What is a Condenser Microphone?

Dave Mostert
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What is a Condenser Microphone, and How Does it Work?

A condenser microphone is a wired audio-recording device that captures sound through a pair of metal plates. The two plates can be very thin and are separated by a distance equal to just a few human hairs. As sound waves pass through this small air gap, they cause the plates to vibrate in sympathy. The vibration is picked up as an electric signal, which is then turned into audio by a transducer. It’s the transducer’s job to convert the vibration into a signal the rest of the electronics in the microphone can understand.

The basic principle behind condenser mics is the same as it is with any moving bridge, like those used in a theremin. This explains why condensers are sometimes referred to as capacitor mics. The capacitor microphone was invented in 1925 by Chester W. Rice of Bell Telephone Laboratories in the wake of the invention of the telephone transmitter and receiver.

When the capacitor microphone was invented, Bell Telephone Labs used it as a replacement for the carbon microphone. Carbon microphones work by loosening a contact between two carbon granules, similar to how a telephone transmitter works by creating an electric arc between two carbon granules. When the arc is turned on, a metallized membrane is uncovered, allowing the speaker to emit a steady stream of vibrations. The carbon microphone had a couple of issues. It could be damaged by mechanical shock and it was susceptible to radio interference.

What Are Condenser Mics Used For?

Condenser mics are used wherever a microphone needs to reliably capture the subtle nuances of a sound with a higher degree of accuracy. They are often used in recording studios and for live performances. However, these mics are also used in various other areas such as sound reinforcement, podcasting, and studio recording.

What is the Difference Between a Dynamic Microphone and a Condenser Microphone?

A dynamic microphone and a condenser microphone differ in how they convert sound energy into electrical energy.

The main difference between a dynamic microphone and a condenser microphone is the way they pick up sound. A dynamic microphone converts sound into moving air. This moving air is then picked up by a diaphragm, attached to a voice coil. The voice coil is connected to a permanent magnet. This magnet is attached to a thin wire. As the magnet moves, it produces an electric current. The diaphragm and coil, in combination, act as a transducer.

The process of sound being converted into voltage is called electromagnetism.

Condenser microphones are a little bit different. They use the same electromagnetism as the dynamic microphone, but are also known as capacitor microphones. They utilize two different conductive plates. One of these plates is flexible and the other is sturdy. The sturdy plate is attached to a diaphragm. Ions are added to the conductive plate to reduce its conductivity (hence the capacitor). This allows the sturdy plate to become an electrical generator. The ions in the sturdy plate vibrate because of the sound vibrations they are exposed to. This vibration produces a current, which is sent through the cables to be recorded. Both dynamic and condenser microphones produce analogue signals.

Summary

In human body, in the respiratory tract, condenser microphones are used to detect the sound.

Different fixed frequency condenser microphones are used to detect the human breath from one side or with an impedance.

A large amount of constant tension is used to fix the diaphragm of the condenser microphone to the membrane of the crystal.

We can also use this microphone in various electronic instruments such as sound level meter, musical instrument, record player or magnetic tape.