An electret microphone is a type of condenser microphone. In most cases, these microphones are used in professional studios, but they can also be excellent for amateur purposes. As a rule, condenser electret microphones are often used to equip home recording studios.
On the modern Russian market you can find a huge assortment of this equipment. Among the existing proposals, you can choose an electret microphone both foreign and domestic production. If we talk about cost issues, then foreign-made microphones are somewhat more expensive than Russian. In most cases, this overpricing is hardly justified, since an electret microphone produced in Russia is not inferior in quality to a foreign one.
Currently, microphones of this type have practically replaced microphones with a different design. The reason is that at a very low price, the electret microphone is characterized by high reliability, low weight and smooth frequency response.
Microphones of this type are condensers, some plates of which are made of a very thin film stretched over a ring. The polyethylene film is irradiated by a beam of electrons that penetrate to a shallow depth and as a result create a space charge that can be stored for a fairly long time.
This type of dielectric has the name "electret" - due to which the microphone is also called electret.
Subsequently, a sufficiently thin layer of metal is used on the film, which is used as one of the electrodes. A metal cylinder acts as another electrode, whose flat surface is not far from the film.
Its vibrations, which are caused by acoustic waves, are able to create an electric current between the electrodes. Due to the fact that the strength of this current is quite small, and the output resistance reaches gigaohms, the transmission of the signal generated by the microphone is quite difficult. As a result, in order to match the low impedance of the amplifier with the high impedance of the microphone, it is necessary to use a matching stage, which is made on a field (unipolar) transistor, which is structurally located in the body of the microphone capsule.
The capsule body must be made of metal capable of shielding the microphone and matching the cascade, protecting it from external fields of electricity.
As a rule, a device is called a capsule here, in whose case is located not only the electret microphone itself, but also the matching cascade.
In order to understand whether this or that microphone amplifier is suitable for connecting an electret microphone , it is quite enough to connect to the input jack of the multimer. If as a result the device shows 2-3 Volts, this means that the amplifier is suitable for working with an electret microphone. Many microphone amplifiers are used in separate computer audio cards or in built-in ones, which are designed specifically for working with electret microphones.
The principle of operation of electret microphones is based on the ability of some materials with a high dielectric constant to change their surface charge as a result of exposure to a sound wave. Electret microphones have very high impedance, which makes it possible to connect them to amplifiers with high input impedance.
By design, these microphones are divided into three categories: electret material is in the front position; electret material deposited on a flexible membrane; The electret is on the back plate.
Today, the leader in the manufacture of professional sound recording equipment is the Octava company, whose microphones have an impeccable reputation.
"Octave" FEM - a series that includes several models of professional electret microphones, which are designed for various conditions of use. Particular attention should be paid to the company's new product - the microphone "Octave" FEM - 222, which is designed to record conferences.