Abstract: A midrange loudspeaker for operation in conjunction with low-frequency and high-frequency loudspeaker modules in a theater sound system, having a reduced depth for deployment in limited space. The midrange module is configured with a plurality of drivers and a waveguide unit that provides uniform sound coverage throughout a theater auditorium with substantially seamless crossovers at 250 Hz and 1.5 kHz and with the vertical beam-width held substantially constant by an electrical filter network.

Abstract: The invention is a method of creating an enlarged listening sweet spot for multiloudspeaker audio reproduction. The method employs a plurality of audio drivers displaced generally in a horizontal dimension for a vertically oriented head of a listener, the drivers operating over a plurality of different passbands. Higher frequency drivers are located closer to one another and displaced more towards a center line of the listening space than lower frequency drivers, thereby causing a smaller change in acoustic ear signals for listeners seated away from the designed-for listening position, but without causing increased low frequency signal capacity requirements for phantom images generally outside the array. Specially adapted signal processing accounting for the layout of the various drivers and their associated crossover networks is employed to create desired audio images.

Abstract: A technique for enhancing audio signals generated from compressed digital audio files is described. The technique uses a Bass Maximizer module, a Harmonic Exciter module and a Quasi Stereo module. The Bass Exciter module enhances the intensity, depth and punch of the bass audio content by creating harmonic sequences from low frequency components contained in the original input signal. The Harmonic Exciter module adds to the treble audio content of the original input signal by generating harmonic series from the high frequency components contained in the input signal. The Quasi Stereo Module creates a stereo image of the enhanced input signal by adding and subtracting delayed and filtered versions of the enhanced input signal with itself to create left and right channeled stereo-like outputs. The technique provides a useful tool to regenerate from an audio signal more pleasant and joyful sounds.

Abstract: Apparatus and method for transmitting and reproducing stereophonic audio signals are disclosed. The method comprises splitting first and second channels into two frequency bands, combining the lower frequency band signals of the two channels, and transmitting the combined signals of the two channels or signals representative thereof. The apparatus comprises: a splitter for splitting each of the two channels into two frequency bands, a combiner, for combining the lower frequency band signals of the two channels, and a transmitter for transmitting the combined signals, or signals representative thereof, and the higher frequency band signals of the two channels, or signals representative thereof.

Abstract: A technique is provided for reducing power consumption of an internally powered console in an audio system through frequency based signal routing. A system employing the technique includes a base unit having an interface for receiving a signal representative of acoustic information. The base unit includes a filter system for splitting the signal into low-frequency and high-frequency component signals. The low-frequency signal is routed to a first audio driver for reproduction. The high-frequency signal is routed to a device that includes a second audio driver. By removing the need to reproduce the low-frequency portion of the acoustic information, the power consumption of the device is reduced.

Abstract: The present invention uses multivoice coil drivers in conjunction with the small satellite speakers of multichannel surround sound systems to achieve an overall linear response between 100 Hz to above 15 KHz. The multivoice coil drivers are designed to respond only to frequencies that fall between conventional upper base and lower midrange crossover frequencies which typically extend between 75 Hz and 225 Hz. The invention relies on the characteristics of human hearing which limits the listener's ability to localize the source of sound approximately to the wavelength of the sound being heard. The system may be incorporated in existing front and rear center speakers or separate enclosures to supplement the overall surround sound system.

Abstract: A speaker apparatus having a first half and a second half, each having a rim and being generally paraboloid shaped, or bowl-shaped. A first opening, or window, is positioned near a vertex of the first half. A second opening is positioned near a vertex of the second half, and a grille positioned within the second opening. A mid-range component may be positioned within the first opening. When the apparatus is assembled, the respective rims of the first and second halves engage to form a generally hollow chamber therebetween.

Abstract: A modular audio loudspeaker array system. The system includes a first speaker module, and a second speaker module, constructed and arranged to radiate sound waves responsive to audio signals. Sound waves radiated by the first speaker module and the sound waves radiated by the second speaker module combine to form a radiation pattern. The system further includes a positioning system, for positioning the first bass module relative to the second bass module at a plurality of fixed predetermined distances; an audio signal input terminal electronically for coupling the loudspeaker array to a source of the audio signals for receiving the audio signals; an audio signal processing device, electronically coupling the audio signal input terminal to the first bass module and to the second bass module, for processing the audio signals and transmitting the audio signals to the first speaker module and to the second loudspeaker module.

Abstract: An improved filter system is disclosed including a low pass filter having a response which rolls off towards a crossover frequency and a high pass filter having a complementary response which rolls off towards the crossover frequency. The responses are arranged such that the combined response of the filters is substantially constant in amplitude at least in the region of the crossover frequency. The response of the low pass filter is defined by a low pass complex transfer function having a first numerator and a first denominator. The response of the high pass filter is defined by a high pass complex transfer function having a second numerator and a second denominator. The desired response is obtained when the second denominator is substantially the same as the first denominator and the sum of the first and second numerators has substantially the same squared modulus as the first or second denominator.

Abstract: A speaker apparatus in which the acoustic sound is radiated by flexural oscillations of a diaphragm in the form of a panel having a substantially flat surface. The speaker apparatus includes a panel-shaped diaphragm the outer rim of which can be oscillated substantially freely at least in the direction along the diaphragm thickness and at least one driver unit constituting an oscillation source secured to the diaphragm surface for imparting oscillations to the diaphragm. The diaphragm is set into flexural oscillations by oscillations applied from the driver unit driven on the basis of the playback input signal. By flexurally oscillating the diaphragm to radiate the acoustic sound, optimum frequency response characteristics can be obtained over a wide frequency range from the low to high frequency range. Moreover, the acoustic sound of optinum sound quality may be radiated in a state of minimum sound pressure level fluctuations over a frequency range from the low to high frequency range.

Abstract: In a sound signal playback machine and method thereof, predetermined high frequency components are extracted from sound signals SL to SC of a main channel by high frequency pass filters 21 to 25, and these high frequency components are respectively played back by speakers. At the same time, predetermined low frequency components are extracted from sound signals SL to SC of the main channel by low frequency pass filters. These low frequency components and sound signal SLFE exclusively used for the low frequency band are added to each other, and the thus obtained addition signal is played back by the speaker 66. In this case, the degree of the low frequency pass filters is set higher than the degree of the high frequency pass filters, and the high frequency component is delayed.

Abstract: This invention is directed a sound system that groups a midrange horn with a HF horn to increase the sound pressure levels while minimizing interference problems. The HF horn may be coupled to at least two HF drivers where they sum or merge into a common throat or wave-guide. The midrange horn may be coaxially mounted with the higher frequency horn. The midrange horn may be coupled to at least two midrange drivers. And the midrange drivers may be mounted substantially perpendicular to the HF drivers. This configuration provides for smaller system sizes, than conventional mounting of the HF horn adjacent to the mid frequency horn. By coaxially mounting the midrange and HF horns, the off-axis interference (lobing) through the crossover region both in the horizontal and vertical planes may be minimized. This configuration produces increased sound pressure levels while minimizing acoustic crossover interference problems.

Abstract: A 3D woofer drive circuit achieves miniaturization of a 3D sound system and reduces the cost thereof. The drive circuit includes two resistors arranged to synthesize an L-channel sound signal with an R-channel sound signal. Each end of a capacitor constituting part of a low pass filter and two fixed terminals of a variable resistor are respectively connected between a connection point of the resistors and a ground terminal which is a reference potential. A speaker terminal for the woofer is connected to a movable terminal of the variable resistor through a buffer amplifier.

Abstract: The sound quality regulation apparatus has one attenuation unit and one amplification unit connected in series in this order in the signal line of the apparatus. The output of the attenuation unit is fed to a multiplicity of sound regulators associated with the split frequency bands of the input signal. Each sound regulator includes a switched capacity filter and a selector for selectively supplying the output of the sound regulator to either the attenuation unit, amplification unit, or none of these units. The sound quality regulation apparatus is thus capable of individually attenuating, enhancing, or not changing split frequency bands of the input signal.

Abstract: A member for producing an audible sound in a vehicle including a speaker area having an upper surface and a lower surface, the speaker area being located on the member. A piezo bimorph is attached to the speaker area, the piezo bimorph including a first piezoelectric element attached to the upper surface of the speaker area, and a second piezoelectric element attached to the lower surface of the speaker area. An amplifier in electrical communication with the piezo bimorph, the amplifier supplying an electrical field to the piezo bimorph, the piezo bimorph causing the speaker area and the member to vibrate, causing an audible sound.

Abstract: An audio loudspeaker comprises: an enclosure; at least two driver units mounted within the enclosure; crossover circuitry located inside the enclosure; and a plurality of input terminals located on the exterior of the enclosure. The input terminals include: first pairs of terminals for each of the driver units, each of the first pairs being connected directly to a respective one of the driver units; a second pair of second terminals having a first crossover circuit connected therebetween and normally electrically isolated from the driver units; and a third pair of third terminals having a second crossover circuit connected therebetween and normally electrically isolated from the driver units. Connector elements are used for interconnecting selected ones of said first, second and third terminals, externally of said enclosure, whereby the crossover circuits may be selectively connected in circuit between one or more of the first terminals and one or more of the driver units.

Abstract: A crossover network for partitioning by frequency an electrical audio signal from an amplifier into a plurality of frequency bands, namely a high frequency band, and a low frequency band, and alternatively a high frequency band, a mid-range frequency band, and a low frequency band. The crossover network is implemented in a simplified configuration and in a series configuration which reduces cost and component matching complexity. In one embodiment, the high frequency driver is configured in shunt with an inductor, a resistive component and a capacitive component connected at least partially in shunt with the low frequency driver. This crossover network provides improved performance and simplified crossover network implementation.

Abstract: A deep bass sound booster device comprises a high-pass filter to which an input sound signal is fed and which permits only a frequency component higher than a predetermined frequency to pass through so as to output a resulting signal, a bass booster to which the input sound signal is fed and which amplifies only a frequency component lower than the predetermined frequency and attenuates another frequency component so as to output a resulting signal, a switch to which the signal output from the bass booster is fed at one end and which, when turned on, outputs that signal at another end, and an adder to which the signal output from the high-pass filter is fed and to which the signal output from the switch is fed, the adder adding together those two signals and outputting a resulting signal.

Abstract: A loudspeaker system includes an enclosure supporting first and second loudspeaker driver assemblies and having an internal volume. At least the first loudspeaker driver assembly is constructed and arranged to radiate sound energy into the listening region outside the enclosure over at least the range of audio frequencies above a predetermined first frequency. The second loudspeaker driver assembly is constructed and arranged to radiate sound energy over a first predetermined range of audio frequencies embracing at least a range of audio frequencies below a second frequency above the first frequency. The first loudspeaker driver assembly, the second loudspeaker driver assembly and the enclosure are constructed and arranged to coact to maintain the pressure in the enclosure substantially constant over at least the range of frequencies between the first and second frequencies.

Abstract: An expansion base with a rearward-emitting expansion speaker for emitting low frequency audio and providing surround sound capability. The frequency response of the expansion speaker includes subwoofer frequencies, and is also extended to 600 Hz or higher, to enhance surround sound and spatial impression effects.

Abstract: An acoustic apparatus comprises an attenuator for attenuating a first audio signal to produce a second audio signal, a low pass filter for reducing high frequency components of the second audio signal to produce a third audio signal, a differential amplifier operative to produce a fourth audio signal corresponding to a difference between the first and third audio signals, and a speaker supplied with the fourth audio signal obtained from the differential amplifier, wherein a cutoff frequency of the low pass filter is selected to be not lower than 2 kHz and not higher than 6 kHz and attenuation of the first audio signal in the attenuator is so selected that a listener is able to recognize a virtual sound source position in front of and at a level higher than an actual position of the speaker.

Abstract: A self-tracking bandpass filter (1) comprises a controllable filter (10) having a signal input (11) for receiving a signal (&phgr;) to be filtered, a bandpass output (13) for providing a bandpass signal (SBP) having a center frequency (f0), and a control input (15) for receiving a control signal (SC); and a control unit (20) coupled to the control input (15) of the controllable filter (10), adapted to generate the control signal (SC) in such a way that the center frequency (f0) of the bandpass characteristic (HB) of the controllable filter (10) is substantially equal to the frequency (f) of the input signal (&phgr;).

Abstract: A crossover network for partitioning by frequency and electrical audio signal from an amplifier into a plurality of frequency bands for presentation to respective drivers or transducers. Such a crossover network couples the respective transducers in a parallel fashion thereby locking the in-phase relationships of signals presented to the respective transducers. The present facilitates a smooth transition between high and low frequencies without creating an abrupt crossover region wherein the phase relationships interject distortion.

Abstract: The present invention provides an audio enhancement apparatus and method which spectrally shapes the differential information in a pair of audio signals so as to create an immersive, three-dimensional effect when the audio signals are acoustically reproduced. In a preferred embodiment, the invention includes a two-transistor amplifier which spectrally shapes the differential information with what are called cross-over networks. The cross-over networks spectrally shape the differential information by selectively emphasizing or de-emphasizing certain frequencies in the differential information. In addition, the preferred embodiment adjusts the level of the sound which is common to both input signals to reduce clipping.

Abstract: The system of the present invention includes, briefly, a point source speaker system, comprising a processor which produces a left minus right (L−R) audio signal, a right plus left (R+L) and a right minus left (R−L) audio signal; three speakers each for audibly transmitting one of the L−R, R+L and R−L audio signals; and a point source speaker enclosure for housing the three speakers in a single enclosure.

Abstract: A crossover network for partitioning by frequency an electrical audio signal from an amplifier into a plurality of frequency bands, namely a high frequency band, and a low frequency band, and alternatively a high frequency band, a mid-range frequency band, and a low frequency band. The crossover network is implemented in a simplified configuration without the required use of capacitors and in a series configuration which reduces cost and component matching complexity. In one embodiment, the high frequency driver is configured in shunt with an inductor with a resistive component connected at least partially in shunt with the low frequency driver. This crossover network provides improved performance and simplified crossover network implementation.

Abstract: An arrayable loudspeaker system having a horn-loaded high frequency compression driver and a low frequency cone driver radiates acoustic energy from a focal point in a polar radiation pattern having amplitude and phase and includes a signal conditioning circuit for amplitude equalization and phase correction. The horn of the system's horn-loaded compression driver is designed in cooperation with the signal conditioning circuit such that the focal point of the loudspeaker system is substantially frequency independent over the operating frequency range of the loudspeaker system and such that over this operating frequency range the loudspeaker's focal point remains substantially fixed in space. Any two or more of such loudspeaker systems can be arrayed by aligning them in respect to their frequency independent focal points and by rotating the loudspeakers about an axis passing through the aligned focal points to obtain a desired coverage.

Abstract: An audio crossover circuit for use with audio speakers is disclosed. The audio crossover circuit includes a pair of inductors that are series connected and inductively coupled and a pair of capacitors. The inductors and capacitors cooperate for achieving a low-pass crossover slope in excess of 30 dB/octave within one half of an octave of the crossover frequency, thereby eliminating the need for additional inductors and capacitors. The crossover circuit also includes a resistor in series with one of the capacitors for further enhancing the crossover slope beyond an octave above the crossover frequency.

Abstract: The present invention phase coherent crossover incorporates a method and apparatus for providing phase coherent crossover (PCC) signals. The PCC method and apparatus involve the utilizing of an all-pass filter for receiving an input signal and producing an all-pass signal, and a partial-pass filter also receiving the input signal and producing a partial-pass signal at a partial-pass output. The PCC method and apparatus further involve the combining of the partial-pass signal produced by the partial-pass filter with the all-pass signal produced by the all-pass filter to produce an opposite partial-pass signal at an opposite partial-pass output.

Abstract: A method of operating a single speaker driver circuit having, a low frequency input coil connected between an audio circuit output and the input of the speaker, a low frequency return coil, connected between the return of the speaker and the return of the audio signal, the low frequency return coil being bifilar wound with the low frequency input coil, and a higher frequency input coil connected between the audio circuit output and the return of the audio circuit, and a secondary coil connected between the input of the speaker, and ground, the higher frequency input coil and the secondary coil being bifilar wound with one another and acting as the primary and the secondary of a transformer so the higher frequency signals passing through the higher frequency input coil induce secondary signals in the secondary coil, and a method of operating an audio frequency reproduction system using such a driver circuit.

Abstract: This invention outlines several applications of piezoelectric vibrators to produce quality flat panel speakers in passenger cabin applications. A system consisting of an audio amplifier and transformer is used to drive the piezo speaker. The electronics are packaged so that they fit in small modules that can be attached to a cabin structure to produce a speaker. The invention includes a variety of flat panel speaker designs, including one in which the existing structure is converted into a speaker, and thin membrane and or panels that are fitted with piezoelectric elements. A system consisting of cabin quieting and flat panel speakers is also discussed where the mid and high frequency audio is produced by panel speakers and the low frequency audio is produced from dynamic loudspeakers. The cabin systems discussed in this patent are applicable to automobiles, aircraft, trucks and buses.

Abstract: This loudspeaker system overcomes the disadvantages of prior art bipolar loudspeaker systems in which the front and rear-mounted driver(s) are connected with the same electrical phase. It compensates for the undesirable cancellation and reinforcement effects of prior art in bipolar loudspeaker design caused by the interaction of the front and rear acoustical output of the two drivers over certain frequency ranges. The introduction of a third side-mounted driver(s) to an enclosure whose depth exceeds its width when viewed from the front compensates for the usual cancellations and reinforcements of acoustic level that would normally occur in previous bipolar loudspeaker designs. This loudspeaker uses electronic, electrical and acoustical frequency-dividing networks to allow compensation of the acoustic level and the interaction of the front, rear and side-mounted driver(s) in such a way as to provide a nearly constant acoustic level over the entire operating range of the loudspeaker.

Abstract: An acoustical transmitting system and method for producing a narrow beam of acoustic energy over a broadband operating frequency range utilizes a parabolic reflector dish, a horn-loaded compression driver for directing acoustic energy toward the dish's reflecting surface, and a low frequency driver mounted behind a central aperture in the dish for producing acoustic energy that combines and interacts with the reflected acoustic energy produced by the horn-loaded compression driver. An input signal processing circuit is provided to condition the audio signal to the horn-loaded compression driver and the low frequency driver to achieve on-axis gain and off-axis cancellations at low frequencies. The addition of the low frequency driver to the reflector dish system effectively extends the ability of the system to produce and transmit acoustic energy in a narrow distribution pattern at frequencies below 1000 Hz using a four foot diameter dish.

Abstract: A speaker system that has a first speaker containing a first speaker unit in a first cavity and a second speaker containing a speaker unit wherein the crossover frequency of the first speaker and second speaker is f.sub.cr : 1.4.ltoreq.Q.sub.1,.ltoreq.10, f.sub.1 <f.sub.2, f.sub.1 .ltoreq.f.sub.cr .ltoreq.f.sub.1 .times.{(Q.sub.1.sup.2 +1.2.times.Q.sub.1)/(Q.sub.1.sup.2 -2.5)}.sup.0.5 .times.k, l.ltoreq.k.ltoreq.{(Q.sub.1,/(Q.sub.1,-1.4) }.sup.2.5, where the fundamental resonance frequency of the first speaker is f.sub.1, the resonance sharpness is Q.sub.1, and the fundamental resonance frequency of the second speaker is f.sub.2.

Abstract: An audio filter for use with loud speakers which substantially eliminates magnetic fields emanating from inductors of the filter by the inductors for each channel being physically oriented and electrically connected so that the magnetic fields generated by the inductors for each channel are self-cancelling. For preferred embodiments, the pair of inductors for each channel are side-by-side in close proximity to each other with current flowing in opposite directions through the coils.

Abstract: A bass audio circuit includes a first filter network which receives left and right channel input signals and produces two filtered signals by attenuating frequencies in the input signals above a first cutoff frequency. The two filtered signals are summed to create a first monophonic signal. A second filter network produces attenuated frequencies in either the input signals or in the first monophonic signal that are above a second cutoff frequency which is lower than the first cutoff frequency. The signals from the second filter network are combined and passed through a phase inverter to derive a second monophonic signal. An output stage individually amplifies the two monophonic signals which then either are applied to a dual voice coil woofer, or are electrically summed and applied to a single voice coil woofer. Alternatively, the two monophonic signals are first summed and applied to a single channel amplifier which drives a single voice coil woofer.

Abstract: A sound reproduction system includes a plurality of loudspeakers arranged in a spaced array which extends onto opposite sides of a center point. The spaced array includes a first pair of loudspeakers equally spaced apart from the center point and disposed at opposite ends of the array and a second pair of loudspeakers spaced inwardly from the first pair and also positioned on opposite sides of and equally spaced from the center point. The sound reproduction system further includes a low-pass filter having an input coupled to an output of a signal generator and an output coupled to an input of each one of the first pair of loudspeakers and a first band-pass filter having an input coupled to the output of the signal generator and an output coupled to an input of each one of the second pair of loudspeakers.

Abstract: In a speaker device equipped with a crossover network according to the present invention, which is used mainly in an automobile sound reproducing system or the like, a capacitor for the crossover network is accommodated within a pole piece of the speaker unit itself to eliminate bulkiness based on an external form of the network unit, thereby permitting the speaker device to be installed in a short time during manufacture of a vehicle or the like.

Abstract: A single speaker driver circuit having, a low frequency input coil connected between an audio circuit output and the input of the speaker, a low frequency return coil, connected between the return of the speaker and the return of the audio signal, the low frequency return coil being bifilar wound with the low frequency input coil, and a higher frequency input coil connected between the audio circuit output and the return of the audio circuit, and a secondary coil connected between the input of the speaker, and ground, the higher frequency input coil and the secondary coil being bifilar wound with one another.

Abstract: A multiple output transformer network for a high-fidelity sound reproducing system which includes a high-frequency speaker and a low-frequency speaker, first and second audio output autotransformers, a high-frequency bandpass filter coupling the first autotransformer to the high-frequency speaker, and a low-frequency bandpass filter coupling the second autotransformer to the second speaker, all of the foregoing components being mounted in a remote speaker unit. The winding of the first autotransformer is connected to the output amplifier of the sound reproducing equipment by a first extension lead, and to ground; and the winding of the second autotransformer is connected to the output amplifier of the sound reproducing equipment by a second extension lead and to ground; and the high-frequency and low-frequency bandpass filters are respectively connected to center taps on the windings of the first and second autotransformers.

Abstract: An audio crossover circuit for use with audio speakers is disclosed. The audio crossover circuit includes a pair of inductors that are series connected and inductively coupled and a pair of capacitors. The inductors and capacitors cooperate for achieving a low-pass crossover slope in excess of 30 dB/octave within one half of an octave of the crossover frequency, thereby eliminating the need for additional inductors and capacitors.

Abstract: An audio crossover system having two crossover networks, one suited to the auditory preferences of women and the other to the auditory preferences of men. The former attenuates mid-range frequencies more than high-range frequencies and attenuates low-range frequencies still more. The latter attenuates mid-range frequencies more than low-range frequencies and attentuates high-range frequencies even more than those in the mid-range.

Abstract: A multiple output transformer network for a high-fidelity sound reproducing system which includes a high-frequency speaker and a low-frequency speaker, first and second output transformers, a high-frequency bandpass filter coupling the secondary of the first output transformer to the high-frequency speaker, and a low-frequency bandpass filter coupling the secondary of the second transformer to the second speaker, all mounted in a remote speaker unit. The primary windings of the transformers are connected to the output amplifier of the sound reproducing equipment by first and second extension leads. The output amplifier includes first and second triodes series connected across a source of unidirectional potential, and first and second capacitors coupling the extension leads to the common connection of the triodes.

Abstract: A multi-output power amplifier is disclosed. The amplifier is divided into two stages. A single voltage amplifier is used as an input amplifying stage and several current amplifiers are used as a second amplifying stage. The inputs to the current amplifiers share a common connection to the output of the voltage amplifier and feedback is provided from the current amplifier outputs to the voltage amplifier input.

Abstract: In a digital channel divider of the present invention, a plurality of filters are connected in parallel, which can set a desired transmission frequency response optionally for a digital input signal, so that signals outputted from each filter are outputted independently. In order to flatten the amplitude characteristic of an overall transmission frequency response of each channel and to obtain a linear phase frequency response, a time series impulse response is calculated based on an inverse characteristic and this time series impulse response is made to be a filter factor, and this filter factor and and the digital input signal are calculated by convolution operations.

Abstract: A damping circuit for speaker systems of the type containing at least one speaker having a speaker coil with an input and an output connection and having a matching coil adapted to be connected in series with the input connection of the speaker coil and a damping coil adapted to be connected in series with the output connection of the speaker coil, the matching and damping coils each having respective input and output ends, and being wound together in the same rotational direction with their respective input ends together and their respective output ends together in a method having a unity coefficient of coupling so that the primary signal current flows through both coils in the same direction, whereby electro-magnetic fields induced around the matching and damping coils interact with one another during passage of signals and damp out signal distortions due to induced transient signals in the matching coil and to reduce signal distortions due to induced transient signals in the speaker coil.

Abstract: A multiple output transformer network for a high-fidelity sound reproducing system which includes a high-frequency speaker and a low-frequency speaker, first and second output transformers, a high frequency by-pass filter coupling the secondary of the first output transformer to the high frequency speaker, and a low-frequency by-pass filter coupling the secondary of the second transformer to the second speaker, all mounted in a remote speaker unit. The by-pass filters have predetermined crossover characteristics. The primary windings of the transformers are connected to the output amplifier of the sound reproducing equipment by first and second extension leads.

Abstract: A sound field offset device having two channels, each of which includes a frequency selection filter for dividing a stereophonic input signal into two frequency bands by a given frequency falling within an audio frequency, at least one digital filter for performing sound field offsetting within a lower frequency band, and at least one loudspeaker assembly for a higher frequency band having a sharp directivity pattern and capable of defining an area to which acoustic power is emitted. This device allows a sound field to be offset in a cost effective and simple manner, by improving the frequency characteristic of a sound field space and by clarifying the sense of locality of acoustic images.

Abstract: In a mobile loudspeaker system comprising a woofer and a tweeter. A resonance circuit is inserted in the network of the woofer so that the frequency characteristic of sound pressure inside the vehicle at a middle-frequency range is substantially flat.

Abstract: The disclosure relates to devices for the measurement of signals in the field of wideband phenomena. More precisely, a device is disclosed for the processing of electrical signals coming from a derivative type of sensor designed to measure an electrical or magnetic field, currents, surface charges or other derivative variables, said processing including the computation of the primitive of the part of said signal having a spectral frequency higher than a low frequency f.sub.1, the device comprising:means for the electronic integration of said signal, from a frequency f.sub.2 higher than said low frequency f.sub.1 ;compensation means amplifying and integrating said signal between the frequencies f.sub.1 and f.sub.2. FIG. 2 .