Abstract: Disclosed is a circuit for preventing an output of a pop noise, which occurs from an audio amplifier when a power switch of an electronic device loading the amplifier is turned on/off. The circuit may comprises an analog switch for switching an electrical connection between an audio amplifier and a speaker, and a signal delay circuit capable of respectively delaying times that the operating states of the analog switch and the power supply are changed when the power switch is turned on/off, and it is structured such that the analog switch is already opened state at the time that the power supply is on/off. Accordingly, it is possible to prevent the pop noise from being outputted through a speaker connected to the amplifier. The circuit of the invention can be applied to a variety of electronic devices having an audio amplifier.

Abstract: An audio amplifier and speaker system are stacked and magnetically coupled together. The audio amplifier is coupled for receiving an audio signal. A first securing assembly is provided on a bottom surface of the amplifier. The first securing assembly may be a foot formed on the bottom surface of the audio amplifier. The speaker is electrically coupled to the amplifier. A second securing assembly is provided on a top surface of the speaker. The second securing assembly may be a receptacle formed in top surface of the speaker. The foot is inserted into the receptacle. The foot and receptacle are magnetically coupled to attach the amplifier to the speaker. The foot has a first electrical connector, and the receptacle has a second electrical connector mated to the first electrical connector to route the audio signal from the amplifier to the speaker.

Abstract: In one embodiment the present invention includes a method for starting up a class D amplifier. The method comprises increasing, gating, and driving. The increasing includes increasing a duty cycle of a pulse train from a first duty cycle to a second duty cycle. The gating includes gating a signal based on the increasing of the duty cycle. The gating results in a gated signal. The driving includes driving an output signal from the gated signal to charge an output capacitor. The output capacitor is coupled to a speaker. The increasing of the duty cycle contributes to the charging of the output capacitor such that switching sounds detectable by the human ear are reduced.

Abstract: An object is to provide an audio circuit in which flow of excessive current through a capacitive speaker and a drive circuit thereof can be prevented while degradation of sound quality of high-pitched tones is suppressed. The audio circuit for driving a capacitive speaker includes: a weighting circuit for performing weighting in conformity with frequency components of an audio signal; and a signal-voltage limiting compression circuit for compressing a signal, which is input to the drive amplifier or which has been output from the drive circuit, at a prescribed compression ratio in accordance with a difference voltage between the output signal of the weighting circuit and a preset threshold voltage when the weighted signal exceeds the threshold voltage.

Abstract: The present patent application comprises a digital to analog converter reference circuit, comprising a capacitor connected to a current source, a positive terminal of the capacitor connected to a first switch, the first switch electrically connecting the positive terminal of the capacitor to a positive input terminal of a DAC circuit, a negative terminal of the capacitor connected to a second switch, the second switch electrically connecting the negative terminal of the capacitor to a negative input terminal of the DAC circuit. In another example, the present patent application comprises a method for converting digital code to an analog signal, comprising charging a reservoir capacitor to a reference voltage level, transferring stored charge from the reservoir capacitor to DAC feedback capacitors, and transferring the stored charge from the DAC feedback capacitors to DAC output terminals.

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 system is provided for use in an audio signal processor to reduce the order of the loop to remove sound artifacts from an audio signal that includes an input for receiving an audio input signal a control loop of order greater than one configured to process the audio input signal and to output a Pulse Width Modulated audio output signal, a circuit for performing a gradual reduction of the order of the control loop such that prior to entering a shut down state the order is reduced to a single order and a circuit to disconnect a Driver Circuit from the Pulse Width modulated signal operated by a timing device designed to switch at the moment of zero average output value.

Abstract: An audio processing apparatus comprising: channel determination section for determining which one of a combination of the first left audio signal and the first right audio signal and a combination of the second left audio signal and the second right audio signal is included in multichannel audio data; and switching section for causing the first amplification section to amplify the first left audio signal and supply the amplified first left audio signal to the first speaker terminal and causing the second amplification section to amplify the first right audio signal and supply the amplified first right audio signal to the second speaker terminal when the combination of the first left audio signal and the first right audio signal is determined to be included; and causing the first amplification section to amplify the second left audio signal and supply the amplified second left audio signal to the third speaker terminal and causing the second amplification section to amplify the second right audio signal and su

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: In order to improve operability of two devices which function in an integrated manner and also function separately in a standalone mode, a navigation device switches an output of an audio signal to a reproducing device during a time when an electrical connection with the reproducing device is being detected (S05), and switches the output of the audio signal to a built-in speaker by switching means during a time when the electrical connection with the reproducing device is not being detected (S11). The reproducing device mixes audio signals simultaneously input from one of a disc reproducing device and a radio receiving portion and from the navigation device during a time when the electrical connection with the navigation device is being detected, and processes the audio signal input from one of the disc reproducing device and the radio receiving portion during a time when the electrical connection with the navigation device is not being detected.

Abstract: A vibration device according to the present invention includes: a diaphragm; a support system member that supports the diaphragm in a manner that allows the diaphragm to vibrate; a tubular voice coil bobbin attached to the diaphragm; a magnet which is disposed on at least one side among an inner circumferential surface side and an outer circumferential surface side of the voice coil bobbin, and which is polarized in a vibration direction of the diaphragm, and which forms a magnetic gap on a side that faces the voice coil bobbin; a voice coil which is attached to the voice coil bobbin so as to be disposed within the magnetic gap, and which vibrates the diaphragm and the voice coil bobbin in response to a driving force generated when an input electrical signal is inputted into the voice coil; and a magnetic material member which is attached to the voice coil bobbin so as to be disposed in a balancing position within the magnetic gap, and which is, when vibrating together with the voice coil bobbin, subjected to

Abstract: The present invention detects whether the supply voltage applied to the power supply terminal (3) is used for the dynamic speaker or for the piezoelectric speaker by the power supply voltage detection circuit (10), switches the gain of the amplifier circuit (8) in accordance with the detection result by the gain switching circuit (11) so that the same output power is produced for the same input signal in the respective speaker driving, and amplifies the input signal from the input terminal (5) by the amplifier circuit (8) having the gain to drive a speaker (1) that is connected to the output terminals (6, 7).

Abstract: There is provided a dock without a power source for a portable digital device with at least one integrated speaker driver. The dock may include a platform for placement of the portable digital device; a protrusion located at the platform for connection of the portable digital device with the dock with the protrusion including a slot for egress of air from at least one hole in a casing of the portable digital device to the dock; and at least one primary chamber to receive air from the portable digital device with the at least one primary chamber having a vented port for the egress of air. Advantageously, sound from the at least one integrated speaker driver is amplified when the portable digital device is connected to the dock. The connection of the portable digital device with the dock may be securable.

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: Systems and methods for performance improvements in digital switching amplifiers using low-pass filtering to reduce noise and distortion. In one embodiment, a digital pulse width modulation (PWM) amplifier includes a signal processing plant configured to receive and process an input audio signal. The amplifier also includes a low-pass filter configured to filter audio signals output by the plant. The filtered output of the plant is added to the input audio signal as feedback. The plant may consist of a modulator and power switch, a noise shaper, or any other type of plant. An analog-to-digital converter (ADC) may be provided to convert the output audio signal to a digital signal. Filtering may be implemented before or after the ADC, and a decimator may be placed after the ADC if it is an oversampling ADC.

Abstract: An amplification circuit and an audio output equipment provided with same are disclosed. The amplification circuit is provided with first, second and third amplifiers and an inverter. The first amplifier amplifies a first audio signal and outputs a first output signal. The inverter inverts a second audio signal and outputs an inverted signal. The second amplifier amplifies the inverted signal and outputs a second output signal. The third amplifier outputs a reference voltage corresponding to a central voltage of the amplitude of the first and the second output signals.

Abstract: A Class D amplifier includes a ramp generator configured to generate a first signal and a second signal. Each of the first signal and the second signal oscillate between a minimum value and a maximum value. A signal generator is configured to receive an input signal, the first signal and the second signal. The input signal has a value that is between the minimum value and the maximum value. A signal generator is configured to generate a third signal and a fourth signal. The third signal is generated based on each of the first signal and the second signal transitioning from a value above the value of the input signal to a value below the value of the input signal. The fourth signal is generated based on each of the first signal and the second signal transitioning from a value below the value of the input signal to a value above the value of the input signal. An output stage is configured to drive a load based on the third signal and the fourth signal.

Abstract: A class G headphone amplifier circuit with improved power efficiency and low EMI. It may use an automatic signal level detector to detect the signal level of incoming signals and determine positive and negative power supplies for headphone amplifiers accordingly. A voltage generator may generate pairs of differential output voltages at a plurality of amplitude steps, and supply to headphone amplifiers the pair with the amplitude determined by the automatic signal level detector. As a result, headphone amplifiers are biased according to the input signal level, and the multiple voltage rails may improve power efficiency and avoid clipping.

Abstract: An amplifier circuit having low-voltage transistors and being configured to operate at a high voltage level is provided. The amplifier circuit includes a driver circuit having a first stage and a second stage connected in series between a power supply and a ground. The driver circuit has a control terminal for receiving a signal for controlling a current flow in the output driver. The amplifier circuit also includes a switch transistor having a drain connected to the power supply, a source connected to the control terminal of the output driver, and a gate. A bias circuit is coupled to the switch transistor. In a first mode of operation, the bias circuit is adapted to turn off the switch transistor, and, in a second mode of operation, the bias circuit is adapted to turn on the switch transistor. The bias circuit is adapted to maintain a gate-to-drain voltage of the switch transistor within a predetermined voltage range.

Abstract: A method and apparatus for selecting and mixing electronic signals. The circuit has an operational amplifier and two or more ganged, tapped-resistors in which the tap divides the resistance into a first and a second resistance. The tapped-resistors are connected so that either the first or the second resistance provides the effective input resistance for that signal at the operational amplifier. The second resistance of one of the tapped-resistors provides the output resistance for all signals at operational amplifier. As the tapped resistors are equivalent and their taps ganged, when the signals are mixed, those signals whose effective input resistance at the operational amplifier is selected to be the second resistance have unit gain, while those signals whose effective input resistance at the operational amplifier is selected to be the first resistance have a gain equal to the second resistance divide by the first resistance.

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: An amplification circuit amplifies an input signal. A signal detecting circuit detects whether the input signal is in a signal present state or in a signal absent state. A period detecting circuit detects a signal present duration for which the signal detecting circuit detects that the input signal is in the signal present state. A time setting circuit sets a control waiting time, depending on the signal present duration detected by the period detecting circuit. A control circuit limits outputting of the amplification circuit after the control waiting time set by the time setting circuit has elapsed since the signal detecting circuit detected the signal absent state of the input signal.

Abstract: The invention provides a Hi-fi sound system for the digital transfer of sound information from a digital signal source (2) to one or several loudspeaker enclosures with integrated amplifiers is described. The system includes a control unit (4) that superimposes a digital signal corresponding to the sound information for all the loudspeakers onto a DC supply current for the amplifier units (9) of the loudspeakers (7). The loudspeakers may be connected in a chain, one after another, or by branching, and the cables (10) may contain as little as two leads and the connection to the control unit (4) and the loudspeakers (amplifier units 9) may be of a simple snap-on or screw type.

Abstract: An audio device and an audio input/output method are described, which is coupled to an audio port, and includes a capacitor, a load, an output amplifying module, and an input amplifying module. The capacitor and the load are coupled to the audio port. The output amplifying module is operated at a first working voltage, for outputting a first audio signal to the audio port. A direct current (DC) level of the first audio signal is substantially zero volts. The input amplifying module is operated at a second working voltage, in order to receive a second audio signal from the audio port. When the audio port is in an output state, the output amplifying module is enabled and the input amplifying module is disabled, and when the audio port is in an input state, the input amplifying module is enabled and the output amplifying module is disabled.

Abstract: A method and apparatus for creating a third signal channel from an input signal received in each of a first and second channel involves inverting a predetermined frequency range of signals in the first channel out of phase with a corresponding frequency range of signals in the second channel. Thereafter, the inverted signal in the first channel and the corresponding frequency signal in the second channel may be communicated to a speaker, which is bridged across the first and second channels, as the third signal channel. This speaker produces sound corresponding to the difference (i.e., the frequency range determined by the predetermined bandwidth of the inverted signal) between the inverted signal in the first channel and the corresponding frequency signal in the second channel.

Abstract: A power foldback circuit to automatically control the power of an audio amplifier by using the volume inputs to a pre-amp source which drives the audio amplifier. In an embodiment, a Universal Serial Bus (USB) on a personal computer is used to drive the audio speakers. In this circuit an audio digital to analog converter (DAC) with a USB interface receives a digitally encoded audio signal from a personal computer (PC). The USB DAC outputs an analog audio signal to a audio amplifier circuit. A supervisory circuit monitors the power used by the audio amplifier and through a volume control circuit lowers the volume control into the USB DAC to prevent the entire circuit from drawing more than the allowed power supplied by the USB connection to the PC.

Abstract: A mobile communication device includes an audio receiving unit, an audio adjusting unit, and an audio output unit. The audio receiving unit receives audio signals. The audio adjusting unit adjusts the audio signals and amplifies the audio signals of a predetermined frequency band. The audio output unit outputs the adjusted audio signals received from the audio adjusting unit.

Abstract: An audio player with illumination effect has an audio play host and a lighting box. The audio play host has a housing in which speakers, a circuit board and a power amplifiers are mounted. The housing further has audio signal connectors, buttons and a display and is defined with at least one mounting hole. The lighting box is mounted on the audio play host and has a casing, at least one lamp socket and at least one lamp. The lamp socket with two ends respectively extends into the housing and the casing to electrically connect the circuit board and hold the lamp. In addition to amplify and output an audio signal from the audio signal connectors, the control circuit determines on and off operations and illuminating intensity of the lighting box.

Abstract: An amplifier circuit includes a first circuit and a second circuit connected in series. The first circuit has a first terminal coupled to a first power supply terminal, a second terminal coupled to an output node, and a control terminal for receiving a first signal for controlling a current flow. The second circuit has a first terminal coupled to the output node, a second terminal couple to a second power supply terminal, and a control terminal for receiving a second signal controlling a current flow in the first circuit. A bias circuit is coupled to the third terminal of the first circuit and is configured to limit a current flow in the first circuit when a voltage at the output node is outside a predetermined voltage range. In an embodiment, the bias circuit includes a plurality of diode devices connected in series and a switch device coupled to the diode devices.

Abstract: A switching audio amplifier adapted in a digital speaking device for driving a speaker is provided. An audio amplification method implemented for the switching audio amplifier is also provided. In the switching audio amplifier, a comparison stage compares an audio input signal with a saw-tooth signal to generate a Pulse Width Modulation (PWM) signal. A driver stage buffers the PWM signal to drive the speaker. A detector detects amplitude of the input signal to generate a control signal, and a saw-tooth generator adjusts a transition rate of the saw-tooth signal based on the control signal.

Abstract: A fiber optical audio preamplifier receives audio signals from an audio source, amplifies the audio signals, and transfers the signals to a power amplifier. The fiber optical audio preamplifier has at least one first signal converter. Each first signal converter acquires one audio signal from one audio source and converts the audio signal to a modulated light signal. At least one fiber optic volume control device that includes a variable optical attenuator that is connected to receive the modulated light signal. A control signal for sets an attenuation factor of the variable optical attenuator for attenuating the modulated light signal to control volume of the audio signal. One second signal converter is in communication with each fiber optic volume control device to receive the attenuated modulated light signal and demodulate the attenuated modulated light signal to recover the audio signal for transmission to the power amplifier.

Abstract: The embodiments described herein relate to amplifier circuits with power rails. The power rails are generated in response to an input signal, which will typically be an audio signal, and with a sufficient magnitude to power the amplifier and to generate an output signal corresponding to the input signal.

Abstract: A wide area fire safety and detection system is disclosed. The system includes a control node configured to execute a first detection routine, wherein the control node has a network interface, and an amplifier having an audio output, wherein the amplifier is configured to communicate the audio output to a plurality of fire safety nodes. The system further includes a remote node in communication with the control node, wherein the remote node has a network interface configured for communication with at least the network interface of the control node, and an audio converter configured to receive the audio output and generated a converted audio output, wherein the converted out is compatible with a microphone input.

Abstract: The invention concerns an accessory (112) for coupling to a portable electronic device (110). The accessory includes an interface (120) for coupling to the portable electronic device, an identifier (124) in which the identifier generates at least in part a parameter and at least one speaker (128). Only if the accessory contains more than one speaker, the parameter generated at least in part by the identifier causes an audio amplifier (148) that drives one of the speakers to be activated. In addition, the parameter generated at least in part by the identifier can cause the audio amplifier to be deactivated if the accessory contains only one speaker.

Abstract: An audio device includes a jack, a switch, an amplifier, an internal sound producer, and a determining circuit. The jack establishes a connection with an external sound producer. The switch is in an opened state when the connection is established, and in a closed state when the connection is open. The amplifier amplifies audio signals to amplified audio signals and sends the amplified audio signals to the switch. The determining circuit receives the amplified audio signals from the switch, and generates a high voltage to control the amplifier not to output the amplified audio signals to the internal sound producer when the switch is in the closed state, and generates a low voltage to control the amplifier to output the amplified audio signals to the internal sound producer. The determined circuit further filters out the amplified audio signals when the switch is in the opened state.

Abstract: A miniature speaker device includes a housing, a speaker mounted on the housing, a passive radiator mounted on the housing and vibrating in resonance with vibration of the speaker and having no driving system and a low frequency range amplification circuit for amplifying sound pressure in frequency components of a low frequency range of a single audio signal input in the speaker.

Abstract: A system and method for recording and reproducing three-dimensional sound events using a discretized, integrated macro-micro sound volume for reproducing a 3D acoustical matrix that reproduces sound including natural propagation and reverberation. The system and method may include sound modeling and synthesis that may enable sound to be reproduced as a volumetric matrix. The volumetric matrix may be captured, transferred, reproduced, or otherwise processed, as a spatial spectra of discretely reproduced sound events with controllable macro-micro relationships.

Abstract: Methods and apparatus for enabling auto-recovery of a digital audio amplifier after a short-circuit are disclosed. In accordance with one embodiment, a short-circuit is detected by both detecting a switching signal at an output of the digital audio amplifier and sensing a mute signal coupled to the digital audio amplifier. Once a short-circuit has been detected, a reset signal is provided to a reset input of the digital audio amplifier when the switching signal indicates that the digital audio amplifier is not switching and the mute signal indicates that the amplifier is in an un-muted state.

Abstract: An amplifier circuit for capacitive transducers, such as miniature electret or condenser microphones, wherein the amplifier circuit comprises bias control means adapted to improve settling of the amplifier circuit. Another aspect of the invention relates to a miniature condenser microphone and a monolithic integrated circuit comprising an amplifier circuit according to the present invention. The present invention provides amplifier circuits of improved performance by resolving traditionally conflicting requirements of maintaining a large input resistance of the amplifier circuit to optimize its noise performance and provide fast settling of the amplifier circuit.

Abstract: A classroom sound amplification system adapted for providing information aiding at diagnosing possible erroneous or inappropriate conditions or configuration of the system is disclosed. The system comprises a microphone device converting a voice to a sound signal and connecting to a sound processing device processing the sound signal and generating a processed sound signal, and a speaker device connecting to the sound processing device and converting the processed sound signal to a processed voice. The microphone device, the sound processing device, the speaker device and one or more A/V-devices are connected to or form part of the control device allowing the control device to collect operational information concerning the operation and/or status of devices of the system by monitoring predefined operational a parameters at various points in time.

Abstract: There is provided a low-cost loudspeaker system which can adjust attenuation and provide protection against an excessive input. Between input terminals and a loudspeaker unit is provided a serial circuit including a plurality of resistor elements. A switch is provided which can switch between connected and disconnected states of two points, which includes one or more resistor elements of the serial circuit therebetween, through an over-current protection element.

Abstract: A dynamic contoured-sound/subwoofer-synthesis system including an adjustable high pass filter coupled to the input terminal, the high pass filter being designed to provide a variety of frequency response shapes in response to adjustments thereof. A primary amplifier is coupled to receive one of the variety of frequency response shapes from the adjustable high pass filter and includes a main operational amplifier (op-amp) with the inverting input coupled to the adjustable high pass filter through a series connected input capacitor and input resistor. The primary amplifier provides low frequency signal gain and shaping of the received frequency response shape. A high frequency signal shaping circuit includes a feedback op-amp coupled to the inverting input of the main op-amp through a feedback resistor and a feedback capacitor.

Abstract: An amplification circuit for driving an audio signal diffuser that includes a generation circuit of a first pre-charging signal, the generation circuit including an amplifier provided with an input terminal for receiving the first pre-charging signal and provided with an output terminal for providing a second pre-charging signal as a function of the first pre-charging signal, and a decoupling capacitor of the amplifier from the diffuser, the capacitor connected to the output terminal for charging by the second pre-charging signal.

Abstract: A personal listening device used in connection with the amplification of signals for enhancing the perceived quality and ambiance of sound heard by listener using stereo headphones or small speaker systems utilizes a difference signal that is cross-fed between stereo channels. The invention provides a perception of spatial presence in music sound when used with either stereo headphones or small speaker systems. The circuitry, wiring and packaging provide for multiple output jacks allowing for convenient sharing of the enhanced output signal from a personal listening device with other persons using headphones. The invention provides effects similar to stereo enhancement, surround sound, and psychoacoustic imagery in a small, inexpensive package for enhancing a user's audio experience.

Abstract: A speaker driver circuit driven by positive and negative voltages, comprising: at least one operational amplifier providing an output to a headphone speaker, and a voltage converter receiving a supplied voltage (VDD), generating r-fold positive and negative voltages (r·VDD and ?r·VDD, wherein r is any positive real number except 1) according to the supplied voltage, and supplying the positive and negative voltages to the operational amplifier for its high and low operation voltage levels respectively.

Abstract: The invention provides an integrated circuit. The integrated circuit receives a first signal from a microphone via a first node. In one embodiment, the integrated circuit comprises a biasing circuit and a buffering circuit. The biasing circuit is coupled between the first node and a second node, drives the microphone with a first voltage source, and filters the first signal to generate a second signal at the second node. In one embodiment, the biasing circuit comprises a first resistor, a first capacitor, and a load element. The first resistor is coupled between the first voltage source and the first node. The first capacitor is coupled between the first node and the second node. The load element is coupled between the second node and a second voltage source. The buffering circuit is coupled between the second node and a third node and buffers the second signal to generate a third signal at the third node.

Abstract: Sound reproduction systems are described that have superior response to pure bass frequency signals from musical instruments such as electric bass guitar and string bass. A first amplifier drives a low frequency woofer and a second amplifier drives a full range speaker system. The bass component of the audio signal handled by the second amplifier is monitored and progressively compressed as the bass energy approaches a critical level that may damage one or more elements of the full range speaker. Speaker protection devices are also described that passively limit damaging pulses into speakers typically caused by plugging in equipment.

Abstract: An amplifier for electric guitar including a plurality of foot switch selectable preamplifier channels which can be set to provide differing sonic characteristics, and also including a power amplifier section for driving a loudspeaker that can be switched between at least two different power or performance capabilities. User operable switching dedicated to at least one of the preamplifier channels is provided to select preferred power amplifier parameters in conjunction with differing channel voicings. Thus, differing preferred power amplifier characteristics may be pre-set and assigned to individual preamplifier channels and called up automatically in conjunction with the remote channel selection.

Abstract: A monitor with reminder sounds is disclosed. The device includes at least a monitor, at least a touch button and an audio player. The touch button is disposed on the monitor for adjusting status of the monitor. The audio player is also arranged on the monitor and is connected with the touch button. When pressing the touch button, the audio player receives a signal and makes a sound. The monitor further includes a detection module that is used to check output image signals of the monitor. When detecting errors of output image signals of the monitor, the detection module sends a detection signal to the audio player so as to make the audio player generate a sound. Thus the user is reminded that whether the touch button is pressed precisely. Furthermore, the device also informs the user that the monitor is in abnormal status. Therefore, the present invention provides users more convenience of use.

Abstract: In one embodiment, an amplification circuit receives an analog signal and adds another signal to the analog signal to modify the minimum amplitude of the analog input signal.