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Re: Bottoming-out revisited

Subject: Re: Bottoming-out revisited
From: "John Hartog" <>
Date: Tue, 24 Jan 2006 06:20:38 -0000
Hi Allen, thanks for your comments.
The breeze behind the falls was not very strong, but it pulsed in an
irregular way that if I were a large diaphragm I should think I would
find it quite irritating.  As you suggest, it might help to use the LF
shelf and throw on an extra layer of wind protection.  Whatever the
NT1-A's were experiencing, the distortion appeared only in the 
PMD-670 recording, not in the RH10/rolls224 recording of the same mics
same exact positioning, so I'll probably just stick with the rh10 next
time I try to record a loud LF environment.

-John Hartog

> It's probably worth of noting that those NT-1A's, like all large
> diaphragms, are very sensitive to pressure gradients at low and
> ultra-low frequencies. You can get waves like the ones in your
> screencap just by waving your hands close to the mics. In
> practice, they're are often of shorter duration, because the
> mics are getting just enough wind to cause an intermittent
> problem, but not enough to make it obvious that wind protection
> is needed.
> 
> With the waterfall, perhaps there was just so much LF that the
> preamp overload was constant, and reasonably periodic. I missed
> a few msgs in this thread, so perhaps I'm off target, but it
> looks like you need a combination of good wind protection (at
> least foam) and some LP shelf. With just foam wind protection,
> my NT-1A's do pretty well in moderate breezes. With real "wind,"
> though, you have to build a hairbag...
> 
> I prefer, of course, to record without anything covering the
> mics, but it's interesting how imperceptible air movement (in a
> sense they're ultra-LF pressure waves, even as low as 1 Hz) can
> produce occasional mild flapping or dimpling of the diaphragm,
> which can masquerade as inexplicable clipping, or an
> intermittent connection, or a flakey pre.







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