Quote:
Darren wrote:
 Nope, I experienced this one myself. No Thomas in the equation here  I have a minimum-opening manifold... 14.5 X 14.5 and the air doesn't flow fast enough or have enough volume for the opening to create any noise whatsoever.
I've placed my head in the opening to get a feel for the flow and the velocity is minimal although I'm not sure I didn't scramble a few cells. I don't recommend this without hearing protection! |
That's actually very interesting to hear actual first hand evidence! I presume you had some cone movement going on? Despite the discussion of the Cult I still wanted there to be considerable air movement. There just had to be with 4 x 15" drivers flapping back and forth by well over half and inch with only one hole for the air to oscillate through. Perhaps my imagination got a bit carried away?
I know what you mean about SPLs close up to an IB too. Even spread out in my array the drivers can produce considerable discomfort at close quarters. It always seems worse in the enclosure because the higher frequencies are stripped away. According to recent Swedish industrial noise research there is vastly reduced (if any) risk of damage from LF compared with HF.
I was once within a few metres of a squealing lathe working on a large stainless steel component. Even wearing approved headphone ear defenders the real sense of acoustic pressure in the air was simply awful up to around eight-ten metres! The operator was standing at 1 metre without any hearing protection and refused to wear any. By coincidence I had my trusty SPL meter with me at the time and it read "only" 110dB(A) @ 1 metre. I imagine the complex squealing sound must have had a very wide frequency spectrum going well up into the ultrasonic. Extremely dangeous to the hearing I would presume even over very short exposures.
I have regularly seen 120dB(C) in the bass from my IB but have never really felt the need for ear protection. My stomach and chest seem to dislike the IB far more than my ears ever do! Storms with very high wind speeds have a similar effect on me! It must be all those free radical infrasonics.
