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Interference buzzing on one mic and not the others (with samples)
Old 2 weeks ago
  #1
Here for the gear
 

Interference buzzing on one mic and not the others (with samples)

Hi all,

Been a long time lurker and have learned a lot here, so thanks for that.

I've been working on a home set up, have done some treatment to basement, etc. Currently running a Focusrite Clarett USB 4pre into a 2011/2012 MB Pro with Reaper.

Acoustic and recording/mixing questions aside, I cannot get rid on an intermittent buzzing that I am pretty sure is coming from some kind of electronic interference. I don't believe it's grounding as it doesn't remedy by touching or moving itt have a Shure SM 81 experiencing the buzz and a Rode NT1a that does not have the issue. I've tried to narrow it to the microphone and believe I have:
- Tried both mics on each input on same xlr cable.
- Tried different cables.
- Moved around / away / re-arrange cables / power cable.
- Brought the SM81 around my house with an old Zoom R8 and eventually found the buzzing disappeared on my second floor in a different area of the house, so I am pretty convinced it is due to something with the electricity.

I'm plugged into a Belkin strip with some moderate RFI noise reduction and also tried noise suppressors on the XLR and power. Nothing is working.

Given that the Rode does not have the issue, I wonder if the SM81 is messed up and maybe I replace with a new one or get a KM 184.

I've attached examples of both, gain adjusted. I rolled off under 100hz, but that's it. Any help would be much appreciated. Thanks!
Attached Files

rode nt1a noise test.wav (3.85 MB, 61 views)

sm81 noise.wav (3.85 MB, 61 views)

Old 1 week ago
  #2
Lives for gear
It isn’t buzz or hum, which are constant level (if the mics and cabling are stationary). My list of suspects would start with the SM81 itself. If you can, putting a different SM81 in the same position with the same cabling and chain would reveal that the problem can be isolated to a single 81, or that all 81s (OK, not ALL, both) have the same problem in that setup. If it is the single 81 that has a problem, I’d get factory service on it. I suspect something has gone wonky in the mic’s 48 volt circuitry.
If both 81s have the same problem, it is external to the mic.
Exception: It may be that all 81s are not sufficiently immune to some electrical or magnetic weirdness in your studio.
Old 1 week ago
  #3
Here for the gear
 

Thanks for that.

Unfortunately I only have this 81, which I purchased used a few years back.

Last night I ran an extension cord down from the room where I got a clean signal and still got the interference. Not as bad, but definitely still there. So it seems it is the mic (whether all or this one, tbd as you note).

Looks like service on it is $150 from Shure, which seems a lot for a $350 mic I picked up for $225. I was looking at trying to pick up a Neumann 184, but after some reading will start first with a like audio cm4.
Old 1 week ago
  #4
Lives for gear
Quote:
Originally Posted by mje13 View Post
Thanks for that.

Unfortunately I only have this 81, which I purchased used a few years back.

Last night I ran an extension cord down from the room where I got a clean signal and still got the interference. Not as bad, but definitely still there. So it seems it is the mic (whether all or this one, tbd as you note).

Looks like service on it is $150 from Shure, which seems a lot for a $350 mic I picked up for $225. I was looking at trying to pick up a Neumann 184, but after some reading will start first with a like audio cm4.
$150 to make the 81 meet factory specs might be a better investment than a new mic.
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