Modulate the rpm of the fan to get acoustic output?

[Hezz]

Wouldn't the doppler distortion caused by the relative motion of the motor and the modulation make a lot of distortion.

This is one of the problems with the blade modulated fan subwoofer. It can put out lots of bass but it is of low quality and high cost. Hardly a practical device for any home use for HT or music listening.

 

[phase_accurate]

The reason the variable pitch unit works is because it's so much easier to change the pitch, than the overall speed. Too bad the cost is so high.

Im not so sure about that. If you resort to mechanics used for model helicopters it should not be too expensive maybe.

Regards

Charles

 

[peter_m]

To get soundwaves out of RPMs I suggest you look at this video. It gets interesting after the first 19 seconds.

Peter