| 摘要 |
A condenser microphone is obtained, in which the bias of a current amplifier circuit in emitter-follower connection immediately after an impedance converter automatically changes in accordance with the switching of phantom power supply voltages and the maximum output level and the maximum permissible input sound pressure level are increased at any power supply voltage. The condenser microphone comprising a transistor Q 2 in emitter-follower connection immediately after an FET 2 that constitutes an impedance converter Q 1 has a constant current diode D 2 connected to an output transformer TRS that also serves as a transformer for phantom power source supply and resistors R 0 and R 1 that divide the voltage on the cathode side of the constant current diode D 2 into a bias voltage that causes the transistor Q 2 to operate.
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