Abstract: A variable equalizer apparatus for forward and/or reverse equalizers in an amplifier. The system can include a structure to allow continuous contact of the signal flow as an equalizer is removed; jumpers with fixed resistors and associated capacitors and inductors to produce a variable range over many different values; and/or variable resistance potentiometers with fixed resistors and associated capacitors and inductors to produce a variable range over separate value equalizers.

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: A M-bridge class-D audio amplifier for portable applications and a method of driving a three-wire audio output device comprises a stereo signal source producing first and second input stereo digital signals; circuitry adapted to receive the first and second input stereo digital signals and produce three stereo signals comprising a first, second, and third digital signal, wherein the three stereo signals generate PWM waves comprising a first, second, and third digital signal PWM wave; exactly three pairs of MOSFETs driven by the first, second, and third digital signal PWM waves respectively; and a three-wire speaker system comprising a first wire driven by the first digital signal PWM wave through the first pair of MOSFETs; a second wire driven by the second digital signal PWM wave through the second pair of MOSFETs; and a common wire driven by the third digital signal PWM wave through the third pair of MOSFETs.

Abstract: A system for and method of enhancing the low frequency response of a loudspeaker for relatively low input level audio signals and protect the loudspeaker for relatively high input level audio signals is disclosed. The system comprises: a crossover network configured so separate an audio input signal into at least two frequency bands including a low frequency band; and a signal compressor responsive to the energy level of the low frequency portion of an input audio signal in the low frequency band and configured to provide amplification gain on the low frequency portion of the input signal when the energy level of the low frequency portion of the input signal is relatively low so as to enhance the low frequency response of the loudspeaker, and attenuation of the low frequency portion of the input signal when the energy level of the low frequency portion of the input signal is relatively high so as to protect the loudspeaker from being overdriven.

Abstract: A system and method for updating the software of a digital audio amplifier. The digital data used to update the amplifier's software is transmitted as an analog signal over analog audio channels to the amplifier. The amplifier is adapted to recognize when an audio signal should be used to update the amplifier's software, instead of merely driving the speakers with the audio signal. Upon receiving such an audio signal, the amplifier decodes the analog signal into digital instructions. The digital instructions are processed to reconfigure the amplifier's operation.

Abstract: An apparatus comprises a first signal circuit path, a noise gate circuit, and a control circuit. The first signal circuit path processes a first electrical signal that includes one or more signal frequencies in the audio frequency band. The first signal circuit path includes a first amplifier circuit configured to provide a first output signal to a speaker load. The noise gate circuit monitors the first electrical signal and generates a first indication when the amplitude of the first electrical signal decreases below a first specified threshold voltage value. The control circuit mutes an output of the first signal circuit path according to the generated indication. The apparatus is formed on a single integrated circuit.

Abstract: Systems for an expander circuit are disclosed. An expander circuit comprising a transmit amplifier for amplifying electrical signals received from a microphone. A rectifier circuit is responsive to the electrical signals and generates a D.C. voltage. A dynamic resistor circuit is coupled to the transmit amplifier for regulating the gain of the transmit amplifier. The dynamic resistor circuit includes a bipolar junction transistor for receiving the D.C. voltage. The bipolar junction transistor is operated such that the collector current is zero and the bipolar junction transistor has a variable impedance seen by the transmit amplifier dependent upon the D.C. voltage.

Abstract: A surge protection circuit acquires a surge signal of a left channel (LC) signal line and a right channel (RC) signal line. After the surge signal transmitting on the LC signal line and the RC signal line are removed, an audio signal outputted from a signal input device are transmitted to an audio output device via the LC signal line and the RC signal line.

Abstract: An effect adding method, includes: applying different gains to a positive side waveform portion and a negative side waveform portion of an audio signal respectively when absolute values of input levels of the positive side waveform portion and the negative side waveform portion are smaller than a predetermined value; producing a higher range component of the audio signal based on a high range component of the audio signal to which the gain is applied, the higher range component being higher in frequency than the high range component; producing a lower range component of the audio signal based on a low range component of the audio signal to which the gain is applied, the lower range component being lower in the frequency than the low range component; and synthesizing an audio signal having an effect sound by adding the audio signal to which the different gains are applied, the higher range component, and the lower range component with each other.

Abstract: Power amplifies are provided to correspond with a plurality of speaker units constituting a speaker array. Driving signals from the power amplifies are supplied to one terminals of the speaker units, and other terminals are connected a common line. Inverters are provided at preceding stages of the power amplifies such that the driving signals supplied to the speaker units being arranged adjacently have an opposite phase respectively. Since a correlation between the driving signals of the adjacent speaker units is high, a current flowing through the common line can be very reduced. An LED display panel can be driven by the similar method.

Abstract: Systems and method to compress digital video based on human factors expressed as a desirability score are provided. A particular method includes passing a digital input signal through a pulse-width modulator and passing an output of the pulse-width modulator through a power switching device. An output of the power switching device has a plurality of pulses. The method includes receiving the output of the power switching device at a first input of a comparator and receiving a reference voltage at a second input of the comparator. The method includes determining a net signal based on an output of the comparator and determining a timing error signal based on the net signal and the digital input signal. The method also includes adjusting the digital input signal to compensate for harmonic distortion based at least in part on the timing error signal.

Abstract: An apparatus for effecting sound stage expansion in an audio system presenting two sound channels includes: (a) A first signal source coupled for providing at least one first signal representing a first sound channel to at least one first input locus of a first amplifying unit. The first amplifying unit participates in presenting the first sound channel. (b) A second signal source coupled for providing at least one second signal representing a second sound channel to at least one second input locus of a second amplifying unit. The second amplifying unit participates in presenting the second sound channel. (c) At least one first filter unit coupling the first signal source with at least one of the at least one second input locus. (d) At least one second filter unit coupling the second signal source with at least one of the at least one first input locus.

Abstract: The present invention relates to an apparatus for sound comprises a sound source generating unit for generating an electric signal from a sound source; N (N?2) amplifiers which are connected with the sound source generating unit; and 2N speakers which are respectively connected with left and right output parts of each of the N amplifiers, wherein there is formed a multiple stereo imaging including a first stereo imaging generated by two speakers which are respectively connected with the left and right output parts of one amplifier selected from the N amplifiers; a first mono imaging generated by N speakers which are connected with the left output parts of each of the N amplifiers; a second mono imaging which are connected with the right output parts of each of the N amplifiers; and a second stereo imaging generated by the first mono imaging and the second mono imaging.

Abstract: An audio power output system with shared output blocking capacitor provides reduced cost and volume in multi-channel audio power output systems. A pair of transducers are series-connected in opposite polarity and a common DC blocking capacitor provides the return path to a power supply rail in common with a pair of audio power output stages having output terminals each connected to one of the other terminals of a corresponding transducer. A signal processing block provides a pair of signals to the inputs of the audio power output stages and process the signals to increase the separation of the audio signals at lower frequencies. The frequency-dependent characteristic of the “widening” between the signals reduces the attenuating effect of the shared capacitor and can be matched to the inverse of the narrowing effect. The signal processing block may be an analog network, or digital signal processing algorithm or circuit.

Abstract: A multi-channel power amplifier for driving a plurality of loads, each associated with a respective channel, each channel comprising a pair of operational amplifiers, first and second, one operational amplifier of each channel being connectable by configuring switches either in a bridge configuration with the other operational amplifier or in single-ended configuration to a constant reference voltage output by a dedicated voltage buffer of the multi-channel amplifier for driving the respective load of the channel, comprises a window comparator for monitoring the level of the input signal of the channel and producing a logic control signal for the configuring switches. Each channel has a dedicated window comparator monitoring the level of the input signal of the channel that generates a logic signal for positioning the switches that configure the output power structure of the channel in single-ended or bridge configuration.

Abstract: A disclosed system and method dynamically controls the perceived volume of a stereo audio program including left and right channel signals. The system comprises: a dynamic volume control configured and arranged so as to maintain a perceived constant volume level of the stereo audio program; and an excessive spatial processing protection processor configured and arranged for controlling the level of a difference signal, created as a function of the right channel signal subtracted from the left channel signal (L?R), relative to the level of a sum signal, created as a function of the right channel signal plus the left channel signal;; wherein the excessive spatial processing protection processor processes the audio signals so as to control the difference (L?R) signal relative to the sum (L+R) signal.

Abstract: An amplifier circuit and a method of signal amplification are provided. The amplifier circuit includes a first amplifier and a charge pump. The first amplifier includes a first terminal, a second terminal, and a third terminal. The first terminal is coupled to a first external voltage. The second terminal is coupled to a negative voltage. The third terminal is coupled to a ground reference voltage. The charge pump is coupled to the first amplifier for providing the negative voltage transformed from a second external voltage.

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: Disclosed is a method of processing an audio signal, including obtaining ratio information between a main signal and a sub-signal and gain range information of an object and modifying parameter information including at least one of an object parameter and a control parameter based on the ratio information and the gain range information. Disclosed is a method of processing an audio signal, including generating ratio information using object information, generating gain range information of an object using the ratio information, and modifying parameter information including at least one of an object parameter and a control parameter based on the gain range information.

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: Disclosed is an electret condenser microphone which reinforces electrostatic discharge protection and noise isolation by adding a series of components in the electret condenser microphone. According to the present invention, it is possible to block TDMA noise by embodying an RC circuit using series resistors and a varistor having a capacitor component in an electret condenser microphone, and to provide ESD protection effect when testing air or contact ESD by mounting two transient voltage suppressor (TVS) diodes. It is possible to block RF noises in various frequency bands, and to reduce TDMA noise level when making a call with a maximum power level, by applying an electret condenser microphone for ESD protection and noise isolation to a mobile communication terminal. Further, since the electret condenser microphone according to the invention uses an internal analog ground, an artwork of a PCB substrate or isolations from other parts is possible.

Abstract: A method for processing an audio signal is disclosed. The present invention includes obtaining a plural-channel audio signal including a speech component signal and other component signals, obtaining gain of the audio signal, obtaining modification strength parameter determining the strength of the modification of the speech component signal, modifying the gain based on the modification strength parameter, and modifying the speech component signal based on the modified gain.

Abstract: Crosstalk cancellation systems for left and right channel stereo audio signals that are played over left and right stereo loudspeakers include circuitry that is configured to apply more crosstalk cancellation delay to a difference signal between the left and right stereo audio signals, than to a sum signal of the left and right channel stereo signals. The circuitry may be configured to apply no crosstalk cancellation delay to the sum signal. Related crosstalk cancellation methods and electronic devices incorporating same are also disclosed.

Abstract: An acoustic calibration sound system includes a coordinate position detecting device and a host. The coordinate position detecting device is used for detecting a position of a listener in a space plane and issuing a corresponding position signal. The host outputs an audio signal. The host has an acoustic characteristic parameter matrix containing multiple acoustic characteristic parameters related to multiple positions in the space plane. The host selects a corresponding acoustic characteristic parameter in response to the position signal. According to the selected acoustic characteristic parameter, the host adjusts the audio signal.

Abstract: An audio power meter includes a circuit for measuring the power of an amplified audio signal outputted by an audio power amplifier to which the audio power meter is connected. The circuit generates an output signal indicative of the power of the amplified audio signal. A first bar display includes a plurality of separately illuminatable segments arranged linearly with respect to one another. Each segment of the plurality of separately illuminatable segments is responsive to the output signal of the circuit and is selectively illuminated in response thereto. When the measured power of the amplified audio signal exceeds a selected threshold power level, the amplified audio signal is attenuated.

Abstract: A subwoofer stereo system with a docking base for docking a portable digital media player comprises a generally hexahedron cabinet made of a panel material for encasing at least an electronic media processing unit and an amplifier for driving stereo speakers. The docking base has an attachment of modular connector board having at least one main connector for the portable digital player and at least one auxiliary phone plug. The docking base is mounted through the top panel extending in part inwardly of the cabinet as well as outwardly in part for receiving the portable player. A first shielding chamber extends from under the top panel invisibly to enclose the inward part of the docking base to isolate it from interior of the cabinet and a second shielding chamber extends from behind under the front panel invisibly to enclose the control interface to isolate it from interior of the cabinet.

Abstract: A multiple-channel audio processor (10) and an associated plurality of power stages (22) in an audio system are disclosed. The audio processor (10) includes a plurality of audio amplifier channels (22), each of which includes a pulse-code-modulation (PCM) to pulse-width-modulation (PWM) conversion function (25), which generates PWM signals for application to the plurality of power stages (22). The audio amplifier channels (20) each also include an interchannel delay function (28) for delaying the PWM edges relative to other channels (20), for reducing noise. The audio amplifier channels (20) each also include delay adjust circuitry (32) for gradually increasing and decreasing the interchannel delay of the channel (20) on startup and shutdown. This permits a single control terminal (VALID) at the processor to globally enable and disable all of the power stages (22).

Abstract: For achieving an audio reproduction with high sound quality, in a multi-channel A/V amplifier, front speakers are driven with a parallel-drive bi-amplifier arrangement upon stereo reproduction. In the case of the multi-channel reproduction mode, the switching circuit allows an output signal of each channel of the decoder to be sent to speakers via amplifiers for each channel in one-to-one correspondence. On the other hand, in the case of the 2-channel stereo reproduction mode, the switching circuit allows at least two amplifiers among the plurality of amplifiers to be connected in parallel between the output signal for each of the channels L and R of the decoder and the speakers for each of the channels L and R, and also allows the timing of the output signals of the respective amplifiers to be varied.

Abstract: A loudspeaker system with three loudspeakers (LF, LR, LB), includes a first and a second amplifier (BF, BR), each of which amplifies a channel of an audio signal. The outputs of the amplifiers (FDA, FIA; RDA, RIA) are in phase opposition, wherein the outputs of the amplifiers (RDA, FIA; RDA, FIA) are each connected to the inputs of the first and second loudspeakers (LF, LR). The outputs of the amplifiers (RDA, FIA; RDA, FIA) are also connected to the inputs of the third loudspeaker (LB). A high-pass filter (HP) and a low-pass filter (TP), which are used to partition the audio signal, are connected in parallel. As the amplifiers, bridge output stages (BF, BR) are provided. The output of the high-pass filter (HPA) is connected to the inputs of the two bridge output stages (BF, BR). An inverter (IF, IR) is provided in each case between the output of the high-pass filter (HPA) and one of the inputs of the bridge output stages (BF, BR).

Abstract: An audio system 10 has a plurality of audio sources 12a-12c for outputting audio signals different from each other. A coefficient device 15d adjusts the gain of the audio signal output from one of the audio sources. A nonvolatile memory 15i stores, as internal gains, gains to be set to the coefficient device in correspondence with the audio sources. When a switch changeover section 17 selects one of the audio sources, the CPU 15h reads from the nonvolatile memory the internal gain corresponding to the audio source selected, and sets the internal gain to the coefficient device.

Abstract: A dynamic surround channel volume control applies a variable gain control to the surround channels of a multi-channel system. Thus the levels of the surround channels are related to the main volume control of the system. This maintains a predictable relationship between the surround channels and the main or front channels.

Abstract: A M-bridge class-D audio amplifier for portable applications and a method of driving a three-wire audio output device comprises a stereo signal source producing a first and second input stereo digital signal; circuitry adapted to receive the first and second input stereo digital signals and produce three stereo signals comprising a first, second, and third digital signal, wherein the three stereo signals generate pulse-width modulation (PWM) waves comprising a first, second, and third digital signal PWM wave; exactly three pairs of MOSFETs driven by the first, second, and third digital signal PWM waves; and a three-wire speaker system comprising a first wire driven by the first digital signal PWM wave; a second wire driven by the second digital signal PWM wave; and a common wire driven by the third digital signal PWM wave.

Abstract: In a speaker system, pulse width modulation signals are utilized for driving said speaker system, and duty cycles of both left audio channel signals and right audio channel signals of an earphone in said speaker system are modulated by said pulse width modulation signals. When the left audio channel or the right audio channel of the earphone has no inputted audio signals with the abovementioned modulated duty cycles, the speaker system may be prevented from unnecessary power consumption. Besides, audio signals from both the left audio channel and the right audio channel of the earphone and outputted from the speaker system may thus be synchronized further by both the pulse width modulation signals and a sawtooth wave source for generating said pulse width modulation signals, for reducing noise and increasing an output audio quality of the speaker system. The abovementioned speaker system is preferably utilized for a Class D amplifier.

Abstract: This invention relates to a wireless classroom sound amplification system. 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 sound processing device further comprises a feedback cancellation unit identifying acoustical feedback in the sound signal and removing the acoustical feedback in the sound signal.

Abstract: According to one embodiment, an electronic device includes a built-in speaker unit, a first amplifier which drives the built-in speaker unit, a first output circuit which outputs, to the first amplifier, an audio signal in a first frequency range, a second amplifier which drives the detachable speaker unit, a plurality of output circuits each outputting an audio signal in a different frequency range, and a selecting unit which, when the detachable speaker unit is attached to the electronic device, obtains information representing characteristics of the detachable speaker unit from the detachable speaker unit, and, based on the information, selects one of the output circuits to output the audio signal to the second amplifier.

Abstract: A gain switching unit receives each of plural gain control data at a different timing, and repeats that process until a switching instruction data is received. Upon receipt of the switching instruction data, the gain switching unit, based on the plural gain control data received so far, switches at an equal timing the respective gain of the variable gain amplifier of each channel that the plural gain control data intend respectively as an object of volume switching.

Abstract: A sound signal reproducing apparatus for supplying sound signals of a plurality of channels to speakers via sound amplifier circuits includes: a power supply voltage controller for controlling a power supply voltage to the sound amplifier circuits; a plurality of filter circuits for passing predetermined frequencies of the output signal of each of the sound amplifier circuits in the plurality of channels; a plurality of level detection circuits for detecting levels of output signals of the plurality of filter circuits; an adder circuit for adding output signals of the plurality of level detection circuits; and a comparator circuit for comparing an output signal of the adder circuit with a reference level, so that an output signal of the comparator circuit controls the power supply voltage controller.

Abstract: A sound system for capturing and reproducing sounds produced by a plurality of sound sources. The system comprises a device for receiving sounds produced by the plurality of sound sources and converting the separately received sounds to a plurality of separate audio signals without mixing the audio signals. The system may further comprise a device for separately storing the plurality of separate audio signals on a recording medium without mixing the audio signals and a device for reading the stored audio signals from the recording medium. The system further includes a reproduction system for recreating the plurality of separate audio signals. Also, the system comprises an amplification network which comprises a plurality of amplifier systems, with one or more separate amplifiers in each amplifier system for separately amplifying each of the separate audio signals.

Abstract: In accordance with an embodiment of the present invention, a dynamics processor includes a non-linear automatic gain control (AGC) responsive to an input audio signal comprised of a plurality of frequency components, each frequency component having associated therewith an amplitude, said non-linear AGC adaptive to develop a modified gain audio signal. A multiband cross-over device is responsive to the modified gain audio signal and is adaptive to generate ‘n’ number of signals, each of said ‘n’ signals having an amplitude and further having a unique frequency band associated therewith.

Abstract: Voltage level translators are presented, inter alia, for operating an operational amplifier integrated circuit designed for operation with a single ended power supply, to operate with a split level power supply having a center tapped ground. A first polarity power supply terminal of a operational amplifier integrated circuit is coupled to a first polarity of the of the split level power supply, and a second polarity power supply terminal of the operational amplifier integrated circuit is coupled to a second polarity of the power supply, with a positive signal input terminal of the operational amplifier being coupled to a center tapped ground of the split level power supply.

Abstract: A digital &Dgr;&Sgr; modulated signal produced by a quantizer (1c) in a &Dgr;&Sgr; modulation processing unit (1) is put in to a feedback loop before inputted to a power switch (2) and converted into an analog signal by a D/A converter (1d). This analog signal is fed back to the input stage (a differentiator (1a)) of the &Dgr;&Sgr; processing unit (1) to prevent the switching distortion of the power switch (2) itself from being introduced into the feedback loop thereby to suppress the influence of the switching distortion.

Abstract: A multimedia computer speaker system includes a pair of amplifiers that provide amplified right and left audio signals to a pair of wide-band speakers. The amplifiers are configured to provide the amplified right and left audio signals that are out of phase with each other. The amplified right and left audio signals are applied to opposite terminals of the two wide-band speakers. These reversed terminal couplings to the wide-band speakers of the phase-reversed signals provide phase-aligned right and left audio playback at the speakers. A subwoofer and a low pass filter are connected as a bridge-tied load to receive the amplified right and left audio signals. The phase of one amplified audio signal is in effect reversed by applying it to the negative terminal of the subwoofer. As a result, low frequency components of a phase reversed amplified audio signal are summed by the subwoofer with low frequency components of the other amplified audio signal to provide a low frequency audio playback.

Abstract: A method of powering an audio output device of a computer system, by determining whether a passive or active audio output device is connected to an audio output jack of the computer system and, based on this determination, providing an appropriate power level to the audio output jack. For example, if the determination is made that a passive audio output device is connected to the audio output jack, then a 3-watt power signal is applied to the audio output jack, but if the determination is made that an active audio output device is connected to the audio output jack, then a ¼-watt power signal is applied to the audio output jack. The type of audio output device present may be determined by sensing an impedance at the audio output jack. This sensing may be performed by comparing a load voltage associated with the impedance to a reference voltage.

Abstract: An acoustical control apparatus for regulating voltage flow in response to an audio signal. The apparatus includes a power supply, a level control network, a multiple active filter network, a phase control network, a comparator network and output control network. The apparatus separates the audio signal into distinct frequency bandwidths and regulates the intensity of voltage flow from and in synchronization with the power supply. The distinct bandwidths and intensity control of the voltage feed triac drivers to allow pulsating voltage to flow to a plurality of lighting circuits. The lighting circuits pulsate to the beat of the audio signal.

Abstract: A method of generating surround sound with channels processing separately includes steps of transmitting left and right channel signals separately to a first multiple frequency phase shift processor, a pre-set equalizer and a second multiple frequency phase shift processor without addition and subtraction thereby providing a stereo sound position enhancement processing, transmitting left and right space signals separately to two multiple frequency phase shift processors, two stereo signal difference processors and a pre-set equalizer to provide a surround sound enhancement processing, and transmitting left channel signals, left space signals, right channel signals and right space signals separately to respective variable amplifiers to adjust output amplitude after the sound position enhancement processing and the surround sound enhancement processing and then summing up output signals to obtain three dimensional effect enhancement.

Abstract: A system and method which generates amplified signals indicative of left and right stereo channels, and uses the signals to drive transducers for each of subwoofer, left stereo, and right stereo channels. The amplification circuitry is operable with a power supply having low peak current capability (i.e., low peak to average current rating) even when amplifying an input signal pair having highly correlated frequency components, since it spreads the peak current demands imposed on the power supply over a full cycle of each of the highly correlated frequency components. A series-connected pair of left and right channel transducers is driven by left and right channel power amplifiers of the amplification circuitry, and the subwoofer channel transducer is connected in parallel with this transducer pair so that all three transducers are driven by two power amplifiers, thus eliminating the need for a third power amplifier to drive the subwoofer channel transducer.

Abstract: A surround sound converter for home audio systems includes outputs for a left front speaker, a right front speaker, a left rear speaker, a right rear speaker, and an auxiliary output to accommodate a rear auxiliary amplifier. The surround sound converter also includes an input for the left and right channel speaker output of an amplifier, a receiver, or any stereo signal device which has an audio amplifier. At least one potentiometer controls the volume balance between the front and rear speakers. A left and right capacitor are used to drive the left and right rear speakers, respectively. An auxiliary output is provided to accommodate adding a rear auxiliary amplifier. A surround sound converter for vehicle audio systems utilizes an automotive stereo. A left front speaker and right front speaker are connected to the normal speaker outputs of the automotive stereo. The left rear speaker is connected to the left rear signal negative and the right rear signal negative.

Abstract: An interchangeable amplifier device includes an amplifier cabinet. The amplifier cabinet has a bottom side, a top side and enclosing side walls for housing the amplifier electronics. The enclosing side walls have a front wall and a back wall. The front wall of the cabinet has a volume control and a power switch. The back wall of the amplifier cabinet has an audio port and an AC power supply cord. The audio port has a plurality of speaker terminals and a plurality of input jacks for receiving audio input for transmission to the stereo speakers. An upgradable power board with at least four flat leads may be plugged into an upgrade slot connector found along the back wall of the amplifier cabinet. The upgradable power board receives a first voltage of input from a transformer when plugged into the upgrade slot connector. The upgradable power board, when plugged in, will resupplying the amplifier with a second voltage of a magnitude greater than the magnitude of the first voltage.

Abstract: A signal regulator regulates an auxiliary signal based upon a primary signal scaled by an external amplifier. The signal regulator receives the primary signal with an unscaled level. Processing circuitry monitors the unscaled level of the primary signal. The primary signal is then output to the external amplifier for scaling, either by amplification or attenuation. The primary signal with a scaled level is in turn received by the signal regulator from the amplifier. The processing circuitry monitors the scaled level of the primary signal from the amplifier, and then generates a gain factor based upon the unscaled level and the scaled level of the primary signal. An auxiliary signal is received by the signal regulator. Adjusting circuitry receives the gain factor from the processing circuitry and adjusts a level of the auxiliary signal based upon the gain factor. The auxiliary signal with the adjusted level is then provided to an external component, for example, a loudspeaker.

Abstract: A power amplifier device for amplifying an audio signal from sound generating circuitry in a micro-computer is provided. The device is retained in a housing secured in a drive bay of the micro-computer containing a disk drive such as a compact disc read only memory drive, a compact disc recordable drive, a digital video disc drive, etc. The amplifier device and disk drive may also be configured in a unitary housing. The device receives a line-level audio signal from the audio circuitry and transmits the signal to a frequency and time response contouring device, to adjust the response of the signal. A power level adjusting mechanism, such as a volume control, adjusts the power level of the signal generated by the frequency and time response device. Amplifiers are coupled to the volume control to amplify the audio signal to a level determined by the volume control. The amplification device connects to at least leftwardly and rightwardly positioned loudspeakers to provide stereophonic sound at the desired level.