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| Number | Title | Issue Date |
| 4980920 | Negative impedance driving apparatus having temperature compensation circuit A driving apparatus for negative-impedance driving a speaker as a load, comprises a detection element, a positive feedback circuit, a temperature compensation circuit, a sensor element, a control circuit, and an input f characteristic control circuit. The... | 12/25/1990 |
| 4969195 | Impedance compensation circuit in a speaker driving system In an impedance compensation circuit of a speaker driving system, an ideal impedance state of the speaker can be equivalently formed by the equivalent impedance means, and is compared with an impedance state of an actual speaker. On the basis of the compa... | 11/06/1990 |
| 4944015 | Audio compression circuit for television audio signals An audio compression circuit for limiting an audio television signal in a linear fashion at a pre-established maximum level is disclosed. The circuit includes a series resistance circuit for establishing a predetermined resistance on an amplifier to estab... | 07/24/1990 |
| 4908868 | Phase polarity test instrument and method The relative phase polarity between two acoustic or electric signals is determined easily, quickly and conclusively with a hand-held instrument providing immediate visual polarity indication. Built-in dual-channel amplification enables a pair of microphon... | 03/13/1990 |
| 4908870 | Motional load driver A motional load driver for driving a motional load having a motional impedance includes an amplifying section for amplifying an input signal and supplying the input signal to a motional load such as a loudspeaker, a current detecting section for generatin... | 03/13/1990 |
| 4887298 | Electronic circuit for sensing disconnect or failure of a power output sense line in an audio power system A detection circuit for detecting the failure or disconnection of a sense line in an audio processing system that provides an audio output signal that drives the input of an audio power amplifier. The audio power amplifier drives a speaker. The audio proc... | 12/12/1989 |
| 4864624 | Piezoelectric loudspeaker with thermal protection A preferred embodiment of a thermal protection circuit for a piezoelectric speaker includes a PTC resistor connected in series with the speaker and a second PTC nonlinear resistive element, such as a light bulb, connected in parallel with the resistor. Th... | 09/05/1989 |
| 4860361 | Acoustic-device cooling unit A cooling unit for cooling an acoustic device installed on the vehicle by using a cooling fan comprises a cooling fan drive circuit which outputs a DC voltage proportional to the input or output signal level of the acoustic device to control the speed of ... | 08/22/1989 |
| 4852176 | Continuous differential signal equalizer A method of processing an audio signal to provide automatic continuous correction for the variable efficiency of the loudspeaker system under varying amplitude and frequency conditions. The signal is continuously sampled for frequency and amplitude compon... | 07/25/1989 |
| 4821328 | Sound reproducing system with Hall effect motional feedback A sound reproducing system with motional feedback utilizes a Hall generator, mechanically driven by the sound generating member of the system and disposed in an inhomogenous magnetic field, as a source of the feedback signal. It is a feature of the presen... | 04/11/1989 |
| 4752959 | Wiring state detecting device for vehicle A wiring state detecting device for vehicle has an operation control device for supplying power to apparatuses mounted on a vehicle, and operating the apparatuses, a battery mounted on the vehicle, a power supply line for connecting the operation control ... | 06/21/1988 |
| 4741040 | Bass-reflex loudspeaker system A bass-reflex loudspeaker system in which, by the addition of a corrective network (7) to an arrangement of a transducer (1) accommodated in a bass-reflex enclosure (2), which transducer is dimensioned such that it cannot be bass-reflexed by means of the ... | 04/26/1988 |
| 4712247 | Electro-acoustic system having a variable reflection/absorption characteristic An electro-acoustic arrangement comprises an amplifier (4) having a first input terminal (5), a second input terminal (5'), a first output terminal (3), a second output terminal (3'), and a series arrangement of a first impedance (1) and an electro-acoust... | 12/08/1987 |
| 4694498 | Automatic sound field correcting system An automatic sound field correcting system with graphic equalizer means to be provided in an audio signal supply line. A test signal such as a pink noise is radiated in the listening space and detected at a predetermined listening point to determine the d... | 09/15/1987 |
| 4607382 | Electroacoustic transducer unit with reduced resonant frequency and mechanical spring with negative spring stiffness, preferably used in such a transducer unit An electroacoustic transducer unit comprises an electroacoustic transducer with a diaphragm (1), a magnet system (2) with an air gap (3), and a voice-coil former (4) with a voice coil (5) arranged in the air gap (3) of the magnet system. The transducer un... | 08/19/1986 |
| 4592088 | Speaker apparatus A speaker apparatus using the so-called motional feedback (MFB) technique in which the sound wave from a speaker (14) is detected by a microphone (10) and the output of the microphone (10) is fed back to a power amplifier (5) for driving the speaker throu... | 05/27/1986 |
| 4583245 | Speaker system protection circuit A circuit and method for protecting speakers and speaker systems from damage due to overload conditions. A crossover circuit splits a broad band input signal into output signals of selected frequency ranges, for driving speakers of corresponding frequency... | 04/15/1986 |
| 4575587 | Signal wrap for transducer fault isolation A signal wrap for transducer fault isolation for use in a telephone system providing remote isolation and identification of malfunctions in end-user telephone equipment such as a handset microphone and handset receiver (earpiece speaker) with an associate... | 03/11/1986 |
| 4573189 | Loudspeaker with high frequency motional feedback A moving-coil loudspeaker system incorporating motional feedback operable at high frequencies, i.e. above about 1000 Hz. The feedback signal is developed by a tiny piezo-electric accelerometer mounted together with a charge amplifier directly on the louds... | 02/25/1986 |
| 4554533 | Method of and apparatus for the testing of warning systems The operational status of a remotely controlled electronic siren is periodically tested, from a command post, without producing audible sound. The test procedure includes energizing the voice coils of the siren loudspeakers with a signal outside of the au... | 11/19/1985 |
| 4450322 | Adjustable speaker system and method of adjustment A speaker assembly and its method of operation are described wherein a plurality of drivers are spatially adjustable relative to each other and to a selected critical listening point in order to establish maximum sound coherency for the system. Means for ... | 05/22/1984 |
| 4406921 | Apparatus for improving linearity of electromechanical transducers An improved circuit for a transducer or loud-speaker as used in the measurement of acoustic quantities such as in impedance audiometers for providing accurate linear read outs.... | 09/27/1983 |
| 4315102 | Speaker cross-over networks The invention comprises improved electroacoustic audio speaker cross-over networks. The improvements comprise both the addition of various passive elements and a novel inductively coupled circuit configuration. The improvements are applied to low pass and... | 02/09/1982 |
| 4284860 | Time doman measurement of moving coil loudspeaker driver parameters A novel method for the measurement of the Thiele-Small small-signal parameters of a moving-coil electromagnetic transducer driver is disclosed. The technique is based on a time domain analysis of the transient response of a loudspeaker voice coil circuit ... | 08/18/1981 |
| 4268719 | Loudspeaker arrangements The invention relates to a loudspeaker housing having a front wall and a back wall and at least two similar electroacoustic transducers. Objects of the invention are to create a loudspeaker having a limited or finite housing but which makes possible a sou... | 05/19/1981 |
| 4209672 | Method and apparatus for measuring characteristics of a loudspeaker A loudspeaker and a microphone are arranged in a normal room, the loudspeaker being supplied with an impulse signal. A direct response sound from the loudspeaker and reflected sounds from wall surfaces in three directions of the normal room are converted ... | 06/24/1980 |
| 4207430 | Optical motional feedback An electrodynamic loudspeaker which comprises a diaphragm which cooperates with a magnet system by means of a moving coil which is connected to said diaphragm and an optical measuring system which comprises two elements--a light source and a detector. At ... | 06/10/1980 |
| 4176251 | Modular switching system A modular switching system including a plurality of switch modules connected in cascade. Each module includes a portion of a signal bus, terminals for connection of an external device, switch means for connecting the external device to the signal bus and ... | 11/27/1979 |
| 4152555 | Artificial ear for telephonometric measurements A device to be used in phonometric measurements on telephone equipment, simulating a human ear, has a generally disk-shaped body with an annular ridge encompassing a frustoconical central recess serving as a wide-open entrance cavity. The body has several... | 05/01/1979 |
| 4124786 | Speaker comparator devices and methods of making and using the same The present invention relates to a passive speaker comparator which allows performance comparison of various speakers utilizing the same program source at the same listening volume level in an audio system providing an audio source and various preamplifyi... | 11/07/1978 |
| 4110571 | Test unit for stereophonic speaker systems A test unit determines the existence of open or short circuits within the speakers and speaker wire harness of a stereophonic front and rear speaker system in a vehicle. The test unit, having a buzzer incorporated therein, is directly electrically attache... | 08/29/1978 |
| 4100380 | Supervisory circuit for monitoring speaker coils In a system with a plurality of loud speaker enclosures, a supervisory system is provided to monitor the speaker coils. Each enclosure has a relay, and the relay winding is series-coupled with the speaker coil, to maintain the relay contact set closed whe... | 07/11/1978 |
| 3997724 | Loudspeaker drive mechanism monitoring assembly A loudspeaker drive mechanism monitoring assembly includes a detection coil for detecting the operative state of a loudspeaker drive mechanism. The loudspeaker drive mechanism includes a permanent magnet assembly defining an air gap having a flux field th... | 12/14/1976 |
| 3989908 | Speaker supervision in a public address system Apparatus and technique for supervising a public address system such that any faults on the lines connected to speakers in the system or any faults within the speaker structures can be detected and suitable corrective action can be taken. To accomplish th... | 11/02/1976 |
