Abstract: A power amplifier includes a class-D amplifier and an input signal supplier. The class-D amplifier includes an input portion and a switching device. The switching device is switched according to an input signal that is input to the input portion so that a current is supplied to a load from a power source via the switching device. The input signal supplier supplies the input signal to the input portion of the class-D amplifier, calculates a virtual output voltage to be output from a virtual power source having a prescribed internal impedance characteristic when a current to flow through the load is output from the virtual power source, and adjust an amplitude of the input signal according to the virtual output voltage.

Abstract: An electroacoustic transducer includes a diaphragm including a pair of convex surfaces respectively including convex surfaces of a pair of longitudinal split tubular members. A valley is formed between one side portions of the pair of longitudinal split tubular members. The electroacoustic transducer further includes: a converter configured to convert between a vibration of the diaphragm in a depth direction of the valley and an electric signal corresponding to the vibration; and a supporter supporting other side portions of the pair of longitudinal split tubular members of the diaphragm so as to allow the other side portions to vibrate in a vibration direction of the vibration.

Abstract: An audio signal processing device receives a plurality of audio signals via a left channel (L) and a right channel (R) so as to produce a composite signal L+R and a difference signal L?R. The composite signal L+R is changed in phase with an all-pass filter, while the difference signal L?R is changed in phase and frequency characteristic with a band-pass filter (e.g. a center frequency of 1 kHz). The band-pass filter has a gently curved frequency characteristic achieving a broad passing band. Additionally, a phase difference of 90 degrees is maintained between the all-pass filter and the band-pass filter over the entire audio frequency range. The composite signal and the difference signal are adjusted in their levels and then mixed together to produce a monaural signal achieving an audio surround effect for widely propagating sound into the surrounding space without degrading sound quality.

Abstract: A self-oscillation frequency varying element for varying the self-oscillation frequency of a self-oscillation loop of a self-oscillating class-D amplifier is placed in the self-oscillation loop. Frequency comparison, cycle comparison, or phase comparison is performed between a self-oscillation signal of the self-oscillating class-D amplifier or a signal corresponding to the self-oscillation signal and a reference frequency signal having a prescribed reference frequency. Alternatively, information corresponding to a frequency or a cycle of a self-oscillation signal of the self-oscillating class-D amplifier or a signal corresponding to the self-oscillation signal is compared with information corresponding to a prescribed reference frequency or reference cycle.

Abstract: A power amplifier includes a class D amplification section and a load current feedback circuit. The class D amplification section includes an input section and a switching section serving as an output stage and switched depending on a signal input to the input section, and outputs current from a power source to a load via the switching section. The load current feedback circuit negatively feeds back the current flowing in the load to the input section of the class D amplification section.

Abstract: An electric stringed musical instrument includes: a string which vibrates by a performance operation; a body which supports the string via a bridge; a pickup sensor mounted on a portion which vibrates by a vibration of the string, the pickup sensor being configured to detect a vibration having propagated from the string and output an electric signal; a supporter having a spring structure which supports the bridge with respect to the body; and a damper mounted on a portion which vibrates by a vibration of the string, the damper being configured to damp a vibration of the bridge.

Abstract: An electroacoustic transducer includes a diaphragm including: a wing-pair portion; and a cone portion. The wing-pair portion includes a pair of convex surfaces having respectively convex surfaces of a pair of longitudinal split tubular members. A valley is formed between one side portions of the pair of convex surfaces. The cone portion surrounds an outer peripheral portion of the wing-pair portion and extends in a conical shape. The electroacoustic transducer further includes: a converter configured to convert between a vibration of the diaphragm in a depth direction of the valley and an electric signal corresponding to the vibration; and a supporter supporting an outer peripheral portion of the cone portion to allow the diaphragm to vibrate in a direction of the vibration.

Abstract: An electroacoustic transducer includes a diaphragm including: a wing-pair portion; and a cone portion. The wing-pair portion includes a pair of convex surfaces having respectively convex surfaces of a pair of longitudinal split tubular members. A valley is formed between one side portions of the pair of convex surfaces. The cone portion surrounds an outer peripheral portion of the wing-pair portion and extends in a conical shape. The electroacoustic transducer further includes: a converter configured to convert between a vibration of the diaphragm in a depth direction of the valley and an electric signal corresponding to the vibration; and a supporter supporting an outer peripheral portion of the cone portion to allow the diaphragm to vibrate in a direction of the vibration.

Abstract: An audio signal processing device receives a plurality of audio signals via a left channel (L) and a right channel (R) so as to produce a composite signal L+R and a difference signal L?R. The composite signal L+R is changed in phase with an all-pass filter, while the difference signal L?R is changed in phase and frequency characteristic with a band-pass filter (e.g. a center frequency of 1 kHz). The band-pass filter has a gently curved frequency characteristic achieving a broad passing band. Additionally, a phase difference of 90 degrees is maintained between the all-pass filter and the band-pass filter over the entire audio frequency range. The composite signal and the difference signal are adjusted in their levels and then mixed together to produce a monaural signal achieving an audio surround effect for widely propagating sound into the surrounding space without degrading sound quality.

Abstract: An electroacoustic transducer includes a diaphragm including: a wing-pair portion; and a cone portion. The wing-pair portion includes a pair of convex surfaces having respectively convex surfaces of a pair of longitudinal split tubular members. A valley is formed between one side portions of the pair of convex surfaces. The cone portion surrounds an outer peripheral portion of the wing-pair portion and extends in a conical shape. The electroacoustic transducer further includes: a converter configured to convert between a vibration of the diaphragm in a depth direction of the valley and an electric signal corresponding to the vibration; and a supporter supporting an outer peripheral portion of the cone portion to allow the diaphragm to vibrate in a direction of the vibration.

Abstract: An electroacoustic transducer includes a diaphragm including a pair of convex surfaces respectively including convex surfaces of a pair of longitudinal split tubular members. A valley is formed between one side portions of the pair of longitudinal split tubular members. The electroacoustic transducer further includes: a converter configured to convert between a vibration of the diaphragm in a depth direction of the valley and an electric signal corresponding to the vibration; and a supporter supporting other side portions of the pair of longitudinal split tubular members of the diaphragm so as to allow the other side portions to vibrate in a vibration direction of the vibration.

Abstract: An audio signal processing device receives a plurality of audio signals via a left channel (L) and a right channel (R) so as to produce a composite signal L+R and a difference signal L?R. The composite signal L+R is changed in phase with an all-pass filter, while the difference signal L?R is changed in phase and frequency characteristic with a band-pass filter (e.g. a center frequency of 1 kHz). The band-pass filter has a gently curved frequency characteristic achieving a broad passing band. Additionally, a phase difference of 90 degrees is maintained between the all-pass filter and the band-pass filter over the entire audio frequency range. The composite signal and the difference signal are adjusted in their levels and then mixed together to produce a monaural signal achieving an audio surround effect for widely propagating sound into the surrounding space without degrading sound quality.

Abstract: A self-oscillation frequency varying element for varying the self-oscillation frequency of a self-oscillation loop of a self-oscillating class-D amplifier is placed in the self-oscillation loop. Frequency comparison, cycle comparison, or phase comparison is performed between a self-oscillation signal of the self-oscillating class-D amplifier or a signal corresponding to the self-oscillation signal and a reference frequency signal having a prescribed reference frequency. Alternatively, information corresponding to a frequency or a cycle of a self-oscillation signal of the self-oscillating class-D amplifier or a signal corresponding to the self-oscillation signal is compared with information corresponding to a prescribed reference frequency or reference cycle.

Abstract: An electric stringed musical instrument includes: a string which vibrates by a performance operation; a body which supports the string via a bridge; a pickup sensor mounted on a portion which vibrates by a vibration of the string, the pickup sensor being configured to detect a vibration having propagated from the string and output an electric signal; a supporter having a spring structure which supports the bridge with respect to the body; and a damper mounted on a portion which vibrates by a vibration of the string, the damper being configured to damp a vibration of the bridge.

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

Abstract: An amplification system of the invention can decrease power consumption in a power amplification section if the power amplification section need not be used. The power consumption in the power amplification section can be decreased by shutting off power feed into a voltage amplification stage by a power control section, and the power feed state into a power amplification stage from a power supply section is not changed. Thus, power feed into the voltage amplification stage of the circuit wherein a large current does not flow needs only to be controlled using limiter means also used for a different application, so that the power consumption of the power amplification section can be decreased without the need for enlarging the circuit scale, with saved space, and simply.

Abstract: A loudspeaker system includes a loudspeaker enclosure having an inside space, a loudspeaker provided on the loudspeaker enclosure, a first diaphragm which has one of ends fixed to a surface of the loudspeaker enclosure and the other end, a second diaphragm which has one of ends fixed to the surface of the loudspeaker enclosure and the other end, a coupling portion having an elasticity, and coupling the other end of the first diaphragm to the other end of the second diaphragm, an opening structure provided in the surface of the loudspeaker enclosure, and a sealing member provided to a portion among the first and second diaphragms, the coupling portion and an edge part of the opening structure, and closing the inside space to hold an airtightness of the loudspeaker enclosure in a state that the first and second diaphragms can be vibrated.

Abstract: Speaker system is constructed of a plurality of speakers each including a bass-reflex type cabinet. The speaker system is designed to differentiate a low-band resonance frequency between the speakers by differentiating inner cubic capacities of the speaker cabinets from each other. Audio signal of a different channel is input to each of the speakers, and only low-frequency signals of all of the channels are added together so that the added result is supplied to all of the speakers. Thus, using the differentiated low-band resonance frequencies, the speaker system permits reproduction of low-pitched sounds with a flat characteristic.

Abstract: An adaptor is connectable between a signal processor and a transmission module. The signal processor has three audio channels for feeding respectively a first audio signal, a second audio signal, and a third audio signal having a frequency range lower than a frequency range of the first and second audio signals. The transmission module has two transmission channels capable of transmitting two audio signals to a codeless speaker. The adaptor has three input terminals for receiving the first, second and third audio signals from the signal processor. The adaptor filters at least one of the first and second audio signals for cutting therefrom a lower frequency range comparative to the lower frequency range of the third audio signal, and adds the third audio signal to the one of the first and second audio signals from which the lower frequency range is cut.