Studio Condenser Microphone

Overview

A studio condenser microphone converts sound into an electrical signal using a charged capacitor whose capacitance changes as sound waves move one of its plates. A thin conductive diaphragm is mounted close to a fixed backplate to form that capacitor; arriving sound pressure flexes the diaphragm, varying the spacing and producing a tiny voltage that mirrors the waveform. Because the moving mass is so small, condensers capture detail and transient response that make them the standard for recording vocals and acoustic instruments. The large-diaphragm, side-address model described here adds switchable patterns and a transformer-coupled output.

The signal starts at the Condenser Capsule, a dual-membrane assembly of gold-sputtered Mylar diaphragms over a drilled brass backplate held by an insulating ring. The capsule's extremely high source impedance cannot drive a cable directly, so it feeds the Impedance-Converter Board, a head-amplifier board built around a low-noise FET impedance converter and an output transformer that produces the balanced, isolated XLR line. A polarization network supplies the capsule's bias voltage from incoming phantom power.

How it works

Pattern and level control come from the Switch Pack: a pattern switch changes the biasing of the two membranes to select omni, cardioid or figure-8 response, while a combined switch inserts a −10 dB pad for loud sources and a low-cut filter to tame proximity bass. The capsule and board sit inside the Headbasket & Body, whose wire-mesh headbasket screens wind, plosives and RF interference while letting sound reach the diaphragm. For use, the mic is held in the Shock Mount, an elastic suspension cradle that isolates the capsule from stand and floor vibration, and the Pop Filter breaks up plosive air blasts from close vocal work.