Hi Russ, and all,
Florian here. I'm new to pure audio recording, but enjoy it. I am not new =
to paying attention to the preservation of ecosystems. I live in NYC.
I choose to post now because I have one broad solution, and one specific s=
olution to this problem which I don't see mentioned.
(TBH, the yahoo groups message format, archives, and delivery schedule, ru=
les, confuses. Apologies if I breach protocol, and thanks to anyone who cor=
rects me.)
(Also, I am NOT a scientist or engineer)
This sounds like a budget project. Which is awesome. I DIY as much as I ca=
n, too. Unfortunately I'm not sure the ideas I have are cost-sensitive. I'v=
e never tried them, but I know for a fact one of them is in ubiquitous use =
by microphone manufacturers. Even if they are not helpful to you, Russ, who=
se project is already completed I'm sure, I figure since there have been ma=
ny responses and no one has brought these up, it may benefit someone intere=
sted in waterproofing, windproofing, and weatherproofing microphones and ar=
rays.
1) Parylene coating
I'll start with the specific one first.
...instead of weatherproofing the enclosure, you could waterPROOF the caps=
ule.
Parylene is, well, here: https://en.wikipedia.org/wiki/Parylene https://en=
.wikipedia.org/wiki/Parylene I'm not a doctor.
The great thing about parylene is that very very, verrrrrry thin coatings =
of it can be made on a substrate. Parylene is commonly used to coat lavalie=
r membranes and sometimes the entire capsule or assembly. This protects aga=
inst sweat, and hydrophones sometimes have a parylene coating too. The stuf=
f once properly applied (not so easy) has excellent mechanical properties f=
or the application, the quality and quantity of motion of the membrane is c=
hanged, but not much, and if the coating and assembly are done in such a wa=
y the element should withstand repeated direct blows from raindrops or even=
jets of water.
If you search "Parylene coating" you'll find like a million businesses whi=
ch offer this as a service product, alongside many other forms of gas depos=
ition and sputtering. For a single microphone, the cost is unlikely to be r=
easonable, but who knows.
2) Hydrophobic mesh
You mention "water resistant" rather than waterproof. So, air (pressure wa=
ve) in, water (droplets) out.
I wonder about wrapping in a hydrophobic mesh. Have you heard about these?=
If not you might want to alphabet-google it, and even then you'll get a li=
st of suppliers who usually only sell to companies rather than individuals =
with the exception of this: http://www.ebay.com/itm/like/181254139613?chn=
=3Dps&dispItem=3D1 http://www.ebay.com/itm/like/181254139613?chn=3Dps&dispI=
tem=3D1 . Not to be confused with "mesoporous hydrophobic" solids/materials=
.
The concepts of droplet contact angle, wettability of a substrate (upon wh=
ich a droplet comes to rest/stops), and pressure, influence their design.
Because H20 has reasonable surface tension, droplets of H20 exhibit varyin=
g degrees of wettability of a given substrate they rest on (with or without=
earth gravity). Contact angle is more or less the measurement of the devia=
tion from a perfect spherical formation of a droplet on a substrate. Rarely=
happens.
anyways, if you create a mesh of thin wires of a material with a large con=
tact angle in respect to H20, like teflon/PTFE, which is superb, when the n=
umber of wires per given area reaches a certain density, and the size of th=
e areas where the wires are not, the pore size, shrinks to an area which is=
at or beyond the contact angle equilibrium, droplets of water can't get th=
rough at a given size and pressure. They skitter about and away. Shrink the=
pore size too much and air can't get through either. Shrink them even more=
and you wind up back in the zany world of mesoporous functional materials,=
which actually separate or ab/dsorb large molecules from small molecules o=
n the, like, molecular level, dude.
What you'd want is a pore size and a material which is a goldilocks, just =
right, size - so that the occlusion of water is maximized, and the attenuat=
ion of acoustic waves in air is minimized and as spectrally linear as possi=
ble. (I should also say that this isn't 100% waterproof. Plunge this deep e=
nough underwater and water gets in, or if the water droplets are smaller th=
an the pores or have ballistic velocities or whatever)
I have not tested and have no knowledge of how good or bad an air interfac=
e mesh might be in terms of sonic alteration, though a quick search of a-g =
patents leads me to believe they are widespread in small diaphragm mics in =
hearing aids and other in-ear applications.
And even if they do alter, that's what EQ is for. Right?
-Florian
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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