Many people do not know the difference between Hollow inductor and solid inductor. In fact, under the same number of turns and volume, Hollow inductor's inductance value is much lower than solid inductor, so hollow inductor is generally more suitable for In the case of a wider frequency, the solid sense reactance has a more serious frequency tendency; that is, the hollow sense reactance allows most audio and audio frequencies to pass, and the solid sense reactance is selective and only allows a part to pass;
