Abstract: A power amplifier includes a first amplifier configured to amplify an input signal and output, from a first output, a first signal in which the input signal is amplified, a second amplifier configured to amplify the first signal and output, from a second output, a second signal in which the first signal is amplified, a third amplifier configured to amplify the second signal and output, from a third output, a third signal in which the second signal is amplified, a capacitor connected between the first output and a mixing node, a first resistor connected between the second output and the mixing node, a first inductor connected between the third output and the mixing node, a second inductor connected between the mixing node and a load, and a feedback circuit configured to negatively feed back a mixed signal of the mixing node to an input of the first amplifier.

Abstract: An object of the present invention is to provide a magnetic circuit for an acoustic transducer, the magnetic circuit enabling peeling of the surface of a member formed by compression-molding a soft magnetic composite material to be suppressed.

Abstract: A single printed-circuit board of a class-D amplifier includes an input ground, an output ground, an input amplifying circuit, a modulation circuit, an output amplifying circuit, and an output filter, a solid pattern, a first feedback circuit, and a second feedback circuit. The solid pattern of the output ground extends into all regions of the input amplifying circuit, the modulation circuit, the output amplifying circuit and the output filter. The first feedback circuit executes a feedback where a voltage at a first connecting point is negatively fed back to an inverting input of the input amplifying circuit. The second feedback circuit executes a feedback where a voltage at a second connecting point is negatively fed back to a non-inverting input of the input amplifying circuit.

Abstract: A signal converter includes a magnetic circuit, a diaphragm, a first coil, a second coil, and a variable resistor. The magnetic circuit has a magnetic gap. The diaphragm is disposed over an opening of the magnetic circuit. The first coil is disposed in the magnetic gap and configured to output an electrical signal based on vibration of the diaphragm. The second coil is disposed in the magnetic gap and configured to brake the diaphragm. The variable resistor is connected to a first end and a second end of the second coil and configured to form a closed loop circuit together with the second coil.

Abstract: A class-D amplifier that amplifies an input signal comprises a control circuit configured to generate a control signal that varies in accordance with a level of the input signal, a first generating circuit configured to generate a first pulse, and a second generating circuit configured to generate a second pulse. A pulse width of the first pulse becomes narrower as the signal level of the input signal becomes smaller, and the pulse width of the first pulse becomes wider as an instantaneous magnitude of the input signal becomes larger. A pulse width of the second pulse becomes narrower as the signal level of the input signal becomes smaller, and the pulse width of the second pulse becomes wider as an instantaneous magnitude of the input signal becomes smaller.

Abstract: In a switching power supply, a rectifying circuit outputs a first voltage. A switching circuit switches the first voltage into a switching voltage. An output circuit generates a second voltage based on the switching voltage. A feedback circuit generates the feedback signal based on the first and second voltages, and includes a carrier wave generation circuit that generates a carrier wave. The carrier wave has a non-linear shape at its rising edge and/or falling edge. A PWM circuit generates a PWM signal based on a comparison between the first voltage and a voltage of the carrier wave. Due to the non-linear shape, as the first voltage is higher, a pulse width of the PWM signal is changeable more greatly based on a change in the first voltage. A low-pass filter generates the feedback signal based on the PWM signal.

Abstract: A signal converter includes a chamber, a first diaphragm, a second diaphragm, and a first converter. The chamber has a first opening at one end and a second opening at a second end opposite the first end. The first diaphragm is disposed so as to cover the first opening. The second diaphragm is disposed so as to cover the second opening. The first converter is disposed in the chamber and configured to generate a first signal based on a vibration of the first diaphragm.

Abstract: An acoustic apparatus includes a class-D amplifier including a current feedback circuit, and a speaker system including a voice coil driven by the class-D amplifier. The speaker system is configured such that, in a case where the speaker system is driven by an ordinary amplifier having a first output resistance lower than a second output impedance of the class-D amplifier, a Q factor of the speaker system falls below a predetermined lower limit of an ordinary Q factor range of an ordinary speaker system. The current feedback circuit is configured to increase the second output impedance of the class-D amplifier by feeding a current flowing to the voice coil back to an input of the class-D amplifier so as to increase a Q factor as the acoustic apparatus higher than the predetermined lower limit of the ordinary Q factor range and within the ordinary Q factor range.

Abstract: Provided is a speaker apparatus including a first speaker having a first surface communicating with an interior and a second surface not communicating with the interior; a second speaker having a first surface communicating with an exterior and a second surface not communicating with the exterior; and a cabinet having boundary surfaces that form an enclosed space. The second surface of the first speaker and the second surface of the second speaker are arranged on the boundary surfaces and are facing the enclosed space.

Abstract: A headphone includes: a housing; a first driver unit disposed in the housing; a partition wall dividing an internal space of the housing into a first space and a second space, the first space containing the first driver unit; a second driver unit attached to the partition wall; and an acoustic adjustment circuit configured to receive a first signal to be input to the first driver unit and generate a second signal to be input to the second driver unit based on the first signal.

Abstract: A signal converter includes a magnetic circuit, a diaphragm, a first coil, a second coil, and a variable resistor. The magnetic circuit has a magnetic gap. The diaphragm is disposed over an opening of the magnetic circuit. The first coil is disposed in the magnetic gap and configured to output an electrical signal based on vibration of the diaphragm. The second coil is disposed in the magnetic gap and configured to brake the diaphragm. The variable resistor is connected to a first end and a second end of the second coil and configured to form a closed loop circuit together with the second coil.

Abstract: A signal converter includes a chamber, a first diaphragm, a second diaphragm, and a first converter. The chamber has a first opening at one end and a second opening at a second end opposite the first end. The first diaphragm is disposed so as to cover the first opening. The second diaphragm is disposed so as to cover the second opening. The first converter is disposed in the chamber and configured to generate a first signal based on a vibration of the first diaphragm.

Abstract: An input device includes a first operating element and a first sensor. The first sensor includes a first conductor, a first coil, and a first magnetic material forming an open magnetic circuit together with the first coil. A positional relationship between the first coil and the first magnetic material is fixed. A first distance between a first end portion of the first magnetic material and the first conductor varies according to the amount of operation on the first operating element. The first sensor outputs a first signal corresponding to the first distance.

Abstract: A class-D amplifier includes: a gain control unit that amplifies an input audio signal in accordance with a compensation gain to generate an input signal Vin; and a pulse width modulator that generates a first pulse Vp whose pulse width changes according to the input signal Vin within a first input range A1 where a value of the generated input signal Vin is higher than a first boundary Vb1, and that generates a second pulse Vn whose pulse width changes according to the generated input signal Vin within a second input range A2. The gain control unit controls the compensation gain so that first inclination of an input/output characteristic of the class-D amplifier in a first section in which the pulse width modulator outputs both the first pulse Vp and the second pulse Vn and second inclination of the input/output characteristic in a second section other than the first section are similar to each other.

Abstract: Pulse width modulators 131P and 131N respectively generate a first pulse Vp whose pulse width changes according to an input signal Vin based on the input signal Vin and a generated first carrier wave C1P, and a second pulse Vn whose pulse width changes according to the input signal Vin based on the input signal Vin and a generated second carrier wave C1N. Wherein due to the non-liner gradient in each of the generated first carrier wave C1P and the generated second carrier wave C1N and, duty ratio of each of the generated first pulse Vp and the generated second pulse Vn is less than 50% in a state where a value of the input signal is zero; and a difference between a pulse width of the first pulse Vp and a pulse width of the second pulse Vn linearly changes according to the input signal Vin.

Abstract: A speaker controller includes a switch that is inserted on a speaker wiring for supplying a sound signal to a speaker. A switch control circuit can extract and hold an ON/OFF control signal for instructing ON/OFF of the switch from an alternating-current signal supplied via the speaker wiring. A switch control circuit controls ON/OFF of the switch based on the ON/OFF control signal. A power supply circuit can generate a power supply voltage for operating the switch control circuit from the alternating-current signal supplied via the speaker wiring.

Abstract: Provided is an acoustic device with which it is possible to make reproduced sound able to be heard across a wide frequency range, from the front and from the rear. This acoustic device is provided with a flat speaker 3 configured to emit sound, from a front and a rear thereof, in a low frequency sound range. Also, provided therein are a first speaker 5F configured to emit sound, in a direction facing the front of the flat speaker, in a mid-to-high frequency sound range, and a second speaker 5R configured to emit sound, in a direction facing the rear of the flat speaker, in the mid-to-high frequency sound range.

Abstract: Provided is a speaker apparatus including a first speaker having a first surface communicating with an interior and a second surface not communicating with the interior; a second speaker having a first surface communicating with an exterior and a second surface not communicating with the exterior; and a cabinet having boundary surfaces that form an enclosed space. The second surface of the first speaker and the second surface of the second speaker are arranged on the boundary surfaces and are facing the enclosed space.

Abstract: Provided is a driving control apparatus that can control relaxation of force in an actuator. The driving control apparatus is provided with: a driving control unit configured to control driving of the actuator according to a driving control signal; and a pressure control unit configured to control, according to a pressure control signal, involvement of the driving control signal in control of pressure to be generated by the actuator.

Abstract: A class D amplifier includes a self-oscillating class D amplification circuit that is driven by an output current signal; and a voltage-current converting circuit that outputs an output current signal in response to an input signal voltage and an output signal voltage from a feedback signal voltage.