Hi
I don't recall the largest number we tested, probably about 12 or 16,
there begins to be a point that doing this indoors even in a wharehouse
becomes dangerous, remember that 132 dB is about 2 pounds of pressure
per square foot and hearing decent bass on the out side of a cinder
block and brick wall means its moving and there not supposed to.
Inside, you can actually get to the point where you have "enough bass".
12 BT-7's can produce 2400 acoustic watts from 28 to 125 HZ, steady
state which is pretty loud. 12 units, close coupled also is large enough
to have some directivity but disregarding that increase in on axis SPL,
2400 acoustic watts from a point source would be about 126.8 dB at 10
meters, at 80 meters about 108 dB and at 160 meters, 102 dB and at 320
meters would have fallen to 96.8 dB. By 5620 meters (3 1/2 miles) the
sound would have fallen to a modest 72.8 dB. I guess thats why the World
music theater got "Bass" complaints from more than 5 miles away when U-2
played there.
A fellow named Gene Patronis, an Acoustic consultant for the gov't
spec'd in 12 contras (with a bunch of other high range stuff) in a
"battle field simulator", a special room at Aberdeen proving grounds
that had 36" thick concrete walls and could reproduce the sound of a 105
mm Howitzer at some distance. The sound system in this room could induce
"shell shock". Gene (a fellow who also like loud noises) said it was
very realistic, although I have no idea what actual levels it got to.
I think the loudest audible range sound we ever made was a compressed
air siren in the 300-600 HZ range (John do you remember that beast ugh).
It measured 155 dB at 6 feet and drained John's Big air compressor tank
in a few seconds, it also broke the welded seams in the steel horn it
was attached to. That was so loud at 20 feet that even with ear plugs
AND muffs with your hands clamped on them, it was still too loud, it
even made the bones in your face hurt. It was designed to shake the dust
out of cloth bag air filters at power plants and fortunately we only had
to build and test one. Nasty Nasty Nasty.
Tom
Ey, the dylithium crystals canna take any more Cap'n