Principle and application of condenser microphone

Thu Dec 23 15:12:07 CST 2021
The core component of condenser microphone is the pole head, which is composed of two metal films; When the sound wave causes its vibration, the different spacing of the metal film causes the different capacitance and generates current. Because the pole head needs a certain voltage for polarization, condenser microphones generally need to use phantom power supply to work. Condenser microphone has the characteristics of high sensitivity and high directivity. Therefore, it is generally used in various professional music, film and television recording, which is very common in the recording studio.
Another kind of condenser microphone is called electret microphone. Electret microphone has the characteristics of small volume, wide frequency range, high fidelity and low cost. It has been widely used in communication equipment, household appliances and other electronic products. When electret microphones are produced, the diaphragm has been subjected to high-voltage polarization treatment and will be permanently charged, so there is no need to add additional polarization voltage. For portability and other requirements, electret condenser microphone can be made very small, so it will affect the sound quality to a certain extent. But theoretically, there should not be much difference in sound quality between electret microphones of the same size and traditional condenser microphones widely used in recording studios.
Chinese name condenser microphone foreign name condenser microphone alias condenser microphone principle an extremely thin gold-plated film capacitor several P farad internal resistance g ohm level features cheap, small volume and high sensitivity
1 working principle
2 features
3 structure
4 purpose
Working principle editing and broadcasting
Condenser microphone
Condenser microphone


The sound pickup principle of condenser microphone is to use an extremely thin gold-plated film as one pole of the capacitor, separated by a few tenths of a millimeter, and another fixed electrode, so as to form a capacitor of several P farads. The film electrode changes the capacity of the capacitor and forms an electrical signal due to the vibration of the sound wave. Because the capacitance is only a few P farads, its internal resistance is very high, Reach the level of G ohms. Therefore, a circuit is needed to convert the G ohm impedance into a general impedance of about 600 ohm. This circuit, also known as the “pre amplification circuit”, is usually integrated inside the condenser microphone and needs a “phantom power supply” to power the circuit. Because of the existence of this pre amplification circuit, condenser microphones must be powered by phantom power supply to work normally. Condenser microphones + phantom power supply are generally very sensitive, which is much more sensitive than common dynamic microphones. In other words, the phantom power supply is necessary for condenser microphones to record whether they are used on computers or other devices, and the recorded sound will not be smaller than that of dynamic microphones. [1]

Feature editing and broadcasting
This kind of microphone is the most common because it is cheap, small and effective. Sometimes it is also called microphone. The specific principle is as follows: on a special layer of material, there is a charge. The charge here is not easy to release. When people talk, the charged film vibrates. As a result, the distance between it and a certain plate is constantly changing, resulting in the change of capacitance. Also, since the charge on it remains unchanged, the voltage will also change according to q = Cu, In this way, the sound signal is converted into an electrical signal. This electrical signal is generally added to a FET inside the microphone to amplify the signal. When connecting to the circuit, pay attention to its correct connection. In addition, piezoelectric microphones are also commonly used in some low-end devices. As shown in Figure 1.
The core component of the condenser microphone is the stage head, which is composed of two metal films; When the sound wave causes its vibration, the different spacing of the metal film causes the different capacitance and generates current. Condenser microphones generally need 48V phantom power supply, microphone amplification equipment or mixer to work.
Condenser microphone is one of the oldest microphone types, which can be traced back to the early 20th century. Compared with other types of microphones, the mechanical structure of condenser microphones is the simplest. It is mainly to paste a thin stretched conductive diaphragm on a metal sheet called the back plate, and use this structure to form a simple capacitor. Then use an external voltage source (usually phantom power supply, but most condenser microphones also have their own power supply device) to supply power to the capacitor. When the sound pressure acts on the diaphragm, the diaphragm will make various slight vibrations along with the waveform, and then this vibration will change the output voltage through the change of capacitance, which constitutes the output signal of the microphone. In fact, capacitance Microphones can also be divided into several types, but their basic working principle is the same. At present, the most popular condenser microphone is the U87 produced by Neumann. [2]

Structure editing and broadcasting
Principle of condenser microphone
Principle of condenser microphone
The general structure of the condenser microphone is shown in the figure “principle of condenser microphone”: the two electrode plates of the capacitor are divided into two parts, which are called diaphragm and back electrode respectively. Single diaphragm microphone pole head, diaphragm and back pole are located on both sides respectively, double diaphragm pole head, back pole is located in the middle, and diaphragm is located on both sides.
The directivity of condenser microphone is accomplished through careful design and debugging of the acoustic path on the opposite side of the diaphragm, which plays a great role in various recording occasions, especially simultaneous and live recording.
Generally speaking (with exceptions of course), condenser microphones are superior to dynamic microphones in sensitivity and expanded high-frequency (sometimes low-frequency) response.
This is related to the working principle that condenser microphones need to convert sound signals into current first. Generally, the diaphragm of condenser microphones is very thin, which is easy to vibrate under the influence of sound pressure, resulting in the corresponding change of voltage between the diaphragm and the rear backplane of the diaphragm compartment. This voltage change will be amplified by the preamplifier and then converted into sound signal output.
Of course, the preamplifier mentioned here refers to the amplifier built into the microphone, rather than the “preamplifier”, that is, the preamplifier on the mixer or interface. Because the diaphragm area of condenser microphone is very small, it is very sensitive to low-frequency or high-frequency sound signals. It is true. Most condenser microphones can accurately capture sound signals that many people can’t hear. [2]
Purpose edit broadcast
Condenser microphone is the best microphone for recording. Its uses include solo, saxophone, flute, steel pipe or woodwind, acoustic guitar or acoustic bass. Condenser microphone is suitable for any place where high-quality sound quality and sound are required. Due to its rugged structure and the ability to handle high sound pressure, condenser microphones are the best choice for live sound reinforcement or live recording. It can pick up the foot drum, guitar and bass speaker. [3]


Post time: Aug-28-2023