Moving iron earphones are earphones that are conducted to the center point of a miniature diaphragm through a precisely structured connecting rod to generate vibration and sound. Moving iron earphones can be easily inserted into the ear canal because the unit is much smaller. This approach effectively reduces the area of the ear part and can be inserted into the deeper part of the ear canal. The geometric structure of the ear canal is much simpler than that of the auricle. It is a round shape, so a soft silicone sleeve has a good sound insulation and anti-leakage effect compared to traditional earplugs.
Inside the moving iron earplugs, the voice coil is wound on a precision iron piece called a "balanced armature" located in the center of the permanent magnetic field. This piece of iron drives the diaphragm to make sound under the action of magnetic force.
The moving coil directly drives the diaphragm, while the moving iron is conducted to the center point of a miniature diaphragm through a precisely structured connecting rod, thereby generating vibration and sound.
The sound insulation effect of moving iron is better than that of moving coil into the ear. Due to the large area of the moving coil unit and the need for more space and air to participate in the vibration during the sound production process, the sound leakage phenomenon cannot be effectively controlled; while the moving iron can effectively reduce the area of the ear part and can be placed deeper Part of the ear canal. (Almost moving coil earphones have vent holes, and moving iron earphones rarely see vent holes. CK9 is an exception.) Because the geometric structure of the ear canal is similar to the circle, it is much simpler than the auricle, so it has a soft texture. Compared with the traditional earplugs, the silicone sleeve has good sound insulation and anti-leakage effect.
The sensitivity of moving iron is higher than that of moving coil. The main reason is that the structure of moving iron unit is almost a closed container structure, which can be driven by a little current. Pay attention to the relationship between sensitivity and resistance. It is precisely because of higher sensitivity that moving iron earphones perform better transiently, and are far better than moving earphones in terms of dynamic performance, instantaneous detail performance, and sound density of music.
The frequency response curve of moving iron headphones is more stable. Dynamic earphones have some audible changes in the frequency response curve under different temperatures, humidity and use. The moving iron shows good stability, making the sound quality more stable and reliable, and not easy to change. A very important reason is that the moving iron units are almost all made of metal materials and are formed by high-precision molds. The vibration diaphragm of the moving coil unit is generally combined with the coil by glue, so there are many influencing elements inside. , There are many individual differences. Therefore, the electroacoustic performance of the unit compared with the moving coil is much more stable.
The moving iron is smaller and lighter. This is due to the characteristics of the moving iron unit. The weight of the diaphragm of the moving iron rises linearly with the increase in the diameter of the unit. Therefore, the moving iron is more suitable for small in-ear earplugs, and it is impossible to make an open type. Or half-open earplugs. This is why the moving iron technology is only used on earplugs.
Moving iron earphones help protect hearing. Moving iron earplugs generally have a good sound insulation effect, and the extremely high sensitivity allows a very small volume to have a good performance, so you can enjoy pure sound without increasing the volume in a noisy environment. Moving iron units are widely used in medical, healthcare, aviation, military and other fields, and hearing aids are more common. Doctors will not recommend products that may harm their health to patients, and most well-known hearing aid brands use moving iron units, so moving iron earphones are more secure than moving coil earphones.
The sound quality of dynamic earphones mainly depends on the material of the diaphragm and the material and structure of the cavity in hardware, and the magnet mainly determines the driveability of the earphone. The design of the cavity plays a vital role in the sound performance of dynamic headphones. From the above, everyone has probably understood the basic structure of the moving iron, and the parts and the moving coil that determine the sound quality of the moving iron earplugs are obviously different.
First of all, the cavity of the moving iron earphone has little effect on the sound quality. This is a distinctive feature of moving iron. The main function of the movable iron cavity is to fix the stability of the movable iron unit and the outlet, and there is no strict and fixed requirement. This is why even a meticulous manufacturer such as Audio-Technica, when producing the CK9, also behaves casually in the handling of the shell. Only the front end of the guide port needs to be tightly sealed due to the need to fix the unit and the filling material, and the requirements for the mold are also quite strict. Some players, and even a few veterans, often talk about the cavity of a moving iron earplug, so the sound, basically it can be determined from the theoretical level that all the remarks are contrived. In fact, as long as the cavity can achieve good sealing, it will not affect the sound performance.
Compared with the moving coil, the moving iron unit has a more sophisticated internal structure and higher production costs (it should be noted that this is not the main reason for the high price of moving iron headphones). It is the foundation of the sound quality of the earphone, and the advantages of the moving iron over other earphones are mainly reflected by it. A good earplug must use a good unit.
In fact, the sound quality of moving iron has a more important aspect. The sound quality of the ER4P that also uses a single unit is much higher than that of the UM1. Of course, the unit accounts for part of the reason, but on the other hand, it depends more on the inside of the moving iron earplug cavity, the element that is in contact with the housing—the sealing ring. This sealing ring reflects more than half of the technical level of moving iron headset manufacturers. The difficulty of moving iron earphones lies not only in the unit, but also in this small sealing ring part. The function of this rubber ring is to further enhance the sealing of the unit, and the other is to modify the sound conduction. Different tuning materials and different craftsmanship will produce different sound performances. Compared with the moving coil, the tuning of the moving iron basically lies in the adjustment of the material and structure of the sealing ring. Its adjustment level requires extremely precise technical level, which mainly determines the difficulty of producing moving iron earphones. Therefore, moving iron can not be produced only with units, and it is not the kind of small cottage that can be assembled at will like moving coils to make a good sound.
The technologies mentioned above are core business secrets, so no matter Shure, UE or Etymotic, they never disclose more technical details to the outside world. This is also one of the reasons why everyone generally knows little about moving iron. It should be noted that the above is only an analysis from the hardware and structure. Like the moving coil, there are many factors that affect the moving iron earphones, and it is difficult to list them all here.