What is a flat earphone?

Flat diaphragm earphone, also called equal magnetic earphone. At present, mainly a few brands such as HiFiMAN in China and Audeze in the United States have such products. In fact, simply speaking, this kind of product is similar to a reduced flat speaker, which means combining the two principles of moving coil and static electricity, that is, embedding the voice coil into the diaphragm, similar to the printed circuit board. Because of the structural advantages, the sound quality of flat headphones is often better than that of traditional moving coils (especially at high frequencies), but they can't be made too small and heavy, so they are not easy to carry, most products are not easy to open, and there are few entry-level products.