Abstract: According to one embodiment, an electronic apparatus includes a speaker, a terminal, an amplifier, a battery, a power supply circuit, and a controller. The terminal is configured to input an audio signal from an external device. The amplifier is configured to amplify the audio signal which is input from the terminal, and to output audio from the speaker. The power supply circuit is configured to supply power from the battery to the amplifier. The controller is configured to control the power supply circuit, based on a residual capacity of the battery and a preset battery level, in order to supply the power to the amplifier when the electronic apparatus is in a non-operative state.

Abstract: An audio reproduction device and system are capable of realizing sounds having natural sound quality with no peculiarities, and provide an excellent audio-image ascending effect which is not varied due to differences among individual persons, thereby making audio images and images coincident with each other. A frequency characteristic correction portion forms a frequency characteristic such that a sound-pressure frequency characteristic of reproduced sound radiated to a viewing position from speakers has a first peak and a second peak, wherein the center frequency of the first peak falls within the range of 6 kHz±15%, and the center frequency of the second peak falls within the range of 13 kHz±20%.

Abstract: Disclosed is a technique for reducing noise superimposed on an output signal while keeping loop gain constant without increasing the circuit scale and without changing the transfer function of the amplifier apparatus (frequency characteristics of gain and phase). According to the technique, there are included a power-supply voltage control unit 7 for detecting the amplitude level S9 of an input audio signal S1 and outputting power with a voltage value indicated by target set voltage value information Vs corresponding to this amplitude level S9, and a PWM modulation unit 2 including a PWM converter 23 for converting the pulse width of the input audio signal S1 and a correction unit for correcting the signal modulated by the PWM converter 23. The PWM modulation unit 2 corrects the pulse width of a PWM signal S5 modulated by the PWM converter 23 so that the correction unit will cancel out a change in amplification gain of a power amplification unit 4 according to the target set voltage value information Vs.

Abstract: An audio system has a connector with a signal pin that interfaces the audio system with an external device. An audio integrated circuit has a digital to analog converter (DAC) and an audio power amplifier having an input coupled to an output of the DAC and an output coupled to an output pin of the audio integrated circuit. Data storage contains stored instructions that program a processor to select an audio output mode of operation namely line-out mode or headphone mode. A configurable output conditioning circuit is coupled between the output pin of the audio integrated circuit and the signal pin of the connector. The conditioning circuit changes the output impedance that is presented at the signal pin, under control of the programmed processor when selecting the audio output mode of operation. Other embodiments are also described and claimed.

Abstract: A low impedance coupling to bias voltage dissipates abnormal charge levels within a microphone in response to a shock event such as dropping or bumping. High impedance coupling to bias voltage is thereafter restored.

Abstract: An apparatus and method for biasing each amplifier of an amplification stage provides that the voltage across each current sensing element of each amplifier of the amplification stage is measured. For each pair of voltage measurements taken, a sum and difference is calculated, where the sum is processed to determine minima peaks and the difference is averaged. A portion of the sum term and the average of the difference term are summed to yield the individual bias current conducted by a first amplifier of the amplification stage. The difference between a portion of the sum term and the average of the difference term is calculated to yield the individual bias current conducted by the second amplifier of the amplification stage. The bias current conducted by the first and second amplifiers may then be individually modified manually, or conversely, may be modified automatically based upon the bias current measurements taken.

Abstract: A microphone amplifier comprises a microphone terminal for connecting a microphone, particularly a MEMS microphone, and an amplifier circuit with an amplifier input that is connected to the microphone terminal, and with an amplifier output that is connected to an output of the microphone amplifier. The amplifier circuit is designed to amplify an input signal present at the amplifier input in order to generate an output signal at the amplifier output. The microphone amplifier further comprises an overload circuit that is designed to detect an overload state within the amplifier circuit and to connect the amplifier input via a switching element, in particular with a low impedance, to a reference potential terminal if the overload state is detected for more than a predetermined time span.

Abstract: Disclosed is a Class-AB/B amplifier comprising a first output stage including a first plurality of amplification devices and a second output stage including a second plurality of amplification devices. According to one embodiment, the first output stage operates when the Class-AB/B amplifier is in a quiescent state and the second output stage operates when the Class-AB/B amplifier is in an active state. The Class-AB/B amplifier also comprises a level shifting circuit that adjusts a control voltage of the second output stage, where the level shifting circuit is adapted to activate the second output stage when the Class-AB/B amplifier enters the active state. Embodiments of the Class-AB/B amplifier may include a level shifting circuit that implements either a fixed or signal-dependent level shift, and a quiescent control circuit that substantially eliminates any systematic offset arising from the active feedback circuit inside the replica bias circuit.

Abstract: According to one embodiment, a digital signal generator includes an amplifying unit, a reference voltage generator and a modulator. The amplifying unit amplifies an analog input signal having a signal level linearly depending on a temperature. The reference voltage generator generates a reference voltage linearly depending on the temperature. The modulator converts the analog input signal amplified by the amplifying unit into a digital output signal based on the reference voltage.

Abstract: A system includes multiple speakers arranged in a speaker array configuration. The system also includes one or more filters configured to filter audio signals and generate filtered audio signals. The one or more filters are configured to operate using filter coefficients associated with a desired beam pattern to be produced by the multiple speakers. The system further includes at least one amplifier configured to amplify the filtered audio signals and provide the amplified filtered audio signals to the speakers. The one or more filters reside within or are coupled to the at least one amplifier. The system may further include a controller configured to modify at least one of the filter coefficients based on a change in the speaker configuration. The filters may operate independently of a centralized processor, and a centralized processor may not even be required to provide electronic beam forming.

Abstract: The invention relates to a sound-emitting device with controllable directivity comprising a plurality of sound sources (7) distributed over the surface of a body 5, each of said sound sources (7) being driven by a separate power amplifier (12), the input terminal of which is provided with the output signal from a corresponding filter (10), such that the frequency response of each individual sound source (7) can be controlled, where each filter (10) is provided with an input signal (11) corresponding to a plurality of input channels Ch1, Ch2 . . . ChN. The body (5) could according to one embodiment of the invention comprise a cylindrical body provided with end pieces (6) at either longitudinal end. The present invention furthermore relates to a method for controlling the individual sound sources of the sound-emitting device in order to obtain a given target directivity.

Abstract: A multimode audio amplifier comprises: a mode controller adapted to provide a control signal; and at least one multimode module, wherein each of the multimode modules has a plurality of operating modes, wherein the operating modes are selected in accordance with the control signal, wherein changing the operating modes results in a measurable change in at least one characteristic of the multimode audio amplifier; wherein the characteristics of the multimode audio amplifier consist of signal to noise ratio (SNR); total harmonic distortion and noise (THD+N); input to output delay; power consumption; and efficiency.

Abstract: A method of optimizing a parametric emitter system having a pot core transformer coupled between an amplifier and an emitter, the method comprising: selecting a number of turns required in a primary winding of the pot core transformer to achieve an optimal level of load impedance experienced by the amplifier; and selecting a number of turns required in a secondary winding of the pot core transformer to achieve electrical resonance between the secondary winding and the emitter.

Abstract: A thermally regulated amplifier system includes an amplifier unit, a temperature-sensing unit and a controller. The amplifier unit includes a power amplifier that has an adjustable gain function. The controller receives temperature readings from the temperature-sensing unit, computes the gain G(n) of the amplifier unit, and provides the computed gain of the amplifier G(n) to the power amplifier unit.

Abstract: An audio distribution system in one embodiment includes a master device, a powered speaker unit, and an expander device. The master device has an output port for receiving a cable carrying an electrical power signal along with a digital audio signal. The speaker unit includes a first port for receiving the electrical power signal and the digital audio power signal, and a second port for sending the signals. A digital-to-analog converter in the speaker unit converts the digital audio signal to an analog audio signal, and a speaker driver uses the signal to produce sound. The expander device is electrically connectable to the second port of the speaker unit for providing electrical power to one or more further speaker units. In another embodiment, the invention provides a master mixer device and a speaker unit.

Abstract: An apparatus for providing an audio signal to drive a speaker system includes first and second audio channels. The first audio channel has a first class-D amplifier for receiving an input signal, and a first reconstruction filter for receiving an output from the first class-D amplifier and reconstructing therefrom an output audio signal for driving the speaker system. The second audio channel has a second class-D amplifier for receiving an input audio signal, and a second reconstruction filter for receiving an output from the second class-D amplifier and reconstructing therefrom an output audio signal for driving the speaker system. The first and second reconstruction filters have corresponding first and second planar inductors, with the second planer inductor being magnetically coupled to the first planar inductor.

Abstract: An audio playing device for an electronic device includes an amplifier circuit, a voltage divider circuit, and a speaker. A south bridge of the electronic device is electrically connected to the amplifier circuit via the voltage divider circuit, and a sound card of the electronic device is electrically connected to the amplifier circuit. The south bridge generates electronic signals corresponding to startup prompt tones of the electronic device, and the electronic signals corresponding to startup prompt tones of the electronic device are transmitted to the speaker via the voltage divider circuit and the amplifier circuit to play. The sound card processes audio files, and electronic signals corresponding to the processed audio files are transmitted to the speaker via the amplifier circuit to play.

Abstract: A sound signal transmitter-receiver includes a differential microphone for receiving sounds respectively at first and second points to convert the receiving sounds into a transmission sound signal; a transmission-reception unit for receiving an incoming signal as a reception sound signal; an addition unit for adding the reception sound signal from the transmission-reception unit and the transmission sound signal to produce an addition signal; and a speaker outputting sound based on the addition signal.

Abstract: An electronic device includes a capacitance electro-acoustic transducer and an audio driver. The audio driver is coupled to the capacitance electro-acoustic transducer. The audio driver includes a high-voltage amplifier for receiving an input audio signal and for transforming the input audio signal into an output audio signal to drive the capacitance electro-acoustic transducer, wherein an absolute voltage value of the input audio signal is smaller than an absolute voltage value of the output audio signal. The output bandwidth of the capacitance electro-acoustic transducer is controlled by the magnitude of the output current of the audio driver. The capacitance electro-acoustic transducer of the present invention can meet different bandwidth requirements and thus achieve saving power, which cannot be achieved by a traditional dynamic electro-acoustic transducer.

Abstract: Provided is a speaker diaphragm or a speaker voice coil bobbin manufactured by a papermaking method and including metal hydroxide by at least an amount of 30 wt % or greater. With this, it is possible to improve rigidity and achieve favorable acoustic quality by an effect of mixing metal hydroxide. Moreover, it is possible to provide a paper-made diaphragm or a voice coil bobbin with flame retardancy without increasing weight or cost.

Abstract: In an amplifier circuit of a capacitor microphone, when a too high input signal from the capacitor microphone is inputted, the levels of output signals of the amplifier circuit are limited. A first feedback capacitor of an operational amplifier is formed using a changeable capacitance type MOS capacitor element, and has a characteristic of increasing the capacitance value CAf1 according to the amplitude of an input signal generated by a capacitor increases. Therefore, CAf (=CAf1+CAF2) increases according to the amplitude of the input signal increases, and accordingly the gain of the operational amplifier decreases, thereby limiting the output signals of the operational amplifier. This realizes the appropriate limitation of the output signals of the operational amplifier, even when the amplitude of the input signal becomes too high.

Abstract: Feedback is reduced by routing an input signal through a kick gate that opens for a predetermined time period then closes. The gate may be kept closed for a predetermined minimum time period before being allowed to open again. The gate is triggered open based on the input signal and may include a plurality of triggering conditions.

Abstract: Configurable analog input circuits are provided. An analog input circuit may include a plurality of configurable input channels, at least one analog-to-digital converter, and at least one processor. Each input channel may include a plurality of switches utilized to select a type of input signal received via the input channel and a set of input terminals selectively utilized to correspond with the selected type of input signal. The at least one analog-to-digital converter may be configured to convert, for each of the plurality of input channels, the selected type of input signal into a digital output. The at least one processor may be configured to control operation of the plurality of switches associated with each of the plurality of configurable input channels.

Abstract: An audio recording and playback device, of the present invention, capable of recording and playing back audio, comprises an audio input section for converting audio input during an audio recording operation into an electrical audio signal, a power feed section for carrying out power feeds to the audio input section by means of a balanced transmission line, an amplifier section for amplifying the audio signal, a boost section for generating a power feed voltage to be applied to the balanced transmission line and outputting to the power feed section, a output voltage changing section for carrying out control to vary the output voltage of the boost section, and a control section for controlling the power feed voltage of the power feed section by controlling the power feed section and the output voltage changing section.

Abstract: A solid-state audio power amplifier providing an instantaneous maximum output voltage capability in excess of its long term power output capability, in which the input signal is supplied from analogue or digital signal processor.

Abstract: Disclosed is an amplifier with which output signal distortion can be reduced, and deterioration in power efficiency can be reduced. The amplifier is provided with a power supply voltage control unit (11) that generates a voltage control signal from a simple envelope of an input signal in order to control a variable voltage power supply (12). The power supply voltage control unit (11) is composed of: a slope comparison processing unit (112) that calculates the slope required to generate a voltage control signal; a total delay time calculation unit (113) that calculates the sum of the delay times between the dots produced by the slope comparison process; and a voltage control signal generation unit (114) that generates a voltage control signal in such a manner that the waveform formed by the voltage control signal, which controls the variable voltage power supply (12), constitutes a waveform that reflects the selected slope or the sum of the slew rate and delay time.

Abstract: The speaker apparatus according to the invention is arranged in a manner that when the magnitude of an audio signal Sin increases temporarily and so a consumption power increases, a DC-DC converter reduces an output voltage Vout to thereby increase an output current Iout and further discharges a capacitor to thereby increase a current supplied to an amplifier. Thus, a power of 2.5 W or more supplied from a USB connection terminal can be temporarily supplied to the amplifier. Further, since the change of the voltage difference between the both ends of the capacitor can be made large, an amount of the electric charges discharged from the capacitor can be made large and so the size of the capacitor can be reduced.

Abstract: An audio signal processing apparatus and method are provided. The apparatus includes a stability determiner and a sigma-delta modulator. The stability determiner divides a frequency band of an input audio signal into one or more sub-frequency bands, compares a level of the input audio signal for each of the sub-frequency bands with a threshold for the sub-frequency band, and generates a stability determination signal according to a result of the comparison. The sigma-delta modulator sigma-delta modulates the input audio signal according to the stability determination signal, and outputs a modulation signal.

Abstract: An electronic audio amplifier circuit, operable in two modes and a battery powered portable audio apparatus incorporating the circuit; and associated apparatuses and methods. When in the first mode the audio apparatus is designed for the direct driving of headphones or a speaker. When in the second mode the audio apparatus is designed to drive a line input of an external amplifying apparatus with a signal that having a higher voltage amplitude for a given signal content than when driving headphone or a speaker. The circuit has common output stage circuitry for use in both modes, and a dual mode power supply circuit, ideally a charge pump circuit, for supplying the output stage in the first mode with a lower supply voltage than in the second mode.

Abstract: A system and method for wirelessly triggering an amplification system are disclosed. In one example, the system for wirelessly triggering the amplification comprises at least one wireless tag, the at least one wireless tag having unique identification (ID) information and an amplification system configured to receive audio signals. Further, the amplification system comprises a wireless reader configured to receive and determine the ID information from the at least one wireless tag, and a processor configured to associate at least one sound effect with the ID information received from the at least one wireless tag and to modify the audio signals to include the at least one sound effect.

Abstract: There is provided a voice coil speaker containing a bobbin having multilayer voice coils formed thereon in which the bobbin and a circuit board are properly arranged. In a voice coil speaker equipped with a bobbin having multilayer voice coils formed thereon and a diaphragm connected to the bobbin, the bobbin and the diaphragm being provided in a speaker body, an audio signal processing circuit board for processing an audio signal is disposed ahead of the diaphragm, and plural output terminals for outputting to the multilayer voice coils are arranged in the peripheral direction of the audio signal processing circuit board.

Abstract: An audio host device has a connector having a speaker contact, a microphone contact, and a reference contact. The reference contact is shared by a microphone and a speaker. The reference contact is also directly coupled to a power return plane of the audio host device. A difference amplifier is provided, having a first cold input, a second cold input, and hot input. The first cold input is coupled to an output of the speaker amplifier, while the second cold input is coupled a sense point for the reference contact. The hot input is coupled to the microphone contact. Other embodiments are also described and claimed.

Abstract: A band-splitting time compensation signal processing device 2 includes a band-splitting circuit 211 for extracting, after extracting a signal of a high-frequency band component or low-frequency band component from an input signal, a signal of the low-frequency band component or high-frequency band component by subtracting the signal of the high-frequency band component or low-frequency band component from the input signal; a delay circuit 212 for delaying, for adjusting arrival time, at least one of the high-frequency band component and low-frequency band component output from the band-splitting circuit 211; and a mixing circuit 213 for combining the high-frequency band component or low-frequency band component output from the delay circuit 212 with the low-frequency band component or high-frequency band component output from the band-splitting circuit 211.

Abstract: The disclosed digital amplifier (200) is provided with a voltage value conversion block (220) for converting a digital value of a digital pulse width of a digital modulation block (210) to a voltage value; and an integration circuit block (230) for generating a triangular wave by way of a master clock and modulating the generated triangular wave on the basis of a signal corresponding to the value of the modulation width of digital pulse width modulation. The disclosed digital amplifier (200) is provided with a low-pass filter (260) for demodulating pulse power that has been power-amplified by way of a drive circuit (250) to analog power of an audio band, and an error amplifier (290) for computing the voltage difference between the voltage of a low-pass filter (280) and the low-pass filter (260) and amplifying thereof.

Abstract: A low-noise pre-amplifier with an active load element is integrated into a microphone. The microphone has an acoustic sensor coupled to the intrinsic pre-amplifier. A controllable current source is coupled to the intrinsic pre-amplifier and supplies a pre-amplifier bias current. A current source controller is coupled to the current source and controls the amplitude of the pre-amplifier bias current to maintain the intrinsic pre-amplifier at a bias point at which the intrinsic pre-amplifier amplifies microphone signals produced by the acoustic sensor. The intrinsic pre-amplifier may be actively regulated at the pre-determined bias point using negative feedback. Alternatively, the intrinsic pre-amplifier may be set to the pre-determined bias point by sweeping the pre-amplifier bias current for the intrinsic pre-amplifier over a range of currents.

Abstract: An audio host device has an electrical interface having a speaker contact, a microphone contact, and a reference contact. The reference contact is shared by a microphone and a speaker. The reference contact is also directly coupled to a power return plane of the audio host device. A difference amplifier is provided, having a cold input and a hot input. The hot input is coupled to the microphone contact. A variable attenuator circuit is also provided having an input coupled to receive a signal from a sense point for the reference contact, and an output coupled to the cold input of the difference amplifier. A controller has an output coupled to control the variable attenuator. Other embodiments are also described and claimed.

Abstract: Addressable amplified speakers assembly, and method for addressing the same, suitable for any permanent or temporary public address paging application. Amplified speakers assembly may incorporate VHF and UHF radios to provide wireless, one-way paging from a few feet to many miles away. These speakers can be added to any existing radio system with minimal effort or cost. The need for routing signal cable is eliminated, greatly reducing installation costs. Each speaker can be programmed for individual, group, or all-page access via DTMF or 2-Tone coding (up to 8 different addresses). The volume of each speaker can also be controlled remotely.

Abstract: Disclosed is a wireless MIC system for automatically paring, which comprises a wireless MIC which includes a paring button at its one side and facilitates a connection mode as it is automatically paired with an amplifier by transmitting a paring request signal when the paring button is on, and initializes a connection related information stored in a storing part when the connection mode is cancelled and converts an acoustic signal into a digital audio signal and transmits to the paired amplifier; and an amplifier which facilitates a connection mode as the wireless MIC and the amplifier are paired by setting a transmission and receiving channel of the amplifier and the wireless MIC, and amplifies a digital audio signal from the wireless MIC and outputs in an acoustic form.

Abstract: A condenser microphone includes: a true condenser microphone (TCM) pickup operable to generate an input signal at a high impedance corresponding to sound picked up thereby; an impedance conversion circuit connected electrically to the TCM pickup, and operable to convert the input signal from the TCM pickup to a converted signal at a low impedance; an amplifier circuit connected electrically to the impedance conversion circuit, disposed to receive a power signal, and operable for amplifying the converted signal so as to generate an output signal; and a phantom voltage module connected electrically to the TCM pickup, disposed to receive the power signal, and operable for generating a phantom signal from the power signal, the phantom signal having a voltage higher than that of the power signal and being provided to the TCM pickup for charging the TCM pickup.

Abstract: An electronic device includes an amplifier, an output unit, a processing unit, and a mute control circuit. The amplifier is for amplifying audio signals and generating amplified audio signals accordingly. The amplifier includes an output port to output the amplified audio signals. The output unit is for emitting sounds corresponding to the amplified audio signals. The processing unit is for generating a mute control signal. The mute control circuit includes a main circuit and an auxiliary circuit. The main circuit is for responding to the mute control signal, and for driving the amplifier to change between a mute state and a play state accordingly. The auxiliary circuit is for enabling the output port of the amplifier to be electrically grounded at the moment of supplying power to the electronic device.

Abstract: Methods are provided for solid-state implementation of a vacuum tube replacement device (VTRD) that includes a communication interface. The communication interface enables the VTRD to command or retrieve information regarding VTRD performance, function, and status. A VTRD may communicate with other VTRDs in a target amplifier retrofitted with compatible VTRDs and to an external user interface for programming or query/response. The methods presented for the vacuum tube replacement device system(s) are equally useful for non-vacuum tube systems such as audio amplifier circuits.

Abstract: A configurable amplifier circuit for a karaoke player is described. In one embodiment, a karaoke player includes: a DVD/CD reader port for coupling to a DVD/CD reader, a microphone input to receive audio signals from an external microphone, an MPEG decoder coupled to the DVD/CD reader port and the microphone input, the MPEG decoder having first and second output terminals, a processor coupled to the MPEG decoder, the processor to control the MPEG decoder, and a configurable amplifier coupled to the first and second output terminals, wherein a first audio signal originating from the first output terminal is selectively amplified by the configurable amplifier circuit in accordance with a second signal originating from the second output terminal.

Abstract: A power supply for supplying electric power comprises a power circuit which supplies L channels of electric power (L: positive integer), a control circuit board which outputs multiple types of control signals including a digital control signal and a PWM signal, a digital-to-analog converter having M channels (M: positive integer less than L) each of which converts the digital control signal into an analog control signal, and N demodulation circuits (N=L?M) each of which generates an analog control signal by demodulating the PWM signal. The control circuit board is electrically connected to the power circuit via the M channels of the digital-to-analog converter and the N demodulation circuits. N is a positive integer not more than M.

Abstract: The present invention concerns an audio amplifier circuit designed to provide an output signal to an audio transducer, said audio amplifier circuit comprising an audio power amplifier designed to receive an audio signal and designed to generate said output signal, a sensor designed to detect an audible sound having at least one noise component, to generate a detected signal. The audio amplifier circuit also includes a processing block configured to receive said detected signal at its input and to generate an off signal at its output, the latter being located at the input of said audio power amplifier. The processing block processes the detected signal according to said input signal to identify said noise component of said detected signal to generate a reference signal. The processing block generates the off signal when the value of said input signal is lower than the value of said reference signal.

Abstract: Disclosed is a differential microphone pre-amplifier circuit (120) for providing an amplified differential signal at a first (A) and a second (B) output terminal of the microphone pre-amplifier (120), including a first voltage controlled current generator (101), a second voltage controlled current generator (102) and a third voltage controlled current generator (103) all being configured to receive, amplify and convert a voltage signal generated by an associated microphone (110) to a current signal output.

Abstract: An amplifier circuit for thermoacoustic device includes a peak hold circuit, an add-subtract circuit, and a power amplifier. The peak hold circuit is configured to accept an audio signal and output a peak hold signal. The add-subtract circuit is configured to accept the audio signal and the peak hold signal, and output a modulated signal after a comparison operation of the audio signal and the peak hold signal. The power amplifier is configured to accept the modulated signal, amplify the modulated signal, and output an amplified voltage signal.

Abstract: A driver controller comprising a state machine for controlling transitions between a plurality of states. An output switch for providing a low impedance path to ground during transition periods. An output stage for decoupling output signal from driver amplifier during the transition periods.

Abstract: The disclosure is related to a method and a device of manufacturing a speaker. First, a roll element is fabricated by a roll-based manufacturing process and by using a material feeder, and the roll element is cut into many sheet elements by using a cutter. An inserting device is used to insert the sheet elements into a temporary storage device, and an extracting device is used to extract the sheet elements from the temporary storage device and place the sheet elements on another roll element fabricated by another roll-based manufacturing process and by using another material feeder. The sheet elements and the other roll element are combined. The roll elements and sheet elements may be vibrating membranes and porous electrodes of a flat speaker.

Abstract: A first selector receives a second input signal and a second reference voltage, and selects either one. A first buffer receives the output signal of the first selector, and outputs the signal thus received to a terminal of the first resistor, and to a terminal of the third resistor. A second selector receives a first input signal and a third input signal, and selects either one. A fourth selector receives, as input signals, the output signal of an operational amplifier, a signal that corresponds to the output signal of the second selector, and a signal that corresponds to the second input signal, and selects one signal selected from among the signals thus received.

Abstract: A dual-coil, dual magnetic gap electromagnetic transducer is provided where each voice coil is wired to include separate leads so that each individual voice coil may be driven by a separate amplifier or by a separate bridged amplifier. Signal processing may further be utilized to increase the output of the loudspeaker, to achieve extreme excursion without extreme distortion and to provide for alternative voice coil designs to address common problems with dual-coil, dual magnetic gap transducers, including, but not limited to, heat generation.