Self-Biased Condenser Microphone with High Capacitance

Abstract

A new kind of condenser microphone with solid dielectric between the electrodes is described. The system employs metallized dielectric foil electret and requires no external dc bias. The lower impedance eliminates the need of a cathode follower and allows the use of a long connecting cable. The frequency response of this system is flat within ±3 dB between 50 and 15 000 cps. The sensitivity of the system is −59 dBV for a sound pressure of 1 dyn/cm2 (74 db SPL).