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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