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?

2 Answers 2


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
    Commented May 31, 2020 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
    Commented Feb 7, 2019 at 15:55
  • 1
    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-
    Commented Feb 7, 2019 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
    Commented Feb 8, 2019 at 0:01
  • 1
    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
    Commented Feb 8, 2019 at 6:36

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