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Rotary Subwoofer? Eminent Technology TRW-17
Posted:
Tue Apr 13, 2010 6:13 pmby EWBrown
I was initially undecided whether to post this under the "speakers" or the "advanced snake oil" topic.
Eminent Technology TRW-17 Rotary Subwoofer
http://www.rotarywoofer.com/
And, "How it works"
http://www.rotarywoofer.com/howitworks.htm
A subwoofer without a cone. Essentially, it consists of large fan, which is equipped with a variable-pitch propellor, the pitch being controlled in amplitude, and direction, by a voice coil mechanism.
An interesting, if not entirely practical, method of generating very low frequency, powerful sound waves.
/ed b
Posted:
Wed Apr 14, 2010 3:40 amby battradio
I would hate to hear it after the bearing started to wear out .
Don't think it would be pactical in a home seting , but in a football stadium for a high school it might put out some nice boom boom boom .
Posted:
Wed Apr 14, 2010 7:41 amby EWBrown
One of the guys over at NNETG (Ed Sawyer) has personally witnessed this device, here are his comments
I've seen/heard this woofer in action, at a show. It was insane. They had to
have a whole floor of the hotel to themselves, since the bass was so immense.
Just absolutely clean, pants-flapping bass down to basically sub-audible levels.
The enclosure was fairly large (think large closet-sized), but could have been smaller.
The blades move the same way helicopter blades move, its' impressively
simple yet also complex enough that DIY'ing it would be challenging.
I talked at length with the designer about it, there were some tradeoffs
(fan speed vs. response, etc.) but all in all, it was an amazing item.
Sadly, priced out of reach for me at the time. Haven't revisited the idea
since but it's a worthy system.
-Ed
Just imagine horn-loading it 8^0
/ed B
Posted:
Wed Apr 14, 2010 9:52 pmby Geek
They used one on Mythbusters :-)
Cheers!
Posted:
Wed Apr 14, 2010 10:07 pmby Ty_Bower
Sadly, priced out of reach for me
Just how far out of reach are these things priced? I think I might like the idea of something that'll chase the rodents off the whole floor of the hotel.
Posted:
Thu Apr 15, 2010 7:49 amby EWBrown
As I recall, "Mythbusters" also created a mechanical "subwoofer" in an old Mercedes-Benz. It had an approximately four foot diameter cone, and it was "pumped" by means of a cam or crankshaft mounted on the car's driveshaft. It was mounted facing upwards in the back seat area.
It ended up tearing itself apart before it could cause any "acoustic damage".
/ed B
Posted:
Thu Apr 15, 2010 2:45 pmby Geek
EWBrown wrote:As I recall, "Mythbusters" also created a mechanical "subwoofer" in an old Mercedes-Benz. It had an approximately four foot diameter cone, and it was "pumped" by means of a cam or crankshaft mounted on the car's driveshaft. It was mounted facing upwards in the back seat area.
It ended up tearing itself apart before it could cause any "acoustic damage".
/ed B
The episode I was thinking of was the one they were subjecting the plant to all sorts of torture in the box.... or was it Grant? XD
Cheers!
Posted:
Sat Apr 17, 2010 6:25 amby Shannon Parks
Perfect for the home theater - particularly in the summer time! :)
Shannon
gut-wrencher
Posted:
Sat Apr 17, 2010 6:06 pmby EWBrown
From the continuing discussion on NNETG, apparently this system can produce sound waves as low as 2 Hz at full output. Feel it, as well as hear it...
The blade pitch control is similar to that used on a helicopter's "cyclic" control.
/ed B
Posted:
Sat Apr 24, 2010 11:58 pmby mesherm
The blade pitch control is similar to that used on a helicopter's "cyclic" control.
As an owner of an RC heli the subwoofer blade pitch control is actually duplicating the action of the "collective" stick in that it changes all the blade's pitch by the same amount. The "cyclic" changes the pitch as the blades reach a particular angle in their rotation. What angle you move the cyclic stick determines where in the rotation the pitch changes.
Posted:
Sun Apr 25, 2010 1:50 pmby EWBrown
Collective would be correct, I had my collective cyclics confused...
Similarly, the old propellor passenger planes had variable pitch props, and these were thrown in reverse after landing, in order to slow the aircraft down, as the LG brakes weren't designed nor capable of performing this on theor own. I just hope that there was an idiot-proofing scheme in place, so that the props couldn't be reversed while in flight. That could truly be a real "let-down"...
/ed B dephiniteively NOT a helo-pilot, either real or R/C