At 1:44 AM -0500 9/21/05, Rob Danielson wrote:
>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.
I've been working with several hours of thunderstorm MS recordings
made with a Sony NH900 HiMD at record levels ranging from "7" to "14"
and I've not come across any "bottoming out" with RodeNT1A/2A
Mics->Rolls PB224->SonyHiMD NH-900. I can confirm that subjects with
very low Hz concentrations do seem to induce more "bottoming out"
effect with the 183's on PIP->NH900. It seems to me there's no
"bottoming out" problem with the NH900 HiMD mic pre or A-D. I wonder
if the pre or AD circuit could be different with the NH700. Rob D.
<snip>
>
>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
>>
>
>--
>Rob Danielson
>Film Department
>University of Wisconsin-Milwaukee
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