Although strictly speaking microphones (scientific name microphones) can be divided into many categories according to different working methods, the two types that are widely used in professional and amateur recording occasions are mainly dynamic microphones and condenser microphones.
We know that the microphone works by the change in air pressure caused by the sound wave induced by the diaphragm, which is very similar to the "working" principle of our ears. The diaphragm of a dynamic microphone (equivalent to our eardrum) is located in the annular gap between a cylindrical magnet and a piece of soft iron. A movable coil suspended between two magnetic poles is connected to the diaphragm. We usually Call it the "voice coil". The sound wave vibrates the diaphragm, so that the voice coil cuts the magnetic lines of force in the circular gap in motion, thereby inducing current and outputting.
The advantages of dynamic microphones are simple structure, low price, stable work, sturdiness and durability, and long life. They are widely used in various recording occasions. However, due to its low sensitivity, the frequency response is not wide enough (the best state is 40Hz～16kHz, and the average hearing limit of the human ear is about 20Hz～20kHz), so if you use a dynamic microphone to record some of the wide frequency and dynamic Sound sources with large and more overtone components (such as an orchestra ensemble, etc.) appear to be a little weak.
In professional recording studios, sound engineers usually use condenser microphones more often. The full name of condenser microphone is "capacitance variable microphone". Its core is a capacitor composed of a very light movable diaphragm plate and a fixed plate. We call this device "pole" or "capacitor box". When the pole tip is applied with a polarization voltage, an electric charge will be generated on the two pole plates. Sound waves vibrate the diaphragm (that is, move the plate), the charge will change, and finally a voltage is generated across the load resistance to form an audio signal.
The sensitivity of the condenser microphone is very high, and the frequency response is also very wide, up to 20Hz～20kHz or wider, which can meet the needs of most professional recording. Its disadvantage is that it is more sensitive to environmental noise, the diaphragm is also relatively fragile, and has a short life span, so it is not suitable for outdoor use.
Since the pole head of the condenser microphone must be applied with a polarized voltage to work, it is necessary to provide power to the condenser microphone if you want to use it. Think about it, if every microphone has to be connected to a power cord and an audio cable, how troublesome it can be. In order to minimize the connection, people came up with a "phantom power supply" method. The so-called "phantom power supply" means that both audio signal current and DC power supply voltage are included in the same cable. In this way, we only need to connect an audio cable to get the polarization voltage and audio signal at the same time.