I got the same "bottoming" effect running a pair of NT1A's into
the Marantz 670. It cleared up with the low shelf enabled.
Although it didn't seem to correlate with very soft air
movement, I suspect that was the cause, or perhaps VLF nodes of
some kind. The unshelfed recordings showed clear LF clipping
when I examined the WAV files.
I occasionally use the Microphone Madness earbud binaural mics
for testing, but I must say, they seem to have no dynamic range
at all. They produce crunchy static when the SPL gets over about
90 (wild guess == mildly loud). Terrible LF response. Great for
recording phone conversations, though.
Allen Cobb
http://acobb.com
http://shakespeare.acobb.com
http://timbreproductions.com
-----Original Message-----
From:
Behalf Of Rob
Danielson
Sent: Wednesday, September 21, 2005 1:45 AM
To:
Subject: Re: [Nature Recordists] Shure 183 > Sony DAT, MD
Hi Curt--
Since it showing up on the line input too, it does make sense to
suspect AD or something unique with the recorders input stage.
If its
in the recorder, wouldn't one expect the same results with a
comparable electret like a Sony ECM55B or 66B? Might confirm
that
next?
I don't think I hear the same kind of bottoming out sound with
the
NT1A's->Rolls->NH-900HiMD that I get with 183-> HiMD (PIP) But,
I
could check that. And the NT1A's really put it out below 30Hz
compared to the 183's.
How have you wired up the 183's on the Art Phantom? How would
you
describe the performance improvements? Rob D.
= = = = = =
At 5:43 PM -0500 9/20/05, Curt Olson wrote:
>I and one or two others here have reported occasional problems
with the
>combination of Shure 183 mics and Sony recorders of various
kinds. The
>recorded signal seems to easily "bottom out" or totally break
up in the
>presence of high-level, low-frequency sounds (such as heavy
doors
>closing or loud vehicles passing by). Further, if I remember
right,
>some folks with Sharp recorders have indicated no such problem.
About
>10 days ago I had another nasty encounter with this phenomenon,
and
>decided it was time to seriously investigate. (The service door
to my
>garage is a perfect sound source for this test, guaranteed to
"bottom
>out" the 183 > Sony mic input combination any time with little
effort.)
>
>When I first discovered the problem earlier this year, I
suspected the
>183s themselves. Some conversations with Rich Peet let me to
try giving
>the mics more power than PIP provides. I ran them off a 9V
battery, and
>more recently off a 12V phantom power supply (ART Phantom II).
They
>seemed to like the increased power, but the low-end "bottoming
out" was
>still there in every case. I've also been able to replicate the
problem
>with Crown GLM-100 E microphones, so that pretty much rules out
the
>183s as being the culprit.
>
>I began considering the Sony mic pre, so I ran the 183s off 12V
phantom
>power directly into the line inputs of my Sony MZ-NHF800 Hi-MD
>recorder. It still "bottomed out."
>
>Next, I ran the 183s off 12V phantom power into the line inputs
the of
>a Lexicon PCM 91 digital reverb (in "bypass" mode) and
digitally from
>there into ProTools. Through this pathway, the recorded signal
was
>perfectly clean. Then I routed that clean signal digitally out
of
>ProTools into a Waves L2 (hardware box) limiter/ADC/DAC (still
clean at
>this point) and into the line input of my Sony MZ-NHF800 Hi-MD
>recorder. And there it was, "bottoming out" again!
>
>I inserted an EQ plug-in into my ProTools channel and found
that a
>high-pass filter with a 6 db/octave slope and a knee of around
90hz
>pretty much eliminated the problem at the Sony line input.
>
>I'm not trained or equipped to investigate any deeper than
that, but
>I'm guessing there has to be a design flaw somewhere in the
Sony input
>path -- possibly the final line driver or, more likely, I
suspect, the
>low-end capabilities of the ADC.
>
>I've experienced this "bottoming out" phenomenon on my
MZ-NHF800
>Hi-MD... and also on my TCD-D7 DAT recorder... and also on my
NT-1
>Digital Micro Recorder. So it seems to go a long way back in
Sony's
>design history.
>
>One workaround is the Sound Professionals SP-SPSB1S:
>
>http://www.minidisco.com/sp-spsb1s.html
>
>A little pricey, maybe, but I picked one up and so far I'm glad
I did.
>
>Any reactions?
>
>Curt Olson
>
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
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----------------------------------------------------------------
----~->
"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
Yahoo! Groups Links
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