I bought an Audio-Technica ATR-6550 Condenser Shotgun Microphone off eBay which works fine most of the time but sometimes picks up noise as heard in this recording. Can anyone identify the problem?


This sounds like a bad mic capsule to me. However, it could also be caused by a bad phantom power source or bad preamp, and so you'll need to do some troubleshooting to figure out which one. Can you borrow or purchase (with a return policy) another mic to try? Are you plugging it into a video camera (the mic's intended use) or something else?

  • I was plugging it into an inline USB audio adapter via several plug adapters (to go from 1/4in mono jack plug to one side of a 3.5mm stereo jack input) and then into a Raspberry Pi via USB. The mic was running on battery. As it was a cheapish eBay purchase and will probably cost more to get fixed than I paid for it, I've bought another mic, although perhaps I should dispute the sale. – drkvogel May 31 '20 at 11:43

The noise you can hear is someone snoring. My advice would be to attend your local GP for assessment and possible treatment.

There's also a bit of static on the track, which is possibly due to a faulty capsule or excess humidity.

  • Yes, it's me snoring, I am recording it in order to detect sleep apnoea, which I suffer from. If you listen past about 20 seconds, the 'static' gets gradually worse until it almost drowns out the recorded sound completely. After a while it subsides. This happens only occasionally. Any idea why? – drkvogel Feb 7 '19 at 15:55
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    It may be dirt or contamination on/in the capsule, or the associated wiring. Condenser mics have a very high impedance sensor that is vulnerable to leakage currents. You probably need to have the mic cleaned/serviced by someone who knows what he's doing. – sh- Feb 7 '19 at 23:05
  • Again, I believe it's a faulty capsule. It could be that excess humidity in the room is causing the diaphragm to break down. Any dirt on the diaphragm would exacerbate the effect. I have no idea why this is an intermittent issue, but I do believe that this is a faulty mic which needs servicing and repair. – Mark Feb 8 '19 at 0:01
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    I would also recommend testing the mic with a different power source. There is a small possibility that it might be a phantom power issue. – Mark Feb 8 '19 at 6:36

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