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.
james1969
@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.
kosst_amojan
516 posts 11-14-2017 4:03am

I’m virtually 100% certain that’s cell phone signal interference. That is exactly what an LTE signal sounds like when it’s being picked up by an unshielded/under-shielded wire in the signal path. I doubt it’s being picked up through the power lines, but I can’t be curtain. If it was, you’d hear it through your TV and computer. I’d be looking at interconnects.
When I first read the OP I though the same thing. It’s the cell tower or an antenna on the cell tower for some other type of technology company. But then I started reading what others had posted. Then I read Al’s (almarg) post and james1969 response.

Another thing that I didn’t think that fit it being the cell tower. If it is an antenna transmitting the signal why wouldn’t it be a constant repeating signal that would recycle itself 24/7? I then listened to the signal in the OP all the way through. It starts out as having a repeating cycle but about around half way through it peters out. Would that be typical of an LTE signal?
https://clyp.it/4b233bmm

For what it’s worth when james1969 brought into the conversation about the subway that runs beneath the building, he lives in, and said he thought there might be a correlation between the noise he is hearing through his audio system and the subway train passing by below I had a moment of deja va. Several years ago there was a posted message where a guy was having a similar noise problem as the OP here is having. He too had the subway running under his building. What are the odds?







Seems like I have been in similar odds before.  Just this weekend I ordered some parts for my turntable from KAB USA, another person with the identical name was ordering parts as well and our orders got combined which turned into an administration mess for Kevin at KAB.  What are the odds?
@james1969

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.
Is the branch circuit that feeds the duplex receptacle outlet a 20 amp, or is it a 15 amp? Go to the electrical panel and look at the handle on the breaker that feeds the circuit. It will say 15 or 20.