The issue of microphone load impedance is irrelevant. At Wildtronics, we st=
rive to improve every aspect of a parabolic microphone, and many of our cus=
tomers utilize and value the low frequency gain found in our products to re=
cord birds, owls, mammals, and human speech. Bass dip is not so hard to sol=
ve, just read the paper from Sten Wahlstrom to see one method. Wildtronics =
uses that method in our Pro Mini, which also does not exhibit bass dip. The=
booster disc and proper construction details used in the Wildtronics Pro M=
ono Series not only reduces bass dip, but also improves gain, subject isola=
tion, and provides a smooth, predictable gain curve. Using a cardioid mic p=
ointed towards the dish does help with the bass dip. However, when using a =
cardioid, the system will have only half the gain (-6dB) -- like a 10 inch =
dish compared to a 20 inch dish. The polar response of a cardioid microphon=
e does not allow it to collect the signal from much of the dish surface are=
a. What does -6dB mean? You will have to be half the distance to your subje=
ct to get that 6dB back. For those who only care about high frequency birds=
, want to use their own microphone, or play around with different mic arran=
gements, Wildtronics offers the less expensive All Purpose Parabolic Kit, w=
hich is of traditional design. =0D
=0D
A word on audio samples. Samples are difficult to compare that are randomly=
recorded alone, without directly comparing a recording made, at the same t=
ime, with a different microphone. Here is a link to such a comparison of 4 =
directional mics simultaneously recorded: https://youtu.be/Z83vgjZEVks http=
s://youtu.be/Z83vgjZEVks. I have to point out an error that Daan Hendricks =
wrote, that having a flat response microphone guarantees a flat response in=
a parabola. No microphone, no matter how flat it is will have a flat respo=
nse in a parabola. The gain curve of the parabola determines the frequency =
response.=0D
=0D
Bruce Rutkoski=0D
Owner=0D
www.wildtronics.com=0D
=0D
=0D
---In <> wrote :=0D
=0D
Marco, Gianni, Bruce and other Gentlemen.=0D
=0D
Since Telinga started in 1981, there have been some holy cows to be killed=
.=0D
=0D
The first we met was a dogm that =94the input impedance of a microphone =
=0D
amplifier must be the same as the output impedence of the microphone=94. =
=0D
Lots of people spend lots of time and money on something they called =0D
=94impedance matching.=94 The dogm lived on until the end of -90. The topi=
c =0D
shouldn=B4t have got any attension at all, really, but a manufacturer =0D
which used a special input transformer put a lot of stress on the =0D
importance of it.=0D
=0D
Another =94expert opinion=94 was that =94you can=B4t record owls with a =
=0D
parabola,=94 which meant that parabolas were totally worthless in all =0D
ways. At Telinga we still get mails occationally about this and Bruce, =0D
here, just recently had to point out that =94There is no reason why you =
=0D
wouldn't be able to record frequencies of 20Hz, it just won't have =0D
gain.=94 Thanks for that.=0D
=0D
Now it seems like a new holy cow is to be born: The Tragedy Of the Bass =
=0D
Dip and the Holy Healing Plate.=0D
=0D
Yes, when a signal hits an omni in focus of a parabol, gets reflected by =
=0D
the parabol and then back to the omni a bit later, there will be a dip =0D
in the frequency curve. It=B4s true. It=B4s been known for some 100 years =
=0D
and hundreds++ of serious DIY people have tried all logic ways to give =0D
a lift to the peak, including the plate that is now on the agenda.=0D
But seriously: How many birds have you lost because of a 6db dip at some =
=0D
600 Hz? None, I=B4m sure. The people recording low-freq. mammals will do =
=0D
best with HQ shotguns anyway.=0D
Even regarding it=B4s low importance, it is a difficult problems to solve.=
=0D
A number of measurements done at Telinga over the years, show that a =0D
plate flattens out the dip a bit, but that new dips and peaks occur at =0D
other frequencies in a more or less random way. (Diagrams can be posted =
=0D
on request.)=0D
=0D
The by far best way to get nice mono sound out of a parabol is to use a =
=0D
suitable cardioid, facing inwards into the dish. Heres is a nice =0D
reference to this subject :=0D
http://daanhendriks.co.uk/wildlife-nature-sound-recording/telinga-tastic-s=
uper-close-up-recordings-of-birds-crickets/ http://daanhendriks.co.uk/wildl=
ife-nature-sound-recording/telinga-tastic-super-close-up-recordings-of-bird=
s-crickets/=0D
=0D
The Telinga Twin-Science mic have both types integrated =96 a fine tuned =
=0D
cardioid facing inwards to the dish and an omni facing out, for windy =0D
conditions and for better handling noise. Then one can select the best =0D
recording by listening in post production.=0D
=0D
Klas-G=F6ran Strandberg, Telinga Microphones, 2017-10-11=0D
=0D
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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