The EI transformer is defined according to the shape of the core of the transformer. The core of the EI transformer is superimposed by the "E" type sheet and the "I" type sheet. EI transformers are generally power frequency transformers (50HZ or 60HZ), power transformers, and some audio transformers.

In terms of sound quality, the EI type transformer has a thick and full-bodied, warm and mellow sound, and the level of the sound field and the resolution of details are average. When the special layered and segmented winding method is adopted, the details and resolution are significantly improved, and the sense of fine extension of the high frequency is also very good, which is different from other types of power transformers.

EI square transformers are divided into lead wire EI transformers, pin-type EI transformers, potted pin-type EI transformers and BK transformers. Their common feature is that the transformers are all made of machine-inserted cold-rolled silicon steel sheets, mass-produced on a large scale, and 100% fully inspected before leaving the factory; the transformers are vacuum-impregnated, automatically baked, and have a beautiful appearance. Terminals can be added to the end of the lead wire of the EI lead wire transformer, which is convenient for customers to use; The pin-type EI transformer is that each winding is led out by pins, which is simple, beautiful, and has good weldability, and can be directly welded on the PCB board; BK transformer has small size, safe and reliable wiring, high protection level and good performance.