Good point, Gianni. At those shorter wavelengths, capsule spacing starts t=
o matter a lot more. Mexican free tailed bats call between 40 and 75kHz. At=
the low end, around, 48kHz and 20C temperatures, the wavelength is only 7.=
Message: 3cm.
Subject: The EM258 capsules are 6mm in diameter, so basically I'd be right in t=
he mess of things, and it would only get worse at the higher frequencies. I=
'll build these using one capsule per channel. =0D
=0D
Peter, I'd like to try recording in stereo. I'm not sold on the idea of ful=
l spectrum audio, but I really would like to try recording in stereo. The C=
ongress Street Bridge, in particular, lets you get within a few feet of the=
bats as they head out to hunt. Depending on where I can set things and sti=
ll get rid of the background traffic noise, it could prove to be a rare rec=
ording opportunity (for me, anyway). I can always pick a channel to get a m=
ono signal. But if I can get decent stereo separation, it would be nice to =
have the ability to record it that way. =0D
=0D
Vicki, I'm planning to use a Zoom F8. It has the ability to do PiP, but at=
this point all my microphones are wired for P48. This is a hold-over from =
my previous recorder, which had noisier preamps on the 3.5mm inputs than on=
the XLR inputs. But with the number of inputs on the F8 it's worked in my =
favor so far. I was planning to wire this the same way.=0D
=0D
=0D
I used a pair of EM258 capsules for a stealth recording rig some years ago=
.. I hot glued a pair of them to the earpieces of some reading glasses and =
covered everything up with a Croakies band that also hid the cord routing d=
own to my recorder. They sound a little more harsh in the high end than the=
EM172 capsules and have a higher noise floor, but if I remember right they=
're a little hotter as well so it's not a huge problem for louder subjects.=
I haven't used those glasses mics much in the last few years though, so I =
might pirate the capsules for this build. (Long story. I have a neuromotor =
condition that means I never stop moving or making noise, so having mics at=
tached to my head just didn't work out.)=0D
=0D
=0D
Gregory, thanks for the reminder of the noise floor on these. I was leanin=
g toward running separate wires so I can pick which frequency domain I want=
to play with. This is just one more reason to do that. I can always try to=
merge them in post to get full spectrum audio, but since the bat calls wil=
l need to be frequency shifted in order to be heard, I'm not sure there's m=
uch point in wiring things to one set of connectors, anyway.=0D
=0D
=0D
Thanks for all the input!=0D
=0D
=0D
Tom=0D
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