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Studio Projects C4 Repair and Disassembly

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Studio Projects C4 Repair and Disassembly

Postby bpap88 » Sat Jan 16, 2021 7:28 pm

Hi all. I just purchased a used pair of Studio Projects C4 SDC mics to use for room ambience and other kinds of secondary needs. One of the mics has a bit of static in the sound when connected. It’s not a constant, pitched sound - just a non-constant bit of sound not unlike newspaper being crumpled in the distance. Normally I’d just return the mics, but I got them via auction at a good enough discount to make a little elbow grease worth my while. I’m trying to disassemble the mic, and am having difficulty doing so. Does anyone have experience with taking one of these apart? There’s a screw (have screwed it IN to clear the housing of the mic), and a raised switch for the pad and HPF that I’ve removed, but it still won’t come apart. I read elsewhere in this forum that one might attempt to screw off the top component that the capsule connects to, but I’ve used enough force in attempting it that I think that part may not be designed to move and I don’t want to risk breaking it. A lot of pencil mics have 3 screws near the base that once screwed in allow the innards to be separated from the casing, but that’s not the case here. Thoughts, suggestions, and tips welcome and appreciated. I’m hoping I might be able to diagnose or see something once I have the housing off. I don’t have any repair experience, but I have a good quality multimeter and a willingness to try to figure it out. Btw, I’ve ruled out an issue with a cord, interface, preamp, or capsule. Thanks in advance!

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Re: Studio Projects C4 Repair and Disassembly

Postby Hugh Robjohns » Sat Jan 16, 2021 9:34 pm

Rustling noises are often the result of dampness around the capsule or impedance conversion circuitry. It might be worth putting the mic somewhere warm and dry for a day or two to see if that helps before gutting the thing.
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Re: Studio Projects C4 Repair and Disassembly

Postby gullfo » Sun Jan 17, 2021 2:04 am

the inner face of the capsule might also be dirty from saliva, duct and as Hugh pointed out moisture exposure. there are a few videos online for cleaning the capsule - i recently did it for a couple of LDC using alcohol on a cotton swap and very gently wiping it. letting it dry thoroughly. and the crackly rustling type sounds went away. afterwards i went through a few others and cleaned them as well - circular spots etc and while they weren't making noise, they seemed happy to be clean :clap: . also, it can help to clean the contact pins as well. i use a brass cleaner and swabs, then wipe off the residue with alcohol and swabs. it's sometimes shocking to see how much grunge comes off cable connections...
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Re: Studio Projects C4 Repair and Disassembly

Postby DanDan » Sun Jan 24, 2021 6:52 pm

I once cleaned a U87 capsule in an old SFO radio studio. Plenty of cigarette smoke! I used IPA and a camel haired artist brush. It came up sparkling but soon after the diaphragm stretched and sagged clinging to the backplate! Disaster. I put it away and returned to it a few months later. Worked fine.... it had dried out and tensioned again. Neumann used to include advice, camel hair artist brush..... medically pure distilled water. I would contact Studio Tech for disassembly advice. But backing up, first thing to try with any noisy condenser is a night or two in the airing cupboard.
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