Making a stereo rig for two shotgun mics - Sennheiser ME-67.
For two years I have been promising nature-recordists to photograph the rig I invented and I usually use for stereo field recording bird sounds. I must say it was inspired by reading many other shock-mounts from the group, especially the one posted by Lang Elliot.
Like a parabola with two mics,
it produces exaggerated angular stereo,
pulling in whole scenes from a good distance. Unlike my parabolas, it is light
and very quick to aim, and fits through narrow game trials in the puckabrush,
sometimes while on the run.
Here, I briefly describe the construction. Let me know what I
have left out, or have not made clear, please post a note to the group.
Although this looks very crude, some sophisticated acoustical principles have been applied to inexpensive materials. Please note these features:
1. the mics cross very near their acoustical diaphragms, minimizing phase delays except above about 10 kHerz.
2. the whole rig is very light, and hardly weighs more than the mics themselves plus the dowel handle.
3. for hand-borne sounds (wrist creaks, muscle hum, movements on handle) to reach the mic diaphragm and thus interfere with the recording, they must:
A. pass through foam to the wooden handle, crossing two sharp impedance barriers - one solid->gas into the foam, the other gas->solid into the handle.
B. the vibration then travels through solids from handle to Styrofoam to rain-gutter-channel.
C. it then must cross two more sharp impedance barriers - one solid->gas
into the foam in which the mic lies, then the other gas->solid into the body
of the microphone.
These are the technical reasons behind why the rig works so well - you can
rotate it to pan for sounds, or carry it along making a recording while
walking on a woodland path -- only if you can move your feet very, very
softly.
The materials needed are shown first.
I actually left out one: the 1 cm. urethane
green or black foam I used to get at rug stores, and now get at sewing stores.
The assembled rig is shown from the top, describing
the first steps of how to make it.
The back of the rig is shown with the next few steps. If the text is
hard to read:
"After mounting channels in grooves, place foam into each channel. Lay assembled mic on foam and hold in place with rubber bands."
"Glue conduit into hole in styrofoam using real foamboard glue (all others will be a disaster). Cut dowel to 22 cm. Turn one end down to fit into conduit. Glue foam on rest of dowel as a handle."
In the field, the handle projects down and slightly back of the Styrofoam
block, and it is covered with the same foam you can use as a cushion under
rugs. This foam de-couples hand noises from the rig handle. The mics are
additionally de-coupled as they lie in a foam bed, held in by rubber bands. The
unique thing about this rig is it holds the mics crossed near their diaphragm
locations, about 30 degrees angle apart. In practice, this can be adjusted by
how the mics lie in the foam and how the rubber bands are adjusted.
The mic cords are usually anchored to the rig, too, using rubber bands as well (not shown). Serious vibrations can travel acoustically along a mic cable into the mic body and ruin a quiet recording.
For a semi-deaf recordist like myself, the rig makes it easier to find a
sound from a hidden singer more quickly than any other I've ever tried. During
the recording, I typically point one of the mics straight at the singer, and
make any whispered announcements into the other mic.
On a number of amusing instances, I have managed to point the left at one
bird and the right at another species and get fairly acceptable recordings of
both simultaneously, one per channel, although the separation is incomplete and usually has to be
later "helped along" by Cool Edit filtering as well.
But an important consideration about this, like all my field equipment is
that it has one feature without which it might be stolen: IT IS ABIDINGLY
UGLY. Anyone seeing this rig would likely run the other way. This employs the
theory that "apparent resale value" is directly related to theft likelihood.
Seeing this, in these photos, you will undoubtedly say to yourself: "This has no
resale value at all, look how he has ruined those perfectly good mics." ( ;^)
That is why the K-6 amps are covered with fuzzy blue sticky material, too, (oh
yeah, and I got the fuzz for free at the dump).
For people who want to feel proud and important when they look lovingly at their equipment, this may well be a turn-off.