2. tech-talk
  3. 132315-8612

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
james1969's avatar
james1969 OP
345 posts
 
No, my phone has no affect.  I wonder if it's because I'm on Verizon, and the offending tower may be a GSM tower?
james1969's avatar
james1969 OP
345 posts
 
I have asked if stopping resistors are used, waiting to hear back.
james1969's avatar
james1969 OP
345 posts
 
I thought it was my interconnects.  I turned off everything except my amps, then I disconnected the interconnects, the noise disappears for a while...but reappeared.  Maybe my speaker cables are suspect too...
kosst_amojan
2,095 posts
 
As sure as I am that it's cell phone noise, I'm almost certain it's not that tower. That tower is serving dozens or hundreds of clients at any one time. If it was the tower it would be practically constant. Something in the building is the source, and it's close. Last night I played around. I got my phone steaming videos last night and put it INSIDE my F5 right up against the left amp board. I could barely hear it. It was strongest when I placed the phone on top of the toroidal and right next to the power cord. Even then I had to be inches from the speaker. 
jea48
2,944 posts
 
james1969 OP286 posts11-16-2017 1:35pmI thought it was my interconnects.  I turned off everything except my amps, then I disconnected the interconnects, the noise disappears for a while...but reappeared.  Maybe my speaker cables are suspect too...

You need the RCA shorting plugs for the amps inputs.


More to discover