What is a condenser microphone?
Condenser microphones are generally high-impedance devices which require amplification to be located near the sensor itself. It is not infrequent for the amplifier to limit the dynamic range of such microphones, but ranges of up to 140 dB are readily available. Stainless steel and other metal parts comprise a condenser microphone. It is stable at different temperatures and other environmental changes. It holds its calibration for long periods. You can also use it as a secondary standard.
Measuring sound pressure
The condenser microphone is a most suitable transducer that is available for the measurements of sound pressures. Unlike the ceramic microphones, it is very insensitive to the vibrations, and this is a distinct advantage in an industrial environment. Hence, some of the most commercially available noise measurement transducers are of the condenser microphone type. A variety of condenser microphones are available. Engineers can measure the sound pressure at frequencies as low as 0.01 Hz and high as 140 Hz.
Two metal plates
The core design of the typical condenser microphone consists of two metal plates. One metal plate is fixed (the backplate) and the other movable (the diaphragm), forming a capacitor. When a sound wave hits the diaphragm, the distance between the two plates changes which produces a change in an electrical characteristic called capacitance. It is the variation of the spacing, due to the motion of the diaphragm relative to the fixed back plate, which produces the electrical signal corresponding to the sound picked up. In order to obtain a signal, condenser microphones require an electrical current to charge the plates. This is usually provided either by a battery or is sent down the microphone cable itself. This latter method is known as phantom powering. Most condenser microphones can operate with phantom power voltages ranging from 11 to 52 VDC. They usually have the mixing console/audio interface.
The sound that the condenser microphones produces is usually clear, crisp and full of detail. However, there are some advantages and disadvantages when talking about condenser microphones.
Advantages & Dissadvantages
The advantages of condenser microphones:
- The diaphragm assembly is light in comparison to dynamic microphones. Hence, it’s more efficient at moving and is capable of capturing a range of high frequencies.
- Easy to obtain a flat frequency response and extended frequency ranges.
- Can be small in design
The disadvantages of condenser microphones:
- There is a limit to the maximum signal level the electronics can handle
- They are more complex than dynamic microphones. Extremes of temperature and humidity affect them.
- Cheaper models can produce a small amount of noise from the electronics