Super low X-sub...

[HornEd]

A couple of decades ago, an elderly couple lived a mile or so from the Southwest Research Foundation in San Antonio, Texas. For many weeks, each noted that the other was getting more and more on edge... but neither would confide in the other what the problem was. One weekend, their son came to visit... and after an hour or two he asked, "What is that funny whispering that I hear?" They both blurted out, "You hear it too!"

It seems that the military had given a grant to the research lab to test the potential to have battlefield commands whispered through a subwoofer sufficiently non-directional as to not give away the commander's position. For weeks the couple had lived in anguish... each thinking that they were hearing voices and fearful of admitting to the other that they were losing it!

For whatever it's worth, I lived on top of a hill further North of the facility... and I called to complain... I couldn't quite make out what they were saying.

Ah, yes, brother Paul & Co. have a ways to go with "our" subwoofers. HornEd

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"Klipsch by the Dozen"

KLF 30's Front Mains

KLF C-7 Front Center

KSW-15 Front Pwr Sub

SB-2 Front Effects

KSW-12 + KLF 10 Rear L&R

KSW-12 + KLF 10 Rear Ctr.

Speaker Support Systems:

Mitsubishi RPHD1080 65"

Yamaha RX-V3000 Receiver

[Guest BobG]

You mean I should ignore the voices telling me to "get out" ?

A few years back Klipsch demoed an interesting sub system at CES. Took four Khorn LF sections, modified them to accept 18" drivers and lined them up horizontally between floor and wall. Then, using eq'd Crown Pro amps (thousands of watts) we had a system which was flat to 7 Hz and could play at something like 117 dB at that frequency. Using demo material with truly deep bass was an interesting experience. We felt like you can in an earthquake and after a few hours we had to leave the room for fear of losing lunch. Had significant interest in the system from the attending dealers. Maybe we should offer to the military.

[HornEd]

BobG, years ago when I was in the military stationed in France... some of my activities brought me in contact with a French military project that involved a subsubwoofer mounted like a 155 howitzer. It threw out an even lower flat curve than your Klipsch demo using some large directional tubes to focus the sound toward the enemy. It was quite disorienting and, potentially lethal so they said, but failed because the non-directional aspect of large waves tended to bite those who sent them out. The SW Research project was strictly a non-directional communication attempt as far as I know. Ignore the voices except, sometimes if you gotta go... you gotta go! HornEd

[Tom Adams]

HornEd & BobG -

Your stories reminded me of my job as a summer engineering intern at a NASA rocket test facility (Stennis Space Center in Miss.)

The low freq. energy emitted by the test firing of Apollo rocket engines (and Space Shuttle main engines) required that acoustical "hot spots" be identified and tracked. It wasn't unusal for windows to be shattered 80 or 100 miles away when the Saturn 5 first stage was tested. The acoustics group would send up a weather balloon, crunch the data it sent back, and determine, geographically, where these "hot spots" were. My job (cheap labor) was to take my trusty 2 ch. reel-to-reel, jump in a raggedy jeep and go to a location out in the boonies that corresponded to some coordinates on a map. The technicians would then swing around to my aziumth this big-a** exponential horn and blast me. I would read to them what sound pressure levels I was picking up and they would either tell me to stay there or send me somewhere else. During the test firing I would talk (about anything I wanted to) on one track while the sound pressure readings were record on the other track. My voice was used to time index the pressure spikes. It was interesting the levels I would be seeing on the recording meter, yet hear nothing.

Oh, that big-a** horn...can't remember the exact dimensions, but it was something on the order of 16 or 17 feet high and 20 or so feet wide at the opening of the horn. It sat atop a tower about 70 feet in the air. The diaphram was driven by 2000 psi compresseed air and the tech's told me they could dial it down to 8hz.

BTW, night test firing was interesting. There you are out in the middle of nowhere, in a jeep with hardly no floorboard, things in the woods making nosies...well, that's another story for another time.

Tom Adams

[Ray Garrison]

One of the coolest things I ever saw was witnessing the launch of Apollo 15 from my uncle's boat anchored as close as the guard would allow us to come to the pad. I recall this was on the order of a few miles, and closer than most folks on land could get. When the first stage booster ignited, the entire spacecraft disappered in this huge cloud of smoke / steam, then (what seemed like forever later) the nose poked itself out of the top of the cloud, followed (slowly) by the rest of the Saturn V. Meanwhile, of course, there's no sound... hadn't reached us yet. Then I saw this, well, really scary sight - you could SEE the sound pressure wavefront flying towards the armada bacause it was FLATTENING OUT THE WAVELETS in the water as it moved towards us. When it hit, it was like one of those really, really loud, deep, shattering blasts of thunder you hear sometimes, and it just didn't stop. Never experienced anything else like it.

Ray

[Tom Adams]

Lucky you Ray. For all the years I was around space program stuff (Dad worked at test facility, I worked there during summers, worked on Shuttle external tank program after college), I've never seen a launch in person.

OTOH, I can relate to the sound of a Saturn V first stage. I've seen 3 test firings of that bad boy. One was *very* close and yes it's both awe inspiring and scary at the same time. It felt like someone was using my chest as a concert bass drum!

Tom Adams