It's the motor. They are using a smallish diameter fan in the base of the unit. And the air intake is a grill full of tiny holes. Neither are good for keeping a system quiet.Original Post Deleted
I've tried replacing the fan in a knockoff unit with high quality, low noise radial fan, but that doesn't t work too well either. Basically, the overall design is a bit flawed regardless of the quality of the motor. It'd be easy to redesign it for low noise (just increase the diameter of the base) but then the fan would look a bit too ugly, I guess.
Last edited by jgl; 31-08-2011 at 08:28 PM.