From: Charles Bragg <>
>
> I have dug out a very old Dan Gibson parabola and want to replace=
the mic with a pair of small omni electret condensors. Sten Wahlstrom's pa=
per on "The Parabolic Reflector as an Acoustical Amplifier" describes a ver=
tical shield in the reflector with a mic on each side for stereo recording,=
but he doesn't discuss materials. I don't really want something thick, bec=
ause it would move the mics away from the focal point. Can anyone suggest a=
good acoustic isolating material that is thin?
There was a very animated discussion on the need or not for a barrier a
while back. You might want to hunt that up in the past posts. About a
year ago or so.
In the Telinga a thin sheet of polycarbonate forms the central barrier
in the DAT Stereo mic. That mic depends on the boundary effects, so has
to have a hard barrier.
> Also, the better shock mounts seem to use neoprene rubber. Is this a good=
choice for DIY? I plan to suspend the mics with heavy rubber bands, but ne=
ed isolation between the reflector and the handle and/or tripod mount.
Rubber bands are really only a short term thing, better is o-rings,
though you have to be more precise in the size you use. The standard
rubber "hardware store" o-rings will work. Rycote suspensions use
silicon o-rings, which are orange color. I've never found anything
saying why they use those. They are nice in that they don't stick to
things the way the rubber ones can. They are also highly resistant to
weathering. They are not very resistant to tearing while installing
them, however. The non-stick property is mildly important in the SASS
setup I use to keep the rings from eventually binding to the mic housing.
I get silicon o-rings from here:
http://www.allorings.com/
They have info on the various o-ring materials. You do have to sort out
the size, as they have a wide range.
You can also get bungee cord in very fine sizes and that works fine.
I've primarily used it to repair the laced type suspensions.
Walt
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