Strange static sound when recording via USB mic

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Level 1

20 points

Strange static sound when recording via USB mic

I am recording via USB mic. I am getting what can best be described as a static sound when there is audio recorded via the USB mic in Logic projects.

I don't think it is a problem with the mic, because I am testing it in a freeware app called Audio Recorder and the sound is clean. Also, if I restart Logic and open an empty project, the sound is clean, but sooner or later the problem happens again. Something seems to happen to set it off, and the problem gets progressively worse.

Any help with this vexing problem would be very appreciated.

PowerPC G5 dual 1.8 GHz, Mac OS X (10.4.11), 2 GB RAM

Posted on Nov 23, 2007 9:01 PM

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Answer 1

Jon H.

Level 2

195 points

Nov 23, 2007 11:38 PM in response to Philip R.

sounds like it could be a buffer size issue because you said it starts out okay, then gets progressively worse. Try increasing the size of the recording buffer.

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Answer 2

Philip R. Author

Level 1

20 points

Nov 24, 2007 7:10 AM in response to Jon H.

Thanks for the idea, I will try this. I restarted the computer and this morning it sounds OK so far at the buffer size I had yesterday (256).

By the way, by "recording buffer" do you mean the I/O buffer?

I should have been more specific, the problem occured whether or not I am actually recording anything (i.e., when Logic is resting with Software Monitoring enabled). Would increasing the buffer size still affect this?

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Answer 3

Philip R. Author

Level 1

20 points

Nov 24, 2007 12:03 PM in response to Jon H.

Hello,

The problem still persists even when setting the I/O buffer to 1024. What happens is this:

- I reset the Core Audio I/O buffer in Audio Preferences (within Logic)
- The problem is fixed
- I start recording
- After about a minute of recording I start getting static whenever I sing something, and the static gets progressively worse
- Even when I stop recording, the problem persists
- If I close Logic and open Audio Recorder (the little freeware app), the problem is fixed

Does anyone have advice?

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Answer 4

Jon H.

Level 2

195 points

Nov 24, 2007 12:13 PM in response to Philip R.

Hmmm. Sorry, but I don't know what could be the prob. It still seems like an I/O buffer issue. I had a similar issue with a Yamaha mLan setup. Just like your problem, everything started out okay, then got worse and worse, even when I was only input-monitoring, just like you talked about.

In my case, I realized I was using a PPC driver which was running in a very handicapped way under Rosetta. Once I updated the driver to Intel-compatible, all was well. So the only thing I can say is make sure your driver software is up-to-date. BTW, what kind of USB mic are you using?. I once had a sampson C01U, and gave it away because it sounded so sucky. It didn't have buffer issues, but was really noisy.

Hope you find your solution.

-J

Message was edited by: Jon H.

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Answer 5

Philip R. Author

Level 1

20 points

Nov 24, 2007 12:51 PM in response to Jon H.

Hi Jon,

Thanks for your reply. I think I solved the problem. It's a Logitech AK5370 (admittedly not pro-grade but for our demo purposes it works).

When I set up my Aggregate Device in Audio MIDI Setup, originally I had "Built-in Audio" selected as the clock. I tried switching the clock to the AK5370 and re-opened Logic. That seems to have fixed the problem.

So far, so good with three separate takes. I'll leave the thread open for a while in case anyone has other comments (or the problem reappears).

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