US3378623A - Tremolo-vibrato circuitry for use with a simulated moving sound source or the like - Google Patents

Description

April-16, 1968 D. M. PARK 3,378,623

TREMOLO-VIBRATO CIRCUITRY FOR USE WITH A SIMULATED MOVING SOUND SOURCE OR THE LIKE Filed May 7, 1965 2 Sheets-Sheet 1 28 ;-"*""""I 21? LAMP I8 42 I DRIVER PHASE 46 I SPLIT 0 26 1 9Q LAMP 21 I m i DRIVER I o 4 44 90 T T 270 PHAS 3 SHIFT 45, 2 27 T i I (I LAMP 22 I I 40 DRIVER I 0 5 PHASE I av SPLIT 25 A Q LAMP 20 DRIVER I 3 68 38 VARIABLE PHASE SHIFT LQVV FREQUENCY 79 TREMQLQ QSCILLATQR ADDING kFIG 1 OSCILLATOR CQNTRQL CIRCUIT (6 CPS.) 48

I 69/ 67 SYNCI-IRONIZING g6 GENERATOR AND LQVV FREQUENCY AMPLIFIER IO VIBRATQ OSCILLATOR OSCILLATQR (12 CBS.) CONTRQL 141 OSCILLATOR 48 SEQUENTIAL L CQNTRQL IMPEDANCE I PHASING gg FFgEQUENCY CONTROL QSCILLATQR (6 CPS/38 VARIABLE FIG 3 I PHASE SHIFT SYNCHRONIZING 66 68 CIRCUIT l P'FC'III LOW FREQUENCY 5o VIBRATO I I NVENTOR.

QSCILLATQR I2CPS /69 I Donald M. Park QSCILLATQR '51 TONE GENERATOR Io I CONTROL AND AMPLIFIER fggfig D. M. PARK 3,378,623 TREMOLO-VIBRATO CIRCUITRY FOR USE WITH A SIMULATED April 16, 1968 MOVING SOUND SOURCE OR THE LIKE 2 Sheets-Sheet :1

Filed May '7, 1965 ATTORNEY R m m hm N w M m h a m w OE om W N JoEzou I Ammo m: $02 368 mOEiGwO 7 02mm; Czwzomfi 303 v 1 Z616 56x6 25Q w wzmiomzu w i Kim wmfii mJm E Amm my mozjomo JoEzou 06355 mi 19,3 58 $538K 0J United States Patent TREMOLO-VIBRATO CIRCUITRY FOR USE WETH A SIMULATED MOVING SOUND SOURCE OR THE LIKE Donald M. Park, deceased, late of Raleigh, NC, by Mary S. Park, executrix, Raleigh, N.C., assignor to The Seeburg Corporation, Chicago, IlL, a corporation of Delaware Continuation-impart of application Ser. No. 425,353, Jan. 13, 1965. This application May 7, i965, Ser. No. 454,771

'5 Claims. (Cl. 84-1.18)

This invention is concerned with repetitive sequential connection of a plurality of speakers with a common audio source and a sound source physically moving from point to point along a defined closed path of travel. The invention is especially useful with musical circuitry for successively and repetitively keying a plurality of physically displaced speakers for the purpose of adding unique tremolo and vibrato effects to sounds produced by electric organs or the like.

This application is a continuation-in-part of an application entitled Sequential Connection of Speakers for Moving Sound Source Simulation or the Like, Ser. No. 425,353, filed Jan. 13, 1965.

Various mechanical means are employed in electric organs for introducing tremolo or vibrato. Generally, such means are directed to orbital movement of a sound source whether in the form of a speaker which is rotated or of an opening of a rotary horn or baffle which registers with a stationary dynamic speaker. In any event, such apparatus is bulky and introduces heat, electrical, mechanical inertia, rumbling and other well known operating and maintenance problems. Furthermore, an analysis of sounds coming from such apparatus reveals a complex mixture of varying tremolo, vibrato, Doppler and other effects. The vibrato and tremolo components are generally not controllable either individually or independently. Desired radiation patterns are not easily obtainable. Frequency response and power handling capabilities are limited.

In the previously referred to co-pending application Ser. No. 425,353, there is disclosed a system which simulates by electrical means the effect of a sound source physically moving in a closed path. In the referred to system a plurality of speakers are connected in parallel to a tone generator through a single amplifier. A variable impedance, such as a light sensitive resistor, is placed in the path of each speaker and means are provided to sequentially light the impedances to vary their respective values according to some predetermined phase relation. Thus, the audio signal originating in the tone generator is sequentially directed to the speakers which are physically displaced. With four speakers physically displaced ninety physical degrees apart and the impedances phased ninety electrical degrees apart, for example, the tone source sounds at if it is physically moving rom speaker to speaker and there is blending of the speaker tones as the sound moves each ninety degree step.

The circuitry of the referred to co-pending application discloses both tremolo or amplitude and vibrato or frequency control of the audio signals which enter the speakers. That is, the variable impedances, the light sensitive resistors, are varied in value at a tremolo rate of about 6 cycles per second and the rotating effect is at this tremolo rate. In addition to varying the mentioned impedances at the tremolo rate the sound source is varied in frequency at a vibrato rate of 6 cycles per second. The ultimate sound heard by the listener thus is an interesting and pleasing combination of both tremolo and vibrato effects.

3,378,623 Patented Apr. 1%, 1968 While the invention of the co-pending application has achieved truly unique sound effects there has been lacking certain desired qualities when compared to the well known Leslie effect. Many of these qualities are found in the present invention. For example, it has been discovered in the present invention that if the tone source is both frequency modulated and amplitude modulated simultaneous with amplitude modulation of the mentioned impedances, new and interesting sounds are produced and which simulate to a high degree the Leslie effect. It has also been discovered that a difference between the amplitude and frequency modulating frequencies can be employed to improve the quality of the Leslie effect.

An object of the present invention is therefore to provide an improved circuitry and speaker system for simulating a moving source of sound.

A further object is to provide an improved circuitry and speaker system which simulate a moving source of sound without requiring physical motion of the source and which exhibits improved tremolo-vibrato quality.

A further object is to provide a circuitry for successively and smoothly keying at a tremolo rate a plurality of physically displaced speakers to a tone source which is subjected to both vibrato and tremolo modulation such that each speaker is connected in turn to the source to realistically simulate a sound moving from speaker to speaker while exhibiting both tremolo and vibrato effects.

Another object is to provide an improved circuitry and system in electrical musical instruments or the like for producing vibrato, tremolo and phase shift effects that can be individually controlled.

Another object is to provide an improved sequential keying circuitry utilizing light sources and light sensitive impedances suitable to sequentially keying devices such as speakers in electrical musical instruments or the like.

Another object is to provide an improved electronic system for realistically simulating the tremolo and vibrato effects of a moving source of sound by means of a plurality of speakers but which requires only one power amplifier.

The foregoing and other objects will appear from the following description and drawings, in which:

FIGURE 1 is a block diagram of an electric organ system incorporating the invention.

FIGURE 2 is a more detailed combined block and circuit diagram following the FIGURE 1 system.

FIGURE 3 is a generalized diagram of an electric organ speaker system incorporating the invention.

The invention is illustrated in FIGURE 1 in connection with an electric organ and with a group of four speakers labeled 1, 2, 3 and 4 which it is desired to sequentially and repetitively connect in the same order (that is, 1, 2, 3, 4) to a common sound source identified as an organ tone generator-amplifier It That is, the object of the circuitry of FIGURE 1 is to make the source of sound seem' to rotate by causing it to come out sequentially and repetitively first from speaker I, then speaker 2, then speaker 3, then speaker 4, then speaker I and so forth. The amplitude variation at each speaker is smooth and blends with the last and next succeeding speaker. The speakers themselves should be understood as being physically displaced as illustrated by FIGURE 1 in which dashed line 11 schematically represents a suitable speaker cabinet containing the respective speakers 1, 2, 3 and 4 physically displaced ninety degrees apart around the inside walls of the cabinet. The physical displacement of the speakers may of course be at other than ninety degrees to achieve different rotative effects and as will be understood from later description there may be more or less than four speakers.

Each speaker has a connection with the tone generator and each such connection is controlled by a light sensitive impedance. In the example of FIGURE 1, the rotating effect is achieved at a tremolo rate, 6 cycles per second, by varying the value of such an impedance in series with each speaker preferably sinusoidally and at the tremolo rate. That is, amplitude modulation is applied to each impedance at a tremolo rate. The impedances may take the form of light sensitive resistors provided by photo- conductive tubes 20, 21, 22 and 23 as illustrated by FIGURE 1 and 2 and which are connected in series connection respectively with speakers 1, 2, 3 and 4. Delco type LDR-25 photo-conductor tubes sold by Delco Division, General Motors Corporation, Kokomo, Ind. are suitable. Tubes 20, 21, 22 and 23 are in turn sensitized by corresponding lamps 25, 26, 27 and 28 and when illuminated their resistance drops abruptly from a high value to a low value.

The voltages which energize the lamps are derived fro-m corresponding lamp driver circuits 30, 31, 32 and 33. The tubes 20, 21, 22 and 23 and the lamps 25, 26, 27 and 28 should in any event preferably exhibit short turn-on and turn-off times to achieve the desired smooth following of the sound around its path. The intensity of the type lamp employed should vary linearly with the voltage across the lamp and the impedance of the photo conductor tube employed should approximate a linear function of the incident light intensity so that the amplitude modulated tone at the speaker approximates sinusoidal modulation. Further reference to use of such variable impedances, namely light sensitive resistors, to gain musical effects may be found in Patent 3,119,890.

The detailed description thus far has primarily dealt with the subject matter of the previously referred to co-pending application Ser. No. 425,353. To continue this description as background for the present invention it has already been mentioned that the value of the irnpedances provided by tubes 20, 21, 22 and 23 are varied sinusoidally and at a tremolo rate. This is accomplished by furnishing the lamp drivers 30, 31, 32 and 33 with driving voltages which are sequentially stepped out of phase by some predetermined electrical phase diiference, a ninety degree phase difference being used. That is, using the voltage driving lamp driver 30 as a reference such voltage has zero phase deviation as indicated in FIGURE 1. The voltage driving lamp driver 31 is however ninety degrees out of phase with that driving driver 30; the voltage driving driver 32 is another ninety degrees or one hundred and eighty degrees out of phase with that driving driver 30; the voltage driving driver 33 is still another ninety degrees or two hundred and seventy degrees out of phase with that driving driver 30.

The described shifting and tremolo rate of energizing lamps 25, 26, 27 and 28 and consequent tremolo rate of illuminating tubes 28, 21, 22 and 23 is obtained by connecting a suitable, for example voltage controlled, low frequency, in the order of 6 cycles per second tremolo oscillator 38- to suitable phase split circuitry 40, phase shift circuitry 41, and phase split circuitry 42 such that four drive voltages phase shifted in the order of zero, 90, 180 and 270 are provided on the respective lines 43, 44, 45 and 46. A suitable oscillator control 48 for example a voltage regulator may be employed to regulate the precise tremolo rate.

From the description thus far, it will be understood that lamps 25, 26, 2'7 and 28 will light sequentially at a tremolo rate and their respective illuminations will be displaced in phase. This sequential phasing of lamps 25, 26, 27 and 28 will in turn cause tubes 20, 21, 22 and 23 to be sequentially illuminated and such illumination phase displaced in a like manner. Thus, any audio signal coming out of tone generator-amplifier will be sequentially directed at a tremolo rate to the speakers 1, 2, 3 and 4 and in the same order. For this reason, the source of sound coming out of the area Where speakers 1, 2, 3 and 4 are located will seem to rotate smoothly from speaker 1 to speaker 2, to speaker 3, to speaker 4, back to speaker I and so forth.

Organ tone generator-amplifier 10 is of course simply representative of one of the several similar tone generators to be found in the typical electric organ and which by voicing circuitry, not shown, are selectively connected to the audio circuits to be heard. Thus, any tone generator could be connected into the circuitry of FIGURE 1 and its tone made to assume a rotating tremolo effect in the manner just described.

While those skilled in the art will appreciate the many possible ways of deriving the required number of phase shifted voltages from tremolo oscillator 38, one circuit is illustrated in more detail in FIGURE 2 in which the respective phase split, phase shift and driver circuits of FIGURE 1 are boxed in dashed lines bearing the same identifying numerals. Before proceeding to the details of FIGURE 2 however, reference is made to FIGURE 3, which is later discussed, to indicate a very generalized representation of the invention and the fact that magnetic, heat, pressure and other kinds of sensitive devices might be employed in place of tubes 20, 21, 22 and 23.

In FIGURE 2, the 90 phase shift circuit 41 is coupled through a capacitor 60 to tremolo oscillator 38 and includes for phase shifting purposes capacitors 61, 62 and resistors 63, 64 and 65. A further coupling capacitor 70 connects phase shift circuit 41 to phase split circuit 42 made up of resistors 71, 72, 73 and 74 and transistor 75 connected as shown. Resistors 73 and 74 should be equal in value. As indicated in FIGURE 2, a 90 shifted voltage wave arriving on line 76 from phase shift circuit 41 results, with properly chosen values, in two voltage waves shifted respectively to 90 and 270 on lines 77 and 78. Since phase shifting and operation of such circuitry is well understood and is not claimed, per se, its specific operation is not dealt with in further detail. Other phase arrangements may also be employed. For example, circuitry could be provided to shift plus 45 on one line and minus 45 on another line and each of these phase split to obtain four voltages successively shifted 90 apart.

The output on line 78 connects through coupling capacitor 80 to the lamp driver 33 which drives lamp 28 through line 81. As illustrated, typical driving circuitry is employed in drivers 30, 31, 32 and 33 and in the phase split circuit 40. The zero or reference phase voltage derived from phase split circuit 40 is fed on line 82 to driver 30 and through line 83 there is developed the corresponding zero phase driving voltage across lamp 25. Similarly, line 84 carries the 180 phase voltage through coupling capacitor 85 to driver 32 such that there is developed in line 86 the corresponding 180 phase driving voltage across lamp 27. In a similar manner of developing voltage and phase, line 87 carries the 90 voltage to lamp 26.

Considering particularly the driver circuit 33 and certain aspects of its operation, the ratio of resistors 34 and 35 determines both the AC and DC voltage across lamp 28 with respect to voltage applied at point 36. The ratio of resistors 37 and 47 determines both the AC and DC voltage across lamp 28 with respect to voltage applied at point 36, the ratio of resistors 37 and 47 determines the bias on the NPN transistor 52 and in conjunction with resistors 34 and 35 determines the reference voltage applied to point 53. In place of the type of resistor-capacitor network comprising capacitor 80 and resistor 37 and 47 for developing the voltage at point 36, point 54 is used as a reference level to supply bias voltage for transistor 55 at point 56.

Considering the operation of the circuitry and system illustrated in FIGURES 1, 2 and 3, it will be seen that the voltages which energize lamps 25, 26, 27 and 28 are successively out of phase by 90. Accordingly, the time of occurrence of minimum impedance or resistance in tubes 2%), 21, 22 and 23 is successively out of phase by 90 time intervals. That is, if the tremolo oscillator is running precisely at 6 cycles per second each 90 phase interval represents a time of one twenty-fourth of a second (V second). In this example, the maximum brightness of the lamps 25-28 will be successively phased A second apart and the time of minimum impedance in tubes 20-23 will be successively phased second apart. As indicated by the drawings, each lamp is biased with direct current (DC) voltage to overcome the two brightness maxima common to an alternating current cycle. This DC bias also sets the level of modulation. With such condition and with the organ tone generator-amplifier in operation, it will be seen that the source of maximum sound intensity will sound as if it is moving from speaker I to speaker 2 to speaker 3, to speaker 4 and back to speaker I at Ms second per cycle intervals, this being a tremolo type sound effect.

With reference to the phasing of the impedance or resistance in tubes 20, 21, 22 and 23, it is noted that it is preferable to achieve a true sinusoidal phasing. However, a periodic wave which in fact departs substantially from a sinusoidal wave will give pleasing effects. The described rate of rotation can of course be controlled by the tremolo oscillator control 48 since the lamp frequency or rate at which maximum lamp intensity moves from lamp to lamp (lamps 25-28) is controlled by control 48. Accordingly, the rate at which minimum impedance moves from tube to tube (tubes -23) is also controlled by control 48 which means that the rate of rotation of the sound originating in tone generator-amplifier 10 and coming from speakers 1, 2, 3 and 4 is controlled by control 4-8, the net effect being to introduce a rate controllable tremolo effect in the sound ultimately heard by the listener.

In the prior co-pending application previously referred to the vibrato oscillator 50' operates at the same frequency as the tremolo oscillator 38 and is connected to the tone source (organ tone generator and amplifier 10) so as to subject the tone source to vibrato or frequency modulation. The tone source in the prior application is not however simultaneously subjected to both tremolo and vibrato. In the present invention however it has been discovered that if the tone source is subjected to the same tremolo or amplitude modulation, preferably 6 cycles per second, as is applied to the impedances ( tubes 20, 21, 22, 23) and is also subjected to a vibrato or frequency modulation operating preferably at twice the frequency of the tremolo modulation, i.e. 12 cycles per second, and the vibrato is furthermore synchronized with the tremolo, a highly realistic Leslie effect is achieved.

In the drawings, it will be noted that vibrato oscillator 50, with an appropriate control 51 such as previously referred to, operates at 12 cycles per second and is connected through a suitable synchronizing circuit 66 to the tremolo oscillator 38 and is also connected to an adding circuit 67. Adding circuit 67 is also connected to receive the output of the tremolo oscillator 38 through a variable phase shift circuit 68 and the output of adding circuit 67 is connected through line 69 to the tone source, the organ tone generator and amplifier 10.

By reason of having the organ tone generator-amplifier 10 modulated simultaneously by the added and synchronized outputs of the 12 cycle vibrato oscillator 50 and the 6 cycle tremolo oscillator 38 a relatively complex audio signal is fed out on line 79 and it is this complex signal which is rotated at the tremolo rate of oscillator 38 among the speakers 1, 2, 3 and 4. Of special interest to the present invention is the fact that the human ear can detect almost no difference between a system operating according to the Leslie effect and a system operating according to the present invention. While the system disclosed in the referred to co-pending application also gave a similar effect the present circuit is even superior in the quality of the effect. Depending on the precise sound effect desired, the system of the present invention offers a number of variables including the physical location of the speakers, the exact tremolo and vibrato frequency values and the phase displacement of the tremolo and vibrato frequencies. With regard to phase displacement a wide latitude is available by reason of the phase shift circuit 68 and such a shifting arrangement also provides a means for compensating for any drift away from some desired phase difference.

As with the circuit of the referred to co-pending application, several distinctions will be noticed between the present invention and the usual Leslie system. In particular the present invention has no physically moving parts and no mechanical, inertia or mechanical wear problems. Additionally, the tremolo and vibrato components are individually and independently controllable in the present invention as to individual and relative frequencies and phases whereas such components become mixed in the conventional Leslie system without any form of independent control or regulation being available. Another aspect of the present invention is to be seen in the fact that the lamp-photoconductor tube arrangement effectively isolates the audio from the tremolo control circuit. Consequently extraneous noise in the control circuitry which might arise in the tremolo oscillator, phase shift, phase split or lamp driver circuits is not introduced into the audio. It can also be seen that sound patterns can be controlled by positioning the speakers and modifying the speakers as desired. Only one amplifier is required and without the complexity of a rotating speaker system, proper attention can be paid to the speaker baffling and loading so that greatly extended frequency response and power handling capabilities can be obtained.

FIGURE 3 illustrates the invention in a somewhat more general sense as applied to simulated sound rotation. As previously mentioned, tubes 20, 21, 22 and 23 may be looked upon simply as being sensitive devices and lamps 25, 26, 27 and 28 and their associated phasing and drive means may be looked upon as sequential impedance phasing means compatible with the character of the lamps sensitivities. Thus, other sensitive" devices such as magnetic, heat, pressure and the like may be employed with compatible sequential impedance phasing means.

Asillustrated in FIGURE 3, the present invention as applied in broad terms to moving sound source simulation may be reduced to a basic system employing the same plurality of speakers 1, 2, 3 and 4 connected in parallel to the tone generator and amplifier 10 and a plurality of sensitive devices or variable impedances, one for each speaker, 137, 138, 139 and 140. A control means 141 labeled sequential impedance phasing control which is compatible with the character of the impedances may be employed to sequentially and smoothly vary the values of the impedances in some predetermined order and phase and at some predetermined frequency such that there is a smooth transistional rotation from speaker to speaker. Other components previously described are connected into the generalized circuit as shown in FIGURE 3. Control means 141 may of course take many forms and the lamp, lamp driver and phase control illustrated in the drawings all refer to a light sensitive type system whereas a comparable system following the invention might be based on magnetic, heat, pressure or other form of sensitivity and still realize the unique sequential keying and rotative character of the invention.

Thus, while a specific embodiment of the invention has been described, it will be apparent that various modifications may be made without departing from the spirit and scope of the invention as set forth in the claims.

What is claimed is:

1. In an electric musical instrument including a tone generator; means to simultaneously amplitude and frequency modulate said tone generator at respective modulating frequencies in the order of six and twelve cycles per second; a plurality of speakers each having an electrical connection to said generator; a plurality of light sensitive impedances, one for each speaker connection and effective when illuminated to make such connection and when not illuminated to block such connection; a plurality of light sources, one for each impedance and effective when energized to illuminate such impedance; a plurality of sources of energizing voltages, one for each light source, said voltage sources being productive of continuous periodic wave voltages of the same predetermined frequency as said tone generator amplitude modulating frequency but sequentially stepped out of phase whereby to cause a repetitive sequential and smoothly varying energization of said light sources and smoothly varying illumination of said imped'ances, said speakers thereby being sequentially connected to said generator in the same sequential phase relation as said voltages and in the repetitive order in which the respective speaker connections are made to produce an audible tone whose source rotates smoothly from speaker to speaker in a corresponding sequence and at said amplitude modulating frequency while said tone is continuously modulated in both amplitude and frequency at said six and twelve cycles as said source moves.

2. In an electric musical instrument including a tone generator; means to simultaneously both amplitude and frequency modulate said tone generator at respective modulating frequencies in the order of six and twelve cycles; a plurality of speakers each having an electrical connection to said generator; a plurality of light sensitive impedances, one for each speaker connection and effective when illuminated to make such connection and when not illuminated to block such connection; a plurality of light sources, one for each impedance and effective when energized to illuminate such impedance and voltage drive means responsive to said amplitude modulating frequency to sequentially and smoothly energize said light sources in some predetermined order and at said amplitude modulating frequency whereby said connections are sequentially made at said amplitude modulating frequency in corresponding order, and tone from said generator is made to sound as if its source were moving smoothly from speaker to speaker in a corresponding sequence while being both amplitude and frequency modulated at said respective six and twelve cycle frequencies during such moving.

3. In an electric musical instrument including a tone generator; a plurality of speakers each having an electrical connection to said generator; a plurality of light sensitive impedances, one being connected in series for each speaker connection and effective when illuminated to make such connection and when not illuminated to shift and drive means being effective to provide on said outputs smoothly varying energizing voltages for said light sources, said voltages being at said tremolo frequency but sequentially stepped out of phase whereby to cause a repetitive smoothly varying sequential energization of said light source and illumination of said impedances, said speakers thereby being sequentially and smoothly connected to said generator in the same sequential phase relation as said voltages and in the repetitive order in which the respective speaker connections are made; a synchronizing circuit connected to synchronize the output frequencies of said tremolo and vibrato oscillators; an adding circuit connected to modulate said tone generator with the sum of the outputs of said tremolo and vibrato oscillators; said tone generator thereby being effective toproduce an audible tone whose source moves smoothly at said tremolo frequency from speaker to speaker in a sequence corresponding to said repetitive order while said tone is simultaneously modulated both in amplitude and frequency at said respective different frequencies.

4. In an electric musical instrument as claimed in claim 3 including variable phase shift means connected between said tremolo oscillator and said adding circuit thereby allowing the relative phases of said tremolo and vibrato oscillators to be shifted prior to modulation of said tone generator.

5. In an electric musical instrument including a tone generator; a plurality of physically displaced speakers connected in parallel to said generator; a plurality of substantially identical impedances, one for each speaker and connected in series between the speaker and said tone generator, said impedances each characterized by having a similar variable impedance characteristic sensitive to a control means of corresponding character; a tremolo oscillator operative at a tremolo frequency in the order of six cycles per second; a vibrato oscillator operative at a vibrato frequency in the order of twelve cycles per second; means connected to synchronize said oscillators and the outputs thereof and modulate therewith said tone generator; sequential impedance phasing control means of said corresponding character respective to said tremolo oscillator and including means to smoothly and sequentially vary the values of said impedances in some predetermined order and phase and at said tremolo frequency, thereby to produce an audible tone whose source moves smoothly at said tremolo frequency from speaker to speaker while said tone is simultaneously modulated by said different tremolo and vibrato frequencies.

No references cited.

ARTHUR GAUSS, Primary Examiner.

D. D. FORRER, Assistant Examiner.

Claims (1)

1. 3. IN AN ELECTRIC MUSICAL INSTRUMENT INCLUDING A TONE GENERATOR; A PLURALITY OF SPEAKERS EACH HAVING AN ELECTRICAL CONNECTION TO SAID GENERATOR; A PLURALITY OF LIGHT SENSITIVE IMPEDANCES, ONE BEING CONNECTED IN SERIES FOR EACH SPEAKER CONNECTION AND EFFECTIVE WHEN ILLUMINATED TO MAKE SUCH CONNECTION AND WHEN NOT ILLUMINATED TO BLOCK SUCH CONNECTION; A PLURALITY OF LIGHT SOURCES, ONE FOR EACH IMPEDANCE AND EFFECTIVE WHEN ENERGIZED TO ILLUMINATE SAID IMPEDANCE; A TREMOLO OSCILLATOR SOURCE OPERATIVE AT A TREMOLO FREQUENCY IN THE ORDER OF SIX CYCLES PER SECOND; A VIBRATO OSCILLATOR SOURCE OPERATIVE AT A VIBRATO FREQUENCY IN THE ORDER OF TWELVE CYCLES PER SECOND; ELECTRICAL PHASE SHIFT AND DRIVE MEANS CONNECTED TO SAID TREMOLO OSCILLATOR AND HAVING A PLURALITY OF OUTPUTS, ONE FOR EACH OF SAID LIGHT SOURCES, SAID ELECTRICAL PHASE SHIFT AND DRIVE MEANS BEING EFFECTIVE TO PROVIDE ON SAID OUTPUTS SMOOTHLY VARYING ENERGIZING VOLTAGES FOR SAID LIGHT SOURCES, SAID VOLTAGES BEING AT SAID TREMOLO FREQUENCY BUT SEQUENTIALLY STEPPED OUT OF PHASE WHEREBY TO CAUSE A REPETITIVE SMOOTHLY VARYING SEQUENTIAL ENERGIZATION OF SAID LIGHT SOURCE AND ILLUMINATION OF SAID IMPEDANCES, SAID SPEAKERS THEREBY BEING SEQUENTIALLY AND SMOOTHLY CONNECTED TO SAID GENERATOR IN THE SAME SEQUENTIAL PHASE RELATION AS SAID VOLTAGES AND IN THE REPETITIVE ORDER IN WHICH THE RESPECTIVE SPEAKER CONNECTIONS ARE MADE; A SYNCHRONIZING CIRCUIT CONNECTED TO SYNCHRONIZE THE OUTPUT FREQUENCIES OF SAID TREMOLO AND VIBRATO OSCILLATORS; AN ADDING CIRCUIT CONNECTED TO MODULATE SAID TONE GENERATOR WITH THE SUM OF THE OUTPUTS OF SAID TREMOLO AND VIBRATO OSCILLATORS; SAID TONE GENERATOR THEREBY BEING EFFECTIVE TO PRODUCE AN AUDIBLE TONE WHOSE SOURCE MOVES SMOOTHLY AT SAID TREMOLO FREQUENCY FROM SPEAKER TO SPEAKER IN A SEQUENCE CORRESPONDING TO SAID REPETITIVE ORDER WHILE SAID TONE IS SIMULTANEOUSLY MODULATED BOTH IN AMPLITUDE AND FREQUENCY AT SAID RESPECTIVE DIFFERENT FREQUENCIES.

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