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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
 
@jea48

This noise issue has been in my system for as long as I have used my system in my current apartment. So it was there before I swapped out my receptacle outlet.  Keep in mind, this noise is just below the noise floor of my apartment, so you have to focus to hear it.  Once you recognize the noise, then it becomes apparent in listening.  I have been on a hunt to chase out all the noise in my system, and this is the last bit of noise that I am aware of.  I can record the noise like I did above with the microphone up to the speaker.  I can see the noise in the real time analyzer as a peak around 6kHz.

I have the plug-in circuit checker on order and it will arrive tomorrow. I also have another receptacle outlet on order as well, as I will be changing the outlet receptacle from a 15 amp to 20 amp outlet receptacle. This is so I can plug the Furman P-2400 IT into the wall. I will be receiving that unit tomorrow as well, so big day for my system tomorrow. There is a possibility I will have my noise issue resolved. I will report back ASAP. 👍🏻
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toddverrone
840 posts
 
It definitely sounds like cell phone interference to me as well. How it's getting into your system, though.. ?
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james1969 OP
347 posts
 
@toddverrone  

I agree, I've listened to people on YouTube playing the sound of cell towers through their test tools, and it sounds like cell tower noise to me as well.

What if the cell phone tower across the street is injecting noise into the electrical system?  Perhaps they have an installation issue?  The cell phone tower was installed about 2 years after I moved in.  But back then, I did not have high resolution system, and was not listening as critically as I am now.
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