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high frequency intermittent noise

I have a noise issue that is intermittent.  Here is what the noise sounds like:

https://clyp.it/4b233bmm

Here is what I know so far:
  • The sound affects all components and is compounded if all components are turned on.  I have turned off my preamp, phono preamp, leaving just my mono blocks on, and the noise still appears.
  • I have turned off everything and unplugged everything in the house including my dimmer switch, and the noise still appears.
  • I have a pair of pro-audio monitors, self powered with class AB amps, and when I plug those into the same outlet, I hear the same noise coming through the pro-audio monitor.  So this rules out my big system.
  • The noise is primarily during the day and goes into the evenings, weekends too, early mornings it does not appear.
  • I live in a pre-war mid-rise building.  I have no ground, I'm using a Nordost QKore grounding system.  This did reduce the noise floor quite a bit, but has no affect on this intermittent noise.
  • I have a cell phone tower directly across the street from my building in Manhattan.
  • Looking at a real time analyzer, I see peak at 2kHz when the noise appears.
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james1969 OP
347 posts
 
@fusian  

I am not using a computer as my source.

I tried the ferrites and they had no affect on the noise.

I got a set of Sony WH-1000XM2 Bluetooth headphones and I can hear the noise very faintly in my headphones in my apartment.  So now this verifies that the noise is air borne and not from my power mains.

Thank you all who participated in this thread. 
toddverrone's avatar
toddverrone
840 posts
 
Man, that sucks. Time to move!
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james1969 OP
347 posts
 
Thanks...unfortunately a move is not in my playbook at this time.  The noise is not very noticeable once music is playing.  Only when there is no music playing then it becomes noticeable.  So, it's tolerable for now.
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toddverrone
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Hey, that's impressive use of perspective. Plenty of members on here are so OCD, they'd be miserable and only able to hear the noise.

I was that way with transformer hum, until I decided not to care
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james1969 OP
347 posts
 
It's all about the music...once the needle drops...I'm very happy.

I was on a quest to solve the noise (which I have lived with for some time) and in the process, I resolved a ground loop issue, and inserted an isolation transformer which really did solve a lot of noise from my power mains.  So the system sound has been elevated, just not 100% dead quiet like I would prefer when sitting right up next to the speaker listening for noise.

Time to move on to the next weak link...👍🏻
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