The View Up Here

Random scribblings about kites, photography, machining, and anything else

Building Microphones

Posted by Tom Benedict on 23/06/2015

The BT-EM-172 microphone capsules I ordered from Frogloggers showed up over the weekend. I wired them into a disused headphone extender cable just to try them out, but headphone cables aren’t shielded, so it picked up all sorts of EM/RF noise that showed up as an unpleasant buzzing in my test recording.

Today the Mogami W3031 microphone cable I’d ordered from Redco Audio also showed up, so I built a new cable. I used a 3.5mm gold plated audio plug from Radio Shack, 6′ of the Mogami cable, and soldered the mics directly onto the end.

Holy… Freakin… Cow…

I tested everything in a relatively noisy environment, both electromagnetically and acoustically. The shielded cable worked wonders on the EM/RF noise, basically dropping it below what I could hear. (Yeah… really quantitative…) The mics themselves performed marvelously. I haven’t tested them with any sort of rigor, but the mics may be lower noise than the ones built into my DR-05. All in all this is a huge move forward toward building a kite aerial sound rig.

In other audio news, early last week I built a micro version of the Crown SASS baffled microphone array. This is another baffle design that’s trying to do the same job the Olson Wing tries to do: create stronger stereo separation in a recording. Just like my rendition of a micro Olson Wing, my rendition of a micro SASS left a lot to be desired: the geometry was off, the materials weren’t ideal, and I generally didn’t understand what I was doing until I’d already done it. But it worked! When I popped it on my DR-05, I clearly got better stereo separation than when I ran without it.

I had an unfortunate opportunity to test it in the field. In the middle of last week one of my daughter’s parakeets flew out of the house. The kids were able to track him visually for about an hour, but by the time I got home they’d lost sight of him. I pulled out my DR-05, popped my micro-SASS on the front, and walked around the neighborhood trying to locate her bird.

After about ten minutes of realizing I could locate practically any sound I was hearing by rotating the recorder, I started hearing parakeets! Multiple parakeets! I panned across the sound, and realized it was coming from the creek behind our house. YAY! I walked back through the neighborhood, tracking the sound of three parakeets all apparently in the same location. Right when I walked up our driveway, they stopped calling.

That’s when I saw my wife walk out of the creek with her cell phone. She’d been trying to attract the bird by playing parakeet sounds on it. Three parakeets, to be precise. I’d been tracking her! So the micro SASS, flawed though it was, performed quite well. I’m planning on building a larger one I can fly from a kite to record ocean waves from above.

Tom

P.S. My daughter’s parakeet is still missing, unfortunately. We put up signs, and my daughter is spending her afternoons looking for him. But at this point I’m not holding out too much hope.

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