Building a Stereo Microphone Array
As my interest in sound recording moved forward, I came to realize that I wanted a stereo mic that I could place separately from the mics built in to my field recorder.
I then set out to purchase a stereo mic, and discovered that a different approach to accomplishing this would be in building my own stereo mic.
After researching the subject of quality stereo mic capsules and based on my research, I found a source for the mic capsules that would give me what I was looking for when it came to sound recording, and the sound that I desired in my recordings.
After receiving the parts that I ordered out of the UK, consisting of the mic capsules, the housings, various fittings, shielded cables, and "Rycote" dead-cats for wind-proofing the mics, I headed in to my workshop and set to work.
The mount consists of the black Delrin center hub seen in the photo, that was turned to size in the lathe.
Then with the hub placed in the indexing head and mounted in the milling machine, and with a precision sized slot-drill, two .375 OD holes were machined in the hub, the holes spaced precisely at an included angle of 110 degrees on the circumference of the hub,
Then the two carbon fiber tubes with a .375 OD were cut to the required length, and inserted in place in their respective holes in the Delrin hub.
Next two aluminum adapters for the mic capsules in their respective housings to mount on were machined to shape, and then inserted into the carbon fiber tube ends sized for an interference fit, with the mic capsules spaced 170mm apart.
Wiith the mic capsules and housings assembled and mounted in place, and with the complete assembly mounted on a "Rycote" shock mount that in turn is mounted on a dedicated tripod, I'm off to the field to do some recording.
For those of you interested, here are the specifications for the mic capsules used.....
Microphone Capsules: Primo EM172-Z1 (matched pair)
Acoustic Principle: Electret Condenser
Frequency Range: 60Hz to 18 kHz
Output Impedence: 2.4 ohms
Signal to Noise ratio: 14dB
Clipping SPL: 119 dB SPL at 1 kHz
Sensitivity: -28 dB +/- 3dB at 1 kHz
Capsule Matching: +/- 0.5 dB
Dynamic Range: 105 dB
Power Requirement: Plug-In Power, 3 volts (2-10V)
Current Consumption: 600 uA
Output Connector: Gold plated 3.5 mm Stereo Plug
Click on the photo for a closer look......