DE2329960A1 - ELECTRONIC MUSICAL INSTRUMENT - Google Patents

Description

The invention relates to an electronic musical instrument with a keypad and switches associated with this keypad for deriving a control voltage the tones of the keypad, with a multivibrator oscillator and a frequency divider for generating the lower octaves and means for generating different ones Sound characteristics.

As things stand today, the electronic organs can be divided into the following main assemblies: master oscillators, frequency dividers, key contacts, sound shapers, amplifiers and loudspeakers. The ones that are already functional with these assemblies The organ is usually expanded with the addition of vibrator, reverberation, sustain and percussion. Further effects are contracussion, mandolin effect and piano forte.

The tone generation in an electronic organ begins with aar generation of the tone frequencies of the highest octave. For this purpose, the conventionally designed organ contains twelve master oscillators.

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_ ₂ _ 2323960

All other tones required in the organ can be played using continued frequency division by the divisor from the highest Derive octave. The sound shaping can in principle be done in two different ways: by using fixed Matched filters, such as low-band or high-pass filters, result in fixed formants. Or you can create concurrent formants suitable mixture of fundamental waves and certain harmonics, which can be selected according to amplitude and frequency «This method is called Sound synthesis. Due to the electronic sound generation, the well-known organs generate sound signals with an organ-like sound character.

The invention is based on the object of creating an electronic organ with which sound signals from brass or woodwind instruments can also be generated. _

The solution to this problem is that the size of the control voltage a puncture of only the highest note of the pressed keys of the nomenclature and the voltage the multivibrator oscillator stimulates the generation of a sound signal of complex waveform, the frequency of which corresponds to the highest tone struck, and that the frequency divider temporarily sets the generated frequencies corresponding to the sound signals to a value and during a selected one Duration reduced to produce the sound of a brass instrument according to the highest note struck, and that the audio signals pass through various sound filters and are amplified to make them audible.

Further refinements of the invention are set out in the subclaims marked.

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Examples of the invention are shown in the drawing and described below. It shows:

Fig. 1 is a block diagram of a preferred inventive

Execution, Fig. 2 is a circuit diagram of the key switch circuit, the tone detector and the sample and hold circuit in Fig. 1,

Fig. 3 is a circuit diagram of the state selector in Fig. 1, Fig. H is a circuit diagram of the wave shaper in Fig. 1, Fig. 5 is a circuit diagram of the voltage controlled oscillator and similar circuits in Fig. 1,

6 shows a partial circuit of a brass instrument filter, FIG. 7 © in © waveform originating from FIG. 6, FIG. 6 shows a partial circuit of a flute sound filter, FIG. 9 shows a modification of a filter according to FIG. 8, FIG a voltage-controlled filter, Fig. 11 shows a circuit of a vibrato oscillator, an i noise source and the associated wiring, and

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Figs. 12 and 13 are waveforms for describing the oscillator according to FIG. 11.

The electronic organ according to Fig. 1 has a plurality of tone generators 1, each of which can consist of a plurality of independent oscillators for each tone of the organ or the tone generators include frequency dividers. In the latter case, as is known, twelve master oscillators are provided for each generator, the cover the top octave, the bottom octaves being obtained by frequency division * Alternatively, and in accordance with newer technology, a single master oscillator can be used, from which all the tones of a manual are obtained by frequency division. In either case, the outputs of the tone generators are conventionally selected by gates controlled from the keypad. The selected tone signals pass an intonation or a tone color circuit k, which is selected by auxiliary flaps (not shown). The outputs of the tone color circuits k lead to a preamplifier 17, which in turn controls a power amplifier 5 to which a loudspeaker 6 or another acoustic radiator system is connected. The gain of the preamplifier 17 is controlled by a function pedal 18 so that the tone amplitude increases when the pedal is depressed. All of this is known and found in many commercial electronic organs.

The present invention comprises a sound replica which is activated simultaneously in superposition with the ordinary organ in response to the depression of the same keys on the manual as the keys of the control gate for sound aerator 1. The output of the sound replica is in various playing states transformed. The various game states are selected by a game state selector 19. The available game states are: l) repetition, 2) percussion, 3) normal or continuous, k) fast reverberation, 5) icings ", * ner

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Anhall and 6) Sustain.

The control of the tones of the tone simulator takes place in response to the actuation of the manual 2, whereby a voltage is selected by the voltage divider 3 and this voltage is conducted via the line 2k ; the voltage represents according to its size only the nomenclature of the highest tone key pressed on manual 2, as it is in the American patent specification SN 213 939 * filing date 3o. December 1971. The voltage on line 2k is fed to a sample and hold circuit 8 which has a voltage at its output which is equal to the voltage on line 2k . The voltage at the output of the circuit 8 is diverted during a time which lasts until all the keys pressed are released or until a different key combination is struck. The sample and hold circuit 8 is activated in response to the control signals generated by a tone detector 7 connected to line 2k to answer any change in the highest tone key. The output frequency of a voltage-controlled oscillator (abbreviated V.CO.) 9 is primarily determined by the controlled voltage originating from the sample and hold circuit 8 *

The V.CO. 9 generates a right eclF signal at its output loa, the fundamental frequency of which corresponds to the highest tone of the pressed keys of manual 2. The output of the V.CO. 9 is applied to a frequency divider chain Io, which has various outputs for generating a field of square-wave signals in chords and in octaves with respect to the voltage generated by the V.CO. 9 generated signal. Typically and for the purposes of the present invention, the output frequencies of the divider chain Io coincide with organ lengths denoted by 32 ', 16', 8, k> , as do the partials 2 2/3 'and 1 1/3 ·.

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The tone signals generated by the frequency divider chain Io are fed to two groups of tone color filters 11 and 12 and a wave shaper 22. The preselection pulse filter 11 for the simulation of brass instruments (such as for trumpet, trombone and saxophone) is applied to the outputs 32 'and 16 · of the chain Io} a sound filter 12 for simulating a flute is connected to the outputs 16', 8 ·, k ', 2 2/3' and 1 1/3 'of the chain Io are applied, the wave shaper 23 for unusual sound simulations is connected to the outputs 32', 16 · and 8 '. The sound filters 11 and 12 and the wave shaper 22 have an input circuit for each of the lengths fed to them. The filters 12 are designed in such a way that the 16 ', 8', h 'tones are combined in a first output line 12a and the 2 2/3 "and 1 1/3" tones are combined on a second output line 12b.

The wave shaper 22 also receives the signals from a noise generator 21 and the pulses from the tone detector 7. In addition, the recateck tone signals, originating from the dividing chain Io, are selectively processed as short pulses or as sawtooth pulses, or they can mainly be unmodified, according to the will of the musician . The length of the pulses is controlled according to the output of the sample and hold circuit 8, so that pressing a lower note taeta results in longer pulses than pressing a high emergency key. The wave shaper 22 includes an operator which is used to select these different waveforms «

The brightness or radiance of wind instruments simulated by the filters 11 is achieved by means of variable wave-shaping circuits which are controlled by depressing the expression pedal 18 to simulate various instruments as a function of the time that elapses after a key has been played is. In the latter case there is less attenuation of the har-

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monic tones are present, whereby a greater luster is achieved with the passage of time after a key is pressed. In response to the depression of the pedal 18, the harmonic content of the tone increases through another wave-shaping Circuit to create a greater shine as the dynamics increase. The sound filter 11 further includes a Device for the simulation of sheet metal instrument reverberation characteristics, in which the amplitude of the sound signal is modulated with an enveloping with exponential characteristics

The filter 12 consists of a series combination of a voltage controlled amplifier and a fixed low pass filter. The gain characteristics of the voltage controlled amplifier is proportional to the output voltage of the sample and hold circuit 8. In this way, the gain of the voltage controlled amplifier is proportional to the fundamental frequency of the input. In this way, the output of the fixed low-pass filter with respect to the fundamental frequency remains constant over a given input frequency width during the attenuation of the harmonics of the input fundamental frequency with a fixed attenuation per octave.

The filter 11 and the wave shaper 22, as well as the linear gates 1h and 15 (which can be designed in accordance with the American patent 3 5 ^ 9 779) obey the control signals that come from the tone detector 7 when they are coupled by the state selector 13 are for a predetermined time, e.g. 20 milliseconds, after the first note of a key combination has been played. The control signals enable the audio signals to pass through the filter 11, the wave shaper 22 and the gates 1 ^, 15. These circuits block the passage of the audio signals until the control signals are deflected. Because of the delay when several keys are mainly pressed one after the other, e.g. at intervals of 20 milliseconds

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the tones originating from the filter 11, the wave shaper 22 and the gates Ik, 15 obey only the highest note played, regardless of which key was struck first. If the musician selects the continuous mode, the tones can come from the gate lk _t 15 and from the wave shaper 22, rather than in the percussion state, as long as the key is depressed, or a sustain effect can be created according to the will of the musician the release of the key for tones originating from the gate Ik and from the wave shaper 22 are generated. On the other hand, when percussion is selected, the control signals fed from the state selector to gates Ik, 15 and wave shaper 22 enable the wave shaper and gate lk _t to produce a controlled sustain, while gate 15 has a fixed, short sustain generated.

In response to one or more enabled tone keys, while one or more other keys are held down, the tone signals coming from filter 11 and wave shaper 22, as well as from gate 1 ^, 15 are shifted to tones with the highest tone of those remaining printed Keys correspond. In response to the release of the keys, the control signals from the state selector 19, from the filter 11, from the wave shaper 22, as well as from the gates Ik and 15 are removed. The circuit arrangement of the sample and hold circuit and the tone detector 7 delays the V.CO. 9 for a predetermined time, e.g. during ko milliseconds, the frequency continues to wander after a key has been released, so that if several keys are released one after the other, tones are produced which are only assigned to the key with the highest tone, regardless of which key was actually released last. If a new key with a higher tone than the pressed key is then pressed, the tones belonging to the new key are transmitted from the filter 11, from the wave shaper 22 and gate Zh ₁ 15 20 milliseconds later after the new "N *.;.: ta

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derived even if another key has just been released beforehand.

Have a random vibrato effect on the V.C.O. 9 originating Signal is selectively derived from a low frequency modulation oscillator 2o over a line 2oa, with the middle frequency of the same can be controlled. Random vibrato is particularly atmospheric in simulating the characteristics of various instruments, especially the tones of brass instruments. The modulation oscillator frequency from the modulation oscillator 2o modulates the V.CO. 9 in an adjustable range of 1 - 50 Hz. The signal varies with random vibrato randomly from the noise generator 21 the output frequency of the modulator 2ο around its center value. t> the amount of the random variation is controllable with typical maximum deviations from _ + 15% around the selected center frequency of the vibrato.

Ια repetition state is the output frequency of the oscillator 2o fixed with no random variations. In response to a signal from the tone detector indicating that any tone has been pressed, the oscillator 20 modulates the V.CO. 9 «a with a fixed frequency. In synchronization with the fixed frequency modulation of the oscillator 2o on the V.CO. 9 the repetition pulses are fed by the oscillator 2o to the state selector 19, which in turn, under the control of the musician, excites the gates Ik and 15 to the repetition effect while a key is depressed.

Another special feature of the circuit including the Tone detector 7 and the sample and hold circuit 8 is the simulation of Portamento, that is a soft or continuous transfer of a tone ie. another, in response on a legatissimo game of keys 2. When stakkatissiaio is played, there is no portamento. The Portamentoeffe ^ t

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is generated selectively in that an electronically controlled switch is disposed in the sample-and-hold circuit 8 which selectively a charging resistor of a storage capacitor short-circuits in response to the Tonindikatorspannung which is supplied to the sample and hold circuit "When LegatissiomspLei tone detector 7 obtains ^β ^ ^η Control signal that opens the switch, as a result of which the storage capacitor is charged with a relatively large charging time constant through the charging resistor, in order to generate a slow transition of the voltage, which is controlled by the YCO 9. When playing Stakkatissinospiel, the tone detector 7 receives a control voltage which short-circuits the switch and thus the charging resistor. For this reason, the voltage across the charging capacitor changes between voltages in discrete steps and the frequency of the oscillator is changed accordingly.

Another tonal effect is generated by automatically flattening a tone, ie by reducing its frequency as it was initially generated, thus precisely simulating certain instruments, in particular brass instruments. The degree of decrease is directly related to the tone associated with the key pressed. For this purpose, the output voltage of the sample and hold electronic circuit 8 _f, which identifies the key pressed, is coupled to the filter 11: and therefore selectively fed to the V, GC, 9 during a transition period when a new tone is made audible Settling time - the voltage associated with the pressed key reduces the frequency of the VCO in order to simulate the decreasing effect.

The output of the wave shaper 22 is a spannungegesteae * '- performed tes filter 13 and a Lautstärkeregeluijgskrei "3 for input of the preamplifier 17 and vce there at one power amplifier 5 to the speaker 6 · The ß..usgzing <* the sound?. ? '

Π f; CPOi f Λ /, -7 -

and 12, coupled by the gates Ik and 15 », run via a further volume control circuit 16 also to the preamplifier 17», the gain of which is controlled as a direct puncture of the depression of the pedal 18, so that the gain and volume increase when the pedal is depressed.

Voltage controlled active filters 13 selectively produce a number of different effects on the tonal output of wave shaper 22. Filter 13 includes low pass, band pass and high pass bipolar transfer functions generated either singly or in parallel combinations for the signal emanating from wave shaper 22. The Q and resonance frequencies of all three transfer functions are the same. Q is preselected by the musician, while the resonant frequency can be selectively controlled by one of the following means: the tone detector voltage originating from sample and hold circuit 8, the blanking envelope characteristic fed to gate Ik, or the position of expression pedal 18. The resonant frequency increases when the frequency of the played note increases or with increasing depression of the expression pedal 18 or when the amplitude of the sample envelope increases.

Tone switch, tone detector and sample and hold circuit according to FIG. 2

Referring now to FIG. 2, there is shown a circuit diagram for the elements of the keypad 2, the voltage divider 3 and the tone detector 7 and the sample and hold circuit 8 of FIG. The voltage carried on line 2k comes from the highest tone selected at a given time, as a result of the nomenclature associated with switches 31, diodes 32 and the values of resistors 33 in voltage divider 3 * voltage divider 3 i3t is connected with its end 3 ^ to the positive pole of a DC voltage source. Higher tones are associated with higher tensions.

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The tone indicator voltage on line 2k is fed through a blocking diode 35 to the base of an NPN emitter follower transistor 36. Via the emitter load resistor 37 of the transistor 36, a voltage which is directly proportional to the voltage on the line 2k drops. The voltage across the emitter load resistor 37 is led in parallel to ordinary monostable multivibrators 38 and 39, which work as a sound game detector and sound release detector.

The monostable multivibrator 38 comprises NPN transistors kl and k2, which are normally biased off and on. The collector of the transistor k2 is connected to the base of the transistor kl via a feedback network consisting of a capacitor k3 and a resistor kk , which has such selected values that a positive pulse, which has a duration of 20 milliseconds, in response to a positive passage pulse is generated, which is fed to the base of the transistor kl. The positive transient pulse can originate from the emitter of the transistor 36 via an AC coupling network including a resistor J * 5 and a capacitor k6 or from the monostable multivibrator 39 which is fed by the AC coupling network which contains a resistor k7 and a capacitor k8.

The collector of the transistor k2 is connected to the base of a3 NPN transistor k $ , which is operated in saturation in response to the positive 20 millisecond-lasting pulse that comes from the collector of the transistor k2. The collector of the transistor k9 is biased by a DC voltage via a resistor 51, originating from the emitter of the transistor 36. In response to the fact that none of the switches 31 4? - ^ - is closed, whereby the transistor 36 is blocked, a zero -Emitter voltage fed from transistor 36 to the collector of transistor k9 and the voltage at the collector of Tran-

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The sistor 49 is thereby essentially kept at its basic level. In response to the closing of any one of the switches 31, the resulting positive voltage on line 24 causes transistor 36 to conduct sufficiently, thereby increasing its emitter voltage to a sufficiently high level to turn off transistor ** 9, the transistor k9 is switched to saturation in response to a pulse from the monostable multivibrator 38. Therefore, if none of the switches 31 is closed or if a switch is closed for less than 2ο milliseconds, the voltage on the collector of transistor ^ 9 remains at its base level · If a switch 3I is closed for longer than 20 milliseconds, the collector voltage of the transistor 1 * 9 becomes positive in response to the changing state of the monostable multivibrator 38. The voltage applied to the collector of the transistor k2 is normally relatively low and jumps up for 20 milliseconds a high level immediately after closing a switch 31; after the 20 millisecond period has elapsed, the voltage at the collector of the transistor returns to its base level.

The note enable detector 39 comprises NPN transistors 55 and 56 which are biased so that the transistor 55 is normally conductive while the transistor 56 is blocked. The collector of transistor 56 is connected to the base of transistor 55 via a feedback path consisting of a series resistor 57 and a capacitor 58t, the time constant having a value such that a pulse of approximately ho milliseconds can be taken from the collector 56 in response to a negative voltage applied to the base of transistor 55 through the. Emitter of the transistor 36 via a wax voltage coupling network, consisting of a capacitor 59 and a resistor 60, is supplied. In response to the highest released tone, as indicated by a decreasing voltage on line Zk and at the emitter of transistor 36,

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1H

a negative pulse is applied to the base of the transistor 55 in order to block this transistor, whereas the transistor 56 becomes conductive. The transistors 55 and 56 remain in their states about ko milliseconds, after which they return to normal, "why can while ko milliseconds) after released a switch ± 3t. positive and negative pulses at the collectors of transistors 55 and 56 are derived.

The positive, leading edge of the ko millisecond pulse at the collector of the transistor 56 is coupled through the capacitor k8 and the resistor kf to the base of the transistor kl in order to overturn the monostable multivibrator 38. This positive, leading edge has the same effect on the monostable multivibrator 38 as a positive pulse which is fed to the monostable multivibrator from the emitter resistor 37 and causes an additional 20 millisecond delay, i.e. a total of 60 milliseconds.

The positive forward voltage, which is built up at the collector of the transistor k9, is used to allow the tone signals from the preselected voice filter 11, flute filter 12 and wave shaper 22 to pass into the output circuit. This creates a delay for all tones, so that if a number of keys are pressed within 20 milliseconds, only the highest tone of the associated tones is propagated, even if the highest tone key was not pressed first. If a number of keys are released consecutively within * fo milliseconds while one or more keys are held down, only the tones from the highest tone key still pressed will be relayed, even if different keys are released at different times. So if all of the keys are released essentially at the same time, there is no positive transition pulse at the collector of the

-Ik-

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sistor k9 _t which opens the outputs of the filters 11, 12 and 22, in such a way that only predetermined key tones struck are propagated, regardless of the row in which the keys are released.

In order to control the selective DC coupling of the tone indicator voltage on line 2k to storage capacitor 71 of sample and hold circuit δ, the voltages at the collectors of transistors k2 and 56 are fed to a flip-flop including two NOR gates J2 and 73. The outputs of the NOR gates 72 and 73 are DC-coupled in the usual cross-coupled manner. One input of the NOR gate 72 has a DC voltage input originating from the collector of the transistor k2, while one input of the NOR gate 73 has a DC voltage input from the collector of the transistor 55. If the voltage at the collector of the transistor k2 changes from a low level to a high DC voltage level, the output of the flip-flop "Jo, connected to the output of the NOR gate 73", switches to a relatively high voltage state, indicating a binary one In contrast to this, a positive voltage at the collector of transistor 55 causes the flip-flop 7o to be fed, so that the flip-flop output has a relatively low binary zero voltage level. In response to a key pressed, the 2ο millisecond pulse is activated, applied to the collector of transistor h2 , the flip-flop 7o, so that a positive voltage from the output of the NOR gate 73 builds up; this positive voltage is maintained until the state of the flip-flop changes in response to a positive voltage arising from the collector of transistor 55, which occurs when a highest tone switch 3I is released.

In response to a positive or binary "one ^w voltage resulting from the output of the gate circuit 73, the Sbei-

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cherkondensator 7I of the sample and hold circuit 8 switched on to address the tone indicator voltage of the line 2h . For this purpose, the positive voltage which is present at the output of the NOR gate 73 toggles the normally blocked NPN transistor Jk into the conductive state. The collector of the transistor 7 ^ is connected to the gate electrode 75 of a field effect transistor (FET) 76, which works as a first voltage-controlled switch of the sample and hold circuit 8. In response to transistor 76 being turned on , a current is drawn from GATE electrode 75 to bias FET 76 into a conductive state.

As stated in the aforementioned American patent application is, the sample and hold circuit 8 has an input network 77 and an output network 78 »where each of these Networks are made up of three transistors to provide impedance isolation and mainly to produce a gain of 1: 1. Therefore, the capacitor 7I is not made by the switching circuit 78 charged.

In response to a new tone key pressed, the voltage on line 2k is fed through input circuit 77 and the source-drain path of FET 76 to storage capacitor 7I. In this way, changes in the voltage on line 2k are coupled to capacitor Jl as long as NOR gate 73 outputs a voltage indicating that a note is being played.

In response to the release of the highest note while another note is still being played, the capacitor TL is disconnected from the voltage on the line 2k for a moment, during ^ o milliseconds. The momentary disconnection of the capacitor 71 causes in response that the transistor Jk is blocked by the output of the NOR gate 73, the gate 73 being switched off.

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the binary zero level flips back in response to the positive ko millisecond pulse originating from the collector of transistor 55. After the ko milliseconds have elapsed, the state of the monostable multivibrator 3S changes, as a result of which a positive pulse is emitted to the collector of the transistor k2. The positive pulse is coupled to the input of the NOR gate and flips the flip-flop 7o back to the state of the binary "one **. In response to the flip-flop 7o flipping over, the FET 76 blocks and the capacitor Jl becomes charged to the voltage of the line 2k. Thereby, transient changes in the release of key switches 31, while a sound is printed, separated from the capacitor 7I and the capacitor speaks only to the voltage on the line 2k, ko milliseconds after the clearance has been carried out .

The voltage of capacitor 71 is held fixed at a value corresponding to the highest tone after all keys have been released because FET 76 idles in response to all keys being released. For this purpose, the base of the normally blocked NPN transistor 81 is connected to the line 2k . In response to the closing of one of the pushbutton switches 3I, the transistor 81 is switched into the saturation region, whereby its collector is essentially connected to ground potential. The negative through voltage at the collector of the transistor 81 is led through a leading capacitor 82 and a short-circuit resistor 83 to the base d >> 3 normally conductive NPN transistor Sk , the collector of which is short-circuited to the base of the transistor Jk. In response to any note played, the transistor Qk blocks, whereby the output voltage of the NOR gate 73 controls the conductive state of the transistor 7 ^ and therefore of the FET * j6. 8k blocked or conductive, whereby the transistor 8 ^ the emitter-base path of transistor 3k kurz3chlie ;; :

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1*

and holds transistor "Jk off , preventing FET 76 from conducting.

In summary, the FET 76 blocks in response to the closing of a pushbutton switch 31, whereby the capacitor 7I is charged to the voltage of the line 2k , whereby the voltage-controlled oscillator 9 oscillates at the frequency predetermined by the voltage on the line 28. In response to an enabled tone causing the voltage on line 2k to decrease, there is a ko millisecond delay in the change in the voltage of capacitor 71 because FET 76 idles for the 10 millisecond period.

If no tone indicator voltage is present on the line 2k after the elapse of the ko milliseconds, the FET 76 remains idle and the voltage across the capacitor J1 is maintained at a level which corresponds to the previous highest tone played. If another tone is printed after the * ίο milliseconds have elapsed, the voltage associated with the new, lower tone is fed through the FET 76 to the capacitor TL . The belonging to this new note "audible tone sounds 2o milliseconds later, after belonging to the tone voltage on the capacitor Jl is stored, by virtue of the positive forward voltage, the transistor from the collector da3 k $ arises. If a new tone is played during the ko millisecond delay period associated with the tone signal release detector, which causes the voltage on line 2k to rise, FET 76 is immediately blocked and the voltage across capacitor J1 adjusts itself to the new value. Twenty milliseconds after the new higher note has been played, a positive through pulse appears at the collector of transistor k9, which hinders the tone signals associated with the newly arrived note.

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Another special feature of the scanning and holding circuit 8 is the simulation of Portamento. To this end, the source-drain path of the FET 76 is connected to the capacitor 71 via a variable resistor <1 which is connected via the source-drain path to an FET 92 which functions as an electronic switch, in response to the output voltage of a monostable multivibrator 93f which is also contained in the audio game detector 7. In response to a Legatissimo game, which will be described further below, the source-drain path of the FET 92 runs empty, as a result of which the capacitor 71 is charged via the resistor 91. In response to a game of Stakkatissimo, the source-drain path of FET 92 acts as a short circuit to resistor 91, changing the voltage on capacitor 71 in discrete steps, mostly instantaneously. In response to the immediate step change in the voltage of the capacitor 71, the frequency of the oscillator 9 is reduced. In contrast, a slow change in the frequency of the oscillator 9 appears in response to a smooth transition in the voltage across the capacitor 7I the frequency of the oscillator 9 to be obtained.

The legatissimo game is recognized by that the input of the monostable multivibrator 93 «bit to the collector of transistor 81 via an AC coupling network connected, which is a capacitor 9 ^ and a resistor 95 contains. The monostable multivibrator 93 comprises the KPN transistors 96 or 97 »those normally used in the conductive or non-conductive State are prestressed. The collector of the transistor

97 is * to the base of transistor 96 through a capacitor

98 and a resistor 99 connected, the values of which are selected so that the monostable multivibrator 93 has an 8 millisecond

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Pulse emits in response to every negative polarity reversal at the collector of transistor 81. As a result, every time a new set of keys is pressed while no other keys are pressed, the monostable multivibrator 93 is stimulated to send an 8 millisecond negative pulse to the set collector the transistor 97 to deliver. The negative pulse has the same voltage as a gate loo of the FET 92 , whereby the FET is switched to the conductive state and the resistor is short-circuited. In response to the release of all keys of a key set before any key of a second set has been pressed (i.e. Stakkatissimo game), this immediately charges capacitor 71 to the voltage associated with the new tone signal on line 2k . However, if the tones are played so that a key is not released until a second key has been pressed (Legatissitno game), the negative pulses do not reach the collector of transistor 97 and there is a high resistance path through resistor 91 to Capacitor 71 »in ^order to achieve a step-like change in voltage.

The state selector, Fig. 3

In Fig. 3 is a circuit diagram of a toilet of the state selector 19 shown. The circuits shown in Fig. 3 are driven by cant roll trigger voltages) originating from the linear gates I ^ and 15; driven, as well as by a gate within the Wave forraers. Switches within the state selector 19 which functionally relate to other circuitry in the system are not shown in Fig. 3, but they are shown in circuit diagrams that correspond to the corresponding belong to special circuits.

The state selector 19 includes a monostable multivibrato ■ * lol, which consists of NPN transistors Io2 and Io3. The K -;! -

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The detector of the transistor Io3 is connected to the base of the transistor Io2 by a series circuit consisting of a resistor Lok and a capacitor Io5 », the values of which are selected so that the monostable multivibrator generates a short-term pulse of the order of 8 milliseconds, usually as Response to a blocking of the transistor Io2 _t, which is controlled in the saturation region, in response to a positive pulse appearing at its base. The result, the short-term pulses that occur at the collector of the transistor Io3, are applied to the base of an inverted NPN transistor I06, the collector of which is connected to the base of the PNP transistor Io7, which in turn is normally blocked. The transistor Io7 is controlled in the conductive state in response to when the transistor I06 becomes conductive, and the transistor Io7, in the conductive state, operates as a constant current source. In order to generate different settling speeds, the current coming from the collector of the transistor Io7 is controlled by varying the impedance of the transistor emitter circuit. In the case of a slow response or a low settling speed, the emitter of the transistor Io7 is connected to a positive voltage of 30 volts of the DC voltage source via a 4.7 k ohm resistor Io8, for a fast response or a high settling speed, during which the switch 111 is closed , the emitter of the transistor Io7 is connected to the positive voltage of 30 volts by the parallel connection of the resistor Io8 and a 1 kH ohm resistor Io9, the current in the second mentioned possibility being about five times as large as in the first.

The constant current coming from the collector of the transistor? Io7, is fed to a pair of triangular wave forming networks 112 and 113 which are connected to the trigger inputs of gates lh and 15; the triangular wave originating from the network 112 is also used as a trigger input to the gate; tar

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of the wave shaper 22 is supplied. Each of networks 112 and 112 includes a parallel connection of a capacitor and a resistor; the capacitor and the resistance of the network 112 are preferably values of one microfarat and 2.2 MOhm. The capacitor and the resistance of the network 113 preferably have values of approximately 0.05 microfarates and 100 kOhms, so that the charging and discharging rates of the former are slower than those of the latter. The voltage across the network 112 is decoupled or isolated from the voltage over the network 113 through a diode IL4, whose anode is connected to the network 113 and its cathode connected to the network 112th

Due to the rate of decay of the triangular or ramp voltage A potentiometer 114 with the circuit 112 is to be controlled by the circuit 112 which produces a steady effect Connected via a coupling resistor 115 and an isolating diode 115a. The potentiometer 11 * 1 is selective with the 3o V DC voltage source connected by switch 116. The positive tap 117 of the potentiometer 11 ^ controls the decay rate the leading edge of the ramp voltage from circuit 112.

The conductive state and the magnitude of the current of the transistor Io7 are determined by the game mode, as is the presence or absence of the sustaine effect resulting from Natzwerk 112. When the system is in percussion moda, so the transistor Io7 becomes conductive in response to this State transferred for 8 milliseconds, that is in response to every positive transmission at the collector of transistor ^ 9 according to Pig. 2; the switch 111 is closed, so that a relatively large current comes from the transistor Io7. The one from the transistor The relatively large current resulting from Io7 causes the capacitors of circuits 112 and 112 to charge rapidly to a relatively high voltage to get a fast echo o -.-. ^ r

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3 η ρ ρ 3 ι / η L 7 ">

to cause a high settling speed and rapid opening, ie to excite the gates Ik, 15 and the gate of the wave shaper 22. These results are obtained by connecting the

Collector of the transistor U ° with the base of the normally
blocked transistor Io2 via an alternating voltage coupling network
works with the capacitor 118 and the resistor 119 is achieved.

After the 8 millisecond opening time of transistor Io7 has elapsed, the control voltages acting on gate lk and waveform shaper 22 from circuit 112 and from circuit 113 on gate 15 decrease. Since the resistor and the capacitor of the circuit 113 are relatively small, the voltage decrease at the gate 15 happens relatively quickly, whereby the gate 15 is blocked relatively quickly. Xm in contrast are
the resistor and capacitor of circuit 112 are selected to enable a Sustaine effect to be created. During the percussion mode, the duration of the sustain is variably controlled by adjusting the position of the sliding tap 117 and by closing the switch 116. With the position of the
Sliding tap 117 »adjusted against the upper end of the sliding resistance Il4, a relatively long-lasting sustaine effect is generated, whereby the gate lh and the wave shaper 22 -during
remain activated for a noticeable period of time to simulate the sustaine effect of a percussion instrument.

In a second functional mode, the continuous mode, the gates lk _t 15 and the gate in the wave shaper 22 are during
2o milliseconds excited after one of the pushbutton switches 31
has been pressed and remains excited until all keys are released. For this purpose, the collector of the transistor * k9 is connected via a direct voltage path to the base of the transistor Io2 via a resistor 119 and a switch 121, * die
Then short-circuit the capacitor 118, the switch 121 being closed when the system is in a continuous motiuj

309881/047 1

7329960

is working. In response to pressing any of the pushbutton switches 31 for a time longer than 20 milliseconds, a positive voltage is generated at the collector of the transistor h $ and coupled through the switch 121 to the transistor Io2 in order to toggle it into the conductive state. The transistor Io2 remains conductive as long as a positive voltage is applied to its base, whereby the transistor Io7 also becomes conductive in order to carry a constant current to the network 112 and 113; as a result, the gates Ik , 15 and the gate of the wave shaper 22 pass sound signals which are supplied as long as one of the pushbutton switches 31 is pressed. During the continuous mode, the attack or settling rate can be selected either slowly or quickly by opening or closing the switch 111, according to the musician's desire. Similarly, by closing and opening the switch Ho, the sustaine effect for tones supplied through the gate Ik and the gate of the wave shaper 22 can be controlled for a relatively long time or for a fixed shorter time.

In the repeat mode, the voltages controlling the fast reverberation periodically come from the circuits 112 and II3 with a frequency that is determined by the modulation oscillator 2ο is determined according to FIG. 1, as long as the pushbutton switches remain pressed. For this purpose the switch 111 is closed and the base of transistor Io2 is alternating voltage ma / Jis connected in series with the resistor 119 »capacitor 122 and switch 123 in order to respond to those coming from the modulation oscillator 2o Address square waves. The switch 123 will be you the musician is then closed when the system is in the Wfderholmod ^ -s works, while at the same time the modulation oscillator 2.> is set in such a way as to generate a random output frequency, causing the monostable multivibrator lol an 8 millisecond pulse in response to every positive transition to a

- 2h - 309881/047 1

ORtGtNAL INSPECTED

Square wave generated by the modulation oscillator. The control voltages come from the circuit 112 and II3 in response to the non-stable multivibrator lol, which is triggered by a square wave in the same way as it is for the excitation of the multivibrator in response to a positive continuous leading edge from the collector of the transistor k9 Tension has been described.

Wave shaper 22 Fig. 4

The circuit of Fig. K responds to the tone signals emanating from the 8 ', 16' and 32 'output of the frequency divider chain Io to selectively artificially produce sawtooth voltages, the pulses and square waves having the same fundamental frequency as the selectively coupled tone input signals. The duration of the pulses depends on the tone of the highest tone key. The square waves generated are essentially the reflection of the input square waves. The various waveforms, in response to the square wave tones applied in Figure k, control unusual tonal effects that are achievable and that simulate various musical instruments; For example, the sawtooth pulse and square waves can be used to simulate a piano, an oboe or a clarinet. These waveforms can be selectively modified by the voltage controlled filter 13 to produce other unusual effects. The wave shaper 22 also selectively obeys random interfering signals, as does a pulse each time changing the state of the monostable multivibrator 38 as shown in FIG. 2 in response to a new high level of sound emanating from line 2k . The interference input can simulate acoustic effects, for example wind, surf or the impact of a drop bridge, while the impulse originating from the monostable multivibrator 38 can generate crackling effects or noises.

- 23 -

309881/047

ORiOlNAL

7329960

The control over the transfer of one or a combination of the 8 ', 16' or 32 · tone signals from the frequency divider chain Io into the wave shaper 22 is carried out selectively by forward-polarized diodes 131, 132 and 133, the cathodes of which are connected to the 8 ¹ , 16 'and J2 ' outputs of the frequency divider chain Io are connected. The diodes 131-133 are selectively polarized by applying a positive voltage to their anodes in response to the closure of the normally open switches 13 ^, 135 and I36, which sequentially allow the sawtooth and square waves to be selectively deflected.

The sawtooth wave generator 141 comprises the NPN transistors ihh and 1 ^ 51 which respond to the square wave inputs, fed through the diodes 131 to 133 ^to derive a pulse having a width indicative of the length allowed by the diodes. For this purpose the anodes of the diodes I3I, 132 and 133 are connected via capacitors 146, 1 ^ 7 and 148 to the base of the transistor lkk , which is normally polarized in the forward direction via the connection of the resistor 150 to the 30 volt DC voltage source at connection 1 ^ 9 · The values of the capacitors lk6, iky and l48 are selected in conjunction with the value of the resistor 150 in order to generate such a turn-on time for pulses originating from the transistor lkk that the pulse width is directly proportional to the length of the input audio signals, that is to say that the Pulse width for the 8 'tone signal is less than the pulse width for the 16 and 32' tone signals.

The transistor 1 ^ 5 is selectively held in the forward direction by connecting its base to the Jo Volt voltage source ^, supplied from terminal 1 ^ 9 via a resistor I52 and a switch 153, which is opened by the musician when these sawtooth waves artificially generate wishes. When the switch - ar 153 is closed, the collector of the transistor l4> is connected to ground, whereby the base of the transistor ihh , di;

- 26 -

30988 1/0 ^ 7 1

ORIGINAL INSPECTS

1st short-circuited by the collector of transistor 1 ^ 5, Cannot be forward-polarized, which causes the sawtooth variations cannot be derived.

In order to enable the sawtooth pulse to be picked up, as well as the other waveforms originating from the wave shaper 22, the sampling of the NPN transistor 153 is provided. The base of the transistor 153 is connected to the voltage tapped off across the network according to FIG is derived. As described above, the voltage level derived from network 112 controls the attack or settling rate and sustain times and is dependent on the system operating mode. In response to the polarity of the base of the transistor 153 in the forward direction, a current flows from the positive Jo volt voltage source, to which the collector of the transistor is connected, to the emitter of the transistor and thereby to the collector of the transistor ihk via the resistor 15 ** ι to enable the decrease of the current at the collector of the transistor ikk .

During operation, negative transitions of the square waves , which are coupled to the base of the transistor ikk from the anodes of the diodes I3I to 133, switch the transistor ikh to the non-conductive state. The transistor ihk remains non-conductive until the voltage across the capacitors 1 ^ 6, 1 ** 7 or 1 ^ 8, which respond to the square waves supplied via one of the forward-biased diodes 13I to 133, reaches such a value as is sufficient to drive the transistor ikk into saturation. As a result, the saving time is determined by the values of the capacitors lk6 to 148 and the resistor 15o, with a positive voltage at the X - »llector of the transistor ikh during a time interval, keni-

309881/047 1

indicative of the length, which is fed to the base of the transistor ikk and the width of the generated pulses is controlled accordingly. The frequency of the generated pulses is the same as the frequency of the input square waves.

The voltage at the collector of the transistor ikk is fed to an integrator, which consists of a resistor 158 and a capacitor 159. In response to the positive voltage originating from the collector of the transistor Ikk , the capacitor 159 is charged and then discharged through the emitter-collector path of the transistor ikk in response to the return of the transistor to the conductive state. The duration of the increasing sloping roof, caused by the integration capacitor 1 ^ 9, is determined by the duration of the pulse originating from the collector of the transistor ikk , while the fall time of the sawtooth wave originating from the integration of the capacitor is essentially constant. As a result, the trailing edge of the sawtooth pulse is controlled by the duration of the supply by the diodes I3I to 133, while the sawtooth frequency equals the fundamental frequency of the input square wave pulse from the frequency divider chain Io. The sawtooth waveform formed on the other side of the integration capacitor 159 is passed through a diode I61 to the output tap 164, the cathode of the diode I6I being connected to a resistor 162 and an inverted large DC voltage separation capacitor I63. In order to generate pulses whose widths are determined by the tone of the highest pressed tone key, the anodes of the diodes 131 to 133 are connected to NPN transistors I65 and I66, which are mutually interconnected, as well as the tone signal and the voltage supply in a similar way to the connections of transistors ikk and 1 ^ 5 In particular, the base of transistor I65 is connected to the anodes of diodes I3I, 132 and 133 through capacitors 167, I68 and 169, the values of which are selected according to similar criteria, according to which dia

309881/047

of the capacitors Ik6 to 1Λ8 are determined. The rate of charge of capacitors 167-169 is controlled by the amplitude of the highest tone indicator voltage on line 12k which is DC coupled to the base of transistor I65 through a junction I71 and a resistor 172 to control the magnitude of the forward voltage of the base of the transistor . In response to variations in the amplitude of the voltage at connection point I7I, the blocking time of transistor I65 is varied. In response to a negative pulse present, which is fed through one of the diodes 131 to 133 and capacitors I67 to the base of the transistor I65, the transistor is toggled into the blocking range and remains blocked until the voltage across one of the capacitors I67 to I69 one Reached a sufficiently high value to flip the transistor in the forward direction and drive it into saturation, which occurs during a time which is controlled by the voltage at the connection point I71, depending on the resistor I72 and depending on which of the Capacitors responds to the incoming square wave.

To enable transistor 165 to be selectively enabled and disabled to deflect the pulses, a switch 173 is connected between a positive DC power supply and the base of transistor I66. In response to the closing of switch 173, the emitter-collector path of transistor I66 shorts the base junction of transistor I65 so as to prevent transistor 165 from conducting. The collector current of the transistor I65 is in response to the control voltage originating from network 112, controlled by the connection of the collector of transistor 165 to the emitter of the transistor 153 via the resistor 17 * "in a similar manner as the transistor Ikk. Dia will be derived pulses at the collector of transistor I65. to output terminal 164 via a pulse shaper circuit? -L-

- 29 -

309881/047 1

ORIGINAL INSPBCTED

a diode 175 which is connected to a load resistor I76 the voltage dropped across resistor 176 to the output terminal via an AC coupling network low impedance is coupled to a capacitor 177 and a resistor 178.

The dissipation of the mirror images of the square wave voltages selectively coupled by diodes I3I through 133 is accomplished by circuit 1 ^ 3 comprising NPN transistors 181 and 181 connected similarly to transistors I65 and 166. The base of the transistor 179 and the collector of the transistor 181 are connected to the anodes of the diodes 131 »132 and 133 via a DC voltage path consisting of the diodes 182 and a current limiting resistor 183; the cathodes of diodes 182 are connected to the base of the transistor to isolate the base from negative switching events possibly originating from capacitors Ik6-148 and I67-169. The square waves are derived at the collector of transistor 179 by the opening of switch 184 and passed through a circuit including a diode 175, a resistor I76 and I78 and a capacitor 177 to junction 1.6k in response to a current flowing from the collector of transistor 179 is pulled through the emitter of transistor 153.

The noise signal from the noise generator 21 is selectively fed to the output terminal 16k under the control of the states of the transistor 153 and the switch 188. For this purpose, the output signal of the noise generator 21 is fed to the base of the NPN transistor I85 via an AC coupling network, consisting of the capacitor I86, which is connected to the noise source. The transistor I85 is normally through the connection of its base with the positive pole of the voltage supply via the resistor I87 in the forward direction g-5 .- ·, *) Λ '..

309881/047 1

ORIGINAL INSPECTED

The forward bias of the base-emitter junction of transistor 185 is relieved by closing switch 188, which normally causes transistor I89 to turn off to forward and bridge the emitter base junction of transistor I85, thereby turning off transistor I85. In response to the switch 188 being in the open state, however, the noise signal is routed to connection point 1.6k via diode 175, resistors I76 and 178 and capacitor I77 when transistor I53 is conductive, by virtue of the DC voltage connection between the collector of transistor 185 and the emitter of transistor 153

In order to derive a relatively short pulse each time a new high tone key is struck, the base of the NPN transistor 19I is coupled in terms of AC voltage via the capacitor 192 and the resistor 193 to the collector of the transistor k2 of the multivibrator 38 of the music game detector according to FIG . The transistor 191 is normally biased in the conductive state by connecting its base through the resistor. 19k with the positive DC power supply. In response to the leading negative edge of the pulse, derived from the collector of the transistor k2 , which occurs during 20 milliseconds after the monostable multivibrator 38 has been driven into the transient state in response to the striking of a new high tone, the transistor 191 is blocked and a positive pulse is fed to junction 16k through diode 175, resistors 176 and 178 and capacitor 177. The duration of this pulse is determined by the values of the capacitor 19 ² and the resistor 193, the components of which control the length of time during which the transistor 191 remains blocked. The pulse can only be derived when the transistor 153 has become conductive. XJm to prevent the pulses, in response to each activation, the monostable multivibrator 98 to the starting point l6h

- 3

309881/0471

to become, the emitter base junction of transistor 1 ° 1 is selectively connected in parallel. The parallel connection occurs in response to the biasing of the emitter-collector path of transistor 195 into conduction due to the musician's closing of switch 196 , which selectively connects the positive DC power supply to the base of transistor 195.

Voltage controlled oscillator and control circuit therefor, Fig. 5

In Fig. 5 is a circuit diagram of a voltage controlled oscillator 9 and a control circuit for it. The basic circuit of the voltage controlled oscillator is essentially the same as in the above-mentioned American patent application, so that a detailed description of the Transistors in connection with the resistors and capacitors does not seem necessary here. The frequency of the oscillator 9 is controlled, among other things, by the amplitude of the DC tone display voltage obtained from the output of the sample and Holding circuit 8 originates, which is connected in terms of DC voltage to the input point of the oscillator. The frequency do3 Oscillator is also determined by the size of the positive DC voltage supply at point 2o2, a variable voltage at point 2o3 »the value of the resistance 2o ^, which the voltage at the point 2ol feeds to the oscillator, the value of essentially the same capacitors 2o5 and 2o6 determines which the collectors and bases of the oscillator transistors cross-coupling with each other.

The square wave output frequency of the oscillator, like appears at its output terminal 2o7, the one with an input connected to the frequency divider chain Io can be expressed by:

- 32 -

309881/047 1

7329960

- V

2RC (V

wherein

R C

Output frequency, Input voltage at point 2ol, DC supply voltage at point 2o2, voltage at point 2o3,

Value of resistance 2ok, Vert each of capacitors 2o5 and 2o6

means.

From equation (1) it can be seen that when V is greater than V

is the frequency of the oscillator 9

Dependence stands on

Variations in the amplitude of the voltage V in such a way that as the voltage at connection point 2o3 increases, the output frequency increases. The voltage at the connection point 2oJ is selectively varied in response to the output of the modulation oscillator 2o and in response to the generation of decongestion effects from various musical instruments, particularly brass instruments, which become flat when first expressed than when the state condition remains the same. A vibrato modulation of the frequency of the oscillator 9 is achieved in that the output frequency of the modulation oscillator 2o is fed to the connection point 2o3. The frequency of the modulation oscillator 2ο can either be fixed in a fixed range between approximately one to fifty Hertz, the frequency usually being adjusted for a vibrato speed of approximately 7 Hertz, or the frequency can be varied randomly around a fundamental frequency within this range. In response to the periodic or random changes in the amplitude of the modulus

- 33 -

309881/0471

ORfQiNAL INSPECT!

7329960

tion oscillator 2 ο originating wave, the frequency of the oscillator 9 is modulated.

The flattening effect is a transition function of the tone display signal carried from the voltage divider 3 to the line 2k. As the pitch of the note increases, the flattening effect decreases. For this purpose, the voltage at connection point 2ol, which indicates the highest tone, originating from the pressing of a pushbutton switch 31, is selectively allowed to pass to connection point 2o3 at a time at which the tone associated with the tone signal originally sounds.

For a realistic simulation of the various brass instruments, the number of flattings required is for different instruments different, e.g. a trombone is originally more flattering in expression than a trumpet, whereby it is necessary to have more flatting effects available to simulate a trombone than to simulate a trumpet. If it is desirable, the flatting effect for one of the instruments, one of several positive DC voltages can be applied to the emitter of the PNP transistor 2o9 be performed by closing one of the switches 211 or 221 connected to the positive DC voltage supply on Terminal 212 are connected through resistors 21o and 222, which have different values. When the switch 211 and the resistor 21o for generating a flatting for a trumpet are provided and when the switch 221 and the resistor 222 are provided for generating a trumpet fiat the value of resistor 222 is smaller than that of resistor 21o, so the emitter current for the trumpet is higher resulting in greater trumpet flatting.

309881/047 1

ORIGINAL INSPECTED

7379960

In response to the closing of one of the switches 211 or 221, the difference in the voltage amplitudes between the tone display voltage on the line 2ol and the emitter voltage of the transistor 2o ^{Q is taken} from the collector of the transistor 2o °, which is connected to ground via a load resistor 213 kit, the through the normally closed emitter-collector path of the NPN transistor 2lU is passed in parallel. The transistor 2l4 is toggled into the conductive state in response to a positive leading edge of the voltage, brought about at the collector of the transistor 2 * 9 * which is connected to the transistor base via an AC coupling network consisting of a capacitor 215 and resistors 216 and 217 _; is fed. A common connection point of the collectors of the transistors 2o ^Q and 2lh is connected to the connection point 2o3 via a relatively large capacitor 218, the point 2o3 being connected to ground via a relatively small load resistor 2o8. When transistor 2Ii * is off, capacitor 218 is charged to a voltage which depends on the emitter current of transistor 2o ° and the value of resistor 213, so that as the highest tone display voltage, Y, increases, the voltage on capacitor 218 decreases .

In response to a momentary switching of transistor 2iU into the conductive state through a positive leading transition edge, which comes from the collector of the transistor U °, the capacitor 218 is connected to the collector-emitter path of the Transistor 21 * 1 suddenly discharged. This causes the tension to drop at the connection point 2o3 suddenly to a value which corresponds to the voltage of the capacitor 218 and therefore with the value of V is linked. This creates a negative transition voltage placed on the line at junction 2o3 causing a flat transient oscillation. The capacitor 218 becomes exponentially charged again after the transistor 21 * »in d ^ n locked state has returned. Because the amplitude represents suddenly decreasing voltage at connection point 2o3 reversed

- 35 -

309881/047 1

ORIGINAL INSPECTED

is proportional to the highest tone, greater plating is produced for lower tones than for higher tone signals.

In FIG. 5, the supply voltage V_ is connected at point P to the emitter of the transistor T5o8 and T5H. The frequency comparison voltage is fed from point 536 to the emitters of the transistors T5o ° and T51o via a resistor 2ok. If a frequency comparison voltage appears at point 2ol, the

is greater than V, the VCO generates an output signal. The fols

The following conditions exist on the assumption that no push button switch is closed and there is a voltage of one volt at point 2ol. Then the transistors are T5o8, T512 and T513 blocked and the transistors T511 »T51 ^ and T515 conductive. When T511 is conductive, the voltage V is applied to the collector of T513 via resistor R515 and resistor R538 the bases of the transistors T5o8 and T5o ° are placed. If the Emitter and the base of transistor Tj? O8 with the same Voltage are applied, the transistor T5o8 is blocked. The transistor T512 is also blocked because its Base to the voltage V through resistors R522, R515 and the transistor T5H is placed and its emitter across the resistor R526 is connected to ground through transistor T51 ^, where transistor T51 ** is saturated and across resistor 2o8 is connected to ground. This is how the emitter base junction is of transistor T512 reverse biased; whereby it is ensured that the transistor is blocked. When the transistor T512 is blocked, the resistor R27a no base current is fed to transistor T513 »If a Volt voltage is present at point 2ol, the collector of transistor T51o cannot lead a base current to transistor T513. These two conditions ensure that transistor T513 is blocked. If the transistor T51 ** is saturated, so is the base-emitter junction of the transistor T.5H due to the voltage V polarized in the forward direction via the resistor R5o5 »

- 36 30988 1/0471

Transistor T51 ^ and connected to ground via resistor 2o8. As a result, the transistor T5H remains switched on and the voltage V is conducted to the emitter of the transistor T515. Of the Transistor T515 is also on because its base-emitter junction is polarized in the forward direction by the voltage V am Emitter across resistor R533, transistor T5l4 and is across the resistor 2o8 connected to ground. When the transistor T515 is conductive, it generates a base current for the Transistor T51 * »from V through resistor R528, which si-

it is established that the transistor T51 ** is saturated. So this presupposed set of conditions is a steady state for the VCO. When a voltage greater than V is applied to point 2o3, a current flows through resistor 2ok to line 55o. As a result, the transistor T51o becomes conductive and the lead 55o is placed on the line 551 via the diode voltage drop. If the diode voltage drop on line 551 is below V, then line 55o is clamped to V. The transistor T5o9 is blocked because its base is also connected to the voltage V. Of the

The collector of the transistor T51o leads a current to the base of the transistor T513 and linearly charges the capacitor C5o5 »and the transistor T51o works as a constant current source. The value of the charging current is determined by the difference in potentials between points 2o3 and 55o, divided by the series resistance of R2oh _t . When the capacitor C5o5 is charged to a voltage level which is sufficient to overcome the base-emitter drop voltage of the transistor T513, the transistor T513 becomes conductive.

The normal operation of the multivibrator will now be described. The voltage at the collector of transistor T513 wandolt

from V to V. This negative voltage jump is over s ν

transferring the capacitor C5o4 and driving the base of the tran sistors T51 ^ to a voltage -V + V. T51 ^ is blocked: γ.1

309881/0471

the collector voltage increases rapidly to the value V. Around

To allow the voltage at the collector of T51 ^ to rise rapidly to the value V, the capacitor C 505 must have the voltage
V can be charged quickly. This is achieved by a large charging current through resistor R526. If T513 is now conductive, T5o8, T5o9 and T512 are also conductive and TJIo,
T511 and T515 blocked. T513 remains in the saturation by a current through the resistor R527 ^a t whereby now the opposite stable state according to the above description
now exists. When the current flowing from point 2ol through resistor 2o ^ no longer flows through transistor T51o
can flow, the base current must to maintain the saturation of the transistor T513 via the transistor T512 and the
Resistor R527 & are fed. The current that originally flowed through transistor T5I0 now switches and flows through
the transistor T5o ° »around the capacitor C5o4 linearly from the

Charge voltage -V + V to a voltage level that corresponds to the
s ν

Transistor T51 ^ for continuous multivibrator oscillations
brings.

If the voltage at point 2ol is defined as V and since it has been shown that the voltage at point 2o2 is V, then we can the charging current through the transistors T5o9 or T51o is as follows be given:

_ _ Vn - Vs

Resistance of

The waveform of the voltage at the base of transistors T513 or T51 ^ is similar to the diagram of FIG. 7.

- 33 -

30988 1/047 1

cv

there .
German dv or
^C dt for this reason: I. f = 1
T T = a 2C (Vs-W) f m 1
2 Δΐ f ^C Vs-Vv I = A. t

C (Vs - Vv) I

Vn - Vs

(R of 2o5 (2c) (Ve-VvJ

It can be seen that the frequency of the VCO is directly proportional to I.

fn m K (Vn-Vs)
Now it becomes obvious why V goes into the equation and

that applies

K β (R of 2ok) (2c) (Vs-VvJ

It can be shown that the loading speed of f is against V is independent of V, which implies that a constant amount of frequency variation of f can be obtained by Varying V, completely independent of V.

- 39 -

309881/047 1

Instrument preselection sound filter, Fig. 6

FIG. 6 shows the circuit diagram of a complete sound filter 231 for simulating a brass instrument, the trumpet, as well as a control circuit 233 for the trumpet simulation channel; Furthermore, a sound filter 232 for simulating a second brass instrument, for example a trombone, is shown as a block. The simulation channel 231 for a trumpet is controlled by the 16 'output of the frequency divider chain Io, while the trombone sound filter 232 is controlled by the 32' output of the frequency divider chain. The channels 231 and 232 are driven in parallel by an output signal which originates from a pulse shaping network 233 with an envelope curve, said output signal obeying the positive voltage present at the collector of the transistor k9 according to FIG. The channels 231 and 232 respond to signals originating from the envelope network 233 in order to generate a simulation of the stopping speed, the reverberation tone color change, the tone color change as a function of the dynamic level and overall the tone quality for the two simulated brass instruments.

The simulation of the swing rate and the swing rate are the same for the two brass instruments, and the envelope pulse shaping network 233 can be used to control the modulation of the envelope of both channels 23I and 232. The rise and fall voltage waveform applied by circuit 233 to channels 231 and 232 is illustrated generally in FIG. 7, in which the output voltage of circuit 233 is plotted as a function of time during the first few, approximately 6 milliseconds after the arrival of a positive, leading edge at the collector of the transistor h® , the voltage built up by the circuit 233 increases with a fairly large exponential rate, as is shown by the line segment 23 **. After the 6 millisecond interval has elapsed, the speed of the Spt-ü-

- ho -

309881/047 1

The increase in the output of the circuit 233 decreases and approaches the exponential course, indicated by the wave-shaped segment piece 235 · With the release of a tone, the waveform from circuit 233 at a rate determined by exponentially decreasing curve portion 236 is displayed.

To enable the waveform shown in Fig. 7 to decrease the circuit 233 has three NPN transistors 237, 233 and 239, which are connected in cascade in such a way that the base of each next stage is connected to the collector of the previous stage. Transistors 237 and 239 are normal reverse biased while transistor 238 is normally biased conductive.

The base of the transistor 237 is coupled in terms of DC voltage via a resistor 2 ^ 1 and a connection terminal 2k2 to the collector of the transistor k9, so that in response to a positive voltage coming from the collector of the transistor k9 , the transistor 237 changes from its normally blocked state to the conductive state State is driven. The resulting voltage decrease at the collector of the transistor 237 is coupled to the base of the transistor, whereby this transistor is blocked. In response to the blocking of the transistor 238, the capacitor 2 ^ 3, which in combination with a diode 2k2 connects the collector-emitter path of the transistor 238 in parallel, is charged by the DC voltage supply which is connected from a connection point 2kk via a resistor 2k5 to the diode 2k2 . As a result, the voltage across the capacitor 2kj increases in accordance with the waveform section 23 * »in FIG.

If the voltage across the capacitor 2k3 reaches a predetermined level, the charging rate of the capacitor is reduced in response to this, since the resistor 2k6 and the diode 2 ^ 7 in series of

- Ul -

309881/0471

Collector of transistor 238 to a +5 volt DC voltage supply are connected at junction 248. In response to the rise in voltage across capacitor 2U3 across the internal diode voltage drop of the diode 247 to a level of 5.5 volts, the diode is polarized in the forward direction, so that a current from the connection point 244 through the resistor 246 and the Diode runs in parallel to increase the charge rate of capacitor 243 slow down, as indicated by the waveform piece 235 in FIG. 7 is shown. The capacitor 243 is charged further until the Voltage reaches a predetermined value, such as 9.5 volts, at which time the capacitor is fully charged.

The capacitor 243 remains charged until all the key switch 31 de-activated are, at which time the voltage at the collector of transistor 49 is applied, drops from the connection point 242 to the base of the transistor 237t ^au f zero, thereby turning the transistor 237 off and the transistor 238 conductive will. The saturation of transistor 238 causes capacitor 2h'J to discharge through resistor 249 and the conductive collector-emitter path of transistor 238 to produce waveform piece 236 in FIG. The voltage changes across capacitor 243 are coupled to the base of transistor 239 and then to the emitter of the transistor which is a driver transistor for channels 231 and 232.

The waveform segments 234 and 235 control the multiple successively incoming fast and slow reverberation speeds for those simulated by channels 231 and 232 Instruments, while waveform segment 236 is the rate of descent the instruments simulated. It has been found that an effective simulation of the instruments by the described Rise and decay rates can be generated.

309881/0471

Channels 231 and 232 are essentially the same with the exception of certain components within the imager that are not must necessarily be included in the latter. However, in order to produce different simulation effects, the circuits have different values of their components as required Since the circuits are constructed in essentially the same way, circuit 231 is below. Exclusion of channel 232 described; the elements that are not in channel 232, but in channel 231 are available, are described below.

When the system for generating the simulation of trumpet tones is activated, the square wave signal, originating from the 16 'output of the frequency divider chain Io, is applied to the base of the NPN transistor 251 via a capacitor 252 and a diode 253 which are ^{polarized in the} forward direction is in response to a positive DC voltage source applied to the anode, which is tapped from point 2 $ k and fed through a resistor 255. If no trumpet simulation is desired, the transistor 251 is conductive, namely through the connection of its base via the switch 211 and the resistor 256 to the DC voltage supply, according to FIGS. 5 and 6; transistor 251 is thereby prevented from passing audio signals because it is held in saturation due to the base current flowing from connection point 212 through resistor 256 and switch 211. Switch 211 is the same switch as it is in Pig. 5 is shown; it is a single pole switch which is arranged so that its contacts connect the connection point 212 to only one of the resistors 21 or 256. As a result, the trumpet-flatting effect is only produced when the switch 211 is activated in order to enable the transistor 251 to respond to the 16 'output of the frequency divider chain Io.

The square wave tone signal that appears on the input capacitor 252 is applied, a pulse waveform gets on the collector of the transistor

309881/0471 - 2 * 3 -

251, the pulse waveform being amplitude modulated due to the voltage applied to the base of transistor 239. The modulation envelope of the audio signal comes about because the voltage supplied to the collector of transistor 25I from Emitter of transistor 239 originates, which has a waveform according to Fig. 7, whereby this simulation of Mehrfachanatiegaraten corresponding to the wave form segments 23 ^ and 235 and one Decay rate according to the Vellenstücksegment 236 allows will.

The tone signal from the collector of transistor 251 becomes passed through a diode 258 to an active bandpass filter 259. The diode 258 causes the band pass filter of any Voltage variations that can occur at the collector of transistor 251 when the trumpet simulation is not separated is isolated is carried out.

The band pass filter 259 is an active filter and includes an NPN transistor 261 and a feedback network from the emitter of the transistor to its base which is responsive to the signal coupled through the diode via capacitor 262. The base of the transistor 26l is polarized in the forward direction by a positive direct voltage, which is applied to the connecting element 263 and is led via a resistor 26k to a connection point between the filter resistor 26 $ and the capacitor 262 . The feedback path from the emitter of the transistor 2ol to its base comprises a capacitor 266, which represents a first parallel connection for the emitter-base junction, as well as the series combination of the resistor 267 and the capacitor 268, which together form a second parallel connection for the emitter - Form base transition. The connection between the resistor. and capacitor 268 is connected to Mas.na via capacitor 269. The edge S-from the output of the bandpass filter 2 * j9 drops across the emitter load resistor 270. The value represents the components of the bandpass filter 259 are selected such that;. · Z '

309881/0471

Main filter frequency is approximately 12oo Hertz.

The filtered output of band pass filter 259 is fed to a variable wave shaper 273 which controls the tone color during the rise phase of the tone signal, the brightness increasing with time when a tone is originally emitted. This effect is achieved by varying the non-linear impedance of circuit 273 so that during the ramp phase the highest frequencies emanating from bandpass filter 259 are attenuated as a variable function of time. For this purpose, the emitter of the transistor 26l is connected to a resistor 27k , which runs in parallel via a non-linear, variable resistor consisting of a capacitor

275 and a diode 276, connected to ground.

When no sound is played, diode 276 is forward biased to form a low resistive parallel path between resistor 27 and ground, thereby making the Filter attenuates the high frequencies of the audio signal. The diode

276 is polarized in the forward direction due to the relatively high voltage at the collector of transistor 237, the voltage of which is used Anode of diode 276 via diode 277 and a bias network, consisting of the series resistors 278 and 279, the transition between them is parallel through the capacitor 28o put on ground. The diode 277 is polarized in such a way that the capacitor 28o is charged to 75 $ of the voltage prevailing at the collector of the transistor 237 in response to the blocking of the Transistor 237t that exists when no sound is pressed and during the first 20 milliseconds after pressing a tone.

In response to the polarity of transistor 237 in the forward direction Twenty milliseconds after a key was originally pressed, diode 277 is reverse biased and the

309881/0471

gate 28o is discharged through diode 276 and resistor 279. As time goes on, the discharge current decreases and so does the resistance diode 276 increases until the diode is no longer biased on. When the resistance of diode 276 increases, the parallel resistance increases from resistor 27 ^ to ground, thereby reducing the attenuation of the highest frequencies of the audio signal passing through circuit 273. For a typical A circuit that simulates the wearing of a trumpet is the variable waveforming caused by diode 276 and the Capacitor 275 »completed in about 200 milliseconds · I / i In response to the release of all keys, a similar variable filtering effect in the opposite direction is generated as the response on the polarity of the diode 276 in the forward direction due to the increasing voltage that arises across the capacitor 28o, resulting from the relatively high voltage at the collector of transistor 237.

It was found that the tone brightness effect caused by the variable impedance between the resistor 27 ^ and Mass is not as important for the trumpet sound as it is for the trumpet simulation. That is why the tone brightness effect is in channel 232 not necessarily present and the components used for this, i.e. the capacitors 275 and 28o, resistors 278 and 279, and diodes 276 and 277 may be separated.

An additional tone color filtering under the control of the musician as a function of the sound volume, a variable wave shaper 282 is generated which receives the sound signal which originates from the tone color control circuit 273. The dynamic ¥ ella.forming through block 282 the musician presses d-J3 Expression pedal 18 controlled. If the expression pedal 18 ni'j'at depressed, the high frequencies of the audio signal can only pass the circuit 282 with substantial attenuation

- ho -

309881/0471

while minimal attenuation and dynamic waveforming of the highest frequencies are generated at the maximum depression of the express pedal.

To this end, circuit 282 has a variable resistive parallel path across the output of circuit 273. The variable resistance parallel path comprises a capacitor 283 and a diode 282 *, the anode of which is connected to the capacitor 283 and its cathode is grounded. The junction between diode 284 and capacitor 283 is with a variable DC voltage via the wiper tap 285 of a potentiometer 286 and connected via a coupling resistor 287. The sliding tap 285 of the resistor 286 is opened by depressing it of the express pedal 18 is controlled so that in response to a full depression of the express pedal, the slide tap only a very low or 0 volt voltage is tapped, whereas when the express pedal is released, a maximum voltage to diode 284 via slide tap 285. In In response to a full depression of the expression pedal 18, the diode 284 is reverse biased, causing a high parallel resistance is generated for the high frequencies of the sound signal and thereby a maximum brightness is achieved. In contrast, the diode 284 is forward-biased in a wide range when the express pedal is not or is not is pushed all the way down in order to produce a large attenuation for the high frequencies of the sound signal and thus to increase the brightness to reduce. That brought out through capacitor 283 and diode 284 Signal is fed to the origin of channel 231 via a switching network that includes a series resistor 288 and includes a capacitor 289.

The output of channel 23I is connected to the output of signal vo.i Channel 232 connected, which is a trumpet simulation and the surge waveform of the emitter generated by transistor 239,

309881/0471

*. f—

as well as an indication of the position of the expression pedal, which is directed to a potentiometer tap within channel 232 is. The audio signals originating from channels 231 and 232 are additively combined to form a complete Generate simulation for the two brass instruments.

Flute sound filter, Fig. 8

In Fig. 8, a flute sound filter 12 is shown partly in a block diagram and partly as a schematic circuit. There are five separate flute sound filter channels 2ol-2o5, each of which is essentially the same except for fixed circuit component values associated with the different channels with different cutoff frequencies. The five channels 2ol, 2o2, 2o3, 2oh and 2o5 respond to the 1 1/3 ', 2 2/3', k't 8 'and 16' square wave output signals of the frequency divider chain Io. The signals filtered in channels 2ol and 2o2 and originating from parts 1 1/3 'and 2 2/3' are combined in an amplifier 2o6, the output of which is led to gate lU. The filtered signals corresponding to the k ', 8' and 16 'outputs of the frequency divider chain are passed through filters 2o3-2o5 to an amplifier 2o7, the output of which is passed to gate 15.

Each of the filters 2ol-2o5 includes a fixed Tlefpaöfiltteil, as well as a variable power amplifier circuit, its gain is directly proportional to the highest Tonaiizel tension on line 24 leading to the filters via the Terminal 2o8 is coupled. With «3 control of the gain each of the filters 2ol-2o5 in response to the highest If the tone key is pressed, the amplitude of the base frequency remains relatively constant over the frequency range of the input signal? a predetermined attenuation of the harmonics that belong to the pressed key is generated, regardless of di ^ "; 0i. \ =, '.ngs-

309881 / (H 7 1

frequency. The filtering of the harmonics, excluding the filtering of the fundamental frequency, ensures that the filter outputs resemble closed sinusoidal wave trains, rather than the square waveform of the filter input, so one to achieve better flute simulation.

For this purpose, in one embodiment, the channel 2ol contains a variable power amplifier with an NPN transistor 211, the base of which responds to the square wave output of the frequency divider chain Io for the 11/3 tone signal. The collector of the transistor 211 is connected to a DC voltage network in order to be biased by the output voltage V of the sample and hold circuit 8 via a resistor 212, while the emitter of the transistor is connected to ground. As the output voltage of the sample and hold circuit increases, the gain of transistor 211 increases accordingly so that the transistor gain is directly and linearly proportional to the highest tone signal on line 2k . Thus, as the highest audio signal voltage on line 2k increases, the gain of amplifier 211 therefore increases.

The output signal at the collector of transistor 211 is coupled to a fixed low-pass filter circuit 213 which can have one or more resistor-capacitance sections in cascade. For the purposes of the present description, the RC filter has two cascade sections 21 * »and 215, which have different cutoff frequencies, so that the cutoff frequency of section 21k is lower than the cutoff frequency of section 215. As a result, the filter circuit 213 generates approximately 6 dB of attenuation for the Input frequencies between the cutoff frequencies of sections 21 * »and 215, over 12 dB attenuation for input frequencies greater than both cutoff frequencies and essentially no attenuation for frequencies less than both of the cutoff frequencies.

309881/0471 ■ - * »

so

Channel 2ol creates a basic attenuation for harmonics of the 1 1/3 'input signal, while the basic frequency can pass without prejudice to the frequency. Attenuation of the harmonics without attenuation of the fundamental frequency is achieved because the gain of transistor 211 is directly proportional to the highest audio signal indicated by the voltage on line 2k. The gain of amplifier 211 and the low-pass filter characteristics of filter circuit 213 are designed so that all fundamental frequencies applied to channels 2ol between the two cutoff frequencies of sections 2lh and 215 can pass through the channel with the same degree of attenuation.

The operation of channel 2ol can perhaps best be described by considering a few examples. Assume that the cutoff frequencies of sections 2lh

and 215 are f and 2f, respectively, and that the gain of the amplifier ο ο

211 one ^ -s or two is for tones that have the fundamental frequencies f and 2f, respectively. Under these circumstances, filter circuit 213 produces approximately 0 dB and 6 dB attenuation for f and 2f, respectively. If the f tone is the highest key struck, the f fundamental oscillation will pass with 0 dB attenuation, while its second harmonic, 2f, is attenuated with 6 dB attenuation and its fourth harmonic, ^ f, even with 18 dB- Attenuation is dampened. If the 2f tone is the highest key pressed _f , the ~ 6dB attenuation, caused by the 2f fundamental frequency through the filter circuit 213, is compensated by the increasing +6 dB gain of the amplifier 211, so that the 2f frequency through the channel 2ol is allowed to pass with 0 dB attenuation hxrid, which is the same if the f fundamental frequency came from the highest pressed Tii.i key. The second harmonic, hf , of the 2f basic frequency is attenuated by channel 2öl with 12 dB.

309881/0471

As an alternative configuration, the spacing of the fundamental frequencies that can pass without attenuation can be made larger while producing the same degree of attenuation for all higher harmonics. In general, this result is achieved by cascading several (N) individual gain stages with controlled gain, each followed by a low pass filter; each of these filters can have the same cut-off frequency in order to achieve the same harmonic attenuation drop as a function of frequency. When N- sections are provided, the attenuation rate of the harmonics is 6n dB per octave. In one embodiment, such a result can be achieved by connecting a transistor linear amplifier 8 between sections 21U and 215 and changing the gain of the linear amplifier in the same way as the gain of transistor 211 is controlled. Such a configuration creates two variable amplifier sections which produce a multiplicative effect of the total filter characteristic. The two variable amplifier sections, in combination with the two low-pass filter sections, generate 0 dB attenuation for all fundamental frequencies equal to or greater than the common cutoff frequency of the filter sections and 12 dB attenuation per octave for all harmonics of the fundamental frequencies.

The same result of 0 dB attenuation for the fundamental frequency and 6 N dB per octave for the harmonics can be obtained with N-sections having various kinds of gain controlling elements as shown in Fig. 9 » wherein two cascade sections 221 and 222 are provided. The gain of each section 221 and 222 is in response to the highest tone indication signal originating from the sample and hold circuit S controlled and coupled to connection point 2o8. Dar Section 221 comprises a variable amplifier and a low pass filter section, which the same configuration as dar ve ---

309881/0471 -;> · ■ -

stronger 211 and the step 2l4 of the channel shown in FIG. The output of stage 221 is fed through DC isolating capacitor 22 ^ and variable resistance diodes 226 and 227 to a low pass filter section which includes a series resistor 228 and a parallel capacitor 229. The bias voltage is applied to the anodes of the diodes 226 and 227 via a resistor 23o from the connection point 2o8 and a connection of the cathodes of the diodes to ground is provided through the resistors 231 and 232. Capacitor 22k is selected to have a value large enough that all frequencies of interest are passed through without attenuation. The cutoff frequency of the filter including resistor 228 and capacitor 229 can be the same or different from the cutoff frequency of the low-pass filter including section 221, depending on whether it is desirable to attenuate certain harmonics to a greater extent than others.

In response to the variation of the direct voltage at the connection point 2o8, the impedances of the diode 226 and 227 are varied. As the voltage at junction 208 increases, the impedance of diodes 226 and 227 decreases, thereby reducing the attenuation exerted by filter section 222 on the input signal. Since each of the sections 221 and 222 comprises a variable gain or variable attenuator which has properties for the signal passing which are directly proportional to the highest tone indication voltage on the line 2k , the attenuation characteristics of the two filter sections for the range of the spacing of the two fundamental frequencies are ineffective .

309881/047

Voltage-controlled filter, Fig »Io

Consider now the voltage controlled filter 13 which is responsive to the tone signals emanating from the wave shaper 22 in response to the 32 ', 16 * and 8 * beeps supplied to the wave shaper 22 as well as in response to the noise and noise signals Key activation tone signals which are also supplied to the wave shaper 22. The filter 13 enables unusual and variable characteristics to be generated by its input signal. The filter comprises means for generating one or a combination of three transfer functions with low-pass, band-pass and high-pass filter characteristics for the input signals. The filter characteristics produced by the filter 13 are variable in terms of the selectivity (Q) and the cutoff or center frequency, which can be regarded as the resonance frequency, depending on the particular wishes of the musician. The resonance frequencies can be determined in response to one of the following quantities: the highest tone indication voltage originating from the sample and hold circuit 8, the position of the expression pedal 18, or the transient control caused by the waveform fed by the state selector 19 to the gate 15 to control the 16 ', 8' and k 'outputs of the flute filters. The selectivity of the filter characteristics, ie of Q, is controlled by a preselection by the operator.

For this purpose, the filter 13 is an active filter, including ordinary DC voltage operational amplifiers 2 ^ 1, 2k2 and 2 ^ 31 which include a phase inversion, ie a negative input, and a non-phase inversion, ie a positive input, so that the output voltage of each amplifier is proportional to the difference in the voltages on their positive and negative input slopes. The amplifier 2kl is responsive to signals on its positive and negative input terminals and is resistor with a negative DC voltage feedback path

309881/0471 -53-

244 provided, whereby the output voltage of the amplifier 24l indicates the difference between the input signals at the positive and negative input terminals. The next inverting input terminals of amplifiers 242 and 243 are connected to ground, while the audio signals are connected to the non-inverting amplifier inputs; these amplifiers are provided with capacitors and 2k6 in their negative feedback loops so that their outputs are proportional to the integral of the signals applied to the inverting input terminals. The output of integrator 243 is coupled via a DC feedback path including a resistor 2hj to the negative input terminal of amplifier 241, which is also responsive to the tone indicator output of wave shaper 22, which is supplied from terminal 164 in FIG. 4 and is coupled in via resistor 248. A two-quadrant multiplier 24 ° is connected between the output of the amplifier 2kl and the negative input terminal of the amplifier 2k2 and responds to the direct voltage at the connection point 251. A similar multiplier 252, connected between the output of amplifier 242 and the negative input terminal of amplifier 243, is responsive to the DC voltage from the junction. The multipliers 24 ° - and 252 each produce output signals of both polarities which are proportional to the products of the voltage at connection point 251 and the output voltages of the amplifiers 2h 1 and 242.

The DC voltage at connection point 251 determines the filter resonance frequency, this is the center frequency of the bandpass filter characteristic, the cutoff frequency of the low-pass and high-pass filter characteristics. The voltage at connection point 251 becomes controlled by the operator using one of the switches 253, 254 or 255 to selectively couple the highest DC audio indicator output voltage of the sample and hold circuit 8, or a DC voltage display in position de3

309881/0471 - 54 -

Expression pedal 18, or the ramp waveform passed to gate 15 by state selector 19 is activated. The express pedal 18 controls the position of the slide tap 26o of the DC energized potentiometer 26l such that the voltage allowed by the switch 25k has a maximum value for maximum depression of the express pedal 18; the DC voltage has a minimum value in response to when the depressing pedal is not depressed.

The selectivity Q of the filter characteristics is determined by a Feedback path between the output of amplifier 242 and fixed to the non-inverting input terminal of the amplifier 2Ul. The feedback path comprises a pair of fixed resistors 256 and 257 »with a potentiometer 258 disposed between them is, which has a sliding tap 259, which has a DC voltage path is connected to the non-inverting input terminal of amplifier 24l; the resistors 256 and 257 and potentiometer 258 create a shunt path for dan Output of amplifier 242 to ground. Resistance 257 is provided to limit the gain of the network, reducing the possibility of oscillation at a frequency within the bandwidth of interest is prevented. The fixed resistor 256 is provided to set the desired value of Q values to reach.

To produce the high-pass, band-pass and low-pass filter characteristics, the output signals of the amplifiers 24l, 242 and 2 ^ 3 are selectively shared by switches 26l, 262 and 263 Output port 264, one or each of the switches can be closed according to the operator's desire, which depends on the desired effect. If more than one the switch 261-263 is closed, the generated by the connection point 264 tapped voltage causes a combination filter effect for the audio signal applied to resistor 248.

309881/0471

It can be shown that the low pass, band pass and high pass filter transfer functions are represented by the following equations:

jw jw 2 ( ² )

^aV dc ^aV dc

dc

(3)

dc

de

Mean:

K = gain of the filter determined by the resistor component values;

k = constant proportionality factor, determined by the relative resistance values of the resistor 256 and the total resistance

the potentiometer 258;
Display
258;

kd ~ In ~ Display of the position of the sliding tap

, ₌ yrrr

w = frequency

aV, a resonance frequency of the circuit; V, β DC voltage at connection point 25I.

309881/0471

It can be seen from equations (2), (3) and (4) that the resonance frequency aV, and Q are identical for each of the transfer functions. As the supply from connection point 251 grows Voltage increases the resonance frequency. Q increases as sliding tap 251 moves toward the joint between resistor 257 and potentiometer 258, while a decrease in Q is produced by moving the potentiometer towards the junction between the resistor 256 and the potentiometer 258 is moved.

Modulation oscillator and noise generator, Fig. 11

Xn Fig. 11 is a circuit diagram for the vibrato oscillator 2o, the noise generator 21 and the control circuit for connection the noise generator and the vibrato oscillator, as well as other control circuits.

Vibrato is a major inaudible musical sequence ornament that gives a tasteful impression of the music adds due to the deflection of a tone from a precise and steady frequency. It is extremely difficult for a musician Playing a flute or a brass instrument and producing a constant frequency tone. The distraction of the constant frequency is what is a vibrato effect in reality represents a random variation of the tone with an inaudible frequency. It was found to be the most accurate simulation the vibrato effect can be obtained by randomly varying the audio frequency at an inaudible modulation frequency which is in the range between approximately 5.5 and 9.5 Hertz. Typically the random variation is plus or minus above the inaudible modulation frequency.

309881 / OA 7 1

To simulate the vibrato effect is in the present invention a relaxation oscillator is provided as a vibrato oscillator, in which a capacitor 27I with a constant charge and discharging current is supplied to produce a triangular waveform. The sloping roof of the following and leading Edges of the triangular oscillation are kept the same because the charge and discharge currents are the same. The duration of the loading and Discharge portions of the waveform can be variable by changing the input voltage level on line 273 of the comparison trigger circuit 272 is varied, which therefore affects the capacitor voltage acts. The trigger level speaks in favor of the random vibrato effect on line 273 to the output of the noise generator 21 at. If a random control of the vibrato frequency is not desired, the comparison trigger circuit 272 is informed via the Line 273 is supplied with a constant input voltage, whereby the charge and discharge currents are supplied to capacitor 271 during non-random time intervals.

In order to achieve constant charging and discharging currents of the capacitor 27I, PNP and KPN transistors 27 ^ and 275 are provided. The transistors 27 ^ and 275 are biased by a resistive voltage divider, which consists of the resistors 351-353, which are connected between the positive DC voltage supply between a connection point 281 and the ground. The voltage divider tap points are tied to the bases of transistors 27 ^ and 275 to produce base biases of plus 28 volts and plus 2 volts, respectively. The emitter-collector paths of the transistors 27 ^ and 275 are individually connected in series with the capacitor 27I, with the emitter the transistor 27 ^, which is connected to the cathode of a diode 276, while the emitter of the transistor 275 with the anode of another diode 277 is connected. The cathode and anode of the diodes 277 ^and 276 have a common connection which is connected to the branch 278 of the variable resistor 279. the

30988 1/047 1

Adjustment of branch point 278 is made by the musician, about the charge and discharge current levels of the capacitor 27I to control and thereby the fundamental oscillation of the vibrato oscillator, When the capacitor 271 is charged, the positive voltage supply at point 281 carries a positive direct current through. the emitter-collector path of the transistor 282 and the coupling resistor 283 passed, which with one end to the resistor 279 is connected, after which the current is passed through diode 276 and. the emitter-collector path of transistor 274 to the capacitor 271 headed. During the discharge of the capacitor 27I the emitter-collector path of the PNP transistor 282 is blocked, while the emitter-collector path of transistor 284 is conductive which was blocked during the period during which the emitter-collector path of transistor 282 was in the conductive state. This creates a discharge path from the capacitor through the emitter-collector path of the transistor 275 »the diode 277t the resistor 279 »the coupling resistor 285 and the emitter-collector path of transistor 284 to ground.

A PNP transistor 282 and NPN transistors 284 and 286 are mutually connected in a flip-flop circuit, such that the emitter-collector path of the transistor 286 is conductive, while transistors 282 and 284 are accordingly non-conductive and non-conductive; the emitter-collector path of transistor 286 is blocked, while the emitter-collector path of transistors 282 and 284 accordingly blocked and conductive. To this end, the base of transistor 282 and the collector of transistor 286 are connected in such a way that they are biased by the positive supply voltage from point 281 via resistors 287 and 288; the base bias for transistor 284 is generated by resistor 289 connected to the common Terminal of resistor 288 and the collector of translator 256 is connected. The base of transistor 286 and the collector

309881/0471 -5P-

gate of transistor 282 are through resistor 289 with each other tied together. To establish positive flip-flop operation, the collector of transistor 284 is connected to the base of the Transistor 286 and the collector of transistor 282 are connected via capacitor 292. The charging circuit for the capacitor has such a value that the capacitor normally has no influence on the oscillation frequency caused by the vibrato oscillator, Has.

The frequency of the vibrato oscillator is controlled by comparing the voltage across the capacitor 271 with the input voltage carried by the line 273 to the comparison trigger network 272. The voltage variations of capacitor 271 are coupled to an isolation amplifier 293 which includes emitter follower sections 29k and 295 in cascade; the base of the Eraitter follower 29 ** is responsive to the voltage of the capacitor 271. The impedance, seen from the capacitor 27I, between the base of the transistor 294 and ground remains constant, despite the variations in the capacitor voltage, whereby the constant charging and discharging currents, which are fed to the capacitor 27I through the transistors 2 ¹ Jk and 27.5, a cause the capacitor voltage dissipated at the emitter of transistor 295 to increase and decrease linearly.

The voltage amplitude originating from the amplifier 293> controls when the transistors 282 and 284 are conductive and non-conductive. For this purpose, the voltage at the emitter of the transistor 295 and, in mirror phase, the voltage variation of the capacitor 271 is fed via a resistor 297 to the emitter of a transistor 296, which is present in the comparison trigger network 272. The base of transistor 296 responds to the voltage on line 273 ^a n, which may be constant or randomly variable, depending on whether the musician selects the repeat play mode or the random mode. In response to the

309881/0471

If the voltage at the emitter of transistor 295 exceeds the voltage between the base and emitter of transistor 292, transistor 296 becomes conductive and a positive current becomes the base
of the transistor 28k to drive this transistor also into the conductive state, whereby the transistor 282 is blocked and the capacitor 27I begins to discharge
via the constant current drain, consisting of the transistor
275, the diode 277, the resistor 279 and the transistor 284. When the capacitor 27I begins to discharge, the voltage at the emitter of the transistor 295 decreases, which in turn reverse biases the emitter-base junction of the transistor 296, whereby the collector of transistor 296 can no longer conduct current to the base of transistor 28k. However, transistor 28k remains conductive because of the bias applied to its base via resistors 287-289.

The discharge current of the capacitor 27I continues through the emitter-collector path of the transistor 28U until an NPN transistor 298 in the comparison trigger network 272 out of saturation
is driven in response to a predetermined low
Voltage level at the emitter of transistor 295, which is coupled to the base of transistor 298 via a coupling resistor 299. In the random vibrato game mode, the base of transistor 298 only responds to the voltage at the emitter of transistor 295 which is passed through resistor 299 to its base-emitter biasing resistor 3ol. However, in replay mode, a
A certain amount of the voltage applied in the forward direction to the base of the transistor 298 whenever a switch 31 is not pressed due to the connection of the collector of the transistor S1 according to FIG. 2 with the base of the transistor 298 via the resistor 3o2 and the switch 3o3 which is only closed when the organ is playing in repeat mode, preventing the oscillator from vibrating. If the system is in
Repeat mode is, a constant voltages ^; ti

309881/047 1 - 61 -

placed on line 273 as described below; when any of the switches 3I is pressed, transistor 81 saturates, canceling the forward voltage of transistor 298, creating a fixed oscillator frequency. In this way the oscillator is synchronized every time a voltage appears on line 2k in response to the actuation of a key.

In response to this, when the voltage on the emitter of transistor 295 is greater than the predetermined level, even if the voltage on capacitor 271 decreases, in the other mode the egg-emitter-collector path of transistor 298 is forwardly polarized and driven into saturation, causing the The transistor collector has a sufficiently low voltage to prevent coupling of the DC voltage from the connection point 281 through the diode "} αΗ , the anode of which is connected to a junction between the collector of the transistor 298 and a connection point of the resistor 3o5, the other connection point of which is connected to the voltage at Purüw 281. In response to the switching back of transistor 298 to the blocked state, since the voltage at the emitter of transistor 295 has reached a predetermined level, the positive voltage from connection point 281 is passed through resistor 3o5 and diode 3o * f routed to the base of transistor 286 and to the collector of transistor 28k , f For the latter, the capacitor 292 can be used. In response to the positive voltage supplied by the diode 30 ^, the transistor 286 becomes conductive and the transistor 28k is blocked. The conductive state of the transistor 286 creates a sufficient voltage drop across the resistor 287 to drive the PNP transistor 282 into the conductive state.

The output signals are jstrated by the oscillator as shown in FIG decreased; an exit is used for the to control the voltage controlled oscillator 9, the

309881/0471

ORIGINAL INSPECTED

The output generates the gate voltages for the state selector 19. The The frequency of the voltage-controlled oscillator 9 responds to the basically triangular voltage variation of the capacitor 271 as it is taken from the emitter of transistor 295 and is coupled to potentiometer 3o5. The sliding grip 306 of the potentiometer 3o5 is positioned to the value of the voltage variations, the voltage being fed to the voltage controlled oscillator 9 by the vibrato oscillator and thereby the modulation index enforced by the vibrato oscillator at the frequency of the voltage controlled oscillator is determined. The sliding tap 306 is connected to the connection point 2o3 of the vibrato oscillator via a coupling capacitor 3 © 7 coupled according to FIG. 5. The repeat output is in the form of pulses that pass each cycle through a differentiating network are tapped, in response to the fundamentally square-wave voltage variations at the collector of the Transistor 282, the differentiating network having a series resistor 3o8 »a capacitor 3 ° 9 and a parallel resistor 3I0 includes. The voltage that drops across resistor 3I0, is fed to the base of transistor Io2 in Fig. 3 in response to the closure of switch 123 during repeat mode, whereby the transistor Io2 is driven into the conductive state once during one cycle of the modulator due to the positive pulses present that drop across resistor 31o.

In response to variations in the voltage on line 273 due to .A disturbance from the interference or noise generator 21, the Etnitter base operating point of transistor 296 for the polarity in Controlled forward direction. When the tension on the line 273 is kept constant, the charging and discharging times are of the capacitor 27I the same as it is in the diagram of FIG. 12a is shown, Fig. 12a the. Pike-corner shaft clamping

- 6; 309881/0471

Illustrates variations between the emitter and collector of transistor 28k . The voltage variations of capacitor 271 are shown in Figure 12b, which shows the linear charge and discharge currents with identical trailing and leading slopes of the square waveform. The peak-to-peak values of the square waveform should be noted. In contrast, in FIG. 13, which shows the waveforms which arise in response to a random disturbance variation on line 273, the peak voltages of the triangular waveform are variable depending on the amplitude of the disturbance signal on line 273 as it is represented by waveform 31 **; the triangular voltage variations 313 have linear, equal roof slopes due to the same charge and discharge currents. The interfering signal on the line has a variable level, controlled by the musician, and a broad interfering characteristic over a frequency range between approximately 50 Hz and 15 to 20 KHz.

The wide noise generator 21 includes an NPN transistor 321, whose Emitter-collector path through the positive voltage from the point fc 281, coupled through resistor 322, is biased. That thermal noise of transistor 321 is caused by the connection of capacitors 323-325 between the collector and Emitter, the base and the emitter and the collector and the base of the transistor 321 are generated. The base bias becomes generated by series resistors 326 and 328. The thermal Noise voltage variations originating from the collector of transistor 321 are AC voltage-wise across a capacitor 329 coupled to the base of an NPN transistor 331 which is a Has feedback network that includes a capacitor 332 and a resistor 333, which is provided to something to attenuate the high frequencies of the noise variations.

- 6 'f -

309881/047 1

The noise signal produced at the collector of transistor 331 is fed via a coupling capacitor 335 to a high-gain multivibrator amplifier, which has a transistor amplifier stage 33 ^ with fixed gain and a stage 336 with variable gain in cascade, both stages in emitter circuit with the emitter to ground are switched. The signal at the collector of the transistor 33 ^ is also given to the base of the emitter follower transistor 337. The 338 of the emitter-follower 337 voltage drop across the emitter load resistor is selectively to the base of transistor 185 of FIG k via the capacitor 186 made to the simulation of wind, wave and added spurious signals in the waveform shaper 22, as described above, too. enable.

The gain of amplifier 336 is determined by the position of the Sliding tap 339 of the variable resistor 3 ^ 1 controlled, which is within the collector base circuit of transistor 336a. The position of the slide tap 339 becomes in correspondence with the desired amount of random frequency variations of the vibrato oscillator 2o selected; the gain is directly proportional to the desired frequency variation. The jamming signal, originating from the collector of transistor 336a which has a waveform cut so that it is composed of two voltage levels consists of a randomly varying trailing and leading edge, is voltage-wise via a capacitor 3 ^ 2 led to a further amplifier stage 3 ^ 3, its Output DC voltage to the base of transistor 296 is coupled via line 237. The DC voltage level at Collector of transistor 3 * »3, fed on line 273, is such that the interfering signal varies over a mean value in order to maintain the vibrato center frequency over which di- » Frequency variations appear at a fixed level determined by the adjustment of resistor 279.

309881/0471

If it is desired to suppress the random variations in the frequency of the vibrato oscillator during the duration of the repeat mode, the collector output of amplifier 336 can be selectively connected in parallel with the ground, creating a constant voltage through transistor 336 to the base of the transistor 296 is supplied via line 273. For this purpose, switch 3 ^^ selectively connects a positive DC voltage at point 3 ^ 5 with the bases of NPN transistors 3 ^ * 3 and 3k6. The base bias voltage fed to transistor 3 ^ 6 when switch 3 **** is closed is sufficient to drive transistor 3 ^ 6 into saturation and thus prevent the interference signal from being coupled to the base of transistor 3 ^ 3. The base of the transistor 3 ^ * 3 is biased due to its connection via the resistor 3 ^ 8 and the switch 3 ^ with the positive DC voltage at point 3 ^ 5 in such a way that the same DC voltage value appears at its output when the interference signal is applied to it will.

While only a specific embodiment of the invention has been described and illustrated, it will be apparent that there are variations within the details of the invention can be made without the spirit of the invention as set out in the claims is to leave.

- 66 - / claims

309881/0471

Claims (1)

Claims Electronic musical instrument with a keypad and switches associated with this keypad for deriving a Control voltage according to the tones of the keypad, with a multivibrator oscillator and a frequency divider, characterized in that the size of the control voltage is a function of only the highest note of the pressed keys of the nomenclature and the tension is the Multivibrator oscillator for generating a sound signal of complex waveform stimulates, the frequency of which is the highest corresponds to struck tone, and that the frequency divider temporarily changes the generated frequencies in accordance with the tone signals reduced to a value and for a selected duration to match the sound of a brass instrument the highest note played, and that the tone signals pass through various sound filters and amplified to make them audible. 2. Electronic musical instrument according to claim 1, characterized in that that trumpets, trombones or saxophones can be simulated as brass instruments, the tones of the simulated instruments being expandable as desired. 3. Electronic musical instrument according to claim 1, characterized in that that the multivibrator oscillator is supplied with the control voltage, the value of which is only a function the highest note played in the nomenclature iat, with the multivibrator oscillator having a frequency control point of normally steady voltage (Vv), a normally off transistor switch, one Additional voltage source of the same polarity as V, 309881/0471 Coupling capacitor that connects the control point to ground via the additional voltage, another transistor switch and means responsive to the selective actuation of the keys to power the auxiliary power source through the Connect transistor switch to ground, using the multivibrator oscillator frequency is a function of the value of the voltage of V. k. Electronic musical instrument according to claim 3 »characterized in that the coupling capacitor is connected with one connection to the frequency control point and with the other connection to the additional voltage source, the additional voltage source being connectable via the transistor switch and the value of this additional voltage selectively assuming various values as a function of V. can. 5. Electronic musical instrument according to claim 1, characterized in that that preselection sound filter, flute filter and others Filters are provided which are used to brighten the frequency spectrum of the audio signals during the complex waveform serve a predetermined time in response to the operation of a key. 6. Electronic musical instrument according to claim 5t, characterized in that that to brighten the frequency spectrum an expression pedal for selective modification of the dynamic level of the audible sound signals is present, the brightening of the frequency spectrum of said sound signal of complex waveform is a direct function of the dynamic level of the audible radiated sound. 7. Electronic musical instrument according to claim 1, characterized through tone color filters to modify the right-o-o-square Sound signals, with a device for generating?.! - There is a vibrato modulation frequency around the audio signal 309881/047 - to ~ and that the amount and the speed of the vibrato modulation to simulate a brass instrument are random is variable. 8. Electronic musical instrument according to claim 7t, characterized in that the device for generating the vibrato modulation comprises a capacitor which successively can be charged and discharged linearly, and that there is also a generator with random interference signals, the level of these interference signals with respect to the level of the The voltage of the capacitor can be controlled during the charging process or during the discharging process, the duration of the charging process and the peak amplitude of the charge on the capacitor · can be varied at random and the resulting voltage is used to generate the vibrato modulation effect. 9 · Electronic musical instrument according to claim 7 »characterized in that the tone color filter has a temporary The plating effect of the frequency of the voltage controlled oscillator in response to the actuation of one of the Create buttons. 10. Electronic musical instrument according to claim 9, characterized characterized in that the duration of the flatting effect is a The function of the value of the control voltage is used to control the frequency of the voltage-controlled audio signal oscillator. 11. Electronic musical instrument according to Claim I _9, characterized in that the tone color filters are voltage-controlled low-pass filters which control the harmonic components of the tone signals in accordance with the desired sound of the brass instrument. - 69 - 309881/04 7 1 12. Electronic musical instrument according to claim 1, characterized by a sample and hold circuit to generate the portamento style of playing by varying the holding voltage, selectively on * pressing one of the keys while another key remains pressed and another Button is released. In that it comprises a "number of buttons 13 · electronic musical instrument according to claim 1, characterized in that a voltage-controlled sound signal _Oezillator? Of a complex frequency spectrum generates _s a means for deriving a control voltage ± n response to the operation of a plurality of keys sur control the Prequens ύ.βε oscillator, said means © erzeug ine voltage *. whose value is a function only of the high-sia tone of the plurality of simultaneously depressed keys, said control voltage for controlling the frequency of the oscillator · .; only after the lapse of a time before ., at least xo milliseconds after actuation orlör c'sr release of the large number of buttons takes place, causing errors if the simultaneity of actuation · or a & r release eil © * · button of the group of actuated pushbuttons keix ^e Etoreffekt® avf the voltage-controlled: true £; ei.nar succession of different ^ re
pass on genes, IV, Electronic MrsifcirsTr / ;; *. !! :: ". ', characterized by eiuen > i * 3.vv> uh && \ - 'ϊ-l ^ a. . • - • iuiliire-i · r ^ it input circuit and. elne-ü: ■ .i: ^t ; gB:, r _i : cri :,. ■ ^ i? :: - ■. Ki.-sLmcl switches sine, wöbe '". *» - .: ο cn er., Αεκ i <· .--: .ί ■:; "·. ί cni:, .. uu'Sa λ-a gate angeovdne ', -i ■' ■ ~ .ία; ^! - «:. ce V rj.'ivh ·: ·:;:.; " sex · E circuit eiviss soap; ·; · Jf ;;: rv r ^ .kcr · .- .-. ^. ■ ...- i. ''' u ', sj κ,. u'i _: on-- off state of G:,; ii! r; ü-- ' Io .rr t ^: ■■ ■: ^ i.:. (■ - r ^ iVcri to "die vorDef, ti ta -, -. v, c,. Vj.ri:; t."it; t.. "^; : ..- r 1 "· .-; · '' tit-r i" trc11voltage Electronic musical instrument according to claim 1h , characterized in that the gate circuit is normally blocked and the gate becomes permeable when one or more of the keys are actuated and is again blocked when all keys are released, and that the gate circuit is also blocked when not all of them are released Group buttons. 16. Electronic musical instrument according to claim 1, characterized through a variety of buttons, a voltage-controlled sound signal oscillator, which has a complex frequency spectrum generated, means for deriving a control voltage in response to actuation of one or a group of buttons to control the frequency of the oscillator, the control voltage being a function only of the tone of the The highest pressed key of several simultaneously pressed keys is a delay circuit that the Control voltage to control the frequency of the oscillator only after a certain time of at least has passed Io milliseconds after pressing or releasing one or a group of buttons, causing errors in the simultaneity of the actuation or release of all keys of a group of keys are not on the voltage-controlled Oscillator during a sequence of various frequency-controlled voltages affects the device for ATegen the control voltage has a sample and hold circuit that cascades between the device is arranged to derive the control voltage and the voltage-controlled oscillator, the Sample and hold circuit has an input and an output, with inputs and outputs between these normally blocked gates are arranged, a © Device for generating time-delayed control pulses to transmit the state of the gate circuit in response to the actuation of one or more of them alone 309881/047 1 of the buttons and in response to the release of one or more of the buttons, the time delay of the control pulses is roughly in the order of 20 milliseconds after pressing or releasing the buttons, a frequency divider chain, which is connected to the output of the voltage-controlled oscillator for generating audio signals of various lengths, control devices for controlling the tone color and the envelope of at least certain of the tone signals as a function of the control voltage, with preset tone filters and / or to the frequency divider chain Flute filters are connected, the outputs of which are routed to a preamplifier and then to a master amplifier are, an expression pedal for selectively generating a further control voltage to control the gain of the Amplifier and to influence the tone colors as a function of depressing the expression pedal, a state selector for selecting the respective play mode, to which a vibrato modulation oscillator is connected, which in turn can be influenced by a noise generator. 309881/0471