and the washer 33 on opposite sides of the dial disk 32 and this washer engaging the shaft 34 with friction, the shaft and hence the knob 35 are retained from movement and the movement is developed in the drum or housing I3 while the shaft and the portions of the rheostat connected thereto are held stationary. This changes the electrical conductivity of the rheostat assembly and hence varies the strength of the electrical impulses which by suitable wiring connect to a radio type of amplifier. A jack connection 80 is used for connection to the amplifier. It will thus be seen that the rheostat may be controlled. either by the finger knob 35 or by the hinged plate 63 while the player is playing the instrument or may be controlled by both, thus changingthe amplitude of the sound from a loud speaker or the like.

In the construction illustrated in Figs. 5 through 9 inclusive, a portion of the guitar body is indicated by the numeral 803. This has an ornamental cover or finished surface Gill and is provided with a deep recess or opening IIDZ. A permanent magnet assembly I05 has two opposite end plates IIl6 with U shaped magnet IU'I fitted therebetween. The magnet has a lower pole E68 and an upper pole I09, the lower pole having a flattened upper surface H0 and the upper pole having a beveled surface III. The magnet assembly is journalled on pintles II2 secured in journal blocks II3. Such pintles may be screw pins engaging in perforations in the end plates I06. The electro-magnet assembly II5 has lower and upper plates H6 and I" with a series of poles II8 extending through these plates and extending slightly above the upper plate. Each pole is in alignment with a string I I9, there being one pole thus directly below each string. The electromagnetic winding I20 forms a coil around the magnet assemblies, these thus being of a usual type. The strings are secured in any suit- CPI able manner as by a bridging piece I2! and the leads from the magnet extend to a jack receiving socket such as shown in Fig. 1.

The tilting mechanism for the wrist control designated by the assembly numeral I25 employs a wrist engaging plate I26 having a hinge with a pintle pin I 21 adjacent the edge I28 which is contiguous to the strings, the pintle being mounted in end journals I29 and I30. A coil compression spring I3I is seated in a recess in the block I and engages the underside of the plate I26. The plate at one side has a downwardly turned arm I 35 through which the pintle pin I21 extends. This arm has a forward extension I36 which has its tip end I31 engaged in a perforation I38 on the plate I06 of the magnet assembly on the side opposite the plate I26. The compression of the spring I3I is such that it normally tilts the magnet assembly downwardly, that is, depresses the outer tip I31 of the arm I35 so that normally under the tension of such spring the poles II8 are spaced a maximum distance from the strings.

A limiting manual control designated by the numeral I40 employs a shaft I which extends through the block I00 being journaled in a perforation I42 and held in place by a riveted end I43 with a washer and preferably a pressed washer I44. This shaft has a finger operating knob I45 at the top attached to the shaft by a set screw I46. A helical or similar shaped screw I41 is secured to the shaft HI and extends outwardly therefrom to contact an offset bent end [48 of a rearward extension I49 of the arm I35. Thus by adjusting the knob I45 andhence the screw I41, the arm I35 and the plate I26 may be tilted on the pintle I21. This may be used to give a manual adjustment of the position of the electromagnet poles and the permanent magnet in reference to the strings or to form a limit to the drop or spacing apart of the magnets from the strings. When this is done, then any pressure by the wrist on the plate I26 operates to tilt the electro-magnets upwardly to bringthem in closer relationship to the strings. Manifestly this shortens the distance between the poles and the strings and thus increases the strength of the electro-magnetic field and hence of the current through the electro-magnet winding. Therefore when the instrumentalist is playing he may at will by pressing on the plate I26 vary the position of the electro-magnet poles from the strings, thus by change of the magnetic lines of force vary the electric current through the magnets and hence the current delivered to a radio type of loud speaker, the change being manifested in the volume of sound from a loud speaker or the like.

In the form of my invention illustrated in Figs. 10, 11 and 12, the instrument block I15 has an ornamental cover I16. At one end there is a recess I11 in which is fitted a U shaped permanent magnet I18. This has its lower arm I19 clamped to the base of the recess by a clamping bolt I80. The upper arm I8I of the magnet extends above the top of the instrument. There are a series of perforations I82 through the end of the magnet and through such perforations extend the strings I83. These may have their ends attached as indicated at I84 to the block in a suitable manner. The strings are thus positioned substantially midway between the lower and upper poles of the permanent magnet.

The slidable electro-magnet assembly I90 employs a slidable strap I9I which is mounted in guide bearings I92 and I93 secured to the instrument block. The strap has a. slight clearance above the lower pole I19 of the magnet. Mounted on this strap is the electro-magnet assembly I95. This assembly has a winding I96 and a series of lower permanent poles I91. A frame I98 of non-magnetic material such as copper strap has a lower bar I99 secured to the top of the electro-magnet assembly I95 from which opposite side pieces 200 extend upwardly and there is an upper strap or bar 20I connecting the sides, this having a clearance below the upper pole I8I of the permanent magnet. A series of complementary pole pieces 202 formed of magnetizable metal are secured to the cross bar 20 I, by providing the bar with a series of perforations 203 and the complementary pole pieces each extend through an opening 203 and are secured by riveting or swaging. It will thus be seen that this construction leaves a space 204 between the lower poles I91 around which is coiled the wire forming the winding I96 and the upper or complementary pole pieces 202, the strings being positioned between these poles as illustrated particularly in Fig. 11.

' The manual control to obtain a sliding movement of the electro-magnets and their associated pole pieces designated by the assembly numeral 2") includes a wrist or arm actuated plate 2 having a hinge connection 2 I 2 with a pintle 2 I 3 to the body of the instrument. An arm 2I4 extends downwardly from the underside of the plate and has a pin and slot connection 2I5 with the end 2I6 of the strap I9I, such strap having a quarter turn 2I1 so that the end is upright. A coil spring 2I8 engages underneath the plate 2| I and the instrument block I 15 or the ornamental cover I16 thereof. Although the strap I9I can only move with a rectilinear motion transversely of the instrument and of the Wires and although the arm 2I4 moves in an arcuate path, the pin and slot connection 215 accommodates the connection between the arm and the strap.

In the manner of operation of the invention of Figs. 10, 11 and 12, when the poles I91 and the complementary pole pieces 202 are in direct alignment, each pair with a string I83, there is the greatest magnetic flux between these poles and hence in the vibration of the strings the greatest electric current is developed in the coil of the electro-magnet. In this position the wrist operated plate 2 is tilted upwardly under the action of the compression spring 2I8 and by a slight depression or tilting downwardly of this plate a transverse movement is given to the strap I9I and hence to the electro-magnet assembly with its poles slightly shifting these to one side in reference to the strings. This slightly moves the poles I91 and complementary pole pieces 202 away from the direct line through the strings so that the strings are no longer in the path of the greatest magnetic flux. Therefore the electric current in the electro-magnet coil is decreased. Manifestly by operating the plate 2 the lateral shift of the electro-magnet with its pull pieces may be obtained and hence the intensity of the electric current generated may be varied which manifests itself in the amplitude of the sound from the loud speaker operated through a radio type of amplification. It will be seen therefore that in the construction of Figs. 10, 11 and 12 as in Figs. through 9, due to a change in magnetic field in reference to the strings, a change or fluctuation may be developed in the electro-magnets and hence a change in the amplitude of the sound from a loud speaker.

Various changes may be made in the details of the construction without departing from the spirit or scope of the invention as defined by the appended claims.

I claim:

1. In a stringed musical instrument in which a plurality of strings are positioned to be plucked by the fingers of a player and in which the instrument is provided with an electro-magnet having an individual pole adjacent each string and an electric winding for transmission of electric current therethrough, the combination of a movable control device mounted on the instrument and positioned approximate thestrings to be engaged by part of the arm, the fingers of which pluck the strings, with means actuated by the control device to increase or decrease the electric current through the electro-magnet whereby on amplifying such current and translating into sound, the amplitude of the, sound may thus be increased or decreased, the means actuated by the control device including a slidable mounting for the electro-magnet whereby the poles may be shifted laterally relative to the strings to displace the poles oifset or in alignment with the strings.

2. In a stringed musical instrument in which an instrument body is provided with a plurality of strings positioned to be plucked by the fingers of the player whose arm is adapted to extend over part of the instrument body approximate the strings and in which an electro-magnetic assembly with a winding for transmission of electric current is positioned in the instrument body adjacent to the strings, the combination of a movable control device mounted on the said body on the side of the assembly of strings over which the player's arm is adapted to contact and move, a movable member actuated by the c: ntrol device and having means to increase or decrease the electric current through the electro-magnet whereby on amplifying such current and translating into sound the amplitude of the sound may be increased or decreased, the movable member including a fixed permanent magnet and an electro-magnet assembly mounted for sliding movement transverse to the assembly of strings, the electro-magnet assembly having a pole piece one for each string and an interconnection between the control device and the electro-magnet assembly for shifting said assembly transverse to the strings to vary the distance between each pole piece and its individual string.

3. In a stringed musical instrument in which an instrument body is provided with a plurality of strings positioned to be plucked by the fingers of the player whose playing arm is adapted to extend over part of the instrument body and in which an electro-magnetic assembly has a permanent magnet and a winding for transmission of electric current with a pole piece associated with each string combined with a movable control device mounted on the said body on the side of the assembly of strings over which the players arm is adapted to move and a connection from the control device to at least part of the electromagnetic assembly operative to vary the distance between the pole pieces and the strings with which they are associated, the permanent magnet being somewhat U shaped and having the winding with the individual pole pieces mounted on one pole of the magnet, the magnet being journaled on pivots transverse to the strings whereby the magnet with the winding and pole pieces may be oscillated in an arc to vary the distance between each pole piece and its associated string in the same plane.

4. A musical instrument having a plurality of strings for emitting difierent tones, an electromagnet assembly having an individual pole adjacent each string and an electric winding for transmission of electric current therethrougll combined with a control device positioned to be actuated by the player of the instrument, the electro-magnet and the poles having a movable mounting in the body for sound amplitude vari-' ation, a connection from the control device to the electro-magnet assembly to vary the distance between the poles and the respective strings to thereby increase or decrease the electric current resulting from the vibration of each string during the playing of the instrument whereby on amplifying such current and translating into sound, the amplitude of sound may thus be increased or decreased.

5. A musical instrument as claimed in claim 4, the electro-magnet assembly being shiftable whereby when actuated by the control device the distance from the poles to the strings is varied while maintaining each pole and its respective string in the same plane.

6. A musical instrument as claimed in claim 4, the electro-magnet assembly having a pivotal mounting in the instrument and the connection from the control device oscillating the electromagnet assembly on its pivot to thereby vary the distance of the poles from the strings while maintaining each pole and its respective string in the same place.

7. A musical instrument as claimed in claim 4, a part at least of the electro-magnet assembly including the poles being slidably mounted in the instrument and a connection from the control device to the sliding part of the electro-magnet assembly sliding such assembly part bodily and thereby shifting each pole laterally from the position of alignment with its respective string.

8. In a stringed musical instrument of the guitar type, the combination of a control device with a lever plate fulcrumed to the instrument by a pintle parallel to the top face of the instrument and also substantially parallel to the set of strings on one side thereof, a spring means normally inclining the plate relative to the top face of the instrument whereby by engaging the lever with the forearm, the fingers of which pluck the strings, said plate may be rotated on its pintie an electro-magnetic pick-up on the instrument and means connecting the lever plate and the pick up for varying the electric current for amplification and transition into sound of changing amplitude.

9. An electro-magnetic pick-up assembly for stringed musical instruments comprising an electro-magnet with poles each adapted for association with a particular string, a pivoting mounting means for attachment to the instrument with its pintle transverse to the assembly of strings a pivot to rotate the magnet and its wound pole pieces in reference to the strings while retaining each pole piece and its associated string in the same plane,

11. An electro-magnetic pick-up assembly for stringed musical instruments including a permanent magnet with electrically wound pole pieces adapted for mounting on the instrument with each pole piece associated with a particular string and means to vary the distances between each pole piece and its associated string, the magnet having a fixed mounting on the instrument and the wound pole pieces being movable transversely of the string to laterally displace each pole piece from the closest position to its associated string.

12. In an electro-magnetic piclr-up assembly for stringed musical instruments, the combination of a magnet with a set of electrically wound pole pieces adapted for mounting on the instrument with each pole piece associated with a particular string, a control device with a lever plate fulcrumed to theinstrument by a pintle parallel to the top face ofthe instrument and also substantially parallel to the set of strings at one side thereof, a spring means normally inclining the plate relative to the top face of the instrument, the lever plate being positioned to be engaged by the forearm, the fingers of which pluck the strings to rotate the plate on its pintle and a connection between the lever plate and the set of pole pieces to move at least the pole pieces to vary the distance between each pole piece and its associated string.

13. In an electro-magnetic pick-up assembly for stringed musical instruments, the combination of a substantially U shaped permanent magnet, a set of electrically wound pole pieces on one pole of the permanent magnet, means for pivotally mounting the permanent magnet on the instrument to align each pole piece and an associated string and means for tilting the permanent magnet and set of pole pieces on the pivto be engaged by oted mounting to vary the spacing of each pole piece and its associated string while maintaining each pole piece and its associated string in the same plane.

14. In an electro-magnetic pick-up assembly for stringed musical instruments, the combination of a substantially U shaped permanent magnet, a set of electrically wound pole pieces on one pole of the permanent magnet, means for pivotally mounting the permanent magnet on the instrument toalign each pole piece and an associated string and means for tilting the permanent magnet and set of pole pieces on the pivoted mounting to vary the spacing of each pole piece and its associated string while maintaining each pole piece and its associated string in the same plane, said tilting means comprising a lever plate fulcrumed to the instrument by a pintle parallel to the top face of the instrument and. also substantially parallel to-the set of strings at one side thereof, a spring means normally inclining the plate relative to the top face of the instrument, the lever being positioned the forearm, the fingers of which pluck the strings to rotate the plate on its pintle and a connection between the lever plate and the permanent magnet whereby the magnet and pole pieces may be tilted on the pivoted mounting.

15. In an electro-magnetic pick-up assembly for stringed musical instruments, the combination of a substantially U shaped permanent magnet with poles, means to fixedly attach the permanent magnet to the instrument, a frame slidably mounted between the poles of the permanent magnet, a set of electrically wound pole pieces mounted in the frame adapted each for aligning with its associated string. the frame being adapted for sliding transversely to the assembly of strings to change the spacing between each pole piece and its associated string.

DHBERT J. DICKERSON.

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