Electronic Player System For Electrically Operated Musical Instruments

Abstract

The invention relates to a player mechanism for electrical musical instruments. Information representing the manipulation of the playing keys and controls of a musical instrument, such as an organ, is converted to electrical signals and recorded on magnetic tape using a conventional cassette recorder. On playback, the recorded signal is "decoded" and used to operate a series of semiconductor "switches" to "play" the same or a similar musical instrument.

Description

This invention relates to a "player" system for musical instruments. The following disclosure illustrates the invention as applied to a keyboard instrument such as an organ, but it should be understood that the system is also suitable for use with electrically operated pianos or other instruments. It is a primary object of the invention to provide an improved "player" system in which information representing the manipulation of the keys and/or controls of the instrument is recorded on magnetic tape. The information recovered upon the "playing" of the tape is then used to again play the same or a similar musical instrument. It is another object of the invention to provide such a system wherein a performer can make his own "record" simultaneous with the ordinary playing of the instrument and which will then be available for relatively instant playback. It is another object to provide a system in which ordinary low cost and readily available tape cassettes are used as the recording medium. It is another object of the invention to provide a system wherein the information required to "play" the musical instrument is recorded in a form that permits the use of relatively low fidelity recording equipment that would be totally unsuitable for making an audio recording of the performance of the instrument. It is an additional object of the invention to provide a system of the character disclosed that is reliable, compact, low in cost, and is exceptionally easy to operate. Still another object of the invention is to provide a system which a single recording channel may be used to control the playing of a musical instrument and in which another channel may be simultaneously recorded for instruction, or for the audio recording of a voice or musical accompaniment. Another object is to provide a system wherein the tone quality or the "registration" of the playback instrument can be controlled by the player mechanism. Still another object is to provide a "player" system capable of operating unattended for long periods of time, such as an hour or more, thereby making practical the use of "player" equipment for providing background music in restaurants, mortuaries, etc. Still another object is to provide a system of transmitting data, representing the manipulation of the playing keys of a musical instrument, over a simple transmission line or other transmission medium, and of "decoding" the data to operate or "play" a remotely located musical instrument. These and other objects and advantages will become apparent from the disclosure which follows.

In the embodiment selected to describe the invention, an Encoding Instrument includes a musical instrument such as an organ which includes a keyboard covering several octaves. Each key has an associated keyswitch which is adapted to energize a musical tone producer when the corresponding key is depressed. The Encoding Instrument includes means for sampling in sequence, at frequently recurring intervals, the "on" or "off" condition of each of the switches. The Encoding Instrument generates a pulse train of square waves in recurring frames, each frame consisting of a series of pulses occurring at about 300 microsecond intervals followed by a dead time interval of about 3 milliseconds. A first series of the pulses are caused to be associated respectively with the aforementioned keyswitches. The Encoding Instrument also includes means for controlling the amplitude of the individual pulses as determined by the instantaneous condition ("on or off" ) of a respective keyswitch. Thus the amplitude of pulses associated with "operated" or "on" keyswitches will be substantially greater than those associated with "nonoperated" or "off" keyswitches. Additional pulses in each frame are similarly used to represent the instantaneous condition of various "stop" switches and of an expression control device. The pulse train is then converted to an A.C. signal capable of being recorded on relatively low fidelity recording equipment such as a cassette tape system, or transmitted over a conventional transmission line or other transmission means.

For playback, a Decode Instrument is connected to a tape player (or other transmission means) and is used for "playing" a musical instrument which may be the same instrument used for "encoding" or which may be a similar instrument. Signal from the tape player is amplified and rectified to recover a pulse train essentially identical to that produced by the Encoding Instrument. The Decoding Instrument uses the "data" or information carried in the pulse train to provide outputs to a series of terminals equal in number to the number of pulses in a frame. A first series of these terminals are connected to actuate or "key" the musical notes associated respectively with the playing keys. Additional actuators operate electrically controlled stops for changing the tonal characteristics of the instrument, and also an expression control for controlling the volume of sound produced by the playback instrument. Since the signal at any decoder output terminal consists of a series of narrow pulses as long as the key is to be "on", a holding circuit in employed to "stretch" the narrow pulses into pulses having a duration equal to the duration of one frame. Synchronizing circuits in the decoder sense the "dead time" to assure that the individual pulses are properly related to their respective decoder output terminals.

In the accompanying drawings:

FIG. 1 is a block diagram of an Encoding Instrument according to the invention;

FIG. 2 is a schematic circuit diagram of a Dead Time Clamp;

FIG. 3 is a Schematic circuit diagram of a Pulse Modifier;

FIG. 4 is a schematic circuit diagram of an Encode Gate;

FIG. 5 is a schematic circuit diagram of an Emplifier and A.C. Converter;

FIG. 6 is a drawing showing the electrical wave forms appearing at various points in the circuit;

FIG. 7 is a block diagram of a Decode Instrument according to the invention;

FIG. 8 is a schematic circuit diagram of a Clock and Data Recovery Circuit;

FIG. 9 is a schematic circuit diagram of a Dead Time Sense and Reset Circuit;

FIG. 10 is a schematic circuit diagram of a Decode Gate;

FIG. 11 is a block diagram of certain parts of an alternate Encode System; and

FIG. 12 is a block diagram of certain parts of an alternate Decode System.

Referring first to FIG. 1, a conventional Clock Pulse Generator 1, generates a continuous train of square wave pulses at a frequency of about 3,000 Hz. These pulses are applied to the input 20 of a Units Decade Counter 2, having four output terminals 21, 22, 23, and 24. The decade counter may be an integrated circuit such as a Motorola type MC880P. Clock Pulse Counts from 0 through 9 are represented by specific binary code combinations of plus and zero outputs on the four output terminals. 8 is a Units Binary Code to Decimal Converter having four input terminals which are connected to the four output terminals of the Units Decade Counter. The Binary Code To Decimal Converter may also be an integrated circuit such as a Motorola type MC870P. The Units Binary Code To Decimal Converter 8, has 10 output terminals 100 through 109, only one of which is energized for each binary code count appearing at the 4 input terminals. Thus outputs appear sequentially on terminals 100 through 109 and repeat for each 10 clock pulses.

The Tens Decade Counter 3, operates in the same manner as the Units Decade Counter 2, except that the input terminal 27 is connected to an output 26 of the Units Decade Counter, which provides one pulse for every 10 pulses appearing on terminal 20. The Tens Decade Counter 3 is connected to the Tens Binary Code To Decimal Converter 9, and outputs appear sequentially at terminals 110 through 119, each occurring for every 10 clcok pulses. Thus any count from 0 through 99 is represented by the combination of an output from one of the terminals 100 through 109 plus an output from one of the terminals 110 through 119. When count 99 has been reached, the sequence is repeated beginning at count zero.

Square wave clock pulses are also applied through an impedance 32 to the data line 30 which is connected to the input terminal 33 of the Amplifier 7.

5 is a Dead Time Clamp, the schematic of which is shown in FIG. 2. As shown in FIG. 2, the Dead Time Clamp includes a transistor switch 38 that shorts terminals 36 and 37 whenever a positive voltage is applied to terminal 35. Terminal 35 is connected to terminal 119 on the Tens Binary Code to Decimal Converter, which has a positive output during counts 90 through 99. Positive voltage is thus applied to the base of transistor 38 through resistor 31. As a result, clock pulses 90 through 99 will be short circuited and prevented from reaching the amplifier input. The signal on the data line will now appear as a series of recurring frames each consisting of 90 positive pulses followed by a dead time equal in length to the duration of ten clock pulses.

The Pulse Modifier6, in the embodiment selected to illustrate the invention consists of a normally closed electronic switch having a control terminal 40 and switched terminals 41 and 42. FIG. 3 is a circuit diagram of the Pulse Modifier. Terminal 41 is connected to the data line 30 through an impedance 44, and terminal 43 is connected to ground at 45. Thus the amplitude of the pulses on the data line are attenuated as determined by the impedances 32 and 44. When a positive voltage is applied to control terminal 40, the circuit between terminals 41 and 42 is opened and the pulses are unattenuated. As shown in FIG. 3, 43 and 46 are switching transistors. With no positive input at terminal 40, transistor 43 is held cut off by resistor 47. Base current thus flows from the power source 50 through resistor 49 and transistor 46 saturates, effectively short circuiting terminals 41 and 42. Applying positive voltage to terminal 40 saturates transistor 43 and "opens" transistor 46.

11 is a conventional keyboard, the keys of which operate the keyswitches 12. One terminal of each keyswitch 12 is connected to the bus 48 which is connected to the power supply 50.

The Encode Gate Assembly 10, consists of a large number of individual multiple input encode gates, one of which is schematically shown in FIG. 4. The outputs of all of the gates are connected to the terminal 52 which is connected to the input terminal 40 of the Pulse Modifier 6. Each gate, (see FIG. 4) has three input terminals 53, 54, and 55. Terminal 55 is connected to a specific keyswitch 12. Terminal 53 is connected to one of the output terminals 100 through 109 of the Units Binary to Decimal Converter 8, and terminal 54 is connected to one of the output terminals 110 through 118 of the Tens Binary to Decimal Converter 9. If all three input terminals are positive, a positive potential is applied through impedance 56 and diode 57 to terminal 52 and to the input terminal 40 of the Pulse Modifier 6. It should be understood that terminals 53 and 54 of each gate of the gate assembly are connected to a different specific pair of terminals, one from the Units Binary to Decimal Converter 8, and one from the Tens Binary to Decimal Converter 9. Accordingly, the two terminals 53 and 54 of a given encode gate will both be positive for only one count in any frame. In addition, the third input terminal 55 of each gate is connected to a specific keyswitch 12. If at the count where the terminals 53 and 54 of a given gate are both positive, the keyswitch 12 connected to the third input 55 is closed, the gate is then effective to produce a plus output. The plus output is connect via terminal 52 to the input terminal 40 of the Pulse Modifier 6 and the pulse on the data line 30 corresponding to that count will be increased in amplitude.

For a musical instrument having 61 playing keys we may provide 61 keying encode gates as have been described. These keying encode gates are identified 10a.

It is frequently desirable in player systems, or in remote control systems, to control the various "Stops" as well as the "Keying" of the musical sounds. This is accomplished by the use of additional stop encode gates 10b, which operate in the same manner as the Keying Encode Gates except that the input terminals 55, of the Stop Encode Gates 10b, are connected to the stop switches 14 which are operated by the stop tablets 13. In a typical embodiment, for example, counts 1 through 61 may be used for "Keying" and counts 62 through 72, for example, may be used for stop control.

An Expression Control 15 operates a multiple position switch 16 for controlling the volume of the playback instrument to be described. An encode gate could be provided for each of the contacts 6, but since switch 16 can be in only one position at any time, the number of encode gates required can be reduced by the use of the eight position Binary Converter, 17. A voltage appearing on any one of the eight input terminals 60 is converted to a binary code output on only three terminals 61, 62, and 63. Each of these 3 terminals is connected to a terminal 55 of one of the three "expression" encode gates 10c.

Also connected to the keyboard 11, and keyswitches 12, is the electrically operated musical instrument 65. Keyswitches 12 in addition to operating the encoder may play the instrument 65 through the cable 66 and the keying terminals 18. The stop switches 14 are also connected by cable 19 to the stop control terminals 25, it being understood that the tone quality and/or other musical characteristics of the sounds produced may be affected by applying D.C. potential to various of the terminals 25, similarly, D.C. potential applied via cable 68 to the terminals 69, affects the volume of sound produced by the instrument 65.

Pulses on the data line 30 are applied to the input 33 of the Amplifier and A.C. Converter 7, the circuit of which is shown in FIG. 5. The purpose of the amplifier and A.C. Converter is to convert the D.C. pulse train on the data line to an A.C. signal capable of being recorded on relatively low fidelity recording equipment, or transmitted by any other transmission medium incapable of maintaining a D.C. reference. FIG. 6a shows a typical pulse train at the input terminal 33.

Referring now to FIG. 5, resistor 71 and capacitor 72 filter out any high frequency transient pulses that may be generated incidental to the operation of the system. Capacitor 73 is selected to differentiate the pulses so that the signal at the output terminal 70 appears as shown in FIG. 6b. Transistor 74 and its associated components 75 through 78 comprise an ordinary common emitter amplifier which is coupled to the emitter follower transistor 80 through resistor 79. The output signal appearing across resistor 81 is connected to output terminal 70.

Switches 85, 86, and 87 selectively connect the output signal on terminal 70 to a recorder 88, which for example, may be an ordinary cassette type such as are commonly used for audio recording, or to a radio transmitter 89, or to an ordinary transmission line 90.

Thus we have "encoded" information representing the manipulation of the playing keys and controls of the musical instrument in a form that can be transmitted by a single pair of wires or by a single "channel" of a broadcast or recording system.

FIG. 7 is a block diagram of a Decode Instrument according to the invention. The Decode Instrument includes an Electrically Operated Musical Instrument 125, which is to be operated or "played" according to the electrical signals produced by the Encode Instrument and transmitted to the Decode Instrument by a suitable transmission means. The block 90 represents a transmission means in the form of an ordinary transmission line. This is the transmission line also labeled 90 in FIG. 1. 126 is a radio receiver capable of receiving signals transmitted by the transmitter 89 of FIG. 1. Switches 128, 129 and 130 connect the signal derived from the selected transmission medium to the input terminal 134 of preamp 135. The preamp is conventional and serves to amplify the signal to a level suitable for further processing. The output of the preamplifier is connected to the input 137 of the Clock and Data Recovery Circuit 138, shown schematically in FIG. 8. Referring now to FIGS. 6, 7 and 8, the waveform of the signal at 137 is as shown in FIG. 6b. Rectifier 141 removes the negative pulses and passes the positive pulses to the base of transistor 142. The waveform at this point is shown at FIG. 6c. Transistors 142 and 143 and their associated components 144 through 148 comprise a squaring amplifier which squares and normalizes the pulses to provide a clock output at terminal 139. This wave form is shown at 6d and is an essentially exact reproduction of the pulses generated by the Clock Pulse Generator 1 of FIG. 1.

The rectifier 141 is connected to the base of transistor 151 through resistor 157 and zener diode 150, which only conducts pulses having amplitudes greater than the breakdown voltage of the zener diode. This breakdown voltage is selected to be greater than the amplitude of the low amplitude pulses in FIG. 6c, but less than the amplitude of the high amplitude pulses. Transistors 151 and 152, and components 153 through 157 comprise a squaring amplifier which normalizes and squares the high amplitude pulses producing an "enable" output at terminal 140 as shown at FIG. 6e.

The clock output pulses at terminal 139 of the Clock and Data Recovery Circuit 138 are used to control Units and Tens Decade Counters 160 and 161, and Units and Tens Binary to Decimal Converters, 162 and 163, which operate in the same manner as those described in connection with FIG. 1. The Units Binary to Decimal Converter 162 has ten output terminals 170 through 179, and the Tens Binary to Decimal Converter 163 has ten output terminals 180 through 189. As previously described, any count of the clock is represented by the combination of a specific output at one of the terminals 170 through 179 plus a specific output at one of the terminals 180 through 189.

In order to synchronize the Decode Instrument to the Encode Instrument, means are provided to sense the dead time in each frame, and during the dead time to reset the Units and Tens Counters so that the first pulse of the next frame will represent count zero. 190 is the Dead Time Sense and Reset Circuit which is shown schematically in FIG. 9. Referring to FIGS. 7 and 9, pulses from the clock output terminal 139 are applied to the input terminal 191 of the Dead Time Sense and Reset Circuit. Pulses at terminal 191 charge capacitor 196 through diode 195. Resistors 200 and 201 and the base emitter impedance of transistor 197 provide a discharge path for capacitor 196. The time constant of the discharge circuit is such that as long as pulses are present, transistor 197 is forward biased to a saturated condition. During the dead time, capacitor 196 discharges and transistor 197 is cut off. When 197 is cut off, positive voltage is momentarily applied to the base of transistor 198 through resistor 203 and capacitor 206.

Transistors 198 and 199 and the associated components 207 through 211 comprise a pulse forming circuit, causing a narrow positive pulse to appear at terminal 192. This is applied to the reset terminals 193 and 194 on the Units and Tens Decade Counters 160 and 161, causing them to reset.

Again referring to FIG. 7, 125 is an electric organ or other Electrically Operated Musical Instrument which may be the same instrument shown in FIG. 1 or may be a similar instrument. The keyboard and keyswitches 220 are connected to the power source 50 and are adapted to key the tones of the instrument through cable 224 when it is desired to "manually" play the instrument. The stop tablets 13 and stop switches 14 control the character of the tones produced, by applying potential to various of the stop control terminals 25, and the expression control 15 controls the volume of sound produced as previously described. In order to key the Musical Instrument 125 from data transmitted by one of the transmission media 90, 126 or 127, a Decode Gate Assembly 225 includes as many individual keying decode gates 225a as there are encode keying gates 10a in the Encode Gate Assembly 10 of FIG. 1. Each decode gate is a multiple input gate the schematic of which is shown in FIG. 10. Referring to FIGS. 7 and 10, each gate has three inputs. The input terminal 229 of each gate is connected to the enable line 226 which is connected to the output terminal 140 of the Clock and Data Recovery Circuit 138. Each gate has an input terminal 227 connected to one of the output terminals 170 through 179 of the Units Binary to Decimal Converter 162, and an input terminal 228 which is connected to one of the output terminals 180 through 189 of the Tens Binary to Decimal Converter 163. If all three inputs are positive, transistor 230 will be forward biased by current flowing through resistor 237, and will saturate, discharging capacitor 231. This causes transistor 232 to cut off, which causes positive voltage to be applied through resistor 234 to the base of the actuator transistor 233, causing it to provide a positive output at its output terminal 235. If the voltage at any of the three input terminals 227, 228 or 229 of a given gate is zero, the transistor 230 will cut off either because there is no positive voltage applied to terminal 229, or because the voltage at the base of transistor 230 is short circuited through one or both of the diodes 212 or 213. This allows capacitor 231 to recharge through resistor 236. The emitter of transistor 232 is connected to a positive offset voltage as determined by the voltage source 239. Whenever the voltage across capacitor 231 exceeds the offset voltage, transistor 232 saturates, removing the positive voltage from the output terminal 235.

To summarize the operation of the decode gate circuits, all three inputs of any particular gate can be positive only during one specific count of a frame, and only providing that a pulse is simultaneously present on the Enable Line 226 as determined by the presence of a high pulse at the input terminal 134 of the preamplifier 135. If it were not for the capacitor 231, any output at 235 would be in the form of a short pulse having a duration equal to one count, and occuring only once in any frame. The holding circuit including capacitor 231, resistor 236, and transistor 232, causes any output to be held for a time at least equal to the duration of one frame, and a continuous D.C. output will be present from a given gate as long as an enable or "high" pulse is present in successive frames during the count assigned to that gate.

Included in the Decode Gate assembly 225 and 61 "Keying" Decode Gates 225a which correspond to the 61 "Keying" Encode Gates 10a of FIG. 1. The output terminals 235 of the 61 "Keying" Decode Gates 225a are connected through cable 250 to key the notes of the Electrically operated Musical Instrument 125. Also included in the Decode Gate assembly are 11 Stop Decode Gates 225b, corresponding to the 11 Stop Encode Gates 10b shown in FIG. 1. The output terminals 235 of these gates are connected via cable 251 to the stop control terminals 25, to control the character of the tones produced by the Musical Instrument 125. Finally the output terminals 235 of the 3 Expression Decode Gates 225c, included in the Decode Gate Assembly 225, are connected via cable 252 to the Binary to 1 of 8 converter 255. This may be an integrated circuit such as the Motorola Type MC 4006. Three input terminals 256, 257 and 258 receive the binary coded expression data, and converts it to a voltage on one of the eight output terminals 221. These terminals are connected through cable 222 to the expression terminals 69 of the Musical Instrument 125, it being understood that the volume of the sound produced is a function of which of the terminals 69 is energized.

The playback device 127, is understood to be any playback device suitable for reproducing the data signals recorded on a magnetic tape or other "record" made with the recorder 88 of FIG. 1. If a multiple channel recording system is used, it is possible to use one or more channels for recording and reproducing "data" for playing the musical instrument 125, and to simultaneously use one or more additional channels for recording and playing audio signals in the conventional manner.

In FIG. 1, a microphone 250 is connected to the audio input terminal 251 for recording such a voice or musical accompaniment. In FIG. 7 the switch 252 selectively connects the audio playback channel from the playback device 127 to an amplifier 254 and a loudspeaker 281.

MODIFIED FORM OF THE INVENTION

It is obvious from the foregoing description, that the principles disclosed can be used to provide apparatus of the described character for use with various sizes and types of electrically operated musical instruments. The high frequency response required of the recording or other transmission means employed, is dependent upon the clock frequency. This in turn is dependent on the number of pulses per frame and on the frame repetition rate. Equipment for medium sized electronic organs can be provided in which the frequency response requirements are not beyond the capability of the single channel of an ordinary cassette recording system. For larger instruments, it is possible to record data on more than one "track" or "channel", and thus multiply the capabilities of the system.

In addition, there are various ways of "sharing" encode gates and decode gates in order to effect economies in the system. FIGS. 11 and 12 illustrate one form of such a "shared" system.

In FIG. 11 the keyboard comprises three groups of playing keys including a middle group 11a, a low octave of keys 11b and a high octave 11c. As in FIG. 1 each key operates a keyswitch and the keyswitches are similarily divided into groups 12a, 12b and 12c. The Keying Encode Gate Assembly 400 corresponds generally with the keying encode gates 10a of FIG. 1, except that both the top and bottom octaves of the keyswitches (12b and 12c) are connected to the single set of Keying Encode Gates 400a. The middle octave keys and keyswitches are connected in the usual way to the other keying encode gates 400b. Since it is almost never required to play in both the top and bottom octaves of the keyboard at the same time, the "shared" system permits the use of the single octave of Keying Encode Gates 400a to serve on an alternate basis to transmit information or "data" representing the manipulation of either the bottom octave of keys, or the top octave of keys. A Top Octave Sensing Circuit 402 associated with the top octave of keys 11c is arranged to "sense" the operation of any key in the top octave, and when any of these keys is operated, to provide an output voltage at the terminal 404. This voltage is applied to the input terminal 405 of the Octave Transfer Encode Gate 406. This gate is identical to the other encode gates as described in connection with FIG. 1, and is associated with one of the counts of the clock as are all the other gates. The result is that whenever any key in the group 11c is depressed, a "high" pulse will appear at the output of the encoder.

Referring now to FIG. 12, the Decode Gate Assembly 450 corresponds generally with the Keying Decode Gates 225a of FIG. 7. The Keying Decode Gates however are divided into a set of Middle Octave Keying Decode Gates 450b, and one octave of Shared Octave Keying Decode Gates 450a. The output terminals of the Middle Octave Keying Decode Gates are connected to the middle octave keying terminals 451 of the Electrically Operated Musical Instrument 125, and "key" the middle octave notes of the instrument as described in connection with FIG. 7. The output terminals 454 of the Shared Octave Keying Decode Gates are connected by the cable 455 to the movable elements 456 of the gang switch 458, which includes an element 456 for each of the output terminals 454. Each of the elements 456 is adapted to make contact with a fixed element 460 or with a fixed element 462, depending upon the position of the trace 465. The trace 458 is operated by the electromagnet 468 such that when energized the magnet causes the trace to move all of the contacts 456 into contact with the elements 462. The switch elements 460 are wired by means of cable 470 to the low octave keying terminals 472 of the Electrically Operated Musical Instrument 125. The switch elements 462 are wired via cable 474 to the high octave keying terminals 475 of the Electrically Operated Musical Instrument 125. The output terminal 477 of an Octave Transfer Decode Gate 378 is connected to the terminal 480 of the electromagnet 468. Thus the output terminals 454 of the Shared Octave Keying Decode Gates, are selectively connected to key either the low octave of the Electrically Operated Musical Instrument, or the high octave, depending upon whether the solenoid 468 is energized by potential from the Octave Transfer Decode Gate.

Only one of many possibilities for sharing encode and decode gates has been shown. It will be obvious to those skilled in art that many other arrangements are equally possible.

Claims

1. A Player System for a Musical Instrument including; in combination: an Encoding Instrument; said encoding instrument comprised of a first series of keyswitches; a pair of output terminals; pulse generating means for producing at said output terminals, recurring frames of pulses, each frame including a series of pulses including as many pulses as there are keyswitches; a pulse modifier for causing the operation of any keyswitch to modify, in a predetermined manner, a specific pulse in each frame; a decoding instrument having a pair of input terminals; signal transmission means connecting the output terminals of said encoding instrument to the input terminals of said decoding instrument; a series of decode gates; each decode gate having an output terminal and a plurality of input terminals; and electrical musical instrument including a series of keying terminals for respectively sounding individual musical notes of said electrical musical instrument; connections between the output terminal of each decode gate to a specific keying terminal; a data recovery circuit including an enable terminal adapted to be energized whenever a modified pulse is present at the input terminals of said decode instrument; an enable line connecting said enable terminal to one input terminal of each decode gate; a clock recovery circuit for deriving a pulse train synchronized to the signals at the input of the decode instrument; means controlled by said pulse train for energizing the additional input terminals of each decode gate for a time coincident with the occurance of a specific single pulse of each frame of pulses appearing at the input

2. A Player System according to claim 1, in which the pulse modifier

3. A Player System according to claim 1, in which the frames of pulses produced by the encode instrument are separated by a dead time interval, and in which the decode instrument includes means for sensing the dead time interval to achieve synchronization of the encode and decode

4. A Player System according to claim 1, in which the transmission means includes a recorder for making a record of signals at the output terminals of the encode instrument, and a playback device for reproducing said

5. A Player System according to claim 1, in which said encode instrument includes additional stop control switches for determining the tonal character of the tones to be produced by the electrical musical instrument; and means for including, in each frame of pulses, additional pulses adapted to represent information relative to the condition of said additional control switches.