Electret microphone

An electret microphone is a kind of condenser microphone. In most cases, such microphones are used in professional studios, but they can be perfect 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 range of this equipment. Among the existing proposals, you can choose an electret microphone of both foreign and domestic production. If we talk about cost issues, then microphones of foreign production are somewhat more expensive than Russian ones. In most cases, this overstatement of prices is not justified, since an electret microphone of Russian production is not inferior in quality to a foreign one.

At present, microphones of this type have almost supplanted microphones with a different design. The reason is that at a very low price an electret microphone is characterized by high reliability, low weight and smooth AFC.

Microphones of this type are capacitors, some of which are made of a very thin film stretched over the ring. The polyethylene film is irradiated by an electron beam that penetrates to a small depth and as a result creates a space charge that can be stored for a sufficiently long time.

This type of dielectric has the name "electret" - so the microphone is also called electret.

Subsequently, a thin layer of metal is applied to the film, which is used as one of the electrodes. The other electrode is a metal cylinder whose flat surface is near the film.

Its oscillations, which are caused by acoustic waves, are capable of creating an electric current between the electrodes. Due to the fact that the strength of this current is small enough, and the output resistance reaches the 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 resistance of the microphone, it is necessary to use a matching stage, which is made on a field (unipolar) transistor, structurally located in the housing of the microphone capsule.

The case of the capsule must be made of metal, capable of screening the microphone and coordinating the cascade, protecting it from external electric fields.

As a rule, a capsule is a device in which the body is not only the electret microphone itself, but also a matching cascade.

In order to understand whether a particular microphone amplifier is suitable for connecting an electret microphone , it is sufficient to connect to the input jack of the multimeter. If, as a result, the instrument shows 2-3 volts, it means that the amplifier is suitable for working together with an electret microphone. Many microphone amplifiers are used in separate computer audio cards or in built-in ones, which are designed just for working with electret microphones.

The principle of operation of electret microphones is based on the possibility of some materials having high dielectric permittivity, changing their surface charge as a result of the sound wave. Electret microphones have very high resistance, so that they can be connected to amplifiers with high input impedance.

According to their design, these microphones are divided into three categories: the electret material is in the frontal position; Electret material is applied to a flexible membrane; The electret is located on the back plate.

To date, the leader in the manufacture of professional sound recording equipment is the company "Octave", whose microphones have an impeccable reputation.

"Octave" MCE - a series that includes several models of professional electret microphones, which are designed for different conditions of use. Particular attention should be paid to the novelty of the company - Octave microphone "MKE-222", which is intended for recording conferences.

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