At 2:42 PM +0000 4/4/06, oryoki2000 wrote:
>It appears that we can't put much faith in the numbers provided by the
>equipment manufacturers (surprise, surprise!). If I had the recorder
>in front of me, what should I do to measure EIN? Or the maximum gain
>that a recorder's preamp can add to the mic input? If we could come
>up with a test procedure, maybe the members of this group can generate
>our own numbers.
>
>How did Raimund Specht collect the information about the Marantz
>PMD671 on his web page at
>http://www.avisoft-saslab.com/tutorial_mic_recorder.htm
I believe he's charting the available numbers to make them more
interpretable. I notice that Raimund's comment," It is sufficient
that the preamplifier noise level is just a few dB's below that of
the microphone" contrasts the Rane notes, "... [at] about a 10 dB
difference, the noise added by the preamp becomes insignificant. "
I've read that 7dB difference is minimal elsewhere.
>I guess I should read the relevant pages at the RANE website, starting
>here
>http://www.rane.com/note148.html
>
>Sometimes I feel like I'm at a wine tasting when I read reports about
>recording gear. Once we have a way to measure EIN and preamp gain,
>how can we measure the "quality" of the preamp output without
>resorting to adjectives like "transparent," "airy," "warm," and
>"detailed?"
Perhaps the biggest drawback in using adjectives is when one doesn't
take time to carefully describe what one is hearing. We are making
experiences and describing qualities, non-numerially should be
accepted as well. In the case of a recorder's pre performance,
transparent" can mean "not heard." Ideally, all noise would stem from
the mics.
When A weighting is used, Table 3 of the Rane Notes 148 enables one
to determine when a pre's noise is low enough to not contribute
noise, even factoring in mic sensitivity. With a mic pre's EIN number
in hand, most of us can determine the bottom line abilities of a mic
pre and avoid doing something unfortunate like spending $2500 on mics
with 10dBA self noise and 25mv/Pa sensitivity and the advice of a
salesperson to also buy a brand new "Pro" recorder that turns out to
have a rating of -116dBu EIN. Dynamic range, distortion and frequency
response are also important, but perhaps of lesser priority assuming
one is not considering buying very inexpensive gear.
Preamp gain is especially important for recording ambience in quiet
locations. I had to use my MP-2 two weeks ago and I can tell the
difference in the resolution of files made with 66dB gain and those
I've made in the same location with HiMD and 75dB gain. 46dB gain
would be quite limiting for this application. Of course, loud calls
and effects present less of a problem. Rob D.
>
>--oryoki
>
--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
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