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Re: AT822 Microphone Noise Floor

Subject: Re: AT822 Microphone Noise Floor
From: Marty Michener <>
Date: Wed, 31 Jul 2002 10:53:47 -0400

Sorry to be so late getting into this discussion; I posted some on this 
darn mic, I think over a year ago.

I bought an AT822 five+ years ago and it is so noisy I have never been able 
to find a natural environment in which I could stomach listening twice to 
any recordings.  I should add that I record animals, usually birds, at some 
distance, so mic noise is very important.  I have found that most sounds in 
nature, except very windy, large leaves rattling and waterfalls, cannot be 
credibly recorded with this mic. I consider it junk for our purposes.

I suppose I could always use it to make digital recordings (MD, HHb) and it 
would supply the tape hiss for which I am now nostalgic (NOT!). ;^)   My 
son now uses the AT822 for his band to shout and drum into, enclosed in a 
sound-proof chamber.

For reasonable stereo in nature, I now use two ME-67 shotgun mics, in an 
"X" arrangement.  This is a modification of a number of shock-mount 
suggestions made by this very group, particularly Walt Knapp and Lang 
Elliot (I wonder how Lang is doing).

Two channels, converging at 40 degrees, are cut in a 6" x 12" trapezoidal 
block of pink Styrofoam 2" building insulation, a material I use a lot 
nowadays - cheep, quiet, waterproof, easy to work, light weight.
The channels start about 6" apart at the back edge, and emerge about 1" 
apart at the front edge.  Into these channels, two short pieces of plastic 
rain gutter-spout are laid, which has had one wall sawed off, so each forms 
a "U".  Into each gutter-spout is placed thick soft urethane foam, to make 
a soft sound cushion for each mic.(camping mattress material).  Around the 
plastic gutter-spout "U" are placed about 6 fairly heavy rubber bands.  The 
channels in the pink foam block are cut to a width so that the rubber bands 
make a tight fit and each stays in the overall block.  Two huge rubber 
bands go around the whole rig sideways to keep the channels, U and mics 
held in.

To mount the mics, you slide each mic in from the front, and the cable and 
connector in from the back, under all the rubber bands, and click them 
together.  Now the mics cross each other, just forward of the block of 
foam, so one mic has to be above the other.  It LOOKS awful, twisted, 
like.  The mics press against each other, foam windscreen to windscreen.

The mics are thus flexibly held about 40 degrees apart in angle, and cross 
each other at a point about three inches distal to their screw-joint with 
the K-6 unit bases. This point gets the mic diaphragms as close as possible 
- the width of the foam windscreens - about 2 - 3 cm.

How to hold it:  Now the whole rig has a diagonal hole drilled through the 
foam near the front edge, into which is glued a short plastic water pipe 
piece.  The field handle: A  3/4" wooden dowel is turned narrower at one 
end, so it snugly fits into the plastic pipe in the rig.  The rest of the 
dowel is glue-coated with soft urethane foam, to isolate wrist sounds from 
the dowel.

With this rig you can move swiftly along a path, WHILE recording in stereo, 
and get so pretty amazing recordings of one habitat fading into another.  I 
know, it needs pictures, which I'll gladly supply if I ever get unbusier.

Best regards to all,

Marty Michener
MIST Software Associates
PO Box 269, Hollis, NH 03049


coming soon : EnjoyBirds, bird identification software for all AOU area.




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