Sup
Did you know that...
Subwoofer refers to either a woofer, or a complete loudspeaker dedicated to the reproduction of
bass audio frequencies, typically from 150 Hz down to 20 Hz.  
    powered subwoofers    
In the case of a rotary woofer, it is
possible to reproduce frequencies down to 1 Hz.
 bye

This spammer passed the checks   ... However the way he posted the link is invalid. Note that posting link here is nearly useless because links posted into the site are visible only to registered users , not even the search boats can see them, so they are directed only to people of the site.   Maybe Andreas is interested in this subwoofer something (however I can make a BURP lower than 1 hz   )

P.S. Note that u'll get an "user doesn't exist if you reply to this message"

It seems to me the person is passing a bit of information.

A Sub Woofer is a large speaker that can produce a bass note down to 20 hertz.
He is stating that a rotary speaker can play or go lower to make a sound although you can only feel it rather
hearing it below 20 hertz.

In most speaker cabinets that play music they have three speakers. A tweeter, midrange and woofer. They where known as a three way system to produce sound threw the audio spectrum. Then cam a Driver or speaker as you will known as a Sub Woofer to produce lower bass tones or notes.