I guess I really didn't want to go here but feel like I am in a
corner. Without the education and armed with my ears and eyes I
defer to those who have put words to their observations. Going
forward.
My 32" dishes are pure parabolics. They have a very defined shelf
where it will not amplify.
If you look at langs prior post with photo of the telinga (on this
list) you will see in the reflection that the curve of his dish is
not a parabolic on the outer edge. It is more close to a cone.
I suggest that the reflection of a sound wave is not the same as the
detection of a sound wave.
I go further to say that the deflection of a sound wave is closer ro
the properties of detection than that of a reflection.
So, A cone is not confined to hearing only the sounds of a full wave
based on the diameter of the orifice in the small center. And a mic
element is not confined to detection of a full wave based on its
size. But to reflect a wave takes a full wavelength in physical size.
And so, a telinga starts to lose gain higher than its expected 22"
size and because it resembles a cone on the outer edge. Its
properties extend below its 22" size on the principal of a cone.
And yes I understand that this review and opionion is my own and is
against a prior post made by Klas who builds this dish.
Rich Peet
--- In Walter Knapp <>
wrote:
> Rich Peet wrote:
> > My 32" dish still has a cutoff shelf above most owls.
>
> Or is this a cutoff of the speaker you used to test it? The use of
pink
> noise out a small speaker is very unlikely to be giving you a true
> picture. Or more correctly telling you more about the speaker. You
need
> something like a large Subwoofer and calibrating that with a sound
meter
> to know much. Small speakers are ok for testing higher frequencies.
For
> low end testing I'd want to be using something like a JBL Eon 15"
or
> similar, way out of what I want to spend on a semi portable
speaker.
> Though I'd love to have a pair.
>
> Bullfrogs are way down below the cutoff you speak of and yet my
Telinga,
> which is much smaller than 32" gets a nice bit of gain on them.
Same
> with things like Gopher frogs, which are even more pure very low
> frequency. It is also highly directional at those frequencies. That
from
> actual usage over several years.
>
> > My ME-67 performed well at low frequencies but was not very
> > directional for owls. It was good at droping the gain of higher
> > pitches off axis. It worked best at reduction of off axis frog
and
> > insect chorus when recording owls but was poor at determination
of
> > the exact direction of the owl. In fact I had to not wear
headphones
> > when recording owls with my shotgun so that I would not go the
wrong
> > direction.
>
> This is certainly true as even a cursory examination of the polar
> diagram for a shotgun will show. At Owl frequencies you have about
a 120
> degree window. Shotguns are only really very directional at higher
> frequencies. For the ME-67 this starts to happen somewhere around
2000 -
> 4000 Hz. The range is about the same for the MKH-416 or MKH-60.
It's
> very slightly lower for the longer MKH-816 or MKH-70, maybe 500Hz
lower,
> ie starting at 1500 - 3500 Hz.
>
> For lower frequencies a Cardioid would probably be nearly
equivalent to
> a shotgun.
>
> Or the omni in the parabolic. Except that's more directional.
>
> Walt
>
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