Walt, I cant find that paper posted online... any chance you might
post it? Thanks, Chris
--- In Walter Knapp <>
wrote:
>
> Posted by: "D Secomb"
> >
> > Thanks for your thoughts Walt and Paul for the information placed
on file.
> > Walt. I can see what you are saying by having a deeper dish so
the
> > focal point within the dish. This statment " And more or less
removes
> > this "advantage" of a cardioid.", are implying that both types of
mics
> > are now equal.
> >
> > When looking at the graph that Paul posted,( were the focal
point is
> > near the edge of the dish) its the cardioid has the edge. A clue
how
> > mics behave in a deeper dish (were the mic is placed inside the
dish)
> > is on the Telinga site on picture gallery 4. Although this is a
test it
> > does indict below 5 000 Hz the omni has the edge and the cardioid
has
> > the edge above it. Maybe Klas can give his thoughts on that.
>
> You might want to read "The Parabolic Reflector as an Acoustical
> Amplifier" a paper by Sten Wahlstrom. It gives much more detail on
the
> acoustical behavior of a parabolic dish. I'm not sure if anyone has
it
> up on their site right now, I posted it several times in the past.
I've
> found it to be about the most accurate description of what's
going on.
>
> Note that the Telinga stereo mic I use is a boundary mic with
multiple
> capsules, so not omni or cardioid mics. There are other mic
choices. And
> I'd somewhat question the polar patterns of omnis or cardioids
being
> purely that in the field of a parabola. You are dealing more with
the
> characteristics of the reflector than the mic.
>
> Walt
>
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