Rotary Subwoofer Combines A Speaker Coil W/ a Fan

What happens when you combine a fan with a sub-woofer? Apparently, you get a high-efficiency ultra low hertz (3-5hz) rotary subwoofer! First thing’s first, believe it or not, these things really do exist. [Chris] got the idea to build his own after seeing the TRW-17, a commercial offering of a...