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First DIY Microphone

Posted by Tom Benedict on 28/06/2015

I really meant my first DIY microphone to be a stereo mic, but I managed to kill one of my BT-EM172 microphone capsules before I finished the thing. I placed an order for three more from Frogloggers and wrote to them to find out what I’d done wrong. Gene from Frogloggers wrote back to tell me that the EM172s aren’t ESD sensitive, and he really didn’t know why the mic died. Even better, he threw an extra one in my order to replace the dead one. That’s customer service!

I built out my remaining cables as two stereos and one mono. I de-soldered my one good mic and put it on the end of the mono cable. I took a tip from Jonathan Green’s page on how to package the microphone once I was done. I didn’t use 1/4″ headphone plugs for housings the way he did, though. I made my own.

Mono Mic Disassembled

The body of the mic is a 0.625″ diameter piece of 6061 aluminum (scrapbox!) that I covered with Cerakote. This is what I used in place of the 1/4″ headphone plug housing on Jonathan’s page. The screen is some fine mesh stainless. I punched out a 1/2″ round using my wife’s disc cutters. The BT-EM172 capsule and cable are shown next, followed by a 1/2″ round of 6mm craft foam. I assembled the stack pretty much in the order shown. I slit the craft foam, fitted it around the cable, shoved it in behind the microphone, and filled the rest of the cavity with hot glue. (For what it’s worth, my hot glue skills are nowhere near as good as Jonathan’s!) Since the hot glue isn’t in direct contact with the mic capsule, I should be able to cut it out if I need to remove the mic in the future. For now, though, it’s sealed.

Mono Mic Assembled

The assembled mic still worked! (YAAAY!) I’m sure the sound is colored somewhat by the housing, but to my untrained ear the differences are impossible to detect. The mic is much more durable in its housing, so I think it’s a fair trade-off.

Just to make life easy I made five sets of parts so I can house the other four mics when they come in. But I think I may make a metal endcap for the other four in place of the hot glue.

No samples to share just yet, but I’m planning to use this in the field sooner rather than later.

– Tom


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