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seth

Ruby Baby

Posts: 5,639 Member Since: 26/01/2011

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Mar 27 17 8:43 AM

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I have a bunch of API mic pre clones I built. One has become intermittently noisy recently - every so often it lets loose with a rainstorm of hissing and crackling. I tried cleaning the pot but it's sealed, so I don't know if anything got in. I also cleaned the connectors. Could that be the opamp? I have a John Hardy 99C in there now. I realize I could just swap opamps, but I want to understand what's making the noise and why if possible. I will post a link.

Here's the audio file of the noise. Is this indicative of something in particular?

Thanks

Last Edited By: seth Mar 27 17 8:52 AM. Edited 2 times

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zmix

Aqua Marine

Posts: 4,189 Member Since:20/01/2011

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Mar 27 17 10:09 AM

Seth, sounds like a human being.. I try to keep the humans out of the studio so I don't have to hear constant "what is that?" noises....

Besides that there is definitely some instability. Pull the opamp and reseat it to clean any possible corrosion on the pins. Failing that swap it for another, but note that swapping an op amp FIRST might clean the pins, eliminating the noise, and you might conclude that you have a bad opamp,, claro?

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seth

Ruby Baby

Posts: 5,639 Member Since:26/01/2011

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Mar 27 17 11:41 PM

Thanks Chuck, reseated the opamp and so far it appears to have resolved the problem. As far as humans in the studio, I'm working on that problem so far without success. Jesse, they were made for a brief time by Eisen Audio and I bought a half-dozen. I had some original API 2622 mic transformers I wanted to put to good use. In ten years or so this is the first problem I've had.

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zmix

Aqua Marine

Posts: 4,189 Member Since:20/01/2011

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Mar 28 17 8:25 AM

seth wrote:
Thanks Chuck, reseated the opamp and so far it appears to have resolved the problem. As far as humans in the studio, I'm working on that problem so far without success. Jesse, they were made for a brief time by Eisen Audio and I bought a half-dozen. I had some original API 2622 mic transformers I wanted to put to good use. In ten years or so this is the first problem I've had.
Oxidation is rather impartial, and apparently never sleeps...

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Mike Rivers

Aqua Marine

Posts: 2,529 Member Since:13/10/2012

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Mar 28 17 12:22 PM

The two things that cause most equipment failures: Connectors and power supplies. Those are usually easy to diagnose and can sometimes difficult to repair permanently, but cleaning contacts is often all it takes to get something working again.

Once you get past the easy stuff, that's when to start worrying about component failures. That's when the fun starts.



For a good time, call mikeriversaudio.wordpress.com

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