Abstract: An apparatus for controlling audio signals having pulse code modulation (PCM) data and methods of operating the same result in efficient modulation of the audio signals. The apparatus for controlling audio signals comprises a PCM data input register configured to store the PCM data. A shift register is coupled to the PCM data input register configured to serially shift the PCM data. A PCM data output register is coupled to the shift register configured to store modified PCM data. An audio magnitude controller is coupled to the shift register configured to control serial shifting of the shift register to provide the modified PCM data.

Abstract: This invention provides an analog audio amplifier having both excellent linearity and high efficiency, which is combined with digital amplifier. The analog-digital combined amplifier comprises a class A, class B or class AB type analog amplifier serving as an independent voltage source; and a class D type digital amplifier serving as a dependent current source in which the analog amplifier and the digital amplifier are connected to each other.

Abstract: A weight is attached to the rear side of a magnetic circuit of a speaker unit. The tip of a boss that projects to the front side from the weight is joined to the rear side of a center pole of the magnetic circuit with a bolt. Even if reactive force that is generated when an electrical signal is converted into mechanical vibration by the magnetic circuit and a voice coil and sound waves are emitted from a vibration plate is transmitted to the magnetic circuit, the vibration of the magnetic circuit is suppressed by the weight. In this manner, sound quality with a good transient characteristic can be obtained.

Abstract: An integrated amplifier and speaker system includes a speaker having a motor assembly and a frame. A power stage of the amplifier is mounted in thermal communication with the motor assembly and/or the frame. Heat generated by the power stage is thereby sunk to the motor assembly and frame.

Abstract: A fully integrated, low cost, amplified electro-acoustic loudspeaker is disclosed in which an amplifier circuit (30, 130, 230, 330, 930, 1030), radio-frequency receiver amplifier circuit (430, 530), optical receiver amplifier circuit (630, 730), or network based amplifier circuit (830) is directly mounted on the loudspeaker's magnetic assembly (105, 505, 705, 805), contained within the loudspeaker's moving assembly (20, 29, 629, 42, 45, 50, 65), or a combination thereof. The amplified loudspeaker's magnetic assembly (5, 105, 405, 505, 705, 805, 905, 1005) is utilized as an electro-magnetic interference shield and/or a heat dissipating element for the attached electronic circuitry. In selected embodiments of the amplified loudspeaker system, the former (42) containing voice coil (45) is additionally utilized for convection cooling of the amplifier circuit (30, 230) or receiver/amplifier circuit combination (430, 630).

Abstract: An electro-acoustic speaker having no permanent magnet. An audio input signal is applied to a pair of parallel coils, each being in series with a diode. The diodes are oppositely acting, so that the coils conduct during alternate half cycles of the input signal. As a result, the coils alternately generate magnetic flux for cooperative establishment of an unidirectional magnetic field. The input signal is also applied to a third coil for generation of a full wave current therethrough. This full wave current produces magnetic flux which establishes an alternating magnetic field. Interactions between the current-carrying coils and their respective magnetic fields produce acceleration forces for a speaker cone.

Abstract: A speaker apparatus capable of reproducing from low-pitched to high-pitched sounds and a voice reproduction system employing the same. The speaker apparatus includes a speaker unit in which a primary coil is mounted in a gap portion between a plate and a center pole of a magnetic circuit, a secondary coil is disposed within the gap in such a manner as to be fixed to a vibration plate, and a secondary electric current is induced in the secondary coil by a signal current flowing through a primary coil, thereby operating the vibration plate; and a speaker driving circuit adapted to drive the primary coil of the speaker unit in accordance with a digital sound signal.

Abstract: An acoustic transducer with partially driven area of the diaphragm such that the driving forces are asymmetric with respect to the frame axis of symmetry or angled with respect to edges of diaphragm support frame to provide uniform frequency response of the transducer. The elongate magnet sections surround portions of the diaphragm with a fringing magnetic field within which a circuit of conductor strips is positioned such that selectively excited vibration modes of the diaphragm provide a smooth frequency response.

Abstract: Class D amplifiers are difficult to incorporate into audio amplifier systems because of the interference created by the amplifier and/or the surrounding circuits. The modulation frequencies f1 and f2 of two class D amplifiers in an audio amplifier system are adjusted so that the frequency f1-f2 of interference between the modulation frequencies is outside the reproducible frequency band B1 of speakers converting the class D amplifier output to audible sound. As a result, interference that may result from simultaneous use of two class D amplifiers for similar purposes is inaudible and not perceived as noise.

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: A speaker apparatus which drives an electromagnetic-coupling-type speaker in accordance with a digital signal is provided with a speaker unit, and a plurality of amplifiers corresponding to the number of quantization bits of a digital audio signal. The output terminals of the amplifiers are connected to the respective primary coils, respectively, and the output impedances of the plurality of the amplifiers are made equal to those of the respective primary coils to which the amplifiers are connected. Each bit of each sample of the digital audio signal is amplified by the plurality of the amplifiers and supplied to the respective primary coils, respectively.

Abstract: A speaker device driving drive coils of a speaker such as an electromagnetically coupled speaker by digital sound signals, where a primary coil of the speaker unit is constituted by 15 pieces of coils, the coils are made to correspond to respective bits excluding MSB of a digital sound of 16 bits issued from a serial/parallel converter, each of the coils are connected in a bridge connection to 4 pieces of FETs respectively opposed to each other and constant current sources are connected to the bridge connection portions whereby a coil drive circuit is constituted, currents from the constant current sources are respectively supplied to the coils and a variable resistor is adjusted by which voltages are changed and the currents of the constant current sources are commonly controlled whereby the volume of the speaker is finely driven.

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: An open-loop speaker amplifier and a dynamic range reduction circuit are disclosed. The speaker amplifier includes a bridge driver and a bridge circuit. The bridge circuit includes a first set of switches and a second set of switches. When the first set of switches are activated, a positive current flows through a speaker load. When the second set of switches are activated, a negative current flows through the speaker load. The bridge driver generates a pulse width modulated signal and a delayed pulse width modulated signal to drive the first and second set of switches of the bridge circuit responsive to a modulation signal. The modulation signal maybe for example, a plurality of pulse code modulated samples representing sound. The dynamic range reduction circuit modifies a selected signal to reduce the dynamic range of the sound reproduced based on the modulation signal. The selected signal is either the modulation signal or a reference signal.

Abstract: A speaker driving device applies a constant voltage of a constant voltage source to a pair of voice coils alternatively by switching the direction of applying the constant voltage based on a binary PDM signal. A .DELTA..SIGMA. modulator produces the binary PDM signal by .DELTA..SIGMA.-modulating a digital audio signal from a digital low-pass filter. The constant voltage is applied to a first voice coil in one direction and is applied to a second voice coil in the reverse direction by switching the direction of applying the constant voltage. The first and second voice coils forms the pair of voice coils. This arrangement causes a current to flow through the first and second voice coils in opposite directions and a diaphragm of a speaker to be driven in two directions opposite to each other. As a result, the speaker is driven more efficiently.

Abstract: A horn speaker in which a cooling device is attached near a moving coil which vibrates a diaphragm. The cooling device may be attached to the inner periphery of a bobbin which is connected to the diaphragm and around the outer periphery of which the moving coil is wound.

Abstract: An integrated amplifier and speaker system includes a speaker having an enclosure having a closed end and an open end; an electro-acoustic driver sealingly mounted in the open end; a reflex duct connected acoustically to the enclosure through a port and having a reflex duct open end proximate to the electro-acoustic driver means; and an amplifier assembly that has an inner surface defining an interior surface of the enclosure. The amplifier subassembly further includes a circuit board that extends within the enclosure. The amplifier is electrically connected to drive the electro-acoustic driver means.

Abstract: A whole-surface driven speaker includes first and second support plates having sound-passing perforations and groups of magnets mounted on the plates. The plates are substantially parallel to each other. A diaphragm is disposed in between the plates. A plurality of conductor strips are mounted on the surface of the diaphragm. The strips are connected to receive pulse-code modulated signals. The strips respectively correspond to a plurality of binary bits of the signals of different bit significance. Each strip has a predetermined width and a predetermined number of windings and carries a predetermined current magnitude such that electromechanical forces on the diaphragm caused by the bit signals flowing through the strips are proportional to the respective bit significance of the strips.

Abstract: Circuitry is provided for simulating and emulating the sounds of a loudspeaker driven by a classic rock and roll guitar amplifier in the form of an electrical signal which, when input to a recording console or used to drive high fidelity headphones or a high quality monitor amplifier and monitor loudspeaker, accurately reproduces such sounds. The circuitry is incorporated at the output of a classic tube-type rock and roll guitar amplifier, and consists of three basic modules: a load impedance module (FIG. 3) designed to offer to the tube amplifier output a load impedance as a function of frequency (FIG. 1) which is modeled after and nearly identical (in both real and imaginary components) to the impedance of a classic rock and roll guitar speaker; a highpass filter circuit (24) which emulates the low frequency resonance and rolloff characteristics (FIG.

Abstract: An electrical transducer comprising a magnet system (1), a diaphragm (5) and a voice-coil device (3, 4), coupled to the diaphragm. The voice coil (3) is situated in an air gap (2) of the magnet system and the magnet system is coupled to a chassis (7). The chassis is provided with a connection unit (10) having at least two coupling means (11, 14) each comprising a first terminal (12 and 15 respectively) for receiving an electric signal and a second terminal (13 and 16 respectively) electrically coupled to said first terminal. Each second terminal is electrically coupled to an electrical connection (20 and 21, respectively) of the voice coil via a lead (18 and 19 respectively). The leads (18, 19) are provided with a spacer (22) made of an electrically non-conductive material, for example, a plastic material (FIG. 2a).

Abstract: An audio arrangement includes a thin speaker/transducer positioned within a portable housing wherein the speaker cavity is dimensioned to move the resonant frequency of the speaker/housing combination up to approximately the free-air cutoff frequency of the speaker/tranducer. The resulting response then falls off at about 6 db/octave below that point. An amplifier having gain increasing at 6 db/octave is placed in the signal input path for creating an essentially flat frequency response in the normally desired audio range.

Abstract: In order to compensate reproduction errors in electroacoustic transducers (W), for example electrodynamic loud-speakers, microphones and pickup systems, computer circuits are used. In a digital computer circuit, the electrical input signals (U.sub.1 ) are converted into altered output signals (U.sub.2) according to the inherent properties of the transducer (W), stored in a memory (PROM), with the aid of a programme, which is likewise stored. When analogue computer circuits are used, the complex inherent response of the converter (W) in respect of the amplitude/frequency response and phase/frequency response is approximated mathematically in a closed, inverse form, and the resulting function is simulated with the aid of integrators (B), summing elements (S), inverters (I) and adjusting members (P).

Abstract: In a planar loudspeaker structure comprising planar membrane for forming a diaphragm on which a voice coil of a conductor pattern is formed, and a magnetic circuit for supplying a DC magnetic flux which crosses the voice coil, the conductor pattern includes first and second zigzag conductor pattern portions which are juxtaposed on substantially the entire area of the membrane and connected in series. Opposite ends of the series connection of the first and second conductor pattern portions are respectively connected to first and second terminals for receiving a low-band component of an input audio signal. A high-band component of the input signal is applied to a third terminal connected to a junction between the first and second conductor pattern portions and supplied only to the second conductor pattern portion.

Abstract: A loudspeaker driver has its front surface adjacent one end of a low loss acoustic waveguide and its rear surface adjacent to one end of a second acoustic waveguide that is one third the length of the first. The other openings of the waveguides face air and couple acoustical energy substantially uniformly over a relatively broad range of frequencies extenting into the bass frequency region. An equalizer includes a notch filter so that the frequency response of the equalizer below a bass cutoff frequency is sufficiently low to prevent audible distortion.

Abstract: An electrodynamic transducer (1) for use in a loudspeaker system for converting an n-bit digitized electric signal (11) into an acoustic signal comprises n voice-coil devices (4.1, 4.2, . . . 4.n) which cooperate with a magnet system (3). The voice-coil devices each comprise a conductor whose length is the same for all the voice-coil devices. The areas of the perpendicular cross-sections of the conductors increase each time by a factor of two starting from the voice-coil device (4.n) corresponding to the least significant bit and going to voice-coil devices corresponding to consecutive more significant bits. The invention enables the transducer to be constructed in a simple manner if the transducer is a moving-coil loudspeaker or if it is a ribbon-type loudspeaker.

Abstract: A subminiature power amplifier for hearing aids configured to be completely self-contained and fit within the user's ear features a Class D amplifier stage. By configuring all signal elements as digital units, circuit balance is readily maintained. A substantial economy of battery drain is achieved while preserving a low value of distortion at low signal levels. Oscillator frequency is governed by a single resistance element. The amplifier and an optional efficiency-improving inductor can be accommodated entirely within the residual volume of the motor chamber of a state-of-the-art earphone housing.

Abstract: A loudspeaker system for converting an n-bit digitized electric signal (11) into an acoustic signal comprises an electrodynamic loudspeaker (1) with n voice-coil sections (4.1, 4.2, . . . 4.n) which cooperate with a magnet system (3). The loudspeaker system further comprises means (18.1, 18.2, . . . 18.n) for short-circuiting a voice-coil section if the value of the bit corresponding to the voice-coil section is such that the relevant voice-coil section is not driven.

Abstract: A method and apparatus for producing low frequency sound (20 to 100 Hz) at levels of intensity above the minimum threshold of human hearing. A mechanical-electrical drive having high power capacity is coupled via a linkage to a sound radiator and is responsive to the electrical input from a sound program source. The drive is capable of large excursions at high forces which are substantially constant irrespective of the extent of excursion.

Abstract: In a loudspeaker system for converting an n-bit digitized electric signal (6) into an acoustic signal a plurality of sections (voice coils 14.1, 14.2, 14.3, 14.p) of a digital loudspeaker (1) are driven directly by the p most significant bits of the n-bit digitized electric signal (6). The loudspeaker (1) comprises at least one additional section (14.p+1). This (p+1).sup.th voice coil receives a signal from a digital-to-analog converter (5), the input signal of the digital-to-analog converter comprising at least the n-p least significant bits (FIG. 2). In a different embodiment the digital-to-analog converter (5) receives all the n bits of the digitized electric signal as the input signal. At least the p sections (14.1 to 14.

Abstract: A dynamic loudspeaker unit having a voice coil formed with two windings in which a capacitor is connected in series to a parallel circuit, one circuit arm being composed of a series circuit of one of the two windings and an inductor and the other circuit arm being composed of the remaining winding. The dynamic loudspeaker unit thus constructed is housed in a bass-reflex type cabinet, whereby a shoulder characteristic having a large Q in a bass zone can be obtained, and due to a combination of the inductor and the capacitor, a desired lowest resonance frequency lower than an actual lowest resonance frequency can be selected. Thus, the reproducible bass range can be extended.

Abstract: A loudspeaker system includes at least one electromagnetic loudspeaker assembly having a single vibratory coil form to which a vibratory diaphragm is attached. Two or more voice coils are wound on the vibratory coil form, each operating within a magnetic field. Electronic circuitry includes a signal conditioning network and a pair of amplifiers, one amplifier for each of the voice coils. The signal conditioning network, possibly preceded by a filter, is arranged to feed the respective amplifiers, the latter being coupled to their respective ones of the voice coils. D.C. currents provide forces in each of the voice coils, such that these forces are caused to oppose one another. The signal currents in the voice coils are such that the difference in the forces developed by the voice coils produce a vibratory motion of the voice coil form and the diaphragm attached thereto. A power supply is provided. A variable impedance circuit is connected between the power supply and the voice coils for adjusting the D.C.