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Old 2nd December 2011, 09:01 PM   #31
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Quote:
Originally Posted by dangus View Post

Regarding the "brown note". I don't think Mythbusters test was reasonable since they did it in free air with subs which must have had negligible response down that low. Is anyone aware of a more credible test (published, or Youtubed)?
I'm friends with the old farts at JBL and they told me a story of the military testing a semi trailer sub intended to disperse crowds. It didn't work as intended, but it scared the heck out of the recrutes and some of them shat themselves, (involuntary fear response) this could be the origin of the Brown note myth.
If I remember the story correctly the tone was 16Hz,18hz and 21hz and sounded like a very loud bear growl. Actually when I saw the Matterhorn it reminded me of the story they told some 20 years ago.

Last edited by revboden; 2nd December 2011 at 09:10 PM.
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Old 2nd December 2011, 11:22 PM   #32
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Originally Posted by revboden View Post
There is one problem with playback under 15hz at 120db, you won't really feel it as much as you will be listening to the room shake and flex (flight response... run away, (Think Monty Python)) so unless you are willing to build a concrete bunker.... their are going to be problems other than building the speakers.

edit: oh yeah, it will also make you nauseous. My reference system is flat to 14Hz and it makes most people (me included) sick if tones under 20Hz are being reproduced at above 90db for more than just a blast in a movie, a sustained 16Hz messes with your inner ear.
There are restaurants that I have found the pipe resonance from the air handling system in the 10-20 Hz range makes dining distinctly unpleasant.

I'd guess a sustained tone of as little as 80 dB down low is all it takes for me to get a feeling of unease.

I definitely did not want to hang out in my shop when I used an 11 Hz tone to break in my BCSW115-4 speakers, and they were not in a box!
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Old 3rd December 2011, 01:40 AM   #33
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One suspects our psyches may be programmed to interpret very loud very low frequencies as either huge predator (sabretooth) about to eat us or earthquake (although before buildings earthquakes were no big deal unless you are near the coast...tsunami!!!)
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Old 3rd December 2011, 03:55 AM   #34
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Originally Posted by running123 View Post
If I wanted a sub to do 5-20 hz at 125 db at 5 meters in a 8000cf room, how would I do this. I want clean output, I can eq the hell out of it to get a flat response, but I don't want to hear drivers moving etc. Thanks.

Budget is 60000.
I suggest you contact Tom Danley
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Old 4th December 2011, 12:44 AM   #35
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Watch reality set in:The Making of the Matterhorn - YouTube
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Old 4th December 2011, 10:49 AM   #36
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Originally Posted by Djim View Post
... That's besides the point these ultra LF wave have no room to develop in a concrete bunker (unless you buy a factory) to produce a 'clean' signal....
... so there can be no bass inside a subwoofer enclosure because its dimensions are far too small to allow the "waves to develop", right?
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Old 4th December 2011, 09:37 PM   #37
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Quote:
Originally Posted by Don Hills View Post
... so there can be no bass inside a subwoofer enclosure because its dimensions are far too small to allow the "waves to develop", right?
Hi Don, those are two different things. In your example one side/wall contains the sound source (cone) that radiates part of its energy into the outside world. Sound bunkers however, suppose to be non absorbing/transmitting sound (till a certain degree). This means the sound is 100% trapped inside the bunker or in other words the sound is reflected by the interior walls. Therefore a sound bunker is acoustically dead below its fundamental.

In case we would build our listening environment with full flexible walls (but heavily damped to prevent it from making other noises), soundwaves larger as the fundamental of the room, would be absorbed and transmitted by the flexible walls. In that case the walls would act similar like the metal housing of a boomcar. The sound waves below the fundamental of the acoustical environment can physically exist as they don’t 'see' the flexing walls as a huge resistance.

Last edited by Djim; 4th December 2011 at 09:55 PM.
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Old 4th December 2011, 10:04 PM   #38
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Don't confuse the propagation of pressure waves with the nice neat sine waves we all see on our scopes.
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Old 4th December 2011, 11:05 PM   #39
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What the hell are you going to listen to that actually has meaningful 5 Hz content? Test tones?
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Old 5th December 2011, 02:21 AM   #40
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Originally Posted by 454Casull View Post
What the hell are you going to listen to that actually has meaningful 5 Hz content? Test tones?
dubstep eg firepower by datsik

yer its a lot of money for one genre but to me its worth it...
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