Really Big Subwoofer

In case you thought you weren't getting enough bass:

http://www.danleysoundlabs.com/matterhorn.htm

Built for the good 'ole USA military.

This is from a fellow CARVER forum member that goes by the very appropriate handle of basspig.

Video of 16hz test sweep levitating carpet

Basspig\'s web site

1. Anybody besides me wonder what the "good ole USA military" is thinking of doing with something that will put out 105db at 250 meters over the range from 15 to 80 Hz? Somehow I doubt if this is for HT LFE.

2. A 12 Hz cutoff sounds pretty wimpy if there's something that will go down about THREE OCTAVES farther at considerably less cost. Look on the Eminent Technology TRW-17, ye basshogs, and despair.

1. Probably a group within the military, the majority of which was without serious audio knowledge, put out specs to be met by any potential builder - so that's what was built for them. That, or knowledge of other things was behind the idea and the specs given hide other possibilities not revealed.

2. Hmm ... the ET TRW-17 ... I remember some folks worrying about an Outlaw product of several years ago regarding some very minor hiss they could hear when placing their ears 6" from a tweeter in their system. Even with physical and acoustic damping, am I not going to hear the TRW-17 whirring away at idle if the environment is otherwise quiet enough? In the right environment, the TRW-17 might be really impressive, like the driver for a very large outdoor bass horn, or in a club which is almost continously pumping out high amplitudes across much of the audio spectrum, but in the normal smaller environment of a house something else may be more suitable.

Acoustic Weapons

There is also this article, The Sonic Weapon of Vladimir Gavreau which is often quoted in these cases and has some interesting claims.

If I remember correctly, I believe that the bladder and some other internal organs have resonances at about 20 Hz.

Could be quite uncomfortable, if I'm correct.

Swiller

Garcianc2003, I just read the Gavreau article - or more accurately, tried to read it and gave up after deciding that the author's scientific ignorance made going any farther a waste of my time. The "waste of time" decision came when I realized that early in the piece infrasonic frequencies were defined as anything below 15 Hz - perfectly reasonable - and then later at numerous points were references to the dreadful effects of "infrasonic" sound at pitches of 37, 43, and even 150 Hz. By that time I had already read that 7 Hz is the "lethal frequency" and noted, as I hope any body reading this will, that this "lethal frequency" is a full octave below the low end of the range of the US military's superwoofer. If there really was/is a Dr. Gavreau and the article is not cut from whole cloth, i.e., total BS - a question someone with more spare time than I have can take up - the general level of pseudoscientific incoherent sensationalism in the piece made it impossible for me to understand his actual work. 'Nuff said.

Bestbang4thebuck, garcianc2003 and all - the Wikipedia article on Gavreau (sorry for doubting his existence) has other material on infrasonics that leave little doubt what the "possibilities not revealed" are for the big military subwoofer. High-level sounds in the upper infrasonic range - just where the BMS is most powerful - seem to cause a variety of unpleasant responses in humans, ranging from "uncanny" feelings to visual hallucinations that could be taken for ghosts, to (possibly) loosening of the bowels. The link from this knowledge to crowd control through induced terror doesn't take rocket science. BMS, indeed!

Where I used to work there was a request by a larger aerospace corp. (Northrop or someone) for a similar thing many years ago. Though it was for a larger room blast chamber testing. A setup of around 20-30K watts and dozens of drivers were used.

The ICE modules they are using in the system described tend not to provide continuous max power and have to drop down their output after several seconds (which is documented in the spec sheet).

They demo'ed this device on FutureWeapons recently on the History Channel...or maybe the Military Channel, I forget.

Psyprof1, you are correct in thinking that it will be used for crowd control. The interesting thing was that it was directional enough to be aimed at individuals (known instigators), though I imagine it would be very uncomfortable for anyone nearby or in the path.