Abstract: A sound field switcher inputs an output sound field signal from a sound field producer. The inputted sound field signal is delayed sequentially by plural delayers, after which they are multiplied by coefficients by plural multipliers, and the multiplied results are all added by an adder. Coefficients stored in an area of a memory indicated by a coefficient counter are read out and set to the plural multipliers. The sound field switcher carries out control of the timing for switching the sound field signal produced by the sound field producer and the timing for the coefficient counter to commence counting. Assuming the time required for switching the sound field to be N sampling periods, in case of carrying out a sound field switching from a sound field A to a sound field B, a sound field switching controller issues an order to the coefficient counter so as to count up one by one from 0 to N, and on each count the coefficients stored in an area of the coefficient memory is set to the multipliers.

Abstract: An audio signal data processing system comprises an input device sequentially supplying incoming audio signal data, a data memory control device writing and reading-out the audio signal data into and from a data memory, a delay memory control device sequentially reading-out the audio signal data from the data memory and storing the data into a delay memory and sequentially reading-out the audio signal data from the delay memory and writing the data into the data memory, an arithmetic device multiplying predetermined coefficient data by the audio signal data having been read-out by the delay memory control device and written into the data memory and summing up results of the multiplication.

Abstract: A sound field control device is capable of producing a sound field effect tone which has a tonal effect providing a listener with a feeling of presence and includes a sound field effect tone generation circuit for generating a sound field effect tone on the basis of sound field information supplied from a source. The sound field effect tone is sounded simultaneously with reproduction of the source signal and a reproduced sound field produced on the basis of the source signal is controlled by this sound field effect tone. In one aspect of the invention, the sound field effect tone generation circuit includes a convolution operation circuit which subjects a signal derived from left and right signals from the source signal to convolution operation with sound field data derived on the basis of the sound field information from the source signal.

Abstract: A reverberation imparting device for electro-acoustically enhancing reverberation in acoustic space comprises a microphone disposed in the acoustic space, a loudspeaker disposed in the acoustic space for diffusing the sound picked up by the microphone, and feedback means comprising a signal processing circuit for electrically processing an electric signal corresponding to the sound picked up by the microphone, an output of the signal processing circuit being supplied to the loudspeaker. The microphone, feedback means and loudspeaker form a feedback loop. The signal processing circuit comprises a circuit for subjecting impulse responses of finite length to a convolution operation. Time axis of reflected sounds is extended and extension of reverberation time thereby is realized without depending upon loop gain. Density of reflected sounds is increased by subjecting impulse responses of finite length to a convolution operation whereby separation of reflected sounds is prevented.

Abstract: A portable musical instrument and associated therewith a radio frequency transmitter for broadcasting to a remote receiver and audio amplifier the sounds generated by the instrument. The user-operated controls vary the sound level sent by the transmitter, vary the mixing of sound levels from pickup groups such as neck and bridge groups of an electrical guitar, and provide control signals for controlling a sound processing unit such as a reverberator associated with the audio power amplifier system. The immediate status of the gain and fader settings is relayed as an ultrasonic modulation on the portable transmitter to actuate unique display conditions in a delay element actuated from the fixed receiver to provide to the user an indication of the status of his settings. Low battery conditions in the transmitter battery unit cause unique signal conditions to be sent to the receiver, resulting in a readily visible warning display configuration. The currently selected mode, e.g.

Abstract: In a musical tone signal generating apparatus, first sampling data and second sampling data are multiplied together by a convolution operation, wherein first sampling data indicates instantaneous amplitude values of a musical tone waveform generated from a keyboard, for example. The second sampling data is obtained from an impulse response waveform signal indicative of a reverberation characteristic of room or an acoustic characteristic of amplifier or musical instrument such as a guitar or a piano. Or, the second sampling data can be obtained from a waveform signal indicative of animal sound, natural sound or the like. Then, the multiplication result of first and second sampling data is combined together into the musical tone waveform data, whereby a musical tone signal corresponding to this musical tone waveform data is generated.

Abstract: A tone signal applied from outside is sampled by a tone sampling device and the sampled waveshape data is written into a memory. During this writing operation and in parallel with the writing operation, a zero crossing point of the waveshape in terms of the sample data of the tone signal is detected. A final address detection circuit stores, each time a zero cross has been detected, a write address of the waveshape sample data with respect to the memory. Address data which is stored in the final address detection circuit when the writing of the waveshape sample data in the memory has been completed is detected as a final address of the sampled waveshape data. The waveshape data in the memory is read out either in a forward direction in a reverse direction using this final address as a start point or an end point and a tone signal corresponding to the sampled waveshape data is sounded. Such address constituting the start point or end point of reading, i.e.

Abstract: An electronic tone generator includes a signal-generating oscillator, a memory circuit for storing tone and time data for each note to be produced and two note producing circuits, each including a first programmable counter electrically connected to the memory circuit and the signal-generating oscillator and for variably dividing signals outputted by the signal-generating oscillator in order to sequentially produce notes of predetermined frequencies and durations according to the data read from the memory circuit. The note outputs of the two note producing circuits are interrelated to produce a music effect.

Abstract: The practice of this invention enables a musician to augment a main "lead voice" performance by extemporaneously deriving from particularly selected notes of the main performance a separate synthesized accompaniment in which particularly selected notes may be controllably time-extended (e.g. sustained) singly or in a group, in effect "detached" from the lead voice. The first of a pair of low profile footswitches enables/cancels accompaniment triggering; the second enables/cancels accompaniment time-extension. Switch logic is implemented such that the first switch can never override the second switch to cancel time-extension; thus a musician operating the switches interactively, typically one with each foot, is enabled, through strategic timing relative to the lead notes, to trigger accompaniment notes from particularly selected lead notes, to controllably time-extend particularly selected accompaniment notes, and to accumulate groups of such time-extended accompaniment notes.

Abstract: An electronic musical instrument for causing a tone generator to generate a musical tone corresponding to a musical performance while controlling an envelope by operation of a pedal. An operated-amount signal generator is provided for detecting an operated amount of the pedal and for generating an operated-amount signal, and an effect adding unit is provided for controlling parameters for effect addition so as to add an effect to a musical tone generated from the musical tone generator in accordance with the operated-amount signal from the operated-amount signal generator. The operated-amount signal from the operated-amount signal generator is changed by the operation of the pedal, and an effect-adding parameter in the effect adding unit is changed accordingly, to thereby add an effect to the generated musical tone.

Abstract: A reverberation imparting device comprises a delay memory storing input signal data at a predetermined sampling period and producing a delay signal corresponding to time interval between writing of the input signal data and reading thereof, a plurality of address each adding delay signals read out from the delay memory, and an output section for delivering out an output of each of the adders as a reverberation signal. The delay signals are divided into groups and processed on the group basis. This simplifies the construction of the device and facilitates setting and changing of the reverberation characteristics.

Abstract: A method and apparatus for processing audio signals utilizing reverberation in combination with directional cues to capture both the temporal and spatial dimensions of a three-dimensional natural reverberant environment. Reverberant streams are generated and directionalized to simulate a selected model environment utilizing pinna cues and other directional cues to simulate reflected sound from various spatial regions of the model environment.

Abstract: In a reverberation tone generating apparatus a digital memory device is used as a delay element. Amplitude data obtained by sampling an input musical tone at a predetermined period are sequentially stored in the digital memory device. The readout of the amplitude data stored before a desired delay time is equal to the readout of the data regarding the input musical tone delayed the desired delay time. By imparting the desired reverberation characteristics to the delayed amplitude data, reverberation tone of the input musical tone is produced. In a modified embodiment, an input musical tone is divided into a plurality of frequency bands and different reverberation characteristics are added to the divided input musical tones respectively.

Abstract: A method and apparatus for increasing perceived reverberant field diffusion in systems providing electro-acoustic reverberant enhancement to rooms or spaces includes independent modulation of the phase of each individual release loudspeaker channel in response to an effectively random infrasonic modulating signal, independently developed for each channel. Each loudspeaker release channel is fed from an electronic reverberator. The release channel signals are timed to emerge into the room at different times. The amplitude of each channel may also be modulated. In one embodiment, independent devices for generating infrasonic modulating signals have the characteristics of at least two frequencies being present within the range of about five seconds/cycle to about five cycles/second, for supplying control signals for achieving modulation in phase and amplitude.

Abstract: A reverberation imparting device comprises a prememory storing an input signal, a level detection circuit responsive to data stored in the prememory for detecting presence or absence of the input signal, a data memory storing a delayed input signal delivered out of the prememory, a fixed type convolution operation circuit for producing a reverberation signal with respect to the data stored in the prememory by using an initial portion of parameters of a reflected sound, an adaptive type convolution operation circuit for producing a reverberation signal with respect to data stored in the data memory by using a plurality of parameters of more significant bits among the remaining portion of the parameters of the reflected sound, and an adder for adding outputs of the fixed type and adaptive type convolution circuits and delivering out the result of addition as a reverberation signal.

Abstract: A preamplifier adapted to receive audio frequency electrical signals generated by a musical instrument for providing controlled output signals therefrom having selected distortion and harmonic signal content is shown wherein the preamplifier includes an amplifier for amplifying audio frequency electrical signals generated by the musical instrument, a first electrical signal processing channel operatively coupled to the amplifier for receiving the amplified audio frequency electrical signals and for producing in response thereto a first controlled output signal wherein the first electrical signal processing channel includes a plurality of selectively interconnectable signal processing circuits at least one of which is capable of at least one of selectively amplifying, distorting and adding preselected harmonic content to the first controlled output signal, a second electrical processing channel operatively coupled to the amplifier for receiving the amplified audio electrical signals and for producing response

Abstract: An audio reverberator system having a piezoelectric transducer filter circuit for outputting selected audio vibrational frequencies having selected amplitudes responsive to inputs from an amplifier. The audio reverberator system includes a piezoelectric transducer having an intrinsic capacitance coupled to an additional circuit element to form a low-pass type filter circuit for attenuating higher frequency inputs to the transducer to provide a desired flat frequency response for an audio vibrational output to vibrate a reverberation plate for production of a desired audio output.

Abstract: A device for forming a stereophonic sound field in a simulated fashion constructed in the form of a monophonic-to-stereophonic conversion circuit in which a monophonic signal is applied to cascade-connected twin-T circuits having different null point frequencies and an output signal of the twin-T circuits is provided as one stereophonic channel signal whereas an output obtained by substracting the one stereophonic channel signal from the monophonic signal is provided as the other stereophonic channel signal. A low-frequency signal attenuating resistor and a high-frequency signal attenuating filter are provided on the output side of the twin-T circuits to equalize peak values in frequency characteristics of the output signal of the twin-T circuits and thus obtained signal is amplified to be equalized in peak level to the monophonic signal and thereafter is applied to a subtractor together with the monophonic signal.

Abstract: An acoustic system comprising an input transducer connected by a first severable path to the input of reverberation means for producing reverberation of the required decay rate of the sound field perceived by the microphone, an output transducer connected by a second severable path to the output of the reverberation means, and detection means which analyzes the status of the sound field or any discrete frequency domain within the sound field and which operates both to connect the input transducer over the first path to the reverberation means and to secure connection of the reverberation means to the output transducer over the second path when the status of the sound field or the discrete frequency domain is analyzed by the detection means as either rising or constant and, conversely, both to sever the connection of the input transducer over the first path to the reverberation means and to connect the reverberation means to the output transducer over the second path when the status of the sound field or the d

Abstract: An input musical tone signal is amplified by a first VCA and then supplied to second and third VCAs. The second and third VCAs are controlled by sine-wave signals which have a 180.degree.-phase difference. Musical tone signals, which have been so controlled that a pan-pot may move right and left, are supplied to right and left loudspeakers. The first VCA is controlled by a sine-wave signal whose phase is different by 90.degree. from the phases of the signals supplied to the second and third VCAs. The volume of a composite musical tone made up of the tones generated by the loudspeakers is thereby controlled, thus also moving the pan-pot to the front and rearward.

Abstract: Tone signals from plural keyboard systems are supplied to an effect imparting circuit via a distribution circuit. The effect imparting circuit comprises plural effect imparting channels and the device can impart a tone effect independently to a tone signal provided to each of the effect imparting channels. The distribution circuit distributes tone signals from the respective keyboard systems to any one or more of the effect imparting channels. An effect selection device is provided for selecting tone effects for the respective keyboard systems and an effect assignment device is also provided for assigning the effects selected in the respective keyboard systems to any of the effect imparting channels according to the selection by this effect selection device. The distribution circuit delivers the respective tone signals to the proper effect imparting channels respectively as controlled by the effect selection and the effect assignment.

Abstract: An apparatus for generating a pseudo-stereo signal comprises at least two signal channels (3, 4), each signal channel (3) comprising a delay line (7) of which an output is fed back to the input (via g.sub.2). The delay lines (7, 8) have tappings (12, 13 and 14, 15 respectively). The tappings (12, 14 and 13, 15 respectively) are coupled to inputs of two signal-combination units (18 and 19, respectively) whose outputs (20, 21) are coupled to two output terminals (22, 23) to supply the pseudo-stereo signal (FIG. 1).

Abstract: In an electronic musical instrument, a reverberation tone most suitable for a selected tone color is applied to a musical tone with the selected tone color. In a modification, the electronic musical instrument is provided with a plurality of keyboards and to musical tones to be produced corresponding to the keyboards reverberation tones are applied independently. In another modification, one of the reverberation tones has a reverberation characteristic different from the other reverberation tone.

Abstract: A reverberator comprises a tapped delay line (2, 3, 4, 5, 10) connected to an analog audio signal source (1) for deriving therefrom at least one pair of output signals which are respectively delayed by first and second different values with respect to the source signal, the ratio of the first to second values being an irrational number. A recirculating delay line (6, 7, 11, 12) is connected to the output of the tapped delay line having a delay element (63, 73, 113, 123) for introducing an additional delay to the output signals of the tapped delay line and a resistive recirculating path (65, 75, 115, 125) for recirculating the additionally delayed signals through the delay element. The output of the recirculating delay line is combined with the source signal to derive a reverberating audio signal.

Abstract: A signal delaying device delays a digital signal corresponding to an audio signal. Input signal data is sequentially written into a memory with regularity and data at an address which was written a predetermined period of time before writing of the present data is read out thereby effecting the delay of the signal. In using, the memory is divided into a number corresponding to the number of channels of input signals, that is, the address designation and the manner of control of writing and reading of the memory is changed in accordance with the number of channels of input signals. The delay time of the signal is set by properly setting the predetermined period of time.

Abstract: The reverberation tone generating apparatus is constituted by a combination of apparatus which generates a reverberation tone having irregular delay time and level and apparatus provided with a feedback loop for an output delayed signal and produces a reverberation tone having regular delay time and level. The combination makes it possible to produce a reverberation tone rich in naturality with circuits of a small size and economical construction.

Abstract: A modulation effect device for use in an electronic musical instrument which utilizes, as a digital modulation circuit, a digital memory device for storing digitized musical tone signals. The digital memory device is accessed by modulation coefficient generating means which supplies a modulated address information to the digital memory device to read out from the memory device a musical tone signal modulated in accordance with the modulated address.

Abstract: A stereo or two channel electronic reverberation device is disclosed comprising an analog delay device which receives audio signals and provides delayed output signals at a plurality of outputs, with the time delay period of each output being different from the delay period of other outputs. Two summing devices each receive inputs from different combinations of the analog delay device outputs to provide two different signals having different reverb components. An additional output delay device is also provided which receives the last output from the analog delay device, delays this signal a time period substantially greater than the time period between any two adjacent analog delay device outputs, and provides this substantially greater delayed signal to only one of said summing devices.

Abstract: A method of determining the physical location of undesired resonance zones induced by acoustic feedback in a spring reverberation unit and damping the vibration of these resonance zones. The improved spring reverberation unit with damping material located at the resonance points of the unit produces a reverberated audio signal which is substantially free from the screeching and howling caused by acoustic feedback.

Abstract: In a device for producing artificial reverberation by means of a one-dimensional waveguide, a one-dimensional waveguide is utilized, which is obtained using digital circuits which contain at least two line sections of different length, each line section consisting of two parallel digital delay arrangements, one for each direction of propagation. At least one three-gate adapter of the digital wave filter type is arranged between two line sections lying side by side, each of two gates of the three-gate adapter being connected with one of the two mutually facing ends of these two line sections, and the dependent gate of the three-gate adapter being terminated with a frequency-dependent absorber of the digital type. By using a digital one-dimensional waveguide with discontinuities and absorbers, it is possible to reverberate a signal diffusely and with a programmable frequency response of the reverberation time without the disadvantage of a reduced sound to noise ratio due to limit cycles.

Abstract: A sound effect imparting device for an electronic musical instrument is capable of imparting a plurality of desired sound effect such as vibrato and reverberation effects to a digital musical tone generated from the electronic musical instrument. The device comprises a digital arithmetic operation unit constructed with a combination of adders, multipliers, delay circuits, etc., a control unit, a parameter memory and a read-out unit.By control data and parameter data which are respectively read out from the control unit and the parameter memory by means of the read-out unit, switching of the operation mode of the digital arithmetic operation unit is controlled in a time-sharing manner, whereby a plurality of sound effects are imparted to a musical tone through digital arithmetic operations.

Abstract: Multiplexed serial data from the keyboard of a musical instrument, such as an electronic organ, is delayed in a shift register to cause generation of musical tones related to the keyswitches closed on the keyboard and combined with the non-delayed serial data for producing mutation voices or chords.

Abstract: A reverberation apparatus is formed of bucket brigade delay circuit having its input connected to a signal source. An output of the delay circuit is connected through a spring-type reverberator to one of two inputs of an adder, the other being connected to the signal input. The output of the adder provides the desired reverberation sound. In one embodiment, two series connected delay circuits and reverberators are provided, each connecting to a respective input of a respective adder. The other inputs of each adder are connected to the signal source and the outputs of the respective adders provide separate stereophonic-like left and right channel outputs.

Abstract: An electronic organ has a digital control circuit with a sampling circuit (3) which generates key identification signals (B) in the form of pulse series wherein the pulses denote the actuated keys (2) of the keyboard (1). Such pulses cause a tone selector or evaluating circuit (12) to transmit tone signals to a voicer circuit (15). A shift register (16, 116 or 216) is provided to delay the key identification signals so that the tone signals which the voicer circuit receives do not correspond to those normally expected on actuation of certain keys. The non-delayed key signal can be superimposed upon the delayed signal or signals (V1, V2) in a suitable summing circuit (17) to thus achieve transpositions, interval couplings and other tonal effects.

Abstract: Tone amplitudes of signals which are generated in an electronic organ are converted into digital values and such values are cyclically memorized by a RAM storage at locations which are selected in accordance with a first function. The locations in the storage are then scanned in accordance with one or more second functions which differ from the first function in dependency on time, the thus ascertained or read-out digital values are thereupon converted into analog values, and the analog values are consolidated into processed tone signals. The second functions are or can be derived from the first function.

Abstract: An electronic reverberation system for use in an electronic musical instrument comprises a random access memory wherein two or more time delay channels are defined by address allocation in a controller circuit. An input analog signal is converted to digital signals by an analog-to-digital converter and the digital signals are processed by the controller into the time delay channels. The channels defined in the random access memory are of differing lengths which can be changed by switch settings. The controller sequentially retrieves stored digital data words from the random access memory channels in seriatum and couples each data word to a digital-to-analog converter. The analog output signal from the digital-to-analog converter is delayed in time by varying amounts due to the length of the channels in the random access memory. A portion of the delayed analog output signal contained in each channel is mixed with the input analog signal to produce a combined signal.

Abstract: An artificial reverberation apparatus for audio frequency signals, comprises a first delay device preceded by an adder. A feedback circuit couples the output of the delay device to an input of the adder to give a loop signal gain of less than unity. The adder is preceded by a second delay device with the same delay time as said first-mentioned delay device. The signal to be delayed is applied to the input of said second delay device and also to the adder via a transmission path. The ratio of the signal gain of the transmission path to the signal gain of said second delay device is equal to but of opposite sign to said loop signal gain. Preferably the signal gain of the transmission path is equal to but of opposite sign to the signal gain of said feedback circuit. Furthermore, a plurality of apparatuses can be connected in cascade with the delay devices of the different apparatuses all having different delays.

Abstract: A reverberation effect is produced in a musical tone generator of the type in which waveshape data points are sequentially and repetitively read out of a memory at a rate corresponding to the fundamental pitch of a musical tone. The reverberation effect is obtained by having a second memory storing waveshape points which are read out simultaneous with those from the first memory. The second data set is scaled by the ADSR envelope function and at selected echo time spacings is pointwise added to the data stored in the first memory. The data read out of the first memory is converted to an analog musical signal having a reverberation effect during the attack or release phase of the musical tone.

Abstract: The present invention relates to economically fabricated means for the generation and processing, member selection, and acoustic radiation of pluralities of individual tone currents originating from at least one high frequency source and formed by note-information temporarily transferred through key depression, from permanent electronic memories to temporary memories in small numbers of standard tone units, in precise duplication of properties of pipe organ sound.There is described an electronic transfer organ for duplicating twenty-six known properties of pipe organ sound. The illustrative, inventive instrument employs completely standardized circuitry except for automatically programmable memories for each organ voice, which contain all the information required to form, switch and variously decouple all the notes in that voice.

Abstract: Room acoustics simulation is achieved by digitally defining delay and weighting parameters and generating sampled analog signal responses. In the early portion of a response term an accurate impulse response is provided and subsequently high echo density is simulated using sampled analog signal Schroeder sections. A sampled data analog signal device is used which employs charge transfer devices as programmable delay media, multiplying digital to analog converters to generate weighting of the analog signal and a general purpose microprocessor as a parameter calculator. The early impulse response characteristic is accomplished by providing a time domain finite impulse response (FIR) section in a transversal filter arrangement which directly feeds to an ultimate output and to parallel comb filter sections which in turn input to at least one all pass section of the so-called Schroeder configuration. The charge transfer devices are employed as programmable delays to propagate the analog signals.

Abstract: In an electronic organ including at least two frequency controlled delay circuits controlled by varying frequency output signals from individual voltage controlled oscillators, an analog modulating and intermixing circuit provides an even vibrato effect by controlling the input signal to the voltage controlled oscillators. The amplitude of a vibrato signal which is mixed with a main voltage control signal for a voltage controlled oscillator to provide a vibrato effect is modulated by the primary voltage control signal. The primary voltage control signal is amplified and passed to the control input of a voltage controlled amplifier which receives the vibrato signal. The amplified primary voltage control signal is mixed with the output of the voltage controlled amplifier to generate the control signals for driving the voltage controlled oscillators.

Abstract: An ambience processor receives and combines the left and right channel signals from a stereophonic amplifier. The resulting composite signal is converted to a sequence of digital signals which are stored in a random access memory. The stored digital representation of the composite signal is read out of the random access memory at different times to separate output circuits which drive left channel and right channel ambience loudspeakers. Reverberation effects are obtained by feeding back portions of the separate output signals to the input of the system.

Abstract: An electronic tone or note generator capable of providing improved musical and tone quality and special sound effects by mixing the outputs of a plurality of note-signal-producing circuits is provided. The electronic tone or note generator of the invention is characterized by the use of a primary electronic note circuit for producing a primary note signal which is a portion of a primary melody, and a secondary electronic note circuit for producing a secondary note signal that is musically related to the primary melody. The relationship between signals can be a time lag between the outputs of the two note signal circuits or a small difference in frequency between the signal outputs of the two note circuits. Additionally, each note signal circuit can output alternate notes of a continuing melody such that a note from one circuit may persist while the next note from the second circuit is played.

Abstract: When the frequency of an input sound signal applied to a shifting type echo-machine is close to that of the shift pulse thereof, a false signal appears at the output terminal of the echo-machine, in addition to the other type of noise signal caused by inclusion of the shift pulse component in the output of the same. The present invention is an echo-machine provided with first and second low pass filters, arranged before and after the delay element included in the echo-machine respectively, with a variable cut-off frequency which varies in accordance with the frequency of the shift pulse thereby eliminating such an erroneous signal and the shift pulse component from the output signal of the echo-machine.

Abstract: An echo effect in a polyphonic digital tone synthesizer in which a musical tone is repeated at a controlled repetitive rate but decreasing peak amplitude when a key is depressed. The tone is repeated until the peak amplitude decays to a predetermined level regardless of when the key is released. If the key remains depressed, the peak amplitude decay recycles so that an echo effect will be repeated. The echo effect is obtained on a plurality of overlapping notes that need not be keyed in unison. The echo control includes an echo envelope register which stores a control word for each key that is depressed. The control word includes bits coded to identify the current amplitude of the echo decay envelope. The value of the control word is decremented at a control rate to provide a decaying echo amplitude. An echo delay register stores a control word for each key depressed, the control word being incremented at a controlled rate.

Abstract: An electronic echo apparatus comprising an input amplifier, an output amplifier connected thereto through a transmission channel, a delay device connected in parallel to said channel, and a feedback path connected in parallel to said delay device, characterized in that said feedback path includes a control means, and in that there is connected to the output of the output amplifier a means for measuring the output signal of said output amplifier, comparing said output signal to a predetermined threshold value and, when said output signal reaches said threshold value, supplying a control signal to said control means for terminating the feedback.

Abstract: The present invention is related to devices for annexing an echo resembling natural reverberation in the course of sound recording, in which a line or lines of coil spring with a portion or portions protruded axially at a right angle are spanned between the drive-transducer and the pickup-transducer.

Abstract: An electronic sound generation system wherein an input signal is frequency modulated, and the modulated signal passes through a series of cascaded shift registers. Amplifiers are provided for compensation of insertion loss in each shift register stage, and a frequency modulation detector is utilized to produce the time-delayed output echo signal.

Abstract: An audio system comprising a record player, tape deck, microphones, or other signal source which generates stereo signals supplied to two main speakers for reproduction; the stereo signals are added together to afford an intermediate signal which is subjected to at least two successive equal delays to generate a plurality of delayed signals which are summed with the intermediate signal in predetermined amplitude and phase relation to generate a spatial effect signal that is essentially free of noticeable reverberations or echoes. This spatial effect signal is reproduced by a separate speaker in the same listening space as the main speakers to add ambience and diffuseness to the total sound field. In the preferred construction two delayed signals are employed, delay is effected with the signals in digital form, and the summing ratio for the intermediate, first delayed, and second delayed signals is approximately 1:2:1 with the intermediate signal and the second delayed signal in phase opposition.

Abstract: An audio system which achieves a concert hall reverberation effect from a stereo input signal. From two stereo input signals the audio system produces quadraphonic signals suitable for application to four speakers in the pattern of a quadraphonic sound reproduction system. The system applies the stereo input signals to a front pair of speakers substantially without alteration while reverberation is added to the stereo input signals for application to the rear speakers which realistically reproduces the impression of concert hall acoustics in the sound reaching the listener from all four speakers. The reverberation is provided by a channel signal delay scheme in combination with a channel interconnection network which achieves long reverberation times with a high echo density that eliminates objectionable, discrete echo effects.