Hi Russ,
I had some success this spring with a home made version of a boundary
microphone like the Wildlife Acoustics SMX-NFC (
https://songsleuth.com/images/documentation/SMX-NFC-Night-Flight-Call-Micro=
phone-Specification.pdf
).
I used a polyethylene cutting board from the grocery store which I sawed
off in to a 10"x10" square and drilled holes for two EM-172 microphone
capsules wired in parallel. I placed the electronics underneath in a
plastic box which I sealed with caulking. The top I covered with plastic
kitchen wrap held down at the edges with duct tape. This waterproofing
survived quite a lot of rain, we had the wettest May on record, and April
had a good amount of rain as well.
I had previously built two microphones similar to the oldbird design (
http://www.oldbird.org/mike_home.htm). Both had problems with water. In one
case it pooled on top of the microphone, in the second the caulking failed
and it actually got into the electronics. Using a flat surface for the
baffle really simplified keeping things dry.
If you use a parabolic microphone you might have problems keeping the
fabric taut enough to avoid water pooling on top. It might also end up
being too directional. In Donald Kroodsma's book Birdsong by the Seasons he
talks about using a parabolic microphone to record night flight calls, but
most people seem to use boundary designs. They're also cheap, that cutting
board cost me all of $5. I didn't test it extensively before mounting it to
my house, but it did seem like I was getting good rejection of off-axis
sound from my microphone.
Hope this helps,
Dan
On Tue, Jun 13, 2017 at 4:00 PM, 'Russ Wigh'
[naturerecordists] <> wrote:
>
>
> Does any know of a light-weight, water resistant, acoustically
> transparent fabric which could be fashioned into a windscreen for a
> parabola. During these idle early summer days I am concocting a plan for =
a
> 24 inch reflector to house a very small lapel microphone which =96 at thi=
s
> point - would be otherwise exposed. Much to the consternation of my wife=
,
> my neighbors, and the community by-laws, I plan to mount this on a frame =
to
> fit over the peak of a dormer roof of my house to pick up night migrants=
.
> At the moment I am leaning toward rip-stop nylon. Other than the mic,
> which I have had for a couple of years, I have about $10.00 invested in t=
he
> project. The parabola will cost me $85, and a 48V connector to power the
> mic, another $50. All pretty reasonable, but I don=92t want to go there
> unless I can pull the whole thing together in theory anyway.
>
>
>
> Thank you in advance,
>
>
>
> Russ Wigh
>
>
>
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