US 3813473 A
An electric guitar having a plurality of strings and including circuitry for adjustably attenuating the input signals from the strings not played, circuitry for adjustably varying the attack of the output signals representing notes and chords, gain control circuitry utilizing a photoconductor, and a mechanically coupled feedback path for applying output signals back to the strings to sustain vibrations.
Description (OCR text may contain errors)
United States Patent Terymenko May 28, 1974 1 ELECTRIC GUITAR SYSTEM 3,514,522 5/1970 Mussulman 84/l.26 x  In e or: u Francis Terymenko, O 3,612,741 10/1971 Marshall 84/].05
Ontario, Canada FOREIGN PATENTS OR APPLICATIONS Assignee: Invest ents France Toronto, Ontario, Canada Przmary ExammerR1chard B. Wllkmson Flledl 1972 Assistant ExaminerU. Weldon  AppL NOJ 301,372 Attorney, Agent, or Firm-Davis, Hoxie, Faithful] &
Hapgood  US. Cl 84/116, 84/1.l2, 84/121  Int. Cl. G10h 3/00  A T 58 Field of Search 84/l.04, 1.05, 1.11, 1.12, An electric gmar havmg Plurahty of Smngs and 84/1 15 L16, 1'19, 124, DIG 10, 1.26 cluding circuitry for adjustably attenuating the input L14 L21 signals from the strings not played, circuitry for adjustably varying the attack of the output signals represent-  References Cited ing notes and chords, gain control circuitry utilizing a UNITED STATES PATENTS photoconductor, and a mechanically coupled feedback path for applying output signals back to the 32332133 131323 lfifi'ffijii: "31:: 221113? Strings gusts" 3,463,868 8/1969 Laube 84/124 7 Claims, 8 Drawing Figures INPUT mom STRING A AUTOMATIC VOICE INPUT M DULE SELECTOR FIG-3) idrreuuArs SIGNAL 5mm ti iniii s ia STEPPING B E ORF VOICE s'mmc FIVE c H gggg gg F MANUAL Emma,
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ELECTRIC GUITAR SYSTEM The present invention is a musical instrument comprising a guitar body having several novel features and associated electronic circuitry.
Current electric guitars, and the devices for modification of their output signals commonly known as fuzz boxes, .have several inherent limitations in performance because of certain aspects of their design. While these limitations do not affect the utility of such guitars and devices for many musical purposes, they do prevent the achievement of desirable musical effects.
For example, with current electric guitars it is difficult to produce a sustained note, that is, a note which will not die down, except by utilizing an extremely high sound volume level. Therefore, a musician must play the guitar very loudly if he desires to use the sustained-note effect. Furthermore, because the sustained-note effect in current electric guitars is dependent on the total acoustical environment of the guitar, it is difficult to predict which notes will sustain themselves in a given setting. This means that a travelling performer has no assurance that a note which will sustain itself in one concert setting will also do so in another.
Current electric guitars severely limit the ability of the performer to play melodies or chords without accompanying interference from the strings not played. Sympathetic vibrations among the strings cause signals to be generated at strings other than those being played, and these spurious signals are amplified and (when the guitar is used in conjunction with a tone modification device) modified along with the desired sounds, producing interfering output signals and, in the latter case, inter-modulation distortion. In fact, it is difficult just to keep conventional guitars silent, especially when they are used in conjunction with tone modification devices.
A third limitation of current electric guitars derives from the fact that the action of a guitar pick on the string makes the guitar in a sense a percussive instrument. This limitation is accentuated by the use of fuzz" boxes and the like. Flowing melodies are difficult to execute, and the louder the instrument is played, the more prominent is the initial click of sound produced by the plucking of the string. g
The present invention overcomes each of these limitations of current electric guitars and thereby allows a performer greater opportunity for display of his ability. A sustained-note effect, reproducible in any acoustical environment independent of the performers volume level, is achieved according to the invention by utilizing a mechanically-coupled feedback path within the guitar of which the string is the frequency-determining factor. The undesirable effects of sympathetic vibration are eliminated by providing performer-controlled, automatic selector circuitry to eliminate unwanted signals from the strings not played. The percussive feature presently inherent in electric guitars is controlled by other performer-controlled, automatic circuitry which gives the melody or chord a bowed rather than struck sound.
These and other features of the invention will be more apparent from the illustrative embodiment described and illustrated in the accompanying drawings, in which:
FIG. 1 is a block diagram of the guitar system of the present invention, as applied to a six-string guitar;
FIG. 2 is a circuit diagram of the Automatic Input Selector stage;
FIG. 3 is a circuit diagram of the Voice Module stage;
FIG. 4 is a circuit diagram of the Mixer stage, also showing the Preset and Stepping Voice Selectors and. in schematic form, the Expression Pedal;
FIG. 5 is a circuit diagram of the AGC and Percussion Regulator stages, also showing, in schematic form, the Volume Pedal;
FIG. 6 is a circuit diagram of the electrical portion of the Sustain Vibration system;
FIG. 7 is a cut-away side view of a guitar body containing the mechanical portion of the Sustain Vibration system; and
FIG. 8 is a top view of the guitar body shown in FIG. 6.
Referring first to FIG. I, this Figure at its left side shows signal inputs from individual pick-ups mounted beneath each of the six guitar strings A, B, C, D, E and F, which, in the present invention may be made of any ferromagnetic material. The signal from a given string will be hereinafter referred to as, e.g., signal A, signal B, etc. Signal A enters the Automatic Input Selector circuitry associated with string A and, if no ATTENU- ATE or blocking signal also enters that Automatic Input Selector circuit, signal A in amplified form is applied to the input of the Voice Module circuitry associated with string A. In the Voice Module, the signal from string A is processed to produce, in this illustrative embodiment, six voices or electronically modified and amplified versions of the original signal. These voices are identified herein by one of the subscripts u-z following the letter of the string from which the signal is derived, as for example, Au, Av, Aw, Ax, Ay, and A2. At the Mixer all of the like voices from the several strings are combined into a single voice, e.g., Au, Bu, Cu, Du, Eu, and Fu are combined into a single voice hereinafter referred to as voice U. Similarly, all the individual v voices are combined to produce voice V, etc.
Referring now in detail to FIG. 2, the circuitry of which it should be understood is repeated for each string, signal A from the magnetic pick-up mounted in the guitar body beneath string A is applied to the base of transistor 01 across the parallel arrangement of potentiometer R1, used to balance the amplitudes of the incoming signals from the various strings, and Cl, which shunts any radio frequency noise to ground, and through coupling capacitor C2. Signal A is also applied to the base of transistor Q3 through coupling capacitor C3.
The function of the Automatic Input Selector (AIS) circuitry shown in FIG. 2 is to provide the performer with the means to attenuate or completely block all signals from the strings not being played at a given time, thereby eliminating unwanted sounds from the melody being played.
Transistor Q1 amplifies the signal, which then passes through capacitor C4 to diode D1. Potentiometer R2 is adjusted to allow only a short burst of negative-going signal to pass diode D1, which in this illustrative embodiment may have a threshold voltage of about 0.3 volts. The spike of signal passed through diode D1 passes through coupling capacitor C5 to transistor Q2,
which is biased into saturation when no signal is applied. The application of the pulse to the base of Q2 results in a strong positive-going burst of signal at the collector. This pulse is applied across diodes DUN-04 to the *A'l'lENUATE" inputs of the AIS circuitry of the other strings, not shown. For example, if the AIS circuitry for string A is being discussed, then diodes D100-04 would be connected to the ATTENUATE circuitry associated with strings B, C, D, E and F.
Direct coupled transistors Q3 and Q4 and their associated resistors comprise a flat response circuit capable of amplifying or attenuating the signal applied at the base of Q3 depending on the bias conditions. The bias conditions in turn are dependent on the state of transistor Q8, connected between the positive source and the collectors of Q3 and Q4. The AIS control is exerted at this point, by causing Q8 to vary between cut-off (in which case the supply voltage to Q3 and O4 is low and the output at the collector of O4 is attenuated) and saturation (in which case the supply voltage to Q3 and O4 is relatively high and the 03-04 combination functions as an amplifier).
The AIS circuitry attenuates a signal in the following way. If string B only is struck, in the manner described above a positive signal pulse appears at the ATTENU- ATE" input of the AIS circuitry of string A and is applied to the base of transistor Q5, through potentiometer R3, which functions as a sensitivity adjustment. Transistors Q5 and Q6 are arranged in flip-flop fashion, so that the ATTENUATE pulse just described puts 05 into saturation and Q6 into cut-off. Had string A been plucked, Q6 would have been put into saturation by the application of the positive burst to the base of 06 through diode D2. With O6 in cut-off, its high collector voltage is applied to the base of transistor 07 across photoconductor PHI, a variable resistor located in the AIS pedal, operation of which is controlled by the performer.
The AIS Pedal, and other performer-controlled pedals discussed below, allinclude a neon bulb and one or more photoconductors. Depression of the pedal by the performer varies the exposure of the photoconductor to the neon bulb NEl and hence the characteristics of the circuit of which it is an element. In the present case, if PHI is at its lowest resistance value (pedal fully depressed), the voltage applied to the base 07 puts that transistor into saturation. This in turn lowers the collector voltage of Q7, which lowers the base voltage of transistor 08, biasing 08 out of saturation and sharply reducing the supply voltage to transistors Q3 and 04. In this way, the application of an ATTENUATE signal to the AIS circuitry of a given string, given the depression by the performer of the AIS Pedal, causes the output from transistor O4 to be attenuated.
The performer can vary the application of this function by depressing the AIS Pedal to less than its full extent, thereby leaving photoconductor PHI with a substantial resistance value. If the pedal is not depressed at all, the resistance of PHI may be made sufficiently high so that no attenuation occurs, in spite of the presence of a signal at the ATTENUATE input. The choice is left to the performer.
Depending on the presence or absence of an AT- TENUATE" signal and the extent to which the Pedal is depressed, a signal of a predetermined strength appears at the collector of Q4. This signal is the input to the Voice Module illustrated in FIG. 3.
The function of the Voice Module of string A, the circuitry of which is repeated for each other string of the guitar, is to processelectronically the amplified signal from the collector of transistor 04, modifying or amplifying that signal to produce, in this embodiment, six voices from signal A.
Through the parallel combination of capacitor C7 and capacitor C8-resistor R4, signal A is applied to the base of transistor Q9. Capacitor C7 has a small value which serves to boost the high frequency response of the circuit to compensate for any losses and to provide clear high notes. The output of Q9, denominated voice Az, is the natural sound of guitar string A.
Through capacitor C9 signal A is applied to the base of transistor Q10, which amplifies it and applies it both to the primary of transformer T1, and, through capacitor C10, across the parallel combination of reversed diodes D4 and D5. The parallel arrangement of diodes D4 and D5 acts as a limiterin reverse, blocking the middle strength values of the signal and passing the positive and negative peaks intact. The output from the parallel arrangement of diodes D4 and D5, signal A with the middle values removed, becomes voice Av.
Through C8 signal A is also applied to the base of Q1]. The collector of O1] is shunted to ground through a large capacitor C11 leaving a residual sawtooth signal which is coupled to the bases of transistors Q12 and Q13. The amplified sawtooth signal at the collector of Q12 becomes voice Aw and is also applied, together with the input to Q12, through capacitor C12 to the secondary of T1 where it mixes with the other current in the secondary to produce voice Au. The collector of Q13 is coupled through capacitor C13 to the limiter composed of diodes D6 and D7. The resulting signal, a near square wave, is the basis for the other three voices.
Through trimmer resistor R5, transistor 014 receives a portion of the signal from the limiter composed of D6 and D7 and projects an amplified image of the signal out of phase with the original (because of the nature of a common-emitter transistor amplifier) into the junction of diodes D8 and D9 through D9. The same signal with the original phase comes to that junction directly from the limiter through D8. Diodes D8 and D9 act as a full wave rectifier, and the signal at their junction is raised one octave. The symmetry of the new signal appearing at the junction of D8 and D9 is controlled by potentiometer RS. This new signal is applied to the base of transistor Q15 through the parallel combination of capacitor C14 and resistor R6, which boosts the high frequency components of the signal. The output of Q15 at its collector is voice Ay and also comprises one possible input to transistor Q16.
Transistor Q16 obtains its input from the collector of either 014 or Q15, depending on the setting of manual switch S1. That is, its input is either the square wave signal from the collector of Q14 or the signal from the collector of Q15, with a very strong second harmonic. Switches similar to S1 are provided in each Voice Module; they allow the performer to choose between two X voices for each string independently of the X voices chosen for the other strings. The output at the collector of Q16 is voice Ax.
It should be understood that all of the preceding circuitry is repeated for each string, so that, in the present six-string illustrative embodiment, the circuitry shown in FIGS. 2 and 3 is repeated six times. The circuits that follow, on the other hand, are constructed only once.
As is illustrated in FIG. 4, the Mixer comprises six separate amplifier circuits, one for each set of similar voices from the six strings. For clarity, only two are illustrated: the circuit carrying the summation of all the u voices, designated U, and the circuit carrying the summation of all the w voices, designated W. It should be understood that the remaining circuits are identical in design to that for these voices.
The u signals Au, Bu, Cu, Du, Eu, and Fu are all combined and applied through capacitor C16 to the base of transistor Q18. Variable resistors R8 and R9, together with capacitors C17 and C 18, control the frequency response of the circuit and hence the tone of the U voice. The amplified output of Q18, voice U, is applied to both the Preset Voice Selector and the Stepping Voice selector. The other Mixer circuits operate similarly. The amplified sawtooth voice W is also used as an input signal to the Percussion Regulator, discussed below. One of the Mixer output signals may also be chosen to drive the Sustain Vibration Amplifier, also discussed below.
The Preset Voice Selector is simply a switch wired to select as its output any one of the six incoming voices, or various combinations of those voices. In the illustrative embodiment, the switch is wired to select any one of U, V, W, X, Y, Z, UY, UZ, VW, VX, WX or WY. These particular outputs are entirely a matter of choice; the ear of the performer being the ultimate decision-maker. Any other outputs could be selected. The output is made available as one input to the Expression Pedal, discussed below.
The Stepping Voice Selector is a stepping relay whose action is controlled by a microswitch actuated by a backward swing of the Expression Pedal. In this illustrative embodiment, the Stepping Voice Selector repeats its cycle every six steps and applies one of the input voices U, V, W, X, Y or Z as a second input to the Expression Pedal.
Footswitch S2 makes available the natural sound of the guitar, voice Z, as a third input to the Expression Pedal, replacing the second input from the Stepping Voice Selector.
The Expression Pedal carries neon bulb NE2 and is designed so that, when the pedal is depressed, NE2 first illuminates only PH3, and then only PH2. The output from the pedal therefore varies from the Stepping Voice Selector signal to the Preset Voice Selector signal as the amount of pedal depression is increased.
The output signal from the Expression Pedal is further processed by the Automatic Gain Control (AGC) circuit and the Percussion Regulator circuit (both shown in FIG. 5) before becoming the ultimate output signal. The signal is applied to the base of transistor 020 through potentiometer R11 and capacitor C20. Potentiometer R11 should be adjusted to keep the maximum incoming signal below a level which would cause distortion in the second stage transistor, Q21. Through conventional amplifier circuitry the signal becomes available at the collector 021 for the Volume Pedal and the ultimate output.
Photoconductor PH4 is connected between the collectors of Q20 and Q21, and the bias values to those transistors are adjusted so that their collector voltages are equal and no DC. current flows through PH4: Since the signal at the collector of 021 is 180 out of phase with the signal at the collector of 020, because of the nature of a common-emitter transistor amplifier, if PH4 has relatively low resistance value, the output from 021 will be attenuated because of negative feedback from the collector of Q21, through PH4, to the base of 021. On the other hand, if PH4 has a relatively high resistance value, little negative feedback will occur and the output from Q21 will not be attenuated.
The resistance level of PH4 is controlled by neon bulb NE3, located in the collector circuit of pnp-type transistor Q22. A portion of the output signal at the collector of Q21 is applied to the base of transistor Q23 through potentiometer R12, the manually-set AGC level control. Transistor Q23 amplifies the signal and passes it to the rectifier circuit composed of diode D11 and capacitor C21. The signal here is converted to a negative D.C. value indicative of the amplitude of the output signal at the collector of Q23. This negative voltage is then applied to the base of transistor Q22. The negative bias causes 022 to conduct, sending current through NE3, thereby reducing the resistance of PH4 and, ultimately, attenuating the signal to the Volume Pedal in an amount dependent on the effective resistance value of R12. Therefore, the signal level at the Volume Pedal is regulated by the value of R12.
Potentiometer R12 controls the ratio of the volume of single notes to the volume of chords. Potentiometer R12 should be adjusted so that single notes do not cause NE3 to light and thus do not cause any attenuation of the output signal but that chords, having a much higher RMS value than single notes, make NE3 glow sufficiently to attenuate the output signal to the strength of the single note output signal.
The Percussion Regulator (FIG. 5) takes as its input the sawtooth voice W from the Mixer. Its function is to remove the sharp click heard when the guitar pick strikes the strings, thereby making melodies sound bowed rather than struck. It operates by causing each note to be eased into audibility, reaching its full volume about one/half second after the note has been struck.
When the Percussion Regulator is not in operation (i.e., if switch S3 is in its open position), very little current flows through NE3 because of the relatively high resistance in series with NE3. Therefore, in this condition the resistance value of PH4 is relatively high and no attenuation occurs. Closing S3, however, puts Q24 into saturation because of the relatively low resistance path thereby established between B- and its base, and this makes NE3 glow brightly. The glow of NE3 attenuates the output at the Volume Pedal by about percent in the manner described above. When any string is plucked, the W voice derived from that string in the Mixer is applied to the base of transistor Q25 and amplified by Q25 and Q26. The interstage coupling capacitor C22 is made relatively small to accentuate the high frequency components of the signal. This is done in order to compensate voice W for its relative weakness in high frequency components which results from the manner in which voice W was generated, i.e., the presence of capacitor Cll between the collector and the base of transistor 011.
The output signal from Q26 is rectified by diode D12 into a positive DC. signal proportional to the strength of the W signal applied. Capacitor C23, of relatively large value, smoothes this signal. This positive signal serves to lower the degree of negative bias at the base of pnp-type transistor Q24, tending to turn this transistor off and thereby dim NE3. Photoconductor PH4 is a comparatively low speed photoconductor, for example a NSL-457, whose frequency response drops off sharply below about 60 Hz, and because of its slow recovery rate and the time delay in the circuit controlling NE3 caused by capacitor C23, the output signal at the collector of 021 rises gradually in strength from a low level determined by the maximum attenuation available by the action of PH4 to its normal unattenuated level, with the initial percussive attack eliminated from the note. The maximum attenuation is that produced by the lowest attainable resistance value of PH4. Potentiometer R13, at the input to the Percussion Regulator, controls the audible duration of the note and the overall sensitivity of the system.
Capacitor C22, by boosting the deficient high frequency component of voice W, ensures that the Percussion Regulator will operate in the same manner for high and low notes. If the high frequency components were not boosted, voice W for a low note would be a stronger signal than voice W for a high note, and this would cause a low note to rise into audibility more rapidly, last longer, and decay from audibility more rapidly than high note. This would be an undesirable musical characteristic.
The Volume Pedal (FIG. 5) is a neonphotoconductor combination as described above which allows the performer to vary the volume of the output signal.
The circuitry just described possesses an additional advantage. One conventional tone modification device in wide use, known as a wah-wah pedal, comprises a passive electrical circuit in series with the output signal of the guitar and including as one element thereof a variable resistance element under the control of the performer. Depending on the instantaneous setting of the resistance, a matter determined by the performer, this device primarily passes only low or high frequencies. In operation, performers attempt to synchronize their depression of the pedal with the playing of the notes, to give each note a similar frequency profile, but this is quite difficult to accomplish.
The present system provides means for obtaining the wah-wah effect automatically without relying on the performer's skill. Neon bulb NE3 is illuminated each time a note is struck, and this causes the resistance of photoconductor PH4 to drop each time in the manner described above. If a photoconductor similar to PH4 were placed in series with the output signal and exposed to NE3, the wah-wah" effect could be achieved automatically.
If the performer desires, a note played on this guitar can be sustained for any desired length of time, at any volume level, in any acoustic environment. This is accomplished, as indicated generally in FIG. 1, by amplifying and shaping one of the voices from the string being played and converting the processed signal into a mechanical vibration conveyed back to the string. In the illustrative embodiment shown, the input signal for the Sustain Vibration system is chosen to be the X signal from the Mixer, but another voice could be used if desired.
The Sustain Vibration circuit, shown in detail in FIG. 6, includes a two stage transistor preamplifier of standard design, a limiter made up of diodes D and D16, the Sustain Pedal, transformer T2, switch S5, and a played.
When the Sustain function is activated, the amplified signal from the power amplifier is converted into a mechanical vibration conveyed back to the guitar string by apparatus shown in FIGS. 7 and 8. The apparatus, shown in relation to guitar body 50, includes a permanent magnet 51 mounted in the guitar and a coil 52 in movable relationship to the magnet and rigidly attached to the underside of extension 53 of guitar bridge 54. FIG. 7 shows this relationship between the coil and extension schematically. The coil, which conveniently may be several turns of copper wire on a form, receives its signal from the power amplifier. It is free to move with respect to the magnet as much as the flexibility of the extension will allow. Bridge 54, including its extension 53, is commonly made of steel and is securely held in place by supporting posts 55. Strings 56 extend from tailpiece 57, across the bridge 54, over pickups 58, and on to the neck of the guitar.
In operation the presence of a signal in coil 52 causes it to vibrate vertically with respect to magnet 51, rigidly mounted in body 50. These vibrations are transmitted to that part of the bridge in contact with the strings by its extension 53, thereby completing a feedback path of which theguitar string is the frequency determining factor. Operation of this system is totally independent of the output volume level of the guitar and the acoustics of the concert setting.
The coil-magnet combination can be mounted anywhere on the guitar provided only that it is not in the inductive range of the pickups. Furthermore, the coil could transmit its vibrational energy to the strings through a connection other than the bridge extension here disclosed. The system should be designed so that there is no dominant resonant frequency in the coilstring coupling within the frequency range of the strings. In addition, correct phase alignment between the signal at the coil and the signal at the pick-ups should be maintained. Correct alignment is obtained by use of switch S5 and transformer T2. The center tap of the transformers secondary winding is common and the two extremes are both available, by activation of S5, as alternate sources for the coil driving signal.
With the sustain vibration system in operation, the performer can play with his left hand only, the minute response found naturally in each string, when fed back to the bridge by the mechanical feedback system here disclosed, being sufficient to sustain the note. This can be done without affecting the quality or volume of the ultimate guitar output.
The following are the values of the circuit components used in the illustrative embodiment of my invention previously discussed:
A. Components discussed RI 470 ohms D1 D100-04 All other diodes C16 C17 C18 C20 C21 C22 C23 10K ohms 1K ohms 120K ohms 470K ohms 24K ohms 500K ohms 500 K ohms 47K ohms 500K ohms 100K ohms 300 ml 30v 6.4 mf 30v 10 ml 30v 25 mf v 25 ml" 30v 0.22 ml' 70v 033 ml' 70v 0.1 ml" 70v 0.22 ml 70v 0.3
680 pf 70v 0.001 ml 70v 0.0015 mf 70v 0.002 ml 70v 0.005 ml 70v 0.03 ml 70v 0.05 ml 70v 0068 ml' 70v 0.01 ml 70v 0.02 ml 70v 0.02 ml 70v 0.033 ml 70v 0.05 ml" 70v 0.05 inf 70v 0.1 ml' 70v 0.133 mf70v 0.168 ml 70v 2S mf'70v 50 ml 70v 100 ml 70v 0.01 ml 70v 0.0[5 ml" 70v 0.02 mf 70v 0.03 ml 70v 0.033 ml 70v 0.05 ml" 70v 0.168 ml" 70v 0.2 ml" 70v 0.22 mf 70v 0.1 ml 70v 0.02 ml 30v 0.25 ml" 30v 0.03 ml 30v 6.4 ml 25v 0.005 ml' 70v 0.01 mf 70v (Phillips EO97AC Polcnliomclcr) (Phillips EO97AC Potcriliomctcr) (Phillips EO97AC Polcnliomclcr) O18 O20 O21 O22 O23 O24 O25 O27 Q28 2N3415 2N3415 2N3415 2N3415 B. Components not specifically discussed 100K ohms 3K ohms 33K ohms no resistor 22K ohms 2.2M ohms 39K ohms 510 ohms 100K ohms 13K ohms 82K ohms K ohms K ohms 18K ohms ohms 120K ohms 0.1 ml 70v 20 ml 25v 3 mf 25v 610 ohms 0.02 ml 30v 30K ohms 68K ohms 8.2K ohms 3.6K ohms 36K ohms 1 1K ohms 680K ohms 15K ohms 4.3K ohms 100 ohms 120K ohms 5.6K ohms 68K ohms 470K ohms 51K ohms 20K ohms 9.1K ohms 56K ohms l.6 mf 70v 2.5 ml 70v 6.4 ml" 70v 100K ohms 3.3K ohms 62K ohms 100K ohms 6.8K ohms 1 10K ohms 1.6 ml 70v 2.5 mf 70v 6.4 mf 70v 15K ohms 2K ohms K ohms 130K ohms 360K ohms 0.02 mf 70v 0.03 ml70v 0.04mf 70v 0.05 ml 70v 0.07 mf 70v 4.7K ohms 100K ohms 68K ohms 1.3M ohms 82K ohms 100K ohms 3K ohms 43K ohms 270K ohms 47K ohms 1.2M ohms 910K ohms 1M ohms 1K ohms 91K ohms 75K ohms 2K ohms K ohms (Phillips EO97AC Potcmiomctcr) I92 I93 I94 I95 I96 I97 I98 I99 200 20I 202 2I6 2I7 2I8 219 220 ZZI 222 223 16K ohms 12K ohms 6.4mf 25v 20K ohms 6.4 mt 25v 62K ohms 47K ohms )IK ohms lK ohms I l0K ohms 39K ohms 43K ohms 8.2K ohms 6.4 mf 25v 33K ohms 56K ohms 2.7K ohms 0.22 mi 70v 43K ohms 56K ohms 3K ohms 33K ohms 0.22 ml 70v 470K ohms 56K ohms 3K ohms 33K ohms 6.4 ml" 25v 62K ohms K ohms 6.4 ml v I600 ml 64v Miscellaneous R8/R9 is an ohmite dual CCU-5041.
All neons are AIA. All photoconductors are Phillips B8-73l-05 except PH4, which is an NSL-457.
(Phillips E097AC Potcntiomctcr) (Phillips EO97AC Potcntiomctcr) potentiometer No.
The transformers TI and T2 are both Armaco At-46.
I claim: I. An electronic plural-stringed musical instrument having:
means associated with each of the strings independently for producing an electrical signal derived from the vibration of that string, and means for selecting only the electrical signal having an amplitude above a threshold level and for attenuating electrical signals derived from the remaining strings. 2. The instrument of claim I wherein the means for selecting includes means for producing control signals for effecting the attenuation of the signals derived from each of the remaining strings. 3. The instrument of claim 2 wherein the degree of attenuation is adjustable.
4. An electronic musical instrument having: a plurality of strings passing over a supporting bridge,
means associated with each of the strings independently for producing an electrical signal derived from the vibration of that string, means for selecting only the electrical signal having an amplitude above a threshold level and for attenuating electrical signals derived from the remaining srings, voicing means for processing the said selected electrical signal, a mixing device coupled to the voicing means for receiving the said processed selected electrical signal, and means connected to the said mixing device for producing a vibratory motion related to the selected signal and applying the motion directly to the bridge only to sustain the vibration of the string originating the selected signal. 5. The instrument of claim 4 wherein the motion producing means includes an electromagnetic coil and core assembly and a substantially rigid connection between the assembly and the bridge.
6. An electronic plural-stringed musical instrument having:
pick-up means associated with each of the strings independently for producingan electrical signal derived from the vibration of the string,
independent amplifier means associated with each of the pick-up means for amplifying the signal from that pick-up means,
means for selecting only an amplified electrical signal from one of the amplifier means having an amplitude above a threshold level and for producing from said amplified signal control signals for effecting the attenuation of the signals derived from each of the remaining strings.
7. The instrument of claim 6 wherein the means for selecting includes diode means having a threshold voltage at the threshold level.