--- Here are two of his salient posts:
"Folks, I need to generate pressure pulses of 3-4psi above ambient, frequency around 1Hz, more or less arbitrary waveform with frequency components up to 40Hz in there (but those are less than 2psi) and delivered via short hose. Currently just air pressure.
I got this (sort of) running with a compressor but after a while my ears fall off from all that noise. Can't really place the compressor outside here. So then I tried various speakers. They don't move enough air around. When I pushed one of them a bit harder a few minutes ago its flexible surround rubber burst, that thin stuff doesn't hold much pressure.
In other words I need something similar to an arbitrary function generator but where the output is air pressure. What I want to avoid is hacking a motor, removing a valve and using the piston.
Any other ideas? Can one buy something like that at less than 4-digit prices?"
Jim Thomps> One of those old style Wagner paint sprayers with the vibratory motor?
"Those are too wimpy. They can't move this much air around. They can shoot out a quart of paint in 10-15 minutes (unless the motor burns up) but I have to move 1/50th of a gallon of air around in less than a second.
Speakers with a big enough amp can do this but they suffer seriously because they are meant to be operated against a fairly rigid air cushion."
-- JF