DIY Homemade Binaural (ish) Stereo Microphone

While shooting some video at a local park, I was disappointed with the quality of the onboard microphone’s audio. I remembered stumbling across a web site describing a way to make a pair of binaural mics using an Altoids box. So… I decided to try and make something for myself.

Most people making these things are doing so to clip the mics to their glasses as an unobtrusive way to record music events. Very cool. However, my needs were different, wanting to do something specifically for “field recordings” — my microphone could be more visible, and I liked the idea of it being able to stand on its own.

First of all, here are some quick samples I’ve recorded with it in the first couple days since completion:

• March 10, 2008: Rainy Morning on the Back Porch
  
  You can hear splashy raindrops, deep rolling thunder, some bizarre bird calls, and even a far-distant train.
• March 10, 2008: Bus Ride into Work
  
  Waiting for the bus, a guy asks me which bus to get on, and I try to use my pass upside-down. Then I exit the bus and take a quick walk to work. You can hear a plane fly overhead, and squeaky walk through the marble-floored lobby with some nice music. Get into the elevator, ride up and walk into the office.
• March 08, 2008: Fire on Bee Creek Road
  
  I was off for a drive, filming and recording out southwest of Lake Travis (near Austin, Texas) when I stumbled upon this grass fire covering several hundred acres. The fire trucks and police were already on the scene, so I pulled off the road to watch a bit. You can hear several cars pass on the road behind, and then the fire helicopter flies overhead on the left on its way to the fire. Finally a guy in a big truck stops and asks me, “Got a Fire?”

Using two omnidirectional electret capsule microphones from Radio Shack (around $4 each), two 10k resistors, two 2.2 micro-farad capacitors, a 9-volt battery, and some wood and other odds and ends I had lying around the workshop, I constructed this visual monstrosity.

Despite its appearance, it seems to sound pretty good — easily beating the camcorder’s onboard mic.

Although I didn’t actually use the following schematic (from MicDIYers), it’s very close to what I built. I only added an on/off switch right inline with the battery. My idea on the box size and placement, was to roughly approximate the spacing and baffling size of a head-like object, somewhat borrowing from the ideas described on www.trackseventeen.com. I used scrap wood from around my shop and didn’t spare much time or effort in making it look good. The door opens up to gain access to the electronics should I need to make a repair. The big wire ‘ears’ are both for protection, and for holding a pair of black dress socks which make adequate wind screens if there isn’t too strong a wind! I may look into making some ‘furries’ for stronger wind someday.

The following pictures link to the corresponding photo pages on Flickr which offer links to nice large photos.

This entry was posted on March 11th, 2008 and is filed under music. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response or Trackback from your own site.