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That's really interesting to see. You can see the pulsing 10-20hz which is extremely noticeable when you ride the bus. I'm not completely sure where it comes from. Likely just the whole bus is resonating like a pipe. I'm fairly certain you get it without any windows open. One of the examples I try to give people of infrasound is the noise of driving at 50MPH with one window down. With the other window down, the sound goes away. But with the pressure cavity created by having one window down, you get almost the same deafening 10-20hz as you hear in the bus. Most people don't equate the subtle (actually deafening) pressure in the bus with normal bass, but they are the same. On the refrigerator test, I'm surprised you didn't get a lower reading actually. One giant pulse of air should have registered between 1-5hz. I suppose what's happening is that the air is just getting out of the way during the first 0.4 seconds and in the last 0.1 seconds (10hz) is when it the noticeable sound pressure is created.

The concept works with any fan. The noise of the fan is what we design for. The blades on the TRW-17 are flat and made of a plastic. That's the idea. You obviously can get a perfect air tight seal, but because a fan can create static 0hz pressure without an airtight seal, it just has to be good enough to not allow the air to do a u-turn and short circuit. If the fan has quiet blades and there is no pitch, the TRW-17 is very quiet. When you start throwing big chunks of air back and forth is when you start to notice the fan noise, but since this also produces bass proportional to that noise, the bass will win out unless you're sitting with your head next to the thing. And yes it is scary when it ejects all the blades, but that only happens with prototypes and hasn't ever happened with a production woofer. Yea, we sell one driven by a 1/3HP motor and one with a 2HP motor. That is an awesome scene! https://www.reddit.com/r/onetruegod/

We're a small company and have been busy the past couple years. I just found some downtime and thought it was about time I learn some web programming. Don't want people to get the impression that we're out of business. I'll see if I can get together some content for a thread that might go beyond what we have on the website. Thanks!

MemX, Thanks. I'm glad to be here. Its good seeing resources that can help us dispel the myth that you can't hear below 20hz. I wish I could just easily send one off for testing, but the unit is very expensive and even shipping it is not a easy task. We'd need a good size deposit to make this happen. So cheeky, but I can't blame you for trying.

Hi Maxmercy, My name is Eric Flament and I work for Eminent Technology. We produce the TRW-17 rotary woofer. Your post is really great. I am working on updating our web page and I stumbled across this website. Do you mind if I link to this post on our website: http://www.rotarywoofer.com?