At 4:45 AM +0000 8/10/09, Al wrote:
>John,
>
>I plan to pick up one of those FL 158 mics, next week - Thanks for
>the links to it. Sounds like it's just what I could really use here.
>The only question/concern I have is: Does it have lower self-noise
>than these Panasonic WM-61A capsules I've been messing with?
Al--
As was also stated by several people on the mic builders list, the
mics you are experimenting with all have high self-noise when used in
applications that require high record gain. Gerald White made a very
careful high-gain, self-noise comparison test with some of the
popular capsules used in this class. The test segments present
capsules in order of increasing self-noise so you can hear the
"jumps" in noise across the edits.
http://tinyurl.com/2bvdc6 (QuickTime Movie 9mb)
The first few mics in the test are more expensive and included for
reference: Telinga EMKS-23, Shure WL-183 and a Rode NT-4. The
following mics include the capsules you are considering. The same
recorder is used with all of the mics with an input noise rating low
enough to not add preamp noise. Effectively, all of the noise you
hear in all of the segments is mic self-noise as the subject recorded
is a quiet room with two clocks.
The amount of audible self-noise in a recording can be considerably
less than that heard in the test if robust sound sources are recorded
and the record gain is lowered. The H2's mic preamp might add some
noise too at high gain settings. If you try both close and far
micing, you can hear these differences yourself. The sound quality of
WM-61A's is regarded as very good when used with louder sound sources.
It depends on the type and number but insects can produce an
impressive amount of sound energy. The insects in a south-facing
grassy field I recorded the other night with Rich Peet in SW
Wisconsin were saturating from -1 to -12dB (96dBFS) with 50 dB of
preamp gain when the mics were placed 6 feet above the ground. The
insect chorus's here are subtle compared to other places. If the
inexpensive capsules were placed on the ground, a gain setting around
30 dB might have been about right for us. The mics we used have about
the same sensitivity as the 61A's. As you probably know, many insect
songs are rich with high frequency variation and these qualities can
really stand out with close-micing.
The uncompressed soundtrack can be extracted from the movie and
analyzed with a sonogram too.
> I made a couple of mics, without any of the recommended mods first.
>Also, a parabolic dish (with parts from the $0.99 store) and, so
>far, the handful of mics all produce quite a bit of noise. Lots of
>background noise.
>I have all the stuff set aside, to perform the various mods, etc.,
>etc. I just haven't had the time yet. I wonder if any of those mods
>will correct the noise problem?
>I miss my cheap Audio Technica ATR-55...at least it didn't have any noise.
AT doesn't provide self-noise ratings for the ATR-55 but its highly
likely you'd find it comparable in self-noise performance if you made
a comparison test with it. Its also likely one could find a pair of
the opposing electret mic capsules similar to WM-61A's inside. ;-)
Rob D.
>
>Thanks,
>
>Al
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