Issue with C12 clone

[Spiritworks]

I built a C12 copy that was working quite nicely for a couple of years. It recently has developed a crinkly/crispy/staticky type of noise in the 10k frequency range. I swapped out the tube and the problem remains. Any suggestions for troubleshooting?

 

[Tim Campbell]

Dirt on the capsule or pcb. Loose connection

 

[ubxf]

Also it might be worth trying a different xlr cable. Seems too simple but it bit me once before

 

[Spiritworks]

I did try a different balanced XLR cable and different preamp, I do not have a second 7pin xlr to try. I did think of a dirty capsule, but the mic is always stored in a plastic bag, inside it's case. Is it safe to use a bottled compressed air to clean off the capsule? I also have 99% isopropyl alcohol. Thanks for the suggestions.

 

[Tim Campbell]

I did try a different balanced XLR cable and different preamp, I do not have a second 7pin xlr to try. I did think of a dirty capsule, but the mic is always stored in a plastic bag, inside it's case. Is it safe to use a bottled compressed air to clean off the capsule? I also have 99% isopropyl alcohol. Thanks for the suggestions.

never, ever put alcohol near a capsule with any acrylic parts. If you have never cleaned a capsule before then don't start with this one unless it is cheap to replace. What capsule is it? Try checking that all connections are tight. try leaving it powered on overnight, perhaps it's moisture.

 

[Spiritworks]

Thank you for the cautionary advice. I don't know what capsule is in it as I had Shannon Rhoades re-work the mic right before he went awol. It was working and sounding beautifully and always kept in its case, so this is a mystery.

 

[Icantthinkofaname]

I did try a different balanced XLR cable and different preamp, I do not have a second 7pin xlr to try. I did think of a dirty capsule, but the mic is always stored in a plastic bag, inside it's case. Is it safe to use a bottled compressed air to clean off the capsule? I also have 99% isopropyl alcohol. Thanks for the suggestions.

I think a lot of people use distilled water and a bit of 99% isopropyl, but if you don't know if it'll damage part of the capsule I wouldn't try it yet.

never, ever put alcohol near a capsule with any acrylic parts. If you have never cleaned a capsule before then don't start with this one unless it is cheap to replace. What capsule is it? Try checking that all connections are tight. try leaving it powered on overnight, perhaps it's moisture.

Do you have any recommendations on what sort of brushes to use?

 

[Tim Campbell]

Clean around the edge of each membrane with a dry q-tip. If it is a short it is between the retaining ring of the membrane and the backplate connections. Cleaning the membranes won't solve this issue and if you have never done it before practice on cheap capsules before ever trying it on a good one. unscrew the connections to the backplate, remove the screws and clean the area around them with ammonia and water solution ( window cleaner)

 

[Delta Sigma]

A friend had an issue with a U67 clone that had a similar noise. This was more of a rustling noise though. He sings quite close to it so I suspected moisture. I found that if I breathed on it, audio would cut out momentarily and then the sound he described would kick in. I sealed it in a vacuum seal bag (did not vacuum of course) with a freshly dried desiccant for two weeks. Fixed the problem.