Abstract: An electromagnetic pickup adapted for use with a multistringed musical instrument having strings formed of a ferromagnetic material having a first wire coil wound in a first direction in an elongated oval shape wherein the first coil has a geometrical distance along its elongated axis which exceeds the distance between the outermost strings wherein the first coil includes an opening which extends through the interior thereof, a second wire coil wound in a second direction and in an elongated oval shape, the geometrical dimensions of which are substantially equal to that of the first coil and wherein the second coil includes a second opening which extends to the interior thereof, and wherein the second coil is positioned in a spaced opposed aligned relationship with the first coil with the first opening in axial alignment with the second opening forming a coil stack assembly having a hollowed-out central cavity, a permanent magnet assembly which is positioned in the hollowed-out central cavity with one pole po

Abstract: A pickup device for an acoustic guitar having metallic strings comprises an electromagnetic pickup detachably attached in a sound hole of the guitar and a piezoelectric pickup detachably attached in the sound hole or to another part of a sound board of the guitar. Outputs of the two kinds of pickups are mixed at a selectable ratio thereby to compensate for difference in the picking-up characteristics of the respective pickups.

Abstract: A transducer for a stringed musical instrument includes a pair of coils mounted adjacent each string of the instrument. The coils have substantially the same number of turns of electrically conducting wire wound thereon, and the wires constituting the coils are of different gauges.

Abstract: A transducer adapted to fretless musical instruments, instruments with non-conductive frets or non-conductive string wrapping, with two or more vibratable strings of magnetically permeable material. The strings pass through a magnetic field. Motion of the strings generates current in the strings. The magnetic field is provided by magnets shaped to concentrate the field across the signal generating portions of the strings. In a preferred embodiment, the coils are wound around the specially shaped magnets to utilize the same magnetic field used to generate current in the strings. Means are provided to passively mix both signals generated in the coil and signals generated in the strings. The circuitry electrically connected to the strings incorporates a method of balancing the uneven output caused by differences in string diameter. There is no special "return" wiring of the neck required. A wide variety of tonal differences are obtainable without active circuitry or signal processing.

Abstract: For controlling the blend between two pickups on an electric guitar, this circuitry provides, over the range of a single simple potentiometer, continuously variable blend between the two pickup signals in a particular phase relationship plus continuously variable blend of the two signals in a reversed phase relationship, eliminating the use of phasing switches, and providing musicians with a wide range of tonal variation under continuous control, for freedom of musical expression and timbre modification not available heretofore. Implementation with operational amplifier integrated circuits facilitates further processing of each pickup signal independently for special effects such as the introduction of controlled distortion.

Abstract: A system and method for instruction in the operation of a keyboard musical instrument, namely, an organ or piano. The system and method teaches the proper fingering for chord triads in the root, first, and second positions so as to play chord triads in the space of a single octave. The system may be operated manually by the student or, in some embodiments thereof, the system may be operated automatically by means of an external storage media device such as a video disc player.

Abstract: This invention relates to a keyboard input coding device comprising a counter for counting ON and OFF duration of signals obtained by pushing a keyboard, an encoder for producing codes of musical interval corresponding to keys of the keyboard, a note-length discriminating circuit for taking count values from the counter based on signals from the keyboard and discriminating a note-length, a note-length memory circuit for receiving or supplying the note-length data from or to the note-length discriminating circuit, a reference time generating circuit for supplying the note-length discriminating circuit with data of partitioning a musical section and a processing control circuit, wherein the discrimination of the note-length is effected by referring to the note-length between sequential notes according to data stored in the memory circuit, thereby a musical note with a note-length to agree well with intention of an operator is coded after correcting the key input duration data according to estimates made from th

Abstract: An improved electromagnetic pickup for a stringed musical instrument includes constant magnetic field providing magnets for each of the strings adjustably aligned adjacent to each of the strings at a sound providing region of a frame of the instrument. The aligned magnets generate a magnetic flux strength and orientation for each string tailored to the particular string and its tonal characteristics. A very high frequency preamplifier subsystem having a very low impedance input is connected to the strings through shielded connectors extending to the string anchors and functions to amplify greatly the minute electrical signals induced in the plurality of strings as they vibrate when the instrument is being played.

Abstract: A solenoid driving apparatus for actuating keys of a player piano is provided in which respective key striking strength data can be applied to respective solenoids of keys, so that musical tones can be reproduced correctly and in which the key striking strength data at the time of musical performance can be compensated for high fidelity reproduction. The solenoid driving apparatus includes a plurality of keys and solenoids provided on each key. When a key is depressed, a first key striking strength data corresponding to key striking strength and a data designating the depressed key are generated. The first key striking strength data is then converted into a second key striking strength data so as to make the latter data in linear proportion to an operating or response speed of the solenoid. In accordance with the second key striking strength data, a solenoid driving data is generated, and is applied to the solenoid corresponding to the key designated by the designating data.

Abstract: A pick-up for an electrical musical instrument of the stringed type which provides better separation between the sound from each string in a humbucking pick-up. This is achieved by longitudinally offsetting from each other a pair of pick-up assemblies mounted in a housing and mounting the pick-up on the body of an electrical musical instrument at an obtuse angle relative to the direction of the strings, the angle of mounting of the housing on the body being a direct function of the longitudinal offset whereby each of the pick-up assemblies is centered under the strings.

Abstract: A sound producing instrument is shown having a plurality of vibrating strings supported over an elongated aluminum sounding board. The strings are solid wires of brass, bronze or steel that are tensioned to produce a range of vibrations within the audible sound range. The strings may be manipulated along their lengths in various ways to control the mode of vibration of each of the respective strings. An electronic means such as a crystal or magnetic microphone is provided adjacent to the sounding board to pick up the vibrations resulting from activating the vibratory motion of the strings, and amplifying means are used to reproduce the sounds developed by the instrument. In one embodiment, the microphone may be caused to move during the pickup by a remote controller, so as to provide different sound effects. A special cylinder is provided for creating special sound effects when used to agitate the strings.

Abstract: An electrical pickup device for a stringed musical instrument having ferromagnetic strings comprises a pair of superposed coaxial bobbins, each axially wound with a coil having its axis perpendicular to the instrument strings. An integral plate of magnetic material is provided comprising a base disposed between the two bobbins perpendicular to the coil axis and two side walls extending upwardly and perpendicularly from the base to at least immediately below the top face of the upper bobbin. A plurality of rod-like permanent magnets extend through at least the upper coil parallel to the axis thereof and contact the base of the integral plate and the magnets have like polarities at the tops thereof.

Abstract: A musical instrument comprised of discrete detachably assembled components permitting easy change of said components. The instrument is provided with a center section and a main body section which furnish the central core for the interconnection of component parts such as the neck, multiple pick-ups and an electronic control module. Appropriate electrical connections are automatically made when the components are placed together.

Abstract: An electric guitar transducer mounting permitting rapid interchange and replacement of transducers in an electric guitar. An electric guitar of any desired contour is formed with an opening extending from the front face through to the back of the guitar body, with this body opening dimensioned to accommodate any one of the generally available transducers (pickups) employed with electric guitars. A sleeve is formed dimensioned to fit within the guitar body opening, and provided with an entry opening from the back of the guitar body to receive a module containing a transducer. The sleeve is formed with electrical terminals engageable with the module and electrically coupled to the wiring in the conventional electric guitar body. The module is formed with a selectively removable top plate engaging and securing a given transducer in the module for selective positioning in the sleeve.

Abstract: This invention discloses a tone control for an electromagnetic pick-up for a stringed musical instrument wherein the electromagnetic pick-up comprises at least a pair of coils and a magnet, comprising means for gradually switching the mutual connection between the coils from parallel to series or vice versa, the switching means comprising at least a ganged pair of rheostats of high rated resistance wherein at one extreme of travel of the sliding members of the ganged potentiometers the coils are connected in parallel and at the other extreme they are connected in series, and at intermediate positions a combination of parallel and series connection output components is outputted.

Abstract: Not only an image signal of a scene of performance of musical instruments and a sound signal of such performance, but also the performance data of a specific musical instrument are recorded by a video system, and by virtue of a reproduction of this record, the image signal, the sound signal and the performance data are separated from each other. Thus, not only the image from the image signal and the electronically reproduced sound from the sound signal, but also a real automatic playing musical instrument such as player piano corresponding to said specific musical instrument is actually driven to effect a performance, whereby the watcher-listener is also able to listen to the performance sound of a real musical instrument.

Abstract: Computer organ tone input for alterable stops is achieved by single-key input through a decoded keyboard which is couple to a logic network and optoelectrical output drive circuitry. The decoder circuitry activates selected optical emitters in an array which is mounted in the optical reader of a computer organ such that the decoder circuitry is electronically isolated from the computer organ. The invention eliminates the need for a tone card library, does not interfere with the sensitive circuitry of the organ and permits instantaneous reprogramming of alterable voices.

Abstract: The present invention provides a system for communicating data among microprocessors which are utilized to control an electronic musical instrument. A master microprocessor transmits a synchronizing signal comprising two, spaced pulses to the other microprocessors causing the other microprocessors to interrupt their operations and become synchronized with the synchronizing signal. Thereafter, according to a prearranged sequence, one microprocessor commences transmitting data while simultaneously the other microprocessors commence inputting data.

Abstract: A transducer adapted to fretless musical instruments, instruments with non-conductive frets or non-conductive string wrapping, with two or more vibratable strings of magnetically permeable material. The strings pass through a magnetic field. Motion of the strings generates current in the strings, as well as in coils placed within the common magnetic field. Means are provided to passively mix both signals generated in the coil and signals generated in the strings. The circuitry electrically connected to the strings incorporates a method of balancing the uneven output caused by differences in string diameter. There is no special "return" wiring of the neck required. A wide variety of tonal differences are obtainable without active circuitry or signal processing. The signal level and impedance is such that it can be connected through a convenient length of cable to a standard musical instrument amplifier.

Abstract: An automatic musical performance device including storage circuits, read out control circuits, and conversion circuits, wherein the storage circuits store a series of musical note data. Each of the musical note data is represented by multi-bits whose number is dependent on its own use frequency which means a degree of repetitive use of the data in a music. The read out control circuits read out the musical note data from said storage circuits and supply the musical note data to the conversion circuits. Then, the conversion circuits perform the code conversion of the musical note data to other musical note data whose number of bits are independent of their own use frequency. In the automatic musical performance device, musical sounds are produced or key depressing positions are indicated in accordance with the musical note data from the conversion circuits.

Abstract: A feedback reducing device for an acoustic electric guitar is in the form of a plug adapted to be snugly received in the sound hole of a guitar. With the plug in place, the sound hole opening is completely covered and the amplified performance of the instrument is not significantly effected.

Abstract: An electrical pickup for a stringed musical instrument comprises a cylindrical permanent magnet and a coil surrounding the magnet and wound lengthwise thereof. The ends of the magnet are fixed to two rigid mounting wires, and the coil is wound on a former comprising a central tubular core and two parallel plates fixed to the tube on diametrically opposite sides thereof. The tube, and thus the former and coil as a whole, can turn on the magnet. The magnet is magnetized so that the magnetic poles thereof are positioned at diametrically opposite edges of the magnet, i.e. at the ends of a diameter of the circular cross-section of the magnet cylinder. Thus the former and coil can be turned between two positions 180.degree. apart in order to reverse the winding direction of the coil around the fixed magnetic axis H of the magnet.

Abstract: An improved pickup system for stringed musical instruments, adaptable to all types of stringed instruments, in which strings pass through the hollow central portion of coils and the magnetic field within coil windings is perpendicular to the windings and parallel to the string axes. The described embodiments include an individual coil encompassing each string and a magnetic field reversed in polarity in portions of a coil oppositely disposed to a string. Magnetic elements provide an enclosed magnetic field limiting pickup response to a short, defined segment of string near an instrument's bridge. Described acoustic pickup embodiments are mounted directly to the bridge and interrupt the circle of acoustic feedback. Violin family pickup embodiments provide preferential sensing of string motions parallel to the string plane and adjustability of string response.

Abstract: An electromechanical piano of the type incorporating asymmetrical tuning forks. To increase vastly the dwell of the forks in the high-pitched range of the piano, a fork-mounting construction is employed wherein only a single screw is associated with each fork. Elastomeric means are provided around each screw and also between opposed edge surfaces of adjacent forks, whereby to prevent rotation of each fork about the axis of its associated mounting screw.

Abstract: A humbucking electromagnetic pickup for musical instruments, such as guitars having ferromagnetic strings. The pickup includes a permanent magnet for generating a flux path through the strings, a sensing coil in the flux path, and a humbucking coil substantially out of the flux path and concentrically wound closely around the periphery of the sensing coil and in opposition thereto to cancel radiating extraneous interfering electromagnetic hum from the sensing coil.

Abstract: A sound pickup for a stringed musical instrument has a hollow open-topped housing with a base plate matingly fitting in the housing; the housing is formed of ABS plastic coated with copper nickel-chrome layers. The base plate is formed of ABS with its outer surface being nickel plated; two parallel slots in the base plate frictionally receive lower edges of parallel elongated coil core blades. An elongated magnet is positioned between the core blades and first and second coil assemblies including elongated slotted plastic bobbins are fitted over the core blades to overlie the magnet with lugs on the bobbins facing opposite ends of the magnet to hold it in position.

Abstract: A process and apparatus are provided for recording electric signals corresponding to piano key operation and for reproducing the piano key operation. The process includes switching a discrete frequency oscillator corresponding to each piano key, algebraically adding the outputs of each oscillator, filtering the algebraic sum of the oscillator outputs through a low pass filter, recording the filtered signal, reproducing said filtered signal through a high pass filter, detecting each frequency in the high pass filtered signal, and energizing an electromechanical device so as to actuate the piano key which had switched the discrete frequency oscillator.

Abstract: A central processor for an electronic organ in the form of a single, forty pin integrated circuit chip employing multiplexed technology and trinary and tri-level inputs to obtain maximum usage from each pin. The solo manual keys, chord keys, rhythm pattern switches and other control functions are multiplexed externally of the chip, fed into the chip as a time division multiplexed four bit byte over four pins, and demultiplexed internally of the chip. The solo manual information is multiplexed internally of the chip to form a single serial data stream, is combined with solo fill note data generated within the chip and then brought out over a single pin for external demultiplexing. The twelve tones of a musical octave are brought into the chip over twelve pins together with various static control signals, are decoded by tri-level decoders internally of the chip, and then utilized to generate the tones of the chords, also internally of the chip.

Abstract: A pitch detecting system is provided for an electric guitar having an existing electromagnetic pick-up for strings. For the purposes of pitch detection, all the signals from the guitar strings are sensed by means of an auxiliary pickup comprising a substantially planar substrate of nonconductive material which is mounted upon the existing pickup, below the strings. A plurality of conductive coils on the substrate are each positioned in alignment with a different pole piece of the existing pick-up. The auxiliary pick-up provides a signal representing the sound of each string to a string separator, which transmits to its output only the signals from the auxiliary pick-up which has the fastest rate of build-up of its input signal. The single output signal from the string separator is provided to a pitch detector. In the pitch detector, a reference point in each cycle of the input signal (i.e.

Abstract: Two magnetically permeable pole pieces have pole faces of predetermined configuration formed thereon, and the pole pieces conduct magnetic flux which interacts with a magnetically permeable string of a stringed instrument. The positioning of the pole faces, the geometric configuration of the pole faces relative to the string, and the predetermined pattern of magnetic flux emanated from the pole faces are arranged so that vibrational movement of the string in one plane creates significant magnetic flux changes in a first pole piece and minimal or no flux changes in the second pole piece. String vibrational movement in a second plane mutually perpendicular to the first plane creates significant magnetic flux changes in the second pole piece and minimum or no flux changes in the first pole piece. The magnetic flux changes are sensed and electrical signals related to the flux changes are derived. The electrical signals are supplied directly to audio amplifying equipment.

Abstract: An electronic musical instrument includes a programmed microprocessor for controlling selected functions of the instrument and a plurality of key and tab switches responsive to a scan control signal repetitively scanning the switches for developing a serial data signal defining operated key and tab switches during each of the scans. An interface circuit is interposed between the key and tab switches and the microprocessor for developing the scan control signal and for receiving the resulting serial data signal. The serial interface circuit includes means for converting the received serial data into a number of first multibit words each representing a depressed key and a number of second multibit words each bit of which represents the operational condition of a respective one of the tab switches.

Abstract: A remote-controlled device for depressing the keys of a keyboard instrument which comprises in the device: separate means for depressing each of the desired keys, each of said means being pivotally mounted on a fulcrum, means for selectively rotating the key-depressing means about its fulcrum so that at least a part of each of the corresponding key-depressing means depresses the desired keys of the instrument's keyboard, above which the device is positioned.This invention is concerned with a device to depress the keys of a keyboard, particularly the keys of a musical instrument. More particularly, the device may be used to depress and keep depressed the keys of the keyboard on a pipe organ, especially when the organ is being tuned.

Abstract: This apparatus pertains to mechanical and electromagnetic apparatus for controlling player piano operation. The conventional player piano paper tape which opens and closes pneumatic holes in a tracker bar is replaced by a valve board and a plurality of electromagnetic valves. Each electromagnetic valve operates to control air passage through one of the holes in the tracker bar.

Abstract: An electromagnetic pickup device for stringed musical instruments using metallic strings has a planar permanent magnet with one of its two main surfaces exposed for facing the instrument strings during use and a pickup coil mounted on the other main surface with the plane of the planar magnet perpendicular to the axis of the coil.

Abstract: An asynchronous interface includes two memories which store multiplexed keyboard information such that while one memory is writing in newly acquired key information from one musical instrument system at the clock rate of that system, the other memory is reading out previously acquired key information to a second musical instrument system at the clock rate of the second system. Periodically, based on timing signals derived from both systems, the read/write roles of the two memories are reversed. Any number of asynchronously clocked systems, each connected to an associated asynchronous interface, may be keyed by a single key multiplexing device or by the multiplexing information from another asynchronous interface.

Abstract: In a pick-up for an electrical musical instrument of the type including first and second pick-up assemblies positioned in parallel, spaced relationship, each of the pick-up assemblies including at least one pole piece operatively associated with the strings of the instrument and a coil wound around the pole pieces, there is disclosed an improved splitter switch whereby whether the coils are connected in series or in parallel, when single coil operation is desired, the coils are connected in series with a capacitor across one of the coils whereby the splitter switch effectively provides single coil operation without decreasing the overall signal level of the pick-up.

Abstract: A magnetic pickup for a stringed musical instrument, comprising a polar magnet having a polar axis extending across its thinnest dimension, a coil having a magnetically permeable pole piece extending upwardly for positioning adjacent an instrument string, with the polar magnet positioned longitudinally parallel to the coil and having its polar axis perpendicular to the winding axis of the coil. Positioned within the coil is either a magnet or a pole piece. The pickup may include a plurality of coils and magnets arranged as described above to increase the effectiveness of the pickup. Also disclosed is a method for manufacturing the pickup which includes setting the pole piece, coil, magnet, and mounting bracket in a mold cavity, and casting the entire unit with potting material.

Abstract: A device mountable on a guitarist's finger for use in altering the normal vibration of a vibrating guitar string and for converting the altered vibrations into electrical impulses is disclosed. The device includes a generally cylindrical string contacting member on which is mounted a microphone-type transducer.

Abstract: An electromagnetic pickup is provided for musical instruments, particularly of the type having vibrating magnetizable strings, which pickup device includes a permanent rectangular bar magnet having a configured surface adjacent to the magnetizable strings to provide a varying magnetic field effecting respective ones of the strings in accordance with their magnetizability, and a coil surrounding the permanent magnet which may be either of a low or high impedance. Thin metal plates or shims are arranged in the pickup intermediate the configured surface of the bar magnet and the magnetizable strings. Various configurations of the magnet surface are included, each of which in combination with the metal plates achieves the natural tone of the respective strings and enhances the balance therebetween of the pickup output.

Abstract: An electromagnetic pickup for stringed instruments such as a guitar includes a pickup coil that is mechanically oscillated at variable frequencies in the field of the magnetically polarized instrument strings for producing an effective tremolo output signal.

Abstract: An electric stringed musical instrument is formed of a body section adapted to detachably receive an interchangeable neck section. The body section mounts the electronic tone and volume controls and includes the electromagnetic pickup which is rendered into operative proximity to the neck strings when the instrument is in the assembled condition. The body section is adapted to interchangeably receive neck sections of various string types and fingerboard widths and the electromagnetic pickup is selectively moveable in the longitudinal, i.e., horizontal direction and also in the vertical direction to accomodate the particular string characteristics of the interchangeable neck section.

Abstract: A magnetic pickup assembly is mounted from a support member bridging across the drum housing. The support member preferably extends diametrically across the drum housing and has slot means or the like permitting the mounting of the pickup assembly at different positions along a radial locus of the drum housing. In a preferred version the support member is of laminated construction to reduce vibration. The pickup assembly, in addition to comprising a pickup coil also comprises a series of ferromagnetic members secured to the drum diaphragm and also disposed spacedly along the radial locus of the housing; the arrangement wherein the pickup coil is adjustable to one of a number of different positions for obtaining different tonal outputs from the instrument.

Abstract: A simulated violoncello having an elongated body shaped in conformity with the fingerboard of a violoncello and a pair of curved panels adapted for confinement between the knees of the user and attached to the body to simulate the knee-held side portions of the resonance box of a violoncello is disclosed. The panels may be attached to a block which slidably engages a rail of trapezoidal cross-section formed along the back of said body and extending along a lower portion of the length thereof, whereby the height of said panels can be adjusted. An elongated floor support arm is attached to a lower end of the block which is removable and reversably disposable upon the rail so as to place the floor support arm in a stored position behind and adjacent the body of the instrument.

Abstract: A simple adjustable mount is insertable in the soundhole of a stringed musical instrument where it supports itself without damage to the instrument. The mounted pickup is adjustable on the mount for desired position.

Abstract: An improved magnetic induction type pickup arrangement incorporated in an electric guitar having a pair of three-coil magnetic type pickup units operable to produce enhanced outputs. The electric guitar includes a switching mechanism for selectively controlling the connection of the three-coil pickup units across the guitar's electric amplifier.

Abstract: A pickup for an electrical musical instrument of the stringed type including first and second pickup assemblies, each pickup assembly including a plurality of metallic, unmagnetized pole pieces operatively associated with the strings of the instrument, the pole pieces being aligned in parallel, spaced-apart relationship, generally perpendicular to the plane of the strings, first ends of all of the pole pieces being closely adjacent to the plane of the strings, second ends of all of the pole pieces being flat and planar.

Abstract: A musical keyboard instrument is disclosed for recording and storing a musical performance and then automatically playing back the performance. As is conventional, a keyboard having a plurality of keys is provided, along with musical tone generators that are associated with the keys. In accordance with the disclosed invention, means are provided for sensing, at a sensing time, those of the keys which are activated. A sequence of frames are generated, each frame including digital information representative of the keys that are activated at a given sensing time. The duration of each frame is a function of the relative locations of the keys activated at a given sensing time, and is therefore a duration which can vary from frame to frame. Each sensing time is determined by the previously completed frame, i.e., when a frame is complete, the statuses of the keys are again sensed so that the next frame can be generated. The sequences of frames are stored on magnetic tape.

Abstract: A stringed instrument is disclosed which incorporates improved design and performance features. An elongated body, hereinafter called the wedge, contains in itself all necessary components and parts making it a totally playable instrument with or without a pair of removable wing bodies. One purpose of the wing body attachments is to provide flexibility for modular electronic add-on components for use with new modern amplification devices. Also the wing bodies may be changed to provide a varity of instrument body designs, colors, finishes and fabrics. The sound produced by each of the strings of the instrument is enhanced by providing each string with at least one individual magnetic pickup which is individually adjustable to that string for optimum performance. Each string is also provided with its own individual bridge support which is completely separated from each other bridge support to prevent any acoustical and/or electrical cross-feed.

Abstract: An electromagnetic pickup for a stringed musical instrument has a plurality of magnet and coil signal generating units each associated with a respective one of the strings, and the housing which contains the signal generating units also contains an associated plurality of adjustable potentiometers whereby the contribution of each generating unit to a composite output signal may be varied. A fixed resistance connected to each potentiometer prevents each generating unit from being turned entirely off, and another fixed resistance in the main output line assures an acceptable input impedance to a tone control and amplifier, or other utilization circuit, to which the pickup is connected.

Abstract: The following specification describes a self-generating electrical pickup to be applied to percussion type musical instruments with vibrating elements of steel or containing ferromagnetic material. The pickup is used in conjunction with an amplifier and loudspeaker to amplify the instrument sound. The pickup makes use of a plurality of pick off coils, one of each is used in proximity to each vibrating element of the musical instrument. Each pick off coil consists of a coil of many turns of fine wire within which is placed an iron core to which is bonded a ceramic permanent magnet. The large surface area of the ceramic magnet adjacent to the musical instrument vibrating element causes large magnetic flux changes in the coil and consequently a large signal voltage which is amplified to drive the loudspeaker. The large signal available, in this design, reduces the effect of 60 Hz hum induced by stray electromagnetic fields. The use of a ceramic magnet provides for a cost effective design.