Abstract:
An electric stringed musical instrument that produces and processes electric signals through an analog circuit has the analog circuit digitally controlled. The digital control is preferably such that it enables desired preset conditions for the analog circuit to be stored and later recalled in a simple, rapid manner by a musician while he or she is playing the instrument. The instrument can additionally, or alternatively, include energy management and string responsiveness features.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to electric stringed musical instruments which generate analog electric signals in response to playing one or more strings of the instrument and which modify the electric signals through an analog circuit mounted on the instrument. It is a particular aspect of the present invention that the analog signal is digitally controlled, preferably such that desired preset conditions for the analog circuit can be stored and later recalled in a simple, rapid manner by a musician while he or she is playing the instrument. Another aspect is to conserve electrical energy when the instrument is operational. Still another aspect is to provide a control signal, such as for use in the energy conservation, in response to movement of at least one of the strings of the instrument. 
     Although the present invention is applicable to and encompasses any electric stringed musical instrument of a type suitable for the digital control referred to in this specification, it will be described with reference specifically to electric guitars. The term &#34;electric guitar&#34; as used in this specification and in the claims encompasses electric bass guitars, electric lead or rhythm guitars, and any other similar instrument despite any differences such as the number and type of pickup, the nature of the analog circuit through which signals from the pickup(s) are processed, and the type and layout of the controls located on the guitar body and manipulated by the musician. 
     A conventional electric guitar has a body to which the strings are attached and on which various controls are located. One or more pickups are mounted on the body beneath the strings so that electric signals are generated in response to movement of the strings. One type of pickup is electromagnetic whereby the electric signals are produced in response to string movement through the magnetic field. An analog circuit typically containing one or more resistors and capacitors connects between the pickup(s) and an output jack in which a cord is plugged to connect the analog circuit of the guitar to a preamplifier or amplifier. One or more of these resistors and capacitors has a variable resistance or capacitance which the musician can change by manipulating the controls which are mounted to the guitar body and connected to the variable analog circuit components. This control allows the musician to change the tone (frequency blend) and volume (magnitude) of the electric signals provided to the output jack. 
     With this conventional analog electric guitar, the guitarist has to manually change the respective control knobs or switches on the guitar body to obtain a desired tone and volume. This can be inconvenient and inexact when the musician has to do this during the course of a live performance each time he or she gets to a musical passage or song that requires the analog circuit parameters to be changed. That is, for a particular passage or song, the musician may know ahead of time that a desired set is to be used; and with a conventional electric guitar, the musician also knows that the desired set will have to be manually input by turning one or more respective knobs or moving one or more switch arms. It would be desirable if such desired settings could be implemented without the musician having to directly make each setting adjustment for all the analog circuit parameters that need to be changed for the desired set, and yet still have the electric guitar otherwise be operated, and sound, the same as the conventional electric guitar. More broadly, there is the need for a digitally controlled analog electric stringed musical instrument that can be operated in a conventional manner and that provides the instrument&#39;s conventional sound. 
     SUMMARY OF THE INVENTION 
     The present invention satisfies the above-noted and other needs by providing a novel and improved digitally controlled analog electric stringed musical instrument and apparatus. The present invention maintains the look, feel and sound of the conventional instrument. It allows for conventional control of the instrument by the musician, but it also enables the musician to store and recall desired settings or presets to which the analog circuit of the instrument is to be configured at the command of the musician. The invention also allows for conventional control by the musician from any preset condition. 
     The present invention provides an electric stringed musical instrument apparatus which comprises a manually operable tone-control member and a manually operable volume-control member (as used in this specification and in the claims, &#34;tone&#34; encompasses all facets pertaining to the frequency composition or nature of the signal/sound, whether by different pickup combinations or resistor/capacitor adjustments or otherwise, whereas &#34;volume&#34; encompasses all facets pertaining to the magnitude or amplitude of the signal/sound). This apparatus of the present invention also comprises an analog circuit for an analog electric signal generated by an electric stringed musical instrument. It further comprises a digital control circuit connected to the tone-control member, the volume-control member, and the analog circuit such that the digital control circuit digitally controls the analog circuit in response to the tone-control member and the volume-control member. Preferably, the digital control circuit includes a memory in which to store a preset combination of tone and volume control information. In this embodiment the apparatus further comprises a manually operable switch connected to the digital control circuit such that actuation of the switch causes the digital control circuit to control the analog circuit in response to the stored preset combination of tone and volume control information. The aforementioned apparatus can be manufactured integrally with the instrument or it can be a separate subassembly for use in converting an existing instrument. 
     As to the instrument itself, the present invention includes, in an electric stringed musical instrument including tone and volume control knobs and a pickup which generates an electric signal in response to movement of one or more strings of the instrument, the improvement comprising a digitally controlled analog circuit which modifies the electric signal from the pickup in response to settings of the tone and volume control knobs. This preferably further comprises a digital memory having storage locations for predetermined tone and volume control information, with the digital memory connected to the digitally controlled analog circuit such that the analog circuit is responsive to predetermined tone and volume control information stored in the storage locations of the digital memory. 
     The present invention also provides an overall electric stringed musical instrument comprising: a body; strings connected to the body; a pickup connected to the body such that the pickup generates an electric signal in response to movement of at least one of the strings; tone adjustment means connected to the body such that a player of the musical instrument can actuate the tone adjustment member; volume adjustment means connected to the body such that the player can actuate the volume adjustment member; an output jack connected to the body; an analog circuit connected to the pickup and the output jack; and digital control means, connected to the body, the tone adjustment means, the volume adjustment means and the analog circuit, for controlling settings of the analog circuit. The digital control means preferably includes means for storing preset information with which to control the analog circuit. 
     In particular implementations of the foregoing, energy conservation is also provided. One specific technique for achieving this includes generating a control signal in response to movement of one or more of the strings. It is to be noted, however, that these advantages or features are suitable for other applications; therefore, these can be defined as follows. 
     With regard to energy conservation in general, the present invention provides an electric stringed musical instrument comprising: a body; strings connected to the body; a pickup connected to the body such that the pickup generates an electric signal in response to movement of at least one of the strings; an output jack connected to the body; and an electrical circuit connected to the pickup and the output jack to provide an output signal to the output jack in response to the electric signal from the pickup, the electrical circuit including means for controlling electrical energization of at least part of the electrical circuit when the instrument is in an operational state. 
     With regard to responsiveness to string movement, the present invention provides an electric stringed musical instrument comprising: a body; strings connected to the body; a pickup connected to the body such that the pickup generates an electric signal in response to movement of at least one of the strings; an output jack connected to the body; and an electrical circuit connected to the pickup and the output jack to provide an output signal to the output jack in response to the electric signal from the pickup, the electrical circuit including means for generating a control signal in response to movement of at least one of the strings. 
     Therefore, from the foregoing, it is a general object of the present invention to provide a novel and improved electric stringed musical instrument and apparatus having one or more of the features referred to above or as otherwise described herein. Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art when the following description of the preferred embodiments is read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of the present invention. 
     FIG. 2 is a partial representation of an electric bass guitar having control members in a conventional layout but adapted in accordance with the present invention. 
     FIG. 3 is a block diagram of controls and digital and analog circuits of the preferred embodiment for the bass guitar illustrated in FIG. 2. 
     FIGS. 4A-4F are schematic circuit diagrams for a particular implementation of the controls and circuits shown in FIG. 3. 
     FIG. 5 is a partial representation of an electric lead or rhythm guitar having control members in a conventional layout but adapted in accordance with the present invention. 
     FIG. 6 is a block diagram of controls and digital and analog circuits of the preferred embodiment for the guitar illustrated in FIG. 5. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1, an electric stringed musical instrument 2 is represented in block diagram form to include the apparatus of the present invention thereby providing the improved, inventive instrument of the present invention as well. The invention includes controls 4 which have the look and feel of conventional control elements that the instrument player or musician manipulates or actuates. These controls operate a digital control circuit 6 of the invention. The digital control circuit 6 controls an analog circuit 8 and it operates one or more status indicators 10. Although the analog circuit 8 is digitally controlled, it transfers and modifies an analog signal from an analog signal generator 12 to an analog signal output connector 14 while maintaining the analog signal in the analog domain. The foregoing results in an apparatus and instrument providing a conventional look, feel and sound but having enhanced control capabilities as will be further described below. 
     Although the present invention is applicable to any suitable type of electric stringed musical instrument, preferred embodiments of the invention depicted in FIG. 1 will be described in FIGS. 2-4 with reference to an electric bass guitar and in FIGS. 5 and 6 with reference to an electric lead or rhythm guitar. 
     Referring to FIG. 2, bass guitar 2a includes a body 16 from which a neck 18 extends and to which strings 20 are connected in conventional manner. Also connected to the body 16 in conventional manner are bridge pickup 22 and neck pickup 24 disposed beneath the strings 20 so that the pickups 22, 24 generate analog signals in response to movement of the strings 20 through magnetic fields of the pickups 22, 24 (if the pickups are of the electromagnetic type) as is well known. The pickups 22, 24 are included in the analog signal generator 12 of FIG. 1. 
     The musician&#39;s controls 4 of FIG. 1 are embodied in FIG. 2 by a treble cut/boost control 26, a midrange cut/boost control 28, a bass cut/boost control 30, a pickup pan control 32, a master volume control 34 and an equalization bypass switch arm 36. These are disposed on the body 16 and operated by the musician in a conventional manner with regard to the respective tone/volume/bypass functions referred to above with regard to each control member. That is, each of these controls (except the toggle switch arm 36, which is connected to a switch) is connected to a rotary member of a respective potentiometer. Additionally, in accordance with this preferred embodiment of the present invention, each of the controls 26-34 has a momentary contact single-pole single-throw push-push switch which the musician activates by depressing and releasing the respective control member 26-34. The control members 26-36 are laid out on the body 16 in a conventional manner so that they have the same look and feel to the musician except for the added feature of the depress/release function of the five knobs 26-34. 
     The aforementioned potentiometers and switches are represented in FIG. 3. These potentiometers (pots) are marked with the reference numeral 38, and the switches are marked with the reference numeral 40. Each of the five potentiometers 38 is connected to a respective one of the control knobs 26-34. Five of the switches 40 are the push-push switches combined with these potentiometers and the sixth switch is the switch to which the equalization bypass switch arm 36 connects. 
     Still referring to FIG. 3, the potentiometers 38 and the switches 40 provide electric inputs to a microcontroller 42 forming part of the preferred embodiment of the digital control circuit 6. The microcontroller 42 is energized from a battery 44 through a power active sense/power management circuit 46. The microcontroller 42 also monitors the battery level through an analog-to-digital (A/D) input as represented in FIG. 3. The outputs of the potentiometers 38 are also input through respective analog-to-digital inputs of the microcontroller 42. 
     The microcontroller 42 includes a microprocessor and program storage memory which holds the program under which the microcontroller operates in accordance with the present invention. Such a program can be readily implemented by one skilled in the arts given a particular microcontroller and the description of the invention given in this specification. An example of such a program is set forth at the end of this detailed description; however, it is to be noted that this is for a prototype and is not intended as a final product. 
     The digital circuit shown in FIG. 3 also includes a memory 47. This has storage locations where the microcontroller stores preset information for setting analog circuit parameters, which preset information is entered by the musician as further described below. 
     The microcontroller 42 provides digital outputs to control digitally controlled potentiometers of the analog circuit 8. The analog circuit 8 as embodied in FIG. 3 includes: a pan circuit 48 controlled by three outputs from the microcontroller 42; a preamplifier circuit 50 which receives the output from the pan circuit 48; and a digitally controlled switch 52 which receives the output from the preamplifier 50 and which also receives an output from an equalization circuit 54 of the analog circuit 8 that also receives the output of the preamplifier 50. The equalization circuit 54 is controlled by the three signal lines controlling the pan circuit 48. The digitally controlled switch 52 is controlled by two other digital outputs from the microcontroller 42. The output from the digitally controlled switch 52 is provided to a volume control circuit 56 of the analog circuit 8. The volume control circuit 56 is controlled by two of the three control signals controlling the pan and equalization circuits 48, 54 and another digital output signal from the microcontroller 42. The output from the volume adjustment circuit 56 is provided to the output connector 14 such as an output jack 59 of the bass guitar 2a (FIG. 2). 
     A particular implementation of the FIG. 3 embodiment is shown in FIGS. 4A-4F. 
     FIG. 4A shows a particular implementation of the microcontroller 42 and memory 47 (specifically implemented as an EEPROM). 
     Battery 44 is shown in FIG. 4A. It provides its energy to the system when a plug is inserted into output jack 59, thereby connecting the negative terminal of the battery 44 to electrical ground and placing the instrument in an operational state. When this happens, voltage conversion and regulator device 58 provides 3.3 volts to energize the microcontroller 42. The microcontroller 42 provides an output signal (POWERON) to enable voltage converter and regulator device 60 and voltage converter and regulator device 62 to provide the respective voltages shown in FIG. 4A. The power on signal is generated in response to an interrupt received by the microcontroller 42. This is provided by the wake-up signal generated through wake-up circuit 63, shown in FIG. 4B, in response to the bridge pickup 22 generating a signal (which occurs when a string is played). Thus, even though the instrument is in an operational state with a first circuit portion energized (microcontroller 42, device 58 and wake-up circuit 63), a second circuit portion (the remainder of the illustrated digital circuit) is in a powered down mode until the instrument is played (or a string is otherwise moved). The microcontroller 42 also has an internal program timer which times out if a wake-up signal is not received within a predetermined time. If this occurs once the microcontroller is generating the power on signal, the microcontroller 42 turns off the power on signal, thereby disabling the devices 60, 62. The invention operates in this lower power mode until another wake-up signal is generated. Thus, power is conserved if the musician does not play the instrument for a predetermined time. The circuits of elements 58, 60, 62 and FIG. 4B are included in the power active sense/power management circuit 46 of FIG. 3. 
     It is contemplated that the foregoing means pertaining to control of electrical energization and to responsiveness to string movement can be implemented in any suitable manner. For example, as to energization control, this can occur in response to manipulation of one or more control knobs or switches on the instrument in addition to or alternatively to occurring in response to movement of one or more strings. For example, such manipulation could generate an interrupt signal to the microcontroller 42, or the microcontroller 42 could periodically poll the devices for any changes indicating that power up is to occur. 
     Also with reference to FIG. 4A, the microcontroller 42 monitors the battery via input 8. 
     FIG. 4A also shows five light emitting diodes (LEDs) 64 embodying the status indicator 10 shown in FIG. 1. Each of the diodes 64 is co-located on the body 16 of the bass guitar 2a with a respective one of the control knobs 26-34 as shown in FIG. 2. 
     As mentioned, the control knobs 26-34 connect to respective potentiometers and push-push momentary contact switches. These potentiometers and switches are shown in FIG. 4C. Specifically, potentiometer 66 and switch 68 are connected to and operated by the control knob 26, potentiometer 70 and switch 72 are connected to and operated by control knob 28, potentiometer 74 and switch 76 are connected to and operated by control knob 30, potentiometer 78 and switch 80 are connected to and operated by control knob 32, and potentiometer 82 and switch 84 are connected to and operated by control knob 34. Switch arm 36 operates momentary mini-toggle switch 86 shown in FIG. 4C. 
     Referring to FIG. 4D, the pickups 22, 24 are connected to input preamplifier circuits 88, 90, respectively. The outputs of these circuits are input to a quad digital potentiometer device 92 shown in FIG. 4E. One of the digitally controlled potentiometers of the device 92 is controllable by the microcontroller 42 to provide a desired blend between the signals from the bridge and neck pickups. This defines the pan signal. 
     The pan signal output of the device 92 is connected to a further preamplifier circuit 94 shown in FIG. 4F. The output of preamplifier 94 is connected to the device 92 of FIG. 4E for equalization control via the bass, midrange and treble controls. Each of these has a respective one of the remaining three digitally controlled potentiometers of the device 92 respectively connected in the resistor-capacitor components shown in FIG. 4E which form a tone adjustment portion to define one or more resistance-capacitance characteristics that impart tone control to the signal from the instrumenmt&#39;s pickup(s). The bass adjustment circuit is identified in FIG. 4E by the reference numeral 96. The midrange adjustment circuit is identified in FIG. 4E by the reference numeral 98. The treble adjustment circuit is identified in FIG. 4E by the reference numeral 100. The resulting equalized output (EQOUT) is returned to a digitally controlled switch device 102 shown in FIG. 4F. The microcontroller 42 provides two switch control signals (EQSW1, EQSW2) to select whether the preamplifier signal (PREAMPSIG) or the equalized output signal (EQOUT) is connected to digitally controlled potentiometer device 104 shown in FIG. 4F. The microcontroller 42 controls a digitally controlled potentiometer of the device 104 to set the resistance characteristic for volume adjustment for the signal (AUDIO) provided as the output audio signal which connects from the device 104 to the output jack 59 shown in FIG. 4A. 
     A specifically programmed implementation of the foregoing allows the player/musician to set up three presets, which will recall tone and/or volume settings previously entered into the memory 47 by the player. The player selects and activates one of the presets by pressing down on the tone knobs, which have the momentary switches built into them. For example, tapping on the treble knob 26 actuates switch 72 which signals the microcontroller 42 to recall preset 1 and send appropriate digital control signals denominated in FIG. 4A as follows: POT1DATA, POT2DATA, POTCLOCK, POTLOAD/, EQSW1, EQSW2. Tapping midrange control knob 28 recalls preset 2, and tapping the bass knob 30 switches to preset 3. This can be very fast since the player just taps the one he/she wants and parameters change immediately. 
     Once a preset has been selected, the control members 26-36 are still active and execute their normal functions, updating the respective parameter from the preset point in response to rotation of control knobs 26-34 or toggling of switch arm 36. The potentiometers to which the knobs 26-34 connect have limits to how far the wipers of the potentiometers can be rotated. This limits the sector through which the respective knobs 26-34 can be rotated. Since these limits might prevent the musician from reaching part of the full range of the respective parameter when the knob&#39;s physical position is different from the preset point, a &#34;ratcheting&#34; technique is used. When the knob reaches the end of its travel and the actual circuit parameter still has room to change further in that direction, the knob is turned back and then turned up again to effectively &#34;ratchet&#34; the value up; this is done quickly as the key to the programmed microcontroller 42 reading and applying this action as a continuing parameter change in the same direction. The advantage of this technique is an immediate response from the knobs, which feels more natural. A similar situation exists with the switch connected to the switch arm 36. A normal toggle switch could be set to a position that is different from the preset. With a momentary on/off/on switch, the switch always returns to the center and avoids the confusion; thus, this is the preferred implementation for the switch 86 operated by the switch arm 36. The player either pushes the switch arm 36 up or down to turn equalization on or off (if it is already on, turning it on again would not do anything). This same switch could be used among several different equalization circuits as well. 
     Storing new values in a storage location of the memory 47 is done by pressing the momentary switch 80 operated by the pan knob 32. This instantly stores the then-existing settings of the potentiometers 38 (i.e., pots 66-82) and the switch 86 into the current preset location selected by one of the knobs 26, 28, 30. This facilitates live playing, where a player might need to adjust a knob in a particular preset. Thus, storing tone and volume information for a preset occurs with minimal interruption in playing. The memory 47 is preferably non-volatile, so entered preset information is not erased when the power is off. 
     To let the player know that knob presses have been registered, the microcontroller 42 turns on the respective LED(s) 64 briefly (so that power consumption is reduced) next to the respective switch and knobs. When storing to the memory 47, the LEDs for both the store button (knob 32 for the above implementation) and the button for the preset being stored to (one of the knobs 26, 28, 30) come on briefly. When battery power gets low (as monitored via pin 8 of the microcontroller 42 of the FIG. 4A implementation), the LED next to the volume knob 34 flashes. 
     There are two ways to turn the circuit on and off in the implementation of FIG. 4. First, when a plug is in the jack 59, the instrument is on and in the preset mode; it can be turned off by pulling the plug out of the jack. Second, the momentary push switch of the volume knob 34 can be used to toggle the presets on and off; therefore, if the player wants to turn the presets off but still use the active equalization and preamp, the player merely taps the volume knob 34. Tapping it again brings the presets back on. 
     Although not shown in the drawings, there is preferably another switch mounted on the guitar to serve as an emergency switch in the event of a failure, such as loss of battery power. This switch would switch the analog circuitry to bypass the digital circuitry as needed at least to allow the analog signals from the pickups to be communicated to the output jack. 
     Another implementation of the invention depicted in FIG. 1 will be described with reference to FIGS. 5 and 6. This implementation pertains to a lead or rhythm guitar 2b. There are several variations for this guitar interface. One example is a guitar where each pickup connects to its own volume and tone circuit before going to the pickup selector; this is the example of FIGS. 5 and 6 as described below. Another is a guitar where the pickups go into the selector switch first and then to a single volume and tone knob. Other non-limiting variations include a presettable acoustic guitar preamp, an after-market product for people who want to upgrade their instrument, and an ultimate guitar that provides the maximum flexibility conceivable. 
     Referring to FIG. 5, the guitar 2b has a body 106 from which a neck 108 extends and to which strings 110 are connected. Dual-coil humbucking pickups 112, 114 are disposed and operate in conventional manner. Mounted and located in conventional manner are a bridge volume knob 116, a bridge tone knob 118, a neck volume knob 120 and a neck tone knob 122. A three-position selector switch actuator arm 124 is also mounted on the body 106. 
     The digital and analog circuits to which these controls connect are represented in FIG. 6. Components of FIG. 6 which can be implemented in the same manner as in the FIG. 3 embodiment are identified by the use of like reference numerals. The principal difference in the FIG. 6 implementation is that the digital output control signals from the microcontroller 42 are used to define pickup configuration, pickup selection and equalization/volume parameters of the type common to lead or rhythm guitars as opposed to the parameters in the bass guitar described above with reference to FIGS. 2-4. In the implementation of FIG. 6, this control is achieved through the output signals from the microcontroller 42 as well as from latches 126 operating digitally controlled potentiometers and digitally controlled switches 128 of the analog circuit connecting the pickups 112, 114 to output jack 130. 
     In the embodiment of FIGS. 5 and 6, a switch 131 operated by switch arm 124 is the preset selector switch which looks and functions just like a typical pickup selector switch, and it is located in the same spot. Rather than switching pickups, it switches among three presets (or other number of presets if a different switch is used) which the user can define. The knobs are also familiar, with the aforementioned volume and tone knobs for each pickup. Each knob connects to a momentary switch built into it just as in the embodiment of FIGS. 2-4. Each such switch is activated by pressing or tapping the knob down towards the guitar body. In a particular implementation of FIGS. 5 and 6, pressing the volume knobs 116, 120 sequences among three settings for the respective pickup--off, double coil, and single coil. The switch under the neck pickup&#39;s tone knob 122 is for phase; it toggles between in-phase and out-of-phase sounds when both pickups are on. The switch under the bridge pickup&#39;s tone knob 118 is the store function. As in the embodiment of FIGS. 2-4, these switches preferably are quick and intuitive to use, and preferably have the added advantage of eliminating the need for any extra switches and knobs. 
     Once the preset selector switch 131 has been switched to select a preset from the memory 47, the knobs 116-122 are still active and execute their normal functions, updating the parameter from the preset point. The previously described &#34;ratcheting&#34; technique can be used to overcome any difference between a preset parameter and the physical position of a knob. 
     Storing new values in memory 47 is done by pressing the momentary switch of the bridge pickup&#39;s tone knob 118. This instantly stores the current pickup configuration and potentiometer voltage settings into the preset location selected by the switch 124. 
     Small LEDs 132 located by each of the knobs are used to indicate the state of the guitar to the player. These LEDs will come on briefly when one of the knobs is pressed or a preset is changed. Two LEDs located next to each of the volume knobs indicate the pickup configuration, with each one representing one of the coils in a dual-coil humbucking pickup. If one is on, it is in single coil mode. If they are both on, it is double coil. If the LEDs do not come on, that pickup is off. The LEDs by the tone knobs come on briefly when those buttons are pressed. The knob with the phase switch has a two-color LED next to it, with green being in-phase and red being out-of-phase. When a new preset is selected, the appropriate LEDs will come on briefly to indicate what is in the preset. When the battery power is low, one of the LEDs will flash. 
     The foregoing implementations preferably use low power, microcontroller technology used in a manner to prolong battery life. It is preferred to use 3.3 volt and low power CMOS components, slow and dual clock speed techniques, and low power &#34;sleep&#34; modes to prolong battery life. Specific analog circuits will function from the analog standpoint the same as conventional analog circuits for the respective types of electric stringed musical instruments to which the present invention is applied. Mounting configurations to minimize size and shielding for low noise layout techniques are preferably used to minimize noise. 
     Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned above as well as those inherent therein. While preferred embodiments of the invention have been described for the purpose of this disclosure, changes in the construction and arrangement of parts and the performance of steps can be made by those skilled in the art, which changes are encompassed within the spirit of this invention as defined by the appended claims. ##SPC1##