Abstract: A switch controller is provided that uses one or more capacitors to generate a slow turn on/slow turn off switch control signals to suppress audible switching noise in an audio switch. In some embodiments, an analog inverter and a capacitor are used to generate the switch control signals, while in other embodiments two capacitors are used to generate the switch control signals. To conserve power between switching states, routing logic is provided that ties the switch control signals to respective voltage rails and disables selected portions of the switch controller.
Abstract: A system and method for enhancing the audio experience on a consumer electronic device is disclosed. A system for enhancing the audio experience on a consumer electronic device including a parametrically configurable processing block is disclosed. An all-digital audio enhancement system suitable for embedding into a low cost, low power application specific integrated circuit is disclosed. A method for configuring an audio enhancement system on a consumer electronic device is also disclosed.
Abstract: A class D audio amplifier which provides both an alternating signal and a DC bias voltage to an electrostatic transducer (9). The amplifier comprises an input module (1) for generating a modulated sequence of pulses in response to an input audio signal, and an output module (3) for amplifying the sequence of pulses, which includes high speed switching output transistors (4, 5). A power supply (6) provides a supply voltage to the switching output transistors (4,5). A low pass filter (8) receives the amplified sequence of pulses and generates an output signal for the transducer. The amplified sequence of pulses from the output module (3) is fed to a voltage multiplier module (10) which provides a constant bias voltage for the electrostatic transducer.
May 18, 2012
August 21, 2014
WARWICK AUDIO TECHNOLOGIES LIMITED
Brian Atkins, Duncan Billson, David Hoare
Abstract: An audio signal adapter device and an audio signal receiving device are provided herein. The audio signal adapter device comprises: an input interface, a USB output interface, and a signal amplifying unit, in which the input interface is a headphone interface, and has a first audio signal input pin, configured to receive an audio signal sent by an audio signal sending device connected with the input interface and to output the audio signal to an input end of the signal amplifying unit; the USB output interface comprises an audio signal output pin; the signal amplifying unit is connected with the first audio signal input pin and the audio signal output pin for outputting an amplified audio signal; the audio signal output pin is a D+ pin or D? pin of the USB output interface.
Abstract: A motherboard includes a motherboard power supply connector and a time delay circuit. The motherboard power supply connector connects a power supply unit. The motherboard power supply connector has a power supply on pin and a power good pin. The power good pin is configured for receiving a power good signal from the power supply unit. The time delay circuit has an input terminal and an output terminal. The input terminal is configured for receiving a power supply on signal. The output terminal is connected to the power supply on pin and is configured for sending the power supply on signal to the power supply on pin after a time delay determined by the time delay circuit.
March 17, 2011
Date of Patent:
August 12, 2014
Hong Fu Jin Precision Industry (ShenZhen) Co., Ltd., Hon Hai Precision Industry Co., Ltd.
Abstract: A driver circuit includes a first driver amplifier that is configured to generate a first output in response to a first reference voltage input and a first audio input; a second driver amplifier that is configured to generate a second output in response to the first reference voltage and a second audio input; and a common mode (CM) amplifier, coupled to the first driver amplifier and the second driver amplifier. The CM amplifier is configured to generate an output in response to a second reference voltage input, the first reference voltage input being a divided version of the output. Gains of the first driver amplifier, second driver amplifier and the CM amplifier are equal. Noise at the output appears across a plurality of resistors coupled at the outputs of the first driver amplifier, second driver amplifier and the CM amplifier and cancels with respect to the output of the CM amplifier.
Abstract: A speaker system includes a first speaker, a second speaker and a driving circuit. The first speaker and the second speaker are different types of speakers. The driving circuit drives the first speaker with a first driving voltage and a first driving current and drives the second speaker with a second driving voltage and a second driving current, wherein the first driving voltage is larger than the second driving voltage and the first driving current is smaller than the second driving current. The present disclosure further provides a speaker driving circuit.
Abstract: A pulse width modulation signal with a less distortion component that is not influenced by a common-mode noise or an offset voltage is generated. Pulse signal generation circuits 6, 7 generate pulse signals S1, S2 whose pulse widths are discharge times t1, t2 of integrators 3, 4, respectively, a PWM signal generation circuit 8 detects discharge end timings of the integrators 3, 4 based on the pulse signals S1, S2, and a pulse whose pulse width is a time between discharge end timing of one of the integrators 4 and discharge end timing of the other one of the integrators 3 is generated so as to be output as a PWM signal Spwm.
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 microphone can include a capacitor capsule, an output buffer amplifier connected to the output of the capacitor capsule, and an audio limiter connected to the output of the output buffer amplifier, wherein the audio limiter limits the output level of the microphone at a threshold level. The microphone can include an adjustable output level. The microphone can include an integrated high-pass filter. The microphone can have an omnidirectional polar pattern.
Abstract: A system is described for maintaining synchrony of operations among a plurality of devices that have independent clocking arrangements. The system includes a task distribution device that distributes tasks to a synchrony group comprising a plurality of devices that are to perform the tasks distributed by the task distribution device in synchrony. The task distribution device distributes each task to the members of the synchrony group over a network. Each task is associated with a time stamp that indicates a time, relative to a clock maintained by the task distribution device, at which the members of the synchrony group are to execute the task.
Abstract: An apparatus comprises a first audio amplifier circuit configured to provide an analog audio signal and an analog switch circuit including a first input configured to receive the analog audio signal, a second input configured to receive a first digital data signal, and a first output configured to provide one of the digital data signal or the analog audio signal. The apparatus also includes a first feedback circuit coupled to the first audio amplifier circuit and the analog switch circuit output, the feedback circuit configured to bias the first audio amplifier circuit.
Abstract: An audio amplifier apparatus includes an audio amplifier which receives a single audio signal and produces a plus phase audio signal and a minus phase audio signal, both dependent upon the single audio signal. The plus phase audio signal and minus phase audio signal are received by first and second inputs of a speaker, respectively. A current sensing circuit senses a level of current received by the first or second inputs of the speaker and outputs a current sensing signal dependent upon the sensed level of current. An amplifying circuit receives and amplifies the current sensing signal. A mixer circuit receives the amplified current sensing signal and an audio drive signal and produces the single audio signal dependent upon the amplified current sensing signal and the audio drive signal. The single audio signal is produced at a node in-between two resistors.
December 18, 2012
June 19, 2014
PANASONIC AUTOMOTIVE SYSTEMS COMPANY OF AMERICA, DIVISION OF PANASONIC CORPOR
Abstract: A differential audio amplifier system and a related system to generate an output signal free or with only very limited clipping are disclosed. It provides a solution to solve the problem of limited electrical speaker amplifier output power available (e.g. inside battery driver applications). A differential speaker amplifier has positive and negative supply rails. In a first embodiment of the disclosure the negative supply rail is connected to the output of an inverting buck-boost converter and the positive supply rail is directly connected to VSS voltage. In a second embodiment of the disclosure the positive supply rail is connected to the output of a buck-boost converter and the negative supply rail is directly connected to a positive battery voltage.
Abstract: An electrostatic transducer loudspeaker includes a filterless class-D amplifier to modulate an audio input signal to generate a modulated signal containing a PWM switching carrier component, and a transformer directly connected at an output side of the filterless class-D amplifier and directly connected at an input side of an electrostatic transducer, whereby the equivalent capacitance of the electrostatic transducer and the equivalent inductance of the transformer establish a resonance circuit to demodulate the modulated signal to generate an AC voltage to drive the electrostatic transducer.
Abstract: A microphone preamplifier circuit (60) is described, adapted to be connected to a microphone circuit (MCD), the microphone circuit (MCD) comprising a microphone (3) and at least one output node (MO, MO?).
Abstract: A control unit alternately repeats a first state in which a first switch and a third switch are on and a second state in which a second switch and a fourth switch are on. A voltage detection unit compares the output voltage that occurs at one terminal (OUT terminal) of an output capacitor with a negative threshold voltage, and generates an abnormality detection signal which is asserted when the output voltage is higher than the threshold voltage Vt. When the abnormality detection signal is asserted, the control unit switches the on resistance of the first switch to a value that is higher than that in a normal state.
Abstract: A voice amplification assembly is provided for facilitating amplification of a voice for public speaking. The assembly provides a portable wireless microphone and a base unit operationally couplable to a pre-existing speaker. A transceiver is positioned in the base unit. The microphone has a transmitter which is operationally coupled to the transceiver. A processor is positioned in base unit and operationally coupled to the transceiver for adjusting and outputting an audio signal received from the microphone through the transceiver. An audio control is operationally coupled to the processor for inputting an adjustment to the audio signal. An output port is configured for connecting to an existing speaker to broadcast the audio signal.
Abstract: Audio is adaptively associated with speakers, depending on the speaker configuration that is present. Each speaker it receives an audio assignment based on its individual spectral characteristics. As more speakers are added, content is adaptively associated with that you speaker, and taken away from the previous.
Abstract: The teachings are directed to a power amplifier expansion card (“amplifier card”) for a computer. The amplifier card receives audio data through an input port and amplifies the audio data to high-level passive speaker power for transmissions through an output port. The amplifier card can comprise a circuit board having (i) at least two audio channels; (ii) an audio power amplification circuit for amplifying audio power to at least 20 W RMS per channel; and (iii) an onboard cooling system. The amplifier card can be used, for example, in a multimedia system having at least a studio controller operably connected to the amplifier card for receiving and processing input audio data. Examples of such multimedia systems include, but are not limited to, a television home entertainment system, an audio home entertainment system, a music production studio system, a gaming system, a personal computing system, or any combination thereof.
Abstract: Audio transmitter circuitry is disclosed that is configurable into different modes by the user, and can output either a differential or single-ended audio signal on two signal wires. Depending on the mode, the transmitter deals with noise on the signal wires by adjusting the input resistance that such noise sees looking into the transmitter. If the transmitter is configured in a differential mode, the input resistance looking back into the transmitter from the perspective of the noise on both signal wires is relatively high. If the transmitter is configured in a single ended mode, the input resistance of noise looking back from the active signal wire into the transmitter is relatively low, to in effect ground such noise back into the transmitter, without significantly presenting such noise to the receiver.
Abstract: In order to generate a multi-channel signal having a number of output channels greater than a number of input channels, a mixer is used for upmixing the input signal to form at least a direct channel signal and at least an ambience channel signal. A speech detector is provided for detecting a section of the input signal, the direct channel signal or the ambience channel signal in which speech portions occur. Based on this detection, a signal modifier modifies the input signal or the ambience channel signal in order to attenuate speech portions in the ambience channel signal, whereas such speech portions in the direct channel signal are attenuated to a lesser extent or not at all. A loudspeaker signal outputter then maps the direct channel signals and the ambience channel signals to loudspeaker signals which are associated to a defined reproduction scheme, such as, for example, a 5.1 scheme.
October 1, 2008
Date of Patent:
May 20, 2014
Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.
Christian Uhle, Oliver Hellmuth, Juergen Herre, Harald Popp, Thorsten Kastner
Abstract: Disclosed is a circuit structure for implementing an adaptive function in a class-D audio power amplifier circuit, comprising an operation amplifier, a pulse width modulator and a driver stage that are sequentially and serially connected, an input terminal of the operation amplifier being connected to an external audio signal output terminal, and an output terminal of the driver stage being connected to a loudspeaker and connected to the input terminal of the operation amplifier via a feedback loop. The circuit structure further comprises: one or a plurality of a carrier adaptive circuit, a frequency adaptive circuit, a driver adaptive circuit, a temperature adaptive circuit.
Abstract: A method for controlling a maximum signal level output to headphones of a wireless device is provided. The method includes: determining an impedance of the headphones; determining a carrier specific maximum signal level for headphones having the impedance; and, adjusting an audio amplifier of the wireless device coupled to the headphones to restrict the maximum signal level output to the headphones to the carrier specific maximum signal level.
Abstract: In accordance with an embodiment, a system for amplifying a signal provided by a capacitive signal source includes a first voltage follower device, a second voltage follower device, and a first capacitor. The first voltage follower device includes an input terminal configured to be coupled to a first terminal of the capacitive signal source, and the second voltage follower device includes an input terminal coupled to the first output terminal of the first voltage follower device, and an output terminal coupled to a second output terminal of the first voltage follower device. Furthermore, first capacitor has a first end coupled to a first output terminal of the first voltage follower device, and a second end configured to be coupled to a second terminal of the capacitive signal source.
Abstract: Methods and apparatus for audio signal clip detection are disclosed. The clip detectors may receive audio signals, from which peak reference signals, indicative of the highest voltage of the received audio signals, may be derived. The received audio signals may also be differentiated and phase-lagged to produce differentiated audio signals which may, in turn, be rectified to produce rectified differentiator signals. The rectified differentiator signals and the peak reference signals may be compared to thereby produce clip detect signals indicative of whether the received audio signals are clipped. The clip detect signals may then be used to indicate whether the received audio signal are clipped.
Abstract: Separate control of the operation of an audio amplifier and a charge pump that synthesizes a negative voltage supply (VSS) for improving the dynamic range of the audio amplifier. The audio amplifier is typically powered by a single positive power supply (VDD) and the charge pump is arranged to synthesize a negative voltage supply rail (VSS) that enables a greater dynamic range for the amplifier's “on” and “shut down” modes of operation. Also, when the audio amplifier enters its shut down mode of operation to create at least some isolation from Line_In audio signals provided at the amplifier's output by other electronic devices, the amplifier's charge pump stays “on” and continues to provide the negative voltage supply rail (VSS). In this way, the greater dynamic range offered by the presence of both the positive and negative voltage rails is provided even if the amplifier is in a shut down mode.
Abstract: The invention relates an electrostatic speaker system comprising—a high voltage switching power amplifier,—an extraction filter having an input coupled to an output of the high voltage switching amplifier, and—an electrostatic speaker element having a capacitive load and an input coupled to an output of the extraction filter. The combination of the extraction filter and capacitive load form a filter circuitry having at least a first filter stage and a second filter stage. The first filter stage comprising a RLC circuit having a resonant frequency ?O and a quality factor Q>½ and wherein the second filter stage being a low pass filter comprises at least one electrical element for damping a signal component at the resonant frequency of the RLC circuit at the output of the extraction filter.
Abstract: An audio amplifier includes a compensation unit, an output unit and a calibration unit. The compensation unit generates a compensation signal based on a digital input signal, a digital reference code, a mode signal and a digital approximation code. The output unit generates an output signal based on the compensated input signal. The calibration unit generates the digital approximation code based on the output signal and the mode signal. The digital approximation code includes a plurality of bits that are generated sequentially.
July 24, 2013
Date of Patent:
April 22, 2014
Samsung Electronics Co., Ltd.
Yong-Hee Lee, Chun Kyun Seok, Wang-Seup Yeum, Seung-Bin You, Bong-Joo Kim
Abstract: A valve power amplifier stage for an audio amplifier, which amplifier stage has at least one thermionic valve and a polarization circuit for polarizing the anode, the cathode and the control grid of the thermionic valve so as to determine the maximum output power. The polarization circuit comprises an adjusting module for adjusting the feed voltage of the anode and the polarization voltage of the control grid so as to adjust the maximum output power of the thermionic valve, and a potentiometer coupled with the adjusting module for allowing a user to control the adjusting means so as to select the desired maximum output power from a plurality of predetermined output power values.
March 16, 2011
Date of Patent:
April 22, 2014
Marco De Virgiliis, Sisinio Olivastri, Mario Fulvio Caramanico
Abstract: An amplification device amplifies sound waves that emit from a portable electronic device. The portable electronic device joins the amplification device at a horizontal orientation that is efficacious for watching videos in wide screen format. A slot in the amplifying device engages a speaker in the portable electronic device. The amplifying device receives sound waves generated by the speaker at a narrow, speaker receiving end, passes the sound waves through an acoustic channel, and finally emits the sound waves from a wide, amplifying end. Increasing surface area at the wide end of the amplifying device lowers the acoustic impedance, and consequently amplifies the sound waves. The sound waves amplify because acoustic impedance is lowered and matched to the proximate air. A cone-shaped dispersion port positions within the acoustic channel to optimize sound wave dispersion. A housing contains the components and has a sloped surface for supporting chargers.
Abstract: An exemplary speaker system includes a speaker, an audio amplifier, a detecting resistor, and a control unit. The audio amplifier is connected to the speaker and outputs a working voltage to the speaker. The detecting resistor is electronically connected between the speaker and the audio amplifier. The control unit is connected between the detecting resistor and the audio amplifier. The control unit detects a voltage of the detecting resistor, calculates a real-time power of the speaker, and compares the real-time power with a rated power of the speaker. When the real-time power equals to or exceeds the rated power, the control unit adjusts the working voltage until the real-time power is below the rated power.
Abstract: An apparatus comprising a first line driver, a second line driver, a charge pump, and a control logic circuit coupled to the first line driver and the second line driver and configured to disable the charge pump when both a first control signal associated with the first line driver and a second control signal associated with the second line driver indicate a charge pump disable state. A network component comprising at least one processor configured to implement a method comprising receiving a first control signal and a second control signal, disabling a charge pump when both the first control signal and the second control signal indicate a charge pump disable state, and operating the charge pump to boost a voltage when the first control signal, the second control signal, or both indicate a charge pump active state.
Abstract: A backup alarm for producing an audible warning signal which warbles or beeps, at selected audible output power (Db) levels includes a computer which drives a speaker by switching drive voltage to the speaker with above audible, high frequency pulses in packets repetitive at audible frequency. The high frequency pulses are pulse width modulated at different ratios selected from tables in memory of the computer in accordance with the voltage from a battery power source which provides the drive voltage so that the audible output power remains constant at the selected level over a wide range of power source voltage. By providing for warning/alarm signal generation by means of an operating system which provides both high, above audible frequency and audible frequency switching, power conservation and warning signal output power control are accomplished without interference.
Abstract: A Class-G amplifier including a first and second driving transistor configured to receive an input voltage; a first supplying terminal connected to the first driving transistor to supply a first supplying voltage. The amplifier also comprises: a second supplying terminal connected to the second driving transistor to supply a second supplying voltage in absolute value higher than said first voltage; a first power transistor connected to the first driving transistor to form a first Sziklai pair structured to be activated by a first input voltage lower in absolute value than the first supplying voltage; a second power transistor connected to the second driving transistor to form a second Sziklai pair structured to be activated by an input signal comprised between the first supplying voltage and the second supplying voltage.
Abstract: An audio source device has an audio connector to which an external load can be connected. An audio signal is amplified and then driven through the connector, wherein the amplification process uses feedback from the return pin of the connector. The return pin is directly connected to a ground break resistor circuit. The ground break resistor circuit is connected between the return pin of the audio connector and circuit ground. A determination is made as to whether the connected external load has a low impedance or a high impedance. When a low impedance load is detected, such as a headset, the ground break resistor circuit is essentially short-circuited. When a high impedance load is detected, the ground break resistor circuit is maintained and its value is set in accordance with the detected load. Other embodiments are also described.
September 28, 2012
April 3, 2014
David C. Breece, III, Nathan Johanningsmeier, Cara S. Yang
Abstract: An amplifier circuit comprises an input, for receiving an input signal to be amplified; a preamplifier, for amplifying the input signal based on a variable gain; a power amplifier for amplifying the signal output from the preamplifier, and a variable voltage power supply for supplying one or more supply voltages to the power amplifier. The supply voltages are adjusted based on the variable gain or the input digital signal. According to other aspects of the invention, a power supply of an amplifier circuit is clocked using a clock signal, whereby the clock signal has a frequency that varies in accordance with a volume signal or an input signal.
Abstract: A speaker control system includes a speaker; an audio amplifier electrically connected to the speaker and used for driving the speaker, the audio amplifier having a shutdown pin and a reference voltage input pin; a switch circuit, a first end of the switch circuit being electrically connected to the shutdown pin and a second end of the switch circuit being connected to the reference voltage input pin; and a processor electrically connected to the shutdown pin and the first end, when the processor outputs a first voltage signal, the audio amplifier being enabled and the reference voltage input pin being kept at a reference voltage, when the processor outputs a second voltage signal, the audio amplifier being disabled and the switch circuit switching the reference voltage input pin from the reference voltage to a low voltage level.
Abstract: An audio console system includes an input for receiving an audio signal. The system may also include a user adjustable input amplifier which may amplify audio signals received from the input with a predefined gain. The system may additionally include a direct out output amplifier provided after the adjustable input amplifier. The direct out output amplifier may output a direct out output signal. The direct out output amplifier may adjust a gain of a signal transmitted from the adjustable input amplifier. The direct output amplifier may be configured in such a way, that, upon a user adjustment of the adjustable input amplifier, the direct out output amplifier may adjust the gain of the direct out output signal inversely to the adjustment of the input amplifier resulting in a predefined gain of the audio signal from the at least one input to the direct out output being maintained.
Abstract: An electrical apparatus includes a frame, a speaker connected to the frame, a digital signal processor in communication with the speaker to receive audio data and control data to control the speaker, the digital signal processor connected to the frame, and a lamp base coupler electrically connected to the speaker and receiver, the lamp base coupler detachably connectable to a power source, when the power source is present. A method of steering the diffused sound field includes, broadcasting at least one calibration audio signal through a plurality of speakers (M) in an audio system, receiving the calibration audio signal in a plurality of microphones spaced apart and positioned about at a listening position, and calculating respective relative speaker placement angles relative to the listening position between each of the plurality of speakers in response to receipt of the calibration audio signal in the plurality of microphones.
Abstract: A terminal having a piezoelectric speaker system includes a control unit to generate a sound source signal, a first amplification unit to provide a voltage to amplify the sound source signal, and a piezoelectric module to vibrate according to the amplified sound source signal, the piezoelectric module being configured to transmit vibrations to a contact medium to generate a sound. A method for generating a sound using a piezoelectric speaker includes amplifying a sound source signal, generating a vibration in a piezoelectric module according to the amplified sound source signal, and transmitting vibration to a contact medium for generating the sound.
Abstract: An audio amplifier for portable devices is provided, which includes a hollow or a solid shell body and an inner container receiving in the shell body, a large opening for sound transmission is defined on the front of the shell body, and a groove is disposed on the top of the shell body, a sound absorbing aperture is defined at the bottom of the groove, the inner container comprises a curve-shaped pipeline which extends inwards from the sound absorbing aperture to the shell body until arriving the large opening for sound transmission, and the width of the curve-shaped pipeline is increased gradually as the curve-shaped pipeline extends inwards.
Abstract: An amplifying device is provided that reduces power consumption and quickly starts amplification of an audio signal of a channel to be used. A control section 17 inputs a control signal for instructing operation or standby into post-amplifying sections 11b and 12b, and inputs a control signal for instructing standby to post-amplifying sections 13b and 14b. In the post-amplifying section 11b, when the control signal for instructing standby or operation is input from the control section 17, a modulation circuit 52 modulates the analog audio signal into a switching signal. An output stage circuit 54 amplifies the output signal. When the control signal for instructing the operation is input from the control section 17, a driving circuit 53 drives the output stage circuit 54 in response to the switching signal, and stops the driving of the output stage circuit 54 when the control signal for instructing standby is input.
Abstract: A switching mode amplifier and method. A voltage divider comprising two series connected reactive components produces, on a center line, a fraction of a voltage received on a first line and a second line. The switching structure produce a fraction of the power supply voltage to the first port or the second port by either one of 1) a first configuration that connects the first port to the first input and the second port to the center line, or 2) a second configuration that connects the first port to the center line and the second port to the second input. A controller responds to a sequence of commands to provide the fraction of the voltage by alternating the switching structure between the first configuration and the second configuration.
Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.
June 3, 2011
Date of Patent:
February 25, 2014
Wolfson Microelectronics plc
John P. Lesso, John L. Pennock, Peter J. Frith
Abstract: A driving circuit for a sound outputting apparatus includes a H-bridge and a charge pump established by six switches for driving two types of loudspeakers, respectively. The six switches include two common switches to be configured in the H-bridge and the charge pump, thereby reducing the costs and circuit area of the driving circuit.
Abstract: An audio amplification apparatus for attachment to a device having a loudspeaker. The apparatus (10) comprises a vibration transducer (30) for attachment to the device having the loudspeaker (20), an amplifier (40) coupled to the vibration transducer (30) for amplifying an electrical signal representing at least in part an audible output of the loudspeaker (24), and an audio output port (52) operably coupled to the amplifier, thereby permitting connection to an audio output device (60).
Abstract: This high fidelity audio amplifier with very low distortion and high efficiency (10) includes: an input (12) for an audio signal to be amplified and an output (14) for feeding a load (16) with the amplified audio signal; a reference voltage generator (18) having very high linearity and low output impedance, capable of receiving as an input the musical signal to be amplified; a power voltage generator (20), the output of which is connected to the output of the reference voltage generator (18), through a coupling impedance (22), the modulus of which is at least ten times lower than the modulus of the impedance of the load (16) capable of being fed by the output (14) of the amplifier; and means (28A, 28B, 30, 32) for inputting at the input of the power voltage generator (20), a representative signal of the current provided at the output by the reference voltage generator (18).