Raimund Specht wrote:
> --- In "Martyn Stewart"
>
>>I agree, I get better response from my
>>Telinga dish to low frequencies
>>than I do from my shotguns
>
>
> I guess that this phenomenon is caused by the infrasound-rejection
> filter that is implemented in the MKH shotguns (Sennheiser added
> that filter in order to reject the inherent sensitivity of shotguns
> to infrasound). They specify a cutoff frequency of 50 Hz. As it can
> be seen from your sonogram, the maximum energy of the grouse sound
> is below 50Hz. It seems, that the Telinga does not have such an
> internal high-pass filter and is therefore able to pick up these low
> frequencies. But the dish should have no significant effect at those
> frequencies.
Sennheiser, in a article on designing infrasound level mics made it
clear it takes special design features to get down to that level,
ordinary mic capsules like in the shotguns don't do it. The MKH-110 is
the mic that he was describing, not a shotgun. Though he did not mention
a specific model.
Most of the current MKH shotguns have a low frequency falloff starting
as high as 200 Hz, even without the high pass switched in. There is no
reason to design them to go lower than voice as the interference tube is
totally ineffective at low frequencies.
The Telinga also has a switchable high pass. Obviously you turn this off
when recording the low stuff.
Since the dish has "no significant effect" at these frequencies perhaps
you will explain the highly accurate directionality it has at these
frequencies. It maintains the same degree of directionality at these low
frequencies as it has at high frequencies. Is it just magic that
provides this directionality? Or maybe physics has been all wet for
these last 50 years as to what's going on. I expect the latter.
Walt
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