During February, March and April 2008 I developed a zoom mic by adding a he=
ad spaced boundary arrangement to a normal stereo parabolic mic and fitted =
a control box so the output could be mixed variably and fed to one recorder=
. Several posts were made to Naturerecordists describing the progress of t=
he project. The final step of this progress was to be the substitution of =
the four sets of triplet capsules (12 cheap rapid mic capsules) with some b=
etter quality items.
I have, at last, managed to do this work. Yesterday I replaced the four tr=
iplet assemblies with four Primo EM 172s
The following is a first test to check if the system as a whole is working =
more or less as it should.
The test comprised placing a portable radio 14 metres away from the zoom m=
ic and then zooming between the boundary and parabolic assemblies. The rea=
ding on the LS-10 showed an increase of about 12/15 dB between the wide fie=
ld and telephoto settings.
I'm not sure if this typical of the difference between a parabolic reflecto=
r and a boundary type rig.
I also seem to hear a reduction in the low end of the white noise when zoom=
ed in on the source compared to the wide field setting. There is some hand=
ling noise when I grip and turn the zoom knob on the handle of the reflecto=
r.
Here is the test recording
http://soundcloud.com/g0sbw/parabolic-zoom-zooming
I have also put some photos, with comments, in a Picassaweb album. The alb=
um contains Audacity screenshots of the waveform and spectrogram of the 48/=
24 .wav file made during the test together with photos of the original trip=
let equipped mic and the latest EM172 retrofit.
https://picasaweb.google.com/G0SBW.PM/ZoomParabolicMic?authuser=3D0&feat=3D=
directlink
Now for some field testing
Cheers, TomR
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