On Tue, Aug 31, 2010 at 1:44 PM, Niels Mayer <nielsmayer(a)gmail.com> wrote: Sort of... It's quite an interesting sub. I've had my eye on that one for years. If you notice the description carefully enough, the blades actuators aren't from servos. There's a voice coil (which at dc and low frequencies) that acts like a solenoid. That's what allows Thigpen's design to work with existing amplifiers. Be careful about what you build if you want to sell one or publish it, because it's patented. Likely the patent doesn't just cover the specific design, but the design principle of variable pitch fan blades as an acoustic transducer. It may be a significant new design if you can make one that has fixed blades and a modulated acoustic impedance or variable speed drive motor. I've spent much time thinking about this one. heh, like those fans that oscillate side to side :) Chuck