This 3″ Magnet Shielded Woofer has housing around the voice coil assembly. It’s generally known that speakers, particularly large ones, include massive magnets that drive the cones’ movement. And it’s widely assumed that putting strong magnets near computer equipment is a prescription for disaster.
Magnetic shielding is used to prevent low-frequency and high-frequency electromagnetic (EM) radiation from infiltrating inside Faraday Cages and sensitive RF testing rooms by bypassing low-frequency and absorbing high-frequency EM radiation. Magnets generate a field of energy that extends beyond the magnet, influencing items such as magnetic computer drives, CRT TVs, and monitors.
In most speakers, the solution is a “bucking magnet,” which is essentially a magnet that has been glued to the same polarity as the speaker driver’s magnet. The magnets oppose each other and contain the magnetic field when positioned this way, which is why the adhesive must be strong. To add some shielding, a metal cap is frequently placed over the entire magnetic assembly.
When we connect the coil to terminals to any source, the coil produces self magnetization, and then the coil repels or attracts by a magnet, thus the changing signal (changing current) attraction and repulsion produce vibration, and we can listen to that vibration, which we name voice.