An infrasonic Helmholtz resonator capable of producing clean sinusoidal frequencies in the range of 6-14 Hz is described.
http://patft.uspto.gov/netacgi/nph-...351.CIUX,CIDX.)&OS=CCL/381/351&RS=CCL/381/351
http://patft.uspto.gov/netacgi/nph-...351.CIUX,CIDX.)&OS=CCL/381/351&RS=CCL/381/351
It appears to be just a very large vented box with a pair of 18" pa drivers. 130 db is claimed as max output at 6 - 20 Hz. The two vents are each tuned to the extents of the passband, like in a bandpass box, except the diagram of the box makes it appear that it's just a variation of a vented box.
I'm not sure how this warrants a patent!
It would be interesting to see what results people got if they modelled this box.
I'm not sure how this warrants a patent!
It would be interesting to see what results people got if they modelled this box.
I beleive the Servodrive Subwoofers will do this. thats why they were invented! to reproduce the 5Hz sounds elephants can make.
The bigger question i have is WHY does the MILITARY need such a device????
It cannot be because they like realistic home movies!
Low frequency energy has been know to make people sick
or ill at ease. i would bet they use this as sort of a weapon why they want to drive someone out of a compound etc.
Zero
The bigger question i have is WHY does the MILITARY need such a device????
It cannot be because they like realistic home movies!
Low frequency energy has been know to make people sick
or ill at ease. i would bet they use this as sort of a weapon why they want to drive someone out of a compound etc.Zero
Zero Cool said:I beleive the Servodrive Subwoofers will do this. thats why they were invented! to reproduce the 5Hz sounds elephants can make.
The bigger question i have is WHY does the MILITARY need such a device????
It cannot be because they like realistic home movies!
Low frequency energy has been know to make people sick
Zero
<Blazing Saddles>
Not only elephants make 5Hz sounds.
</Blazing Saddles>
But seriously, that's exactly why the military wants WOMDs - as an area interdiction device, it's distinctly more civilian-friendly than sustained fire.
Francois.
My thoughts precisely! What does the army want with something like this! It was discussed in terms of its in room output level and power to drive it. Sounds like a big subwoofer to me, not a military device. A weapon would be much more robust, and would be constructed along similar lines as the servodrive, except they would probably make it more robust, not use exposed paper drivers! If you wanted to make a weapon subwoofer you would probably make a horn loaded servodrive!
Coming back down to earth, perhaps they would use it in their training in some way, in simulators. Perhaps the fact that subsonic sound makes people feel sick is part of it - getting pilots, soldiers, etc accustomed to what makes most people feel sick. Who knows ...
Coming back down to earth, perhaps they would use it in their training in some way, in simulators. Perhaps the fact that subsonic sound makes people feel sick is part of it - getting pilots, soldiers, etc accustomed to what makes most people feel sick. Who knows ...
WOMD = Weapon Of Mass Destruction
I don't think they use this as a weapon as such. Maybe for training simulators or maybe for the development of acoustical homing devices. The infrasonic waves generated by tank engines or helicopter rotors travel quite far in the open space.
For this purpose they once developed a thingie they called MOAS (mobile acoustic source) that could generate 145 dB down to 15 Hz. It was a huge horn on a trailer fed by a steerable valve, controlling air-flow from a car-engine driven compressor.
I wasn't able to find any pictures on the web anymore unfortunately (it looked impressive to say the least).
BTW: I also agree that the discussed construction wouldn't be worth being patented IMHO.
Regards
Charles
P.S.: Some said that the meaning of MOAS was Mother Of All Speakers.
I don't think they use this as a weapon as such. Maybe for training simulators or maybe for the development of acoustical homing devices. The infrasonic waves generated by tank engines or helicopter rotors travel quite far in the open space.
For this purpose they once developed a thingie they called MOAS (mobile acoustic source) that could generate 145 dB down to 15 Hz. It was a huge horn on a trailer fed by a steerable valve, controlling air-flow from a car-engine driven compressor.
I wasn't able to find any pictures on the web anymore unfortunately (it looked impressive to say the least).
BTW: I also agree that the discussed construction wouldn't be worth being patented IMHO.
Regards
Charles
P.S.: Some said that the meaning of MOAS was Mother Of All Speakers.
It sounds like its just a big box with something along the lines of a driver coupled in a sealed box to a passive radiator that in turn plays into another enclosure tuned to the same frequency as the PR but using ports instead.
Heh, I guess BOSE isn't the only one who wastes time and money patenting things that don't warrant a patent.
Heh, I guess BOSE isn't the only one who wastes time and money patenting things that don't warrant a patent.
paulspencer said:
The US patent office is out of control. They will grant virtually any patent that's applied for, provided that a lawyer writes it in Patent-Speak. Then if anyone cries, "But I've been doing that for thirty years," they let the lawyers sort it out in court. I'll bet you could patent the dinner fork, or rather, "a multi-pronged personal food delivery tool." Do you want to sue the US government over the big-honking subwoofer patent? Not me. Let's just hope they go after those guys who drive their cars around making atomic bomb sounds. Yeah, that's my fantasy.
Several years ago when you could buy surplus equipment directly from an army installation- well, much easier than now anyway, my dad bought a pallet full of modified Cerwin Vega LP36's the army used for earthquake simulation from Redstone Arsenal in my hometown. He still uses them today. A research company also in my hometown called Wyle Labs at one time had a device that could perform similarly to the device described in the patent, but at much larger sound pressures. They used it for shake testing and extreme environment type stuff. It was driven by a rack of Techron amps... 7780's as I remember- the ones used for mri machines and the like. Cool stuff!
Sounds like you are describing an acoustic lever, which is a very interesting new technology, developed by Dr Earl Geddes. There are three chambers - one is a rear sealed chamber, then an intermediate chamber into which the driver radiates, and which also has a passive radiator which is smaller than the driver, which is attached to another passive radiator which is larger than the driver and is the only moving part which is allowed to radiate to the exterior. This gives an increase in output like a bandpass, but does not trade bandwidth to do it. The output is significantly more than a bandpass box. Unfortunately for diyers, you have to purchase Dr Earl's software to design it, and this grants a license to build only one of them for your own use! This is discussed in the Loudspeaker design cookbook.
The "water bags" refer to the SRT "Hydrosonic" subwoofer which contains a water bladder. According to the review in the magazine-formerly-known-as-Stereophile's-Guide-To-Home-Theatre, the bladder didn't appear to have any useful effect. http://www.ultimateavmag.com/features/704way/index4.html
The fact that this patent treats the Hydrosonic sub seriously could be read as a sign that the entire patent is not to be taken seriously.
The fact that this patent treats the Hydrosonic sub seriously could be read as a sign that the entire patent is not to be taken seriously.
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