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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.
james1969
Post removed 
kosst_amojan
2,095 posts
 
I'm not sure where this 700-800 MHz figure came from, but LTE bands usually operate up in the 1.7 - 2.4 GHz region. 

@atmasphere 
Nelson is good indeed. Maybe I shouldn't be surprised the F5 is resistant to that kind of interference. It's all resistors and it's designed to shrug off MHz range ringing because of it's crazy wide bandwidth. 
atmasphere's avatar
atmasphere
7,068 posts
 
It's all resistors and it's designed to shrug off MHz range ringing because of it's crazy wide bandwidth.
We had to be careful too for the same reason.
xti16
1,495 posts
 
James check out this video especially parts 1 and 4.

https://www.youtube.com/watch?time_continue=5&v=Y3RNnm8s3nQ
If you have a Raidho/Ansuz/Aavik dealer nearby and ask if you can have an in home demo. Although I don’t have any electrical problems like you I can say after adding the D-TC power cable everything became much more clear. I could also say I can play music about 2db louder. I also have the new version 2 and I can’t believe how much more ’control’ I have in the music. Not sure what you budget is but these do come with a hefty window sticker. For that reason this should be your last resort.
Good Luck
james1969's avatar
james1969 OP
345 posts
 
@xti16 

Very interesting - parts 1 and 4.  I may try to seek these power cables for audition to see if there is any affect.  Thank you for the link.
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