Getting esoteric on infrasound Re: [sdiy]

[metasonix]

>plywook horns of varying size, with a pivoting flapper
>at the throat, actuated by a motor and cam. These
>horns were arranged in a wall firing at the house
>being tested.
>You can generate a lot of acoustic power out of such a
>structure.

Harry Olson of RCA was building such things back in the 1930s.....
circa 1960, he even devised a very nice, highly linear 
subwoofer that used compressed air and a solenoid modulated valve. 
Supposedly it was capable of 150+ dbA peaks using
only a 25-watt amplifier to drive the valve. (don't ask how much
the compressor needed....)


E. Barbour

designer, METASONIX (www.metasonix.com)
and senior editor, Vacuum Tube Valley magazine