You could get two bat detectors, but if they're heterodyne then I guess you=
'd have to make sure the mixing frequency is exactly the same on both. I se=
e there's at least one stereo bat detector available.
Sent from my iPhone
On 26 Feb 2018, at 8:21 pm, <=
r.com> [naturerecordists] <<naturere=
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.=
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.
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.
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 m=
y 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 f=
avor so far. I was planning to wire this the same way.
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 co=
vered everything up with a Croakies band that also hid the cord routing dow=
n to my recorder. They sound a little more harsh in the high end than the E=
M172 capsules and have a higher noise floor, but if I remember right they'r=
e 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 mi=
ght pirate the capsules for this build. (Long story. I have a neuromotor co=
ndition that means I never stop moving or making noise, so having mics atta=
ched to my head just didn't work out.)
Gregory, thanks for the reminder of the noise floor on these. I was leaning=
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 will=
need to be frequency shifted in order to be heard, I'm not sure there's mu=
ch point in wiring things to one set of connectors, anyway.
Thanks for all the input!