DAN
> > I don't like the look of the tube and the end cap area where the mike
>> has to be. There is so much obstruction. You want the mike to sit in
>> a spot where, pointing back toward the reflector, it can see the
>> whole surface of the reflector without obstruction. I see no reason
>> for having such a heavy structure there. Imagine something like a
>> lampshade harp.
WALT
>Imagine such a thing hitting brush. Or snagging in it. I've been there
>and done that. That is why the structure was not lightened much more. I
>expect the mic end to be able to bump something without losing
>alignment, or worse, breaking.
DAN
I see your point, I was only thinking of the acoustics. How about a
stiff wire cage?
>The mic will see the entire parabolic on a sonic level.
Won't there be shadowing at high frequencies? If the sound is out of
focus, it might have a point source image in the reflector, and I
would expect the high frequencies to fall off when that point is
behind a post.
When the sound is in focus, won't there be a high-frequency
attenuation effect, (above some crossover point depending on the
dimensions of the slots) as half the high-frequency signal
approaching the microphone is reflected away?
I'm also imagining resonances across the small dimension of the
remaining tube roughening high frequency responce. Maybe an
over-fertile imagination.
> I've tried both
>styles over the years and both work the same. This is just a lampshade
>harp that's closer to the mic and 4 legged. This is a less expensive
>method while still providing necessary mic protection and the theme is
>inexpensive homemade parabolics that are relatively easy to construct.
Understood. Bigger holes?
>Also think about Omni's being used in parabolics pointing away from the
>dish. That works, even though the Omni pickup has no direct view at all,
>the body of the mic is in the way.
Yeah, I see it, but knowing how directional omni's are at the high
end, I don't believe it. It's time to flip a mike both ways in the
focus of a dish pointing at some pink noise, and watch what happens
on an analyzer.
>You are dealing with a pressure variation, it's not light and not a
>water wave. The focus is actually a small volume in which the pressure
>variations from sound are pretty even. You have to do a fair amount to
>mess it up.
I'm not sure about that. High frequencies have wavelengths in the
half-inch range, and small dimensions still matter.
>At least for the kind of frequency response of a inexpensive
>tie tac mic.
I know inexpensive mikes sound much better when someone pays
attention to the acoustics around them.
>Were we using a heavier duty reflector, and willing to drill holes in it
>then a bridge design is common. I used one of those for years. And the
>bridge structure on that was 3/4" wide and in the field of view blocking
>part of the reflector in two directions. It worked fine. (it also
>snagged brush, and had exposed mic wiring which cost me a couple mics)
>Since I was avoiding drilling holes in a 1mm thick Telinga reflector all
>support will have to come off the center.
Yes, all the old ones I've seen have had a either a bar across,
mostly home-brews, or a crooked arm, as in the little Sonys. The
Telinga is a radical new design, exciting.
>I've got the mic that it's designed to fit, and a working MZ-R30. So
>I'll see what I can pick up in the next few days. Then we will know for
>sure. My worry is more I might have cut it a slight bit too short for
>accurate focus, I estimated off the Telinga setup, and the mic there is
>in a large chunk of foam so I'm not positive of it's exact location.
Looking forward to your reports.
-Dan Dugan
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