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 condenser microphone unit that has a capacitor element with a large effective area and a high signal-noise ratio but does not have frequency-dependence occurring with sound waves beyond the audio frequency range. A solid cylindrical fixed electrode pole is used as a fixed electrode. A diaphragm includes a rectangular synthetic resin film having a length smaller than or equal to the axis length of the fixed electrode pole, and a width equal to a circumferential length of the fixed electrode pole, the synthetic resin film including an electrode film on one face and ribs on the other face and entirely partitioned by the ribs into a plurality of diaphragm regions. The synthetic resin film is attached to an entire outer periphery of the fixed electrode pole such that the ribs are in contact with the outer periphery.

Abstract: A boundary microphone is provided that does not generate spark discharge during an operation of a switch. The boundary microphone includes a microphone unit 6, and a switching unit (a button 4, a tube 9, a detector 10, a comparator, and a switching circuit) that switches turning-on or turning-off of output signals from the microphone unit 6, wherein the switching unit (the button 4, the tube 9, the detector 10, the comparator, and the switching circuit) includes an air chamber 9 and a controller that controls the turning-on or turning-off based on the air pressure inside the air chamber 9.

Abstract: A unidirectional condenser microphone having a front opening portion and a rear opening portion for respectively passing sound waves to a front surface and a back surface of a diaphragm of a microphone unit, the unidirectional condenser microphone includes: an acoustic tube provided in the front opening portion; a first air chamber provided between the rear opening portion and the back surface of the diaphragm of the microphone unit, and having a predetermined acoustic capacity; and a second air chamber communicating into the first air chamber, and having an acoustic capacity larger than the predetermined acoustic capacity, wherein sensitivity to a direction of 0° with respect to a directional axis is improved by the first air chamber and the acoustic tube, and a proximity effect due to the sound wave from a direction of 180° with respect to the directional axis is prevented by the second air chamber.

Abstract: The microphone device includes a tubular support of a conductive material. A microphone unit is provided at one end of the support and grounded to the support. A cable passes through the support and includes core wires connected to a signal output terminal of the microphone unit. A conductive covering material that covers the core wires and is electrically connected to the support.

Abstract: There are provided a microphone stand having a connector supporting groove, and a microphone body supported by the microphone stand as a result of insertion of a connector case into the connector supporting groove. A resilient conductive cloth which comes into contact with the connector case is arranged in the connector supporting groove, with the connector case inserted in the connector supporting groove. The conductive cloth is preferably arranged in a ring shape along a lower bottom portion of the annularly formed connector supporting groove. This configuration mitigates rattling generated between the connector supporting groove and the connector case, thereby suppressing generation of a vibration noise due to microphone shaking.

Abstract: A microphone joint is provided that includes movable parts having preferable electrical connection, movability, and fixing force. The microphone joint is to be coupled to a unit case accommodating a microphone unit and a connector case accommodating a connector configured to output signals from the microphone unit to an external device. The microphone joint includes a first unit to be coupled to the unit case, a second unit to be coupled to the connector case, and a conductive member disposed between the first unit and the second unit. The first unit is supported by the second unit with the conductive member and is rotatable relative to the second unit. The conductive member has resilience.

Abstract: A stereo microphone includes an omnidirectional microphone unit, a bidirectional side-channel microphone unit arranged to be perpendicular to a direction of a sound collecting axis outside the omnidirectional microphone unit, a right-channel microphone unit arranged to form a predetermined angle with respect to the side-channel microphone unit on a plane including the sound collecting axis outside the omnidirectional microphone unit, and a left-channel microphone unit arranged to form a predetermined angle with respect to the side-channel microphone unit and the right-channel microphone unit on the plane including the sound collecting axis outside the omnidirectional microphone unit.

Abstract: Provided is a unidirectional microphone including ribbon diaphragms which is reduced in dimensions. The microphone includes a bidirectional ribbon microphone unit and an omnidirectional condenser microphone unit. The ribbon microphone unit includes a pair of ribbon diaphragms. The condenser microphone unit is disposed between the pair of ribbon diaphragms.

Abstract: In a unidirectional dynamic microphone unit, a cylindrical tube is provided to cover the microphone unit, a cylindrical wall of a first cylindrical portion that is included in the cylindrical tube and extends to at least the rearward is provided with a rear sound wave introducing portion weighted such that an acoustic resistance value is gradually made smaller toward the rearward side from positions of sound holes for taking in a sound wave transmitting around from the rearward side, preferably formed of a trumpet-shaped opening, and it is possible to enhance the sensibility to sound pressures without degradation of the frequency response and the directionality.

Abstract: A narrow directional microphone includes a unit case having a front end portion to which a microphone unit is mounted, and a side surface functioning as a grip, an acoustic tube formed of resin material in a tubular shape, covering the microphone unit, and attached to the front end portion of the unit case such that the microphone unit is positioned to an inner bottom portion of the acoustic tube, a piezoelectric film that is arranged in at least one part of the acoustic tube, and that generates a detection output based on a mechanical deformation of the acoustic tube, and an output signal processing unit including an attenuation circuit that attenuates an audio signal from the microphone unit with the detection output from the piezoelectric film and sends the attenuated audio signal to a signal output unit.

Abstract: There is provided a boundary microphone inside which a unidirectional microphone unit is contained, the microphone including: a base plate; and a cover plate attached onto an upper face side thereof, wherein a thin and long tubular groove acting as an acoustic tube for making unidirectivity of the microphone unit a narrow directivity is formed on the base plate side, and therein, the microphone unit is contained. In order to prevent liquid from entering the tubular groove from the outside, between a peripheral edge part of the cover plate and the upper face of the base plate, a spacer that is composed of a water repellent thin film material and allows an inside of the tubular groove and outside air to communicate via acoustic resistance with a thin air layer is disposed so as to enclose an entire periphery of the tubular groove.

Abstract: A condenser microphone unit includes a diaphragm vibrated by acoustic waves, a fixed electrode disposed to face the diaphragm, and an insulation base making contact with a rim portion of the fixed electrode to support the fixed electrode, wherein a ring-shaped protrusion is provided on a rim portion of the insulation base, the ring-shaped protrusion protruding toward the fixed electrode with a radially inward taper and having a ring-shaped distal face to oppose the rim portion of the fixed electrode, the distal face of the ring-shaped protrusion supports the rim portion of the fixed electrode, and an adhesive is provided on a tapered surface of the ring-shaped protrusion positioned between the insulation base and the fixed electrode, the adhesive having property to shrink by curing. When the adhesive is cured, contact portions of the insulation base and the fixed electrode are tightly bonded together.

Abstract: A condenser microphone unit is provided that can flatten a frequency response in a high frequency band. The condenser microphone unit includes a unit case having an acoustic-wave entering hole, and a diaphragm accommodated in the unit case. The diaphragm is configured to vibrate in response to acoustic waves from the acoustic-wave entering hole. In the condenser microphone unit, an acoustic resistor is disposed between the acoustic-wave entering hole and the diaphragm. The acoustic resistor includes two elastic members in pressure contact with each other. At least one of the two elastic members is curved in a convex shape before contacting the other of the two elastic members by the pressure contact. A convex surface of one of the two elastic members is a surface that comes in pressure contact with the other elastic member.

Abstract: A connector for a microphone and a microphone are provided that can prevent loose connections to a microphone stand. The connector for the microphone is to be inserted into a connector support hole of a microphone stand. The connector includes pins to be electrically connected to the microphone stand, a connector body accommodating the pins, a sleeve disposed on the outer circumferential surface of the connector body, and an elastic member for biasing the sleeve toward the rear end of the connector body. The sleeve has an insertion portion to be inserted into a space between the connector body and the connector support hole.

Abstract: A microphone is provided that ensures the electrical connection between a unit case and an audio-signal output circuit board. The microphone includes a unit case 10 having a shape of a hollow cylinder with a closed end and accommodating an electroacoustic transducer 20, an audio-signal output circuit board 40 connected to the electroacoustic transducer, and a microphone case accommodating the unit case and the audio-signal output circuit board, wherein the audio-signal output circuit board has a receiver 41 disposed on a portion of the peripheral edge of the audio-signal output circuit board, and an open end 11 of the unit case comes into contact with the receiver and is positioned when the unit case and the audio-signal output circuit board are accommodated in the microphone case.

Abstract: A microphone includes a microphone unit that converts a sound into an electrical signal. A tubular housing houses the microphone unit and includes a rear opening portion in a side surface. A step portion surrounds the rear opening portion in an inner surface of the housing. A plate-like shielding member is attached to the step portion from an inner surface side of the housing, and a circuit board housed in the housing in contact with the shielding member includes a ground pattern its side surface and in a contact position between the circuit board and the shielding member.

Abstract: A condenser microphone includes a first grounded-plate electron tube having a plate to which a dc power is supplied, and a cathode provided with an output terminal, a self-biasing circuit that is connected to the cathode of the first electron tube and that generates a grid bias voltage of the first electron tube by voltage drop with a cathode current, and a second grounded-cathode electron tube having a plate to which a series circuit of the first electron tube and the self-biasing circuit is connected as a load circuit. A positive phase output from a first condenser microphone unit is supplied to a grid of the first electron tube, and a reverse phase output from a second condenser microphone unit is supplied to a grid of the second electron tube.

Abstract: An audio output circuit of a condenser microphone includes a condenser microphone unit, first and second impedance conversion circuits that receive a positive phase output signal and a reverse phase output signal from the condenser microphone unit, first and second output circuits that output an audio signal from the condenser microphone unit in a balanced line to a balanced output terminals upon receipt of outputs of the first and second impedance conversion circuits. First and second impedance conversion circuits respectively use FETs as source follower circuits and supply first and second impedance conversion outputs generated across source resistors to the first and second output circuits. A voltage regulating device that generates a constant voltage is connected in series to the source resistors. With this configuration, an audio output circuit of a condenser microphone is provided, which solves a problem of operation instability caused by variation of Idss's of the FETs.

Abstract: To obtain a unidirectional microphone with high sound quality, which achieves unidirectivity while preventing deterioration in sound quality of a ribbon microphone. A unidirectional condenser microphone and bi-directional ribbon microphones are included, and the unidirectional condenser microphone and the bi-directional ribbon microphones are disposed such that a 0° direction of a sound collecting axis of the unidirectional condenser microphone accords with a 180° direction of sound collecting axes of the bi-directional ribbon microphones, and an output of the unidirectional condenser microphone is subtracted from an output of the 180° direction of the bi-directional ribbon microphones.