Abstract: An ear pad to be mounted to a base body to which a speaker unit is fixed includes an elastic body in which a plurality of elastic members having different coefficients of restitution are laminated together in a sound emitting direction of the speaker unit. A skin material covers an exterior of the elastic body. The elastic body includes a first elastic member arranged at a side of the base body, and a second elastic member laminated on and fixed to the first elastic member. The first and second elastic members respectively have ring shapes having a substantially same external diameter. The second elastic member has an inner peripheral surface having a different dimension compared to an inner peripheral surface of the first elastic member, and has a portion having a larger inner diameter than an inner diameter of the first elastic member.

Abstract: In an impedance converter using an electron tube as an active element, output impedance can be made sufficiently low, and the number of circuit elements therefor is decreased and a circuit configuration therefor is made simple. Provided is an impedance converter having an electron tube cathode-follower connected. The impedance converter includes a bias diode that provides a bias voltage to a cathode of the electron tube, high resistance elements that provide a voltage of the bias diode to a grid of the electron tube, a load circuit connected to the electron tube, and a complementary emitter output circuit including two transistors, respective bases of which are connected to one end and the other end of the bias diode.

Abstract: A dynamic microphone that enables taking a long propagation path of a sound wave on a back side of a diaphragm, and by which unidirectivity can be obtained even at a low frequency. The dynamic microphone includes: a dynamic microphone unit; and an air chamber provided on a back side of a diaphragm of the dynamic microphone unit, wherein the air chamber is folded back to make a propagation path of a sound wave on the back side of the diaphragm long, a plurality of acoustic resistors is arranged in the air chamber at intervals to each other in a direction of the propagation path of a sound wave, and acoustic resistance values of the plurality of acoustic resistors become higher as the propagation path of a sound wave goes away from the diaphragm.

Abstract: Provided is a condenser microphone unit that prevents eccentricity as much as possible and achieves improvement of assembly accuracy. A condenser microphone unit including a diaphragm that vibrates upon receiving a sound wave and made by a plurality of configuration components that are assembled, the condenser microphone unit includes a base member including an opening portion to which the plurality of configuration components is attached, and an adjustment member having an outer diameter corresponding to a diameter of the opening portion, and mounted to a side surface of one or more components accommodated in the opening portion, of the plurality of configuration components. The adjustment member is a frame body exhibiting an annular shape and including a notch portion notched to have a pair of end portions, and is fixed in the opening portion in a state of being mounted to the side surface of the one or more components.

Abstract: A narrow-angle directional microphone includes: a microphone case; an acoustic tube fit in the microphone case with a gap between the acoustic tube and the microphone case; a microphone element arranged at one end side of the acoustic tube with a clearance that allows a front acoustic terminal and a rear acoustic terminal to communicate into each other between the microphone element and the microphone case; and an acoustic resistance body having elasticity positioned over between the one end side of the acoustic tube and the microphone element to block a passage between the front acoustic terminal and the rear acoustic terminal,whereby adjustments of a degree of compression of the acoustic resistance body are achieved by changes to an interval between the acoustic tube and the microphone element.

Abstract: In an electrodynamic acoustic transducer which uses a surface potential of an electret dielectric film as a polarization voltage, prevention of partial suctional adhesion of a diaphragm caused by variation in surface potential across the electret dielectric film is ensured in a simple way. In an electrodynamic acoustic transducer including a diaphragm and a fixed pole which are arranged with a predetermined interval so as to face each other, a facing surface of either one of the diaphragm and the fixed pole having an electret dielectric film, a surface of the electret dielectric film is divided into a plurality of segment regions, and a predetermined surface potential is given to each of the segment regions by a polarization processing unit.

Abstract: A condenser type electroacoustic transducer includes a diaphragm, a fixed electrode having a surface facing the diaphragm, and a dielectric disposed in a partial region on the surface of the fixed electrode.

Abstract: Provided is an impedance conversion circuit of a condenser microphone which includes a first electron tube operated in grounded-cathode mode to whose grid an output signal from a condenser microphone unit is inputted, and from whose plate a signal is outputted, a first emitter-follower circuit configured to receive a signal based on a plate output of the first electron tube and amplify a current, and a first feedback element configured to transmit a feedback signal from an emitter of a transistor configuring the first emitter-follower circuit to the grid of the first electron tube. And the impedance conversion circuit can achieve a wide dynamic range while using a voltage amplifier circuit with an electron tube at an initial stage.

Abstract: A moving-magnet type pickup cartridge is disclosed, which includes a cantilever, a stylus chip attached to a front end part in a longitudinal direction of the cantilever, a damper disposed at a base end part in the longitudinal direction of the cantilever and configured to support the cantilever in a swingable manner, a magnet disposed in the longitudinal direction of the cantilever and immediately above the stylus chip at the front end part of the cantilever, and configured to vibrate with vibration of the stylus chip, and a yoke formed in a U-shape, having generating coils being wound thereon, and having magnetic poles at both leg parts thereof being disposed to face the magnet. With this configuration, there is provided a moving-magnet type pickup cartridge enables not only to ensure a large output signal but also to obtain a faithfully reproduced sound with little distortion.

Abstract: A condenser microphone utilizes a PLL circuit which includes a phase shift oscillator having an RC network that uses an electrostatic capacitance of the condenser microphone unit varying upon reception of a sound pressure and a resistance value of a variable resistance element; a phase detection unit that compares phases of a fixed frequency signal from a reference signal oscillator and an oscillation output signal from the phase shift oscillator and outputs a phase difference signal corresponding to a phase difference; a loop filter that extracts a control signal when receiving the phase difference signal from the phase detection unit; and a driver circuit that changes a resistance value of the variable resistance element provided in the phase shift oscillator based on the control signal obtained from the loop filter. The control signal obtained from the loop filter of the PLL circuit is used as an audio output signal.

Abstract: Provided is a condenser microphone including an audio-signal outputting printed circuit board and a rear case that are in stable electrical connection with each other. The condenser microphone includes a microphone unit 10, an audio-signal outputting printed circuit board 20 connected with the microphone unit 10, a rear case 30 having deep groove 31a, the deep groove 31a receiving the audio-signal outputting printed circuit board 20, a mounting groove 31b being formed on the outer periphery of the rear case 30, the mounting groove 31b receiving a mounting member 50, a fitting groove 21 being formed on the audio-signal outputting printed circuit board 20, the fitting groove 21 receiving the mounting member 50.

Abstract: An acoustic impedance on a rear acoustic terminal side is set such that satisfactory directionality is obtained even in a high tone range. A rear portion of a sealing member 30A fitted to a unit case 10 is formed in a convex spherical shape, ranging from an apex part 301 to a hem part 302. The sealing member 30A forms an acoustic distributed constant circuit including: a first portion 310 in which a cross-sectional area of a sound path continuously increases, the sound path running from acoustic resistance parts AR as sound holes 28a of an electroacoustic transducer 20 to reach a rear acoustic terminal 12 through an air chamber A; and a second portion 320 on the rear acoustic terminal 12 side in which a cross-sectional area continuously decreases toward a direction farther from a sound pickup source.

Abstract: A dynamic microphone includes: a diaphragm; a voice coil fixed to the diaphragm; a magnetic circuit which includes a magnetic gap in which the voice coil is arranged and generates a magnetic field in the magnetic gap; a volume reducing member which is attached to the magnetic circuit, is arranged in a back surface space of the diaphragm, and reduces a volume in an air chamber in the back surface space; a communication passage which is formed along between the volume reducing member and the magnetic circuit and communicates the back surface space with a back side air chamber; and an acoustic resistance which is attached to the magnetic circuit and intervenes between the communication passage and the back side air chamber.

Abstract: Provided is a variable directivity electret condenser microphone that can simplify a circuit configuration, and outputs an audio signal in an unbalanced manner. Included are electrically independent first and second electret condenser microphone units in which first and second fixed electrodes are arranged back to back and facing each other in a mutually non-conductive state, and first and second diaphragms are arranged facing the first and second fixed electrodes with fixed intervals from the first and second fixed electrodes, respectively, a first impedance converter having an input terminal connected to the first fixed electrode, a DC cut capacitor selectively connected between an output terminal of the first impedance converter and an input terminal of the second impedance converter, and a directivity variable switche that can alternatively select a mode from at least a first directivity mode to a third directivity mode.

Abstract: Provided is, in a microphone configured such that a microphone head including a microphone unit is attachably/detachably mounted to a microphone main body, a microphone which enables easy attachment/detachment of the microphone head, and which can perform a mute operation not only after removal of the microphone head but also in attachment/detachment of the microphone head. The microphone includes a mute circuit provided to a side of the microphone main body, and driven by an input of a mute command signal, a first mute control circuit provided to aside of the microphone head, and including a switch that switches disconnection/conduction of a wire, and a second mute control circuit provided to the side of the microphone main body, and electrically connected with the first mute control circuit and generates the mute command signal, in a state where the microphone head is coupled, and in attachment/detachment of the microphone head.

Abstract: An acoustic tube attaching unit that attaches an acoustic tube to a side of a main body case where a microphone unit is mounted. The acoustic tube attaching unit includes first and second elastic members lying between a fixing member and a washer, and bolts that tight the fixing member and the washer in an axial direction. A peripheral edge surface of the first elastic member is formed in a linear manner, and a peripheral edge surface of the second elastic member is formed in a recessed surface manner, so that the peripheral edge surface of the first elastic member protrudes in an outer peripheral direction by elastic deformation by the tightening of the bolts. The acoustic tube is attached to the main body case side by fixing action to an inner wall of the acoustic tube by the protrusion of the first elastic member in the outer peripheral direction.

Abstract: Provided is a headphone unit including a housing having a convex portion and accommodating a driver unit, a support in contact with part of the outer surface of the convex portion, and a frictional member in contact with the support and the outer surface of the convex portion. The frictional member generates greater friction against the convex portion than the friction between the support and the convex portion. The housing is swingably joined to the support.

Abstract: A unidirectional condenser microphone unit is provided that have directionality unaffected by the external environment, and a method of manufacturing the unidirectional condenser microphone. The unidirectional condenser microphone unit having an interior and an exterior, the unidirectional condenser microphone includes a diaphragm, a fixed electrode facing the diaphragm, the fixed electrode constituting a capacitor with the diaphragm, an insulating base disposed in a back face side of the fixed electrode, the insulating base supporting the fixed electrode, an air chamber disposed in the back face side of the fixed electrode, and a gap disposed between the fixed electrode and the insulating base. The fixed electrode includes at least one sound hole in communication with the air chamber. The insulating base includes a communication hole establishing communication between the gap and the exterior of the microphone unit. The air chamber and the gap are in communication with each other.

Abstract: The orientation of the directional axis and the directionality of a microphone are adjusted through a simple configuration.