http://www.rotarywoofer.com/ Quote: Want to hear what 5Hz sounds like? A new woofer technology unlike any other and a new product category for home audio. This is the first home audio woofer delivering true response to DC. The Thigpen Rotary Woofer is the worlds first true infrasonic home audio or home theater woofer. Conventional subwoofers roll off rapidly below 20Hz. With no cone the rotary woofer achieves high efficiency at very low frequencies. Most subwoofers have a difficult time producing acoustic output below 20Hz at audible levels. They generally require large amounts of equalization, distortion rises rapidly, and even the most expensive available cannot produce significant output below 10Hz. Subwoofer electronics usually contain a cutoff filter which sharply rolls off content to the subwoofer below 20Hz to protect the speaker. On the other hand, the rotary woofer has enough acoustic output to move an open door back and forth .5” between 1 and 5Hz! It has enough output to find resonance frequencies of walls and ceilings in a room. It requires no equalization to achieve flat response to below 1Hz. Microphones have low frequency capability that far exceeds the low frequency output of current subwoofers. In many cases infrasonic information is in a recording, it is not being reproduced by the sound system. A missing link in sound reproduction. Experience special effects like never before. If you want to hear and feel the 4-5 hertz fundamental frequency from a helicopter rotor, the low frequency rumble of wind, the space of a concert hall or infrasonic information contained in an explosion, this is the only woofer technology available. Over the years the generally accepted low frequency limit of hearing has been 20Hz, some suggesting 16Hz. However nothing existed to produce significant enough output to change this belief. This development will spawn new special effects and we will begin to understand the true low frequency limit of human hearing. Currently engineering development is underway for rotary woofer utilization in theme park attractions, concert venues, and professional audio. This may be old news to some but it is still fascinating.