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
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