Condenser microphone is a kind of microphone to convert the sound signal into electrical signal by the change of capacitance size. This kind of microphone is the most common one. The built-in microphone of recorder is of this kind, because it is cheap, compact, and the effect is not bad. Sometimes it is also called “mic head”.
The condenser microphone has two metal plates, one of which is coated with electret film (most of which is perfluoroethylene propylene) and grounded. The other plate is connected to the gate of field-effect transistor, and a diode is connected between the gate and the source. When the electret diaphragm itself has a charge, the surface charge is Q, and the capacitance between the plates is C, the voltage generated on the electrode head is U= Q/C. When the electret diaphragm is subjected to vibration or air friction, the distance between the two plates is changed due to vibration, that is, the capacitance C changes, while the electric quantity Q remains unchanged, which will cause the voltage change. The magnitude of the voltage change reflects the strength of the external sound pressure. The frequency of the voltage change reflects the frequency of the external sound, which is the working principle of the electret microphone.
The advantages of condenser microphones:
Can convert sound into electrical signal directly.
Condenser microphone is based on the principle of capacitance charge and discharge between conductors. It uses ultra-thin metal or gold-plated plastic film as diaphragms to induce sound pressure, so as to change the static voltage between conductors and directly convert it into electrical energy signal. Practical output impedance and sensitivity can be obtained by coupling electronic circuits.
Can show the characteristics of the original sound reproduction.
Audio experts pursue “original sound reproduction” as the highest level of sound. From the analysis of the basic design principle of the microphone, it is not difficult to find that the condenser microphone not only relies on the precise mechanism manufacturing technology, but also combines with the complex electronic circuit, which can directly convert the sound into electrical signal. It has extremely superior characteristics congenitally, and has become the best choice for those who pursue “original sound reproduction” as a result.
Has a very wide frequency response range.
The diaphragm is the main component of microphone to sense sound and convert it into electrical signal. The material and mechanism design of diaphragm determine the sound quality of microphones. Since the diaphragm of condenser microphone can be made of extremely thin material, and the induced sound pressure can be directly converted into audio signal, the frequency response bass can be extended to the ultra-low frequency below 10Hz, and the treble can easily reach the ultra-high frequency of tens of kHz, showing very wide frequency response characteristics.
Has super high sensitivity.
Since there is no voice coil load on the diaphragm, it can adopt extremely thin design, so it not only has excellent frequency response, but also has excellent sensitivity, which can sense extremely weak sound wave and output the most delicate and accurate original sound.
Fast transient response characteristics.
In addition to the characteristics of the diaphragm that determine the frequency response and sensitivity of the microphone, the ability to respond to sound waves, the so-called “transient response” characteristics, is one of the most important factors affecting the sound of the microphone. The speed of the microphone’s transient response characteristics is determined by the weight of the entire diaphragm. The lighter the diaphragm, the faster the response speed. The extremely thin diaphragm of the condenser capsule has extremely fast transient response characteristics, which can show majestic, enthusiastic and powerful sound and precise audio and video. In particular, there is no sound staining and “box sound” in the mid and bass, and the cold and ethereal treble is the most significant timbre characteristic of the capacitive type. The transient response characteristics of the condenser capsule are much better than those of the moving coil.
Has features of ultra-low touch noise.
When using a handheld microphone, the touch noise caused by contact with the palm makes the original sound mixed with extra noise, which has a huge impact on the sound quality, especially for wireless microphones with pre-amplifier circuits. Therefore, touch noise has become an important factor to judge the quality of microphones. From the physical phenomenon, the goose feather and the copper plate fall to the floor, we almost cannot hear the sound of the goose feather falling, while the copper plate falls very loud, indicating that lighter materials have less impact than heavier ones. In the same way, the diaphragm of a condenser microphone is relatively light, and inherently has the excellent characteristics of “ultra-low touch noise”.
Has the characteristics of drop resistance and impact resistance.
When using the microphone, it is inevitably to lead to malfunctions or abnormalities due to accidental drop and collision. Since the condenser capsule is composed of light plastic parts and a strong light metal shell, the impact force of falling to the ground is small, and the failure rate of damage is low.
Small size and light weight
Condenser microphone adopts ultra-thin diaphragm, which has the characteristics of small size, light weight, high sensitivity and superior frequency response, so it can be designed as an ultra-small microphone(commonly known as little bee and little ant) and widely used.
Best fit for wireless microphone.
Condenser microphones have the above-mentioned excellent characteristics and have become the favorite of sound engineering experts and singers. Wireless microphones have become a trend in the world today to sing on stage or karaoke at home. Wireless microphones has all the advantages of condenser microphones because it can provide the bias voltage required by condenser microphone, so it has become the best microphone that professional audio experts dream of in the digital audio era.
The disadvantages of condenser microphones:
The structure is complicated, the cost is expensive, the sound film is fragile and afraid of moisture, and it is difficult to promote.