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.
David
Walter Knapp wrote:
>
> Posted by: "no_mas_films"
>
> > Paul, thank you very much for posting this file! Although the book is
> > long out of print, I think his conclusions are valid and will hold
> > sway in my choice of microphones for the parabolic I am currently
> > building. So far, I have purchased a used AT4041 from eBay and this
> > passage reinforces it's use. Thanks again, and could you scan and
> > post the rest of this book? :-) Chris
>
> Parabolas back then tended to have longer focal lengths relative to dish
> depth. This placed the mic out in the interference pattern in front of
> the dish as described. A cardioid would not fully compensate for this.
> Also, placed out that far it's wide pickup would include sound direct
> from the side that was not part of the reflected sound. The real answer
> was to go to dishes that were deeper relative to the focal length, thus
> placing the mic within the dish. This is a better and more direct method
> of compensating for the interference patterns. And more or less removes
> this "advantage" of a cardioid. Most modern parabolic dishes are deeper.
>
> To my mind the even better way to go is to set up the parabola as stereo.
>
> Walt
>
>
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