DIY Tape Op mics - where have all the instructions gone?

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notbillcosby
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Post by notbillcosby » Thu Jul 28, 2011 7:38 am

A few days back, I got a pile of misc electronics goodies from a friend. In said pile was a baggy of 10 tiny tiny electret capsules, about half the size of the ones used for "the" mic. I've made two mics using these tiny capsules (omnis, housed in an XLR end like normal) and they sound pretty cool, especially up close to drums! I'd never thought about the possibility of close micing with omnis and actually having very listenable bleed from drum mic to drum mic... probably because I never had any omnis that I'd be willing to risk getting whacked with a drum stick!

Anyway, these mics buzz the closer I get them to certain lights in my room. Does that spell grounding or insulation issue? One of the two I made has a jumper from pin 2 to the tab inside that (i believe) grounds to the case (haven't multimetered it yet, duh.) and on the other I tried pin 3. Neither seemed to fix anything. Could this be a power supply ground issue? Maybe I would've been better off if I didn't add the jumper in the mic...?

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Scodiddly
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Post by Scodiddly » Thu Jul 28, 2011 11:21 am

You need better shielding of the capsule. Maybe just a wrap of copper foil tape or something.

notbillcosby
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Post by notbillcosby » Fri Jul 29, 2011 9:32 pm

Are you talking about the inside of the mic body, or specifically just the capsule? If I wrap the sides in tape, won't I still get interference through the top and back? That tape will still run to the same terminal that the casing is currently, does this just provide some extra thickness, basically, to keep electrical noise out?

Excuse my complete ignorance, and thanks for your help!

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Scodiddly
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Post by Scodiddly » Sat Jul 30, 2011 5:29 am

It's generally the back of the capsule where electrical noise gets in. Inside the capsule is a very high impedance area, necessary to make things work but very susceptible to noise. The front and the sides of the capsule are surrounded by metal or at least metal mesh, but the back is just circuit board which can let noise through.

You can either make the whole mic body out of metal or metal-covered materials, or just try to cover the back of the capsule. The rest of the circuitry is somewhat susceptible to noise, but not as much as the capsule itself.

notbillcosby
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Post by notbillcosby » Sat Jul 30, 2011 5:36 am

Alright, that makes sense. The mic body is metal, except for the rubber boot at the end of the XLR plug, which is where I have the tiny capsule mounted. I'm not sure how to cover the back of said capsule with metal without shorting it out! Would epoxy help? Do i just stuff in some sort of copper (or something) insulation back a ways in the boot?

Also, when i touch the exposed metal on the side of the capsule, it makes it reeeeal buzzy. Is that normal, or did I miss a ground somewhere? It does it on both mics (one with pin 2 to ground and one with pin 3 to ground. I've since snipped the jumper on the 'pin 2' mic so that none of them jump to the case, like the schematic shows. Still buzzy)

notbillcosby
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Post by notbillcosby » Mon Aug 01, 2011 4:48 pm

Following the Tape Op Omni schematic, I used a cardioid capsule and mounted it "paper clip style" inside what used to be a junk 58-style dynamic. It works great! Complete airflow around the capsule this way without having to figure out how to do it in an XLR end.

The mic sounds great, though it is lacking in low end response. The omni mics are supposed to get an increase in low freq response when you epoxy the back of the capsule, but I can't do that on a cardioid. Is there anything else I can do to "open up" the low end other than hitting it with an EQ afterwards?

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Scodiddly
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Post by Scodiddly » Mon Aug 01, 2011 6:41 pm

Just EQ the cardioid. I don't think you'd have any luck trying to physically modify the capsule to get the sound you want.

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Post by mostfamiliar » Thu May 29, 2014 6:09 pm

Is anyone still into these? I've been thinking about building a pair with the JLI capsule since the panasonics are hard to find these days.

creaturesleeper
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Post by creaturesleeper » Wed Jun 11, 2014 8:14 pm

I built two...one I stuffed into an old Karoake metal bodied mic and screwed an xlr into the end and the other into some other thriftstore mic body...they sound completly different but I have used them as a pair and got cool sounds...they look really fucked but sound cool...

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