Condenser microphones tend to generate a high-quality audio signal and are one of the most popular mic choices for today’s studio recording applications. A condenser microphone (also known as a capacitor microphone) converts sound energy to electrical energy by modulating the charge across an air capacitor formed by a flexible diaphragm and a fixed backplate. When sound waves move the diaphragm, the capacitance changes. In DC-polarized condenser microphones (the most common general type) the resulting fluctuation in voltage creates an electrical approximation of the sound wave; in RF condenser microphones the varying capacitance modulates a radio-frequency carrier which is then detected to recover the audio signal.
Active circuitry is required to transform the very high impedance of a DC-polarized capsule's output to a usable low impedance. 48V Phantom power is commonly used to supply current to this circuitry. Other methods include dedicated power supplies (most often seen with tube condensers) and batteries (often seen with electret condensers).