An historical aside:
The first setup I ever saw to listen to birds outdoors was a pair of
dynamics to preamps to Harmon-Kardon 30 watt amps, and KLH speakers inside.=
Those amps were the Push-Pull pair of 6L6 tubes, on a shelf in the
vestibule, warming the ceiling, on the doorway out to the pond.
When? September of 1957.
Where?The brand new Cornell Lab of Ornithology which would be my home for
the next four years. So I got to play with these amps a lot - (like all
night when I wanted to).
For those of you who have been there since, please note that the Tompkins
Country Airport, also visible to the west from those plate-glass windows,
has now gotten much busier, not to mention Sapsucker Road itself. On Monday=
evenings, during the college year, we had seminars, organized by Doc Allen,=
with slide shows and live bird demonstrations. Especially in the spring,
we left the mic=3D>speakers turned on during these slide-talks, but turned=
down very low, with the bitterns and Barred Owls and peepers providing a
nice ambience for the talk, even if the occasional run-up at brakes and
take-offs DID NOT, when someone (usually me) ran for the manual volume
controls.
Which brings me to my question: Has anyone designed and built an amp or
preamp for this situation, as I-always-planned-to-but-never-did? :-)
I always planned to build a variable-gain amp, which essentially kept a
running DC voltage proportional to the time-averaged LOW FREQ noise levels,=
used to vary (reduce) the overall gain to the speakers. You would have a
fast attack and slow decay. This would mean not only that the airplanes
warming-up at Tompkins Country would not overload the sound output, but the=
whole thing would almost shut OFF during such disturbances. I was always
worried about how this would react to wind, thunder, etc with
mixed-frequency contents.
Anyone?
-- best regards, Marty Michener
MIST Software Assoc. Inc., P. O. Box 269, Hollis, NH 03049
http://www.enjoybirds.com/
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