Generally speaking, it is divided into 7 categories of earphones: piezoelectric, moving iron, moving coil, electrostatic, pneumatic, isomagnetism, electret.
Piezoelectric: Use the piezoelectric effect of piezoelectric ceramics to produce sound. High efficiency and high frequency. Disadvantages: large distortion, high drive voltage, poor low-frequency response, poor impact resistance. This type of headset is mostly used for telegraph transmission and reception, and is now basically eliminated. A few earphones use piezoelectric ceramics as the tweeter sound unit.
Moving iron: The electromagnet is used to generate an alternating magnetic field. The vibrating part is a piece of iron suspended in front of the electromagnet. When the signal passes through the electromagnet, the magnetic field of the electromagnet will change, which makes the iron piece vibrate and sound. The advantages are long service life and high efficiency. The disadvantage is that the distortion is large and the frequency response is narrow. Often used in early telephone handsets.
Dynamic: This is the most common form of earphones now. The coil is fixed on the diaphragm and placed in a fixed magnetic field generated by a permanent magnet. The signal passes through the coil to cut the lines of magnetic force, thereby driving the diaphragm to vibrate and sound together. The advantages are relatively easy production, good linearity, low distortion, and wide frequency response. The disadvantage is low efficiency (not a shortcoming).
Static electricity: also known as electrostatic flat diaphragm, is to directly electroplate or print aluminum (or other conductive metal) coil on a thin plastic film, and place it in a strong electrostatic field (usually by a DC high voltage generator and a fixed metal sheet (Net), when the signal passes through the coil, it cuts the electric field and drives the diaphragm to vibrate and make sound. The advantages are good linearity, low distortion (electric field is more uniform than magnetic field), good transient response (light diaphragm mass), and good high frequency response. The disadvantage is that the low frequency response is not good, the special drive circuit and electrostatic generator are required, and the price is expensive. The efficiency is not high.
Pneumatic: Air pump and air valve are used to control air flow, and directly control air pressure and flow rate, which makes the air vibrate. Sometimes the air valve is replaced with a high-power speaker. Such earphones are commonly used on airplanes, and this earphone is actually just an airway. The advantages are no electric drive, unlimited parallel connection and high efficiency. The disadvantage is that the distortion is large, the frequency response is narrow, and there is noise.
Isomagnetic type: The principle of isomagnetic electroacoustic transducer and moving coil electroacoustic transducer is the same, but the structure is different. The isomagnetic electroacoustic transducer uses a planar vibration mode, and multiple sets of voice coil wires are laid on the planar diaphragm, and there are magnetic circuits corresponding to one of them. Because the diaphragm is thin and light, and can be fully driven, it has a wide frequency band, good high-frequency characteristics and transient characteristics, and low distortion, but the sensitivity is lower than that of ordinary moving coil electroacoustic transducers.
Electret: The electret electroacoustic transducer is a special electrostatic electroacoustic transducer. Modern technology can use corona discharge or electron bombardment at high temperature and high pressure, so that certain media (electret materials) can maintain electric charge even after the external electric field is removed. In contrast, our familiar example is that certain ferromagnetic materials (permanent magnetic materials) can retain their magnetism after being magnetized, and we call them permanent magnets. Therefore, electrets are often called “permanent electric bodies”. In fact, whether it is “permanent magnet” or “permanent electricity”, it is only relatively speaking, they will also “loss of magnetism” and “loss of electricity” as the use time or external conditions change. In other words, their performance also has a “lifetime”. The service life of an excellent electret can reach more than 15 years.
I think the current situation of earphones and audiophiles are somewhat similar. They can be roughly divided into European sound and American sound, or they can be said to be monitor type and music type.
There are many products produced in European countries for monitor headphones. Its characteristics are that the low frequency components are slightly lacking and the other frequency bands are very balanced, less sound dyeing, and the sound is faithful, restrained, transparent and cold, which is close to the sound characteristics of professional monitor headphones. Suitable for the performance of classical music and symphonic music.
The representative products of music headphones are KOSS, Goethe, and Alice. This kind of earphone fully embodies the Americans’ pragmatism and informality to satisfy the sense of hearing. It modifies and polishes the sound, but does not overemphasize the authenticity of the sound, the sound is thick and warm, the bass is strong, the rhythm is strong, and the sound is full of sensibility. And musicality, it is suitable for many types of music, especially for light music, modern music, and popular music.
The music performance characteristics and suitable music types of the above two headphones are not absolute, but they have their own focus.
It should also be pointed out that no matter what style of headphones, their high-end products and high-end models are very faithful performance music, and there is no obvious sound dyeing, but they all maintain their own styles.
The representative brands of Japanese earphones are Audio-Technica and Sony. Most of the low-end earphones of these two brands are produced in China, including Taiwan and Southeast Asia.
The sound characteristics of Japanese headphones are different from the above two types. The human voice is the characteristic of this kind of headphones. The sound is warm and has appropriate modifications. Of course, his professional monitor headphones are another case, they are authentic monitor sounds.
When some people mention modification, it is connected with distortion. In fact, modification must modify and polish the sound signal in every audio equipment and every link. Even European headphones are modified because there are different brands in Europe. The sound is not exactly the same, the key is whether the modification is appropriate. (Bluetooth headset manufacturers, bluetooth headset OEM, bluetooth headset wholesale, Internet cafe game headset wholesale)