After Eric Benjamin told me how well the A-T 3032 omnis had measured
in his lab, I ordered a pair to evaluate. The specs say that they
have a self-noise level equivalent to 16 dB SPL. Eric said he
measured the one he got at 8 dBA! I suspect a lot of the difference
(being quieter than the spec) had to do with A-T quoting their noise
level from a flat measurement, whereas most manufacturers will quote
a weighted (dBA) measurement because it produces a better number.
Even if the noise level of the 3032s was 16 dBA, they would be at
least 6 dB quieter than the 183s, at about double the cost. Well
worth looking into.
The mics arrived Friday. My lab examination showed their hiss level
to be 13 dB lower than the 183's. Sharon Perry and I had signed
ourselves up to do attended soundscape monitoring and recording at
Muir Woods Saturday night, a time slot that the younger volunteers
tend to neglect. I had a 722 recorder on hand waiting for a customer
to pay for it, so I took the opportunity to both field-test the mics
and get some field experience with the 722. I used gaffers tape to
improvise a rig for the occasion; I taped them to my cowboy hat:
http://www.dandugan.com/downloads/Dan_testing_3032s_and_722.jpg
We did the five Muir Woods soundscape monitoring locations twice, in
the night (midnight--2:00 AM) and sunrise (half-hour before
sunrise--two hours after) time slots. On each pass we each did three
locations, doubling up on the Ben Johnson Trail location, then
splitting up to do two more each.
That spot is about five minutes uphill from the end of the main trail
that goes along Redwood Creek. It takes half an hour to walk there
from the entrance. We were about twenty feet apart on the trail, both
facing downhill towards Bridge 4 and the creek (not visible through
the trees). It was an inky dark night, overcast with no moon, and the
park was very, very quiet. On the way in we heard nothing but the
creek.
Sharon recorded with my shoulder-mounted-183s vest, and I recorded
with the 3032s on my hat. The samples below include one of the few
sounds we heard, a ship's whistle from the ocean a few miles over
ridges to the west. First is Sharon's (you can hear her breathing),
then mine:
http://www.dandugan.com/downloads/183_vs_3032_ship.mp3
After a too-short three hours of sleep in the education building, we
hiked back out to do the sunrise time slot. It was raining, a good
test for the humidity tolerance of the new gear. We started recording
at 6:15 AM as the sky began to lighten (sunrise was 6:40). Not much
happened then either, but the rain sound was nice and ravens were
active:
http://www.dandugan.com/downloads/183_vs_3032_ravens.mp3
I matched the levels for both samples approximately using the raven
calls. The differences are dramatic; when the noise level goes away,
subtle ambience is unveiled. This is why we talk about these numbers
so much, folks.
The 3032s aren't lavaliers; they're not really suitable for body
mounting. I'm thinking I'll use them with a Jecklin disk. They list
for $259 and are selling for around $169 each. They're medium sized,
as mics go, and low-medium priced.
Thanks, Eric, for a fabulous discovery.
Dan Dugan
________________________________________________________________________
________________________________________________________________________
"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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