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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
james1969's avatar
james1969 OP
345 posts
 
The subway goes right under my building.
jea48
2,944 posts
 
@james1969 ,

You would need to establish a direct correlation between the subway train passing under your apartment building at the same times you are hearing the RFI noise through the speakers of your audio system. You need to start keeping a log.

I have been trying to research, over the net, noise in an audio system caused by cell towers.

From the Link toddverrone posted.
Keep phones away from audio gear

Stages are carpeted in audio gear. The farther mobile phones are away from this equipment AND (very important) their cabling, the less likely they are to interfere. Most good engineers seem to impose an effective but draconian policy on talent: absolutely no cell phones anywhere on stage or off stage. All personal electronics are to be left in the green room, no exceptions, and all those in violation, famous or not, are chastised. Engineers everywhere would be wise to adopt similar policies.


@james1969

LOL, "Do you know where your cell phone is at this very moment?" For a test turn the thing off and get it as far from your audio system as possible.

What wall is your audio system set against? Out side wall? Directly facing cell tower?
Adjoining wall with neighbor?

When it comes to GSM buzz, not just any ferrite core will do. You must use one that has the correct number of turns and is made from material optimized for attenuating high frequency GSM signal, which can be anywhere from 800 MHz to 1800 MHz.

GMS buzz?
LTE?
TDMA ?

In layman terms please!


Re: On-site Cell Tower Interference
« Reply #2 on: October 03, 2012, 10:03:56 pm »

It’s highly unlikely the cell site will induce RFI problems with any properly designed audio equipment, or any other system inside the building.

First, cellular/PCS sector antennas are highly directional. Directly below the antenna is a major null with signal levels easily being 50-70dB below on axis carrier level (based on antenna type and design) before building attenuation is considered.

Second, you can request engineering data from the cellular/PCS service provider(s) and/or tower management firm which will tell you antenna make(s) and model(s), antenna array(s) design, location(s) and ERP of each TX antenna. An outside RF consultant can assist in determining RFI potential. Logged Henry Cohen

CP Communications www.cpcomms.com
Radio Active Designs www.radioactiverf.com Tom Young
http://forums.prosoundweb.com/index.php?topic=140277.0

Send that guy an email, if possible.

@james1969

Can you see the antennas on the tower from your window? Higher? Lower?
https://www.google.com/search?source=hp&ei=mKoNWpfxCMrPmwGUyrK4Bw&q=picture+of+antennas+on+c...

Here’s some EE talk.
https://electronics.stackexchange.com/questions/32830/why-does-gsm-cause-speakers-to-buzz


Jim

james1969's avatar
james1969 OP
345 posts
 
@jea48   

LOL, Yes, I know where my cell phone is.  I tried turning it off, no effect.

My system does sit against the outside wall, which is at the same level as the cell phone tower.  I do not directly face the tower, but the tower is in direct line of sight just 2 units to my right, so for line of sight purposes, it may as well be right in front of my unit.  I also have the Empire State Building in direct line of sight, and a friend of mine thinks the Empire State Building is radiating all kinds of emissions...says I need to be wearing sunscreen while listening to my system because of the Empire State Building.

I will post a photo on my system page so you can see the towers.

The problem with the towers is they are nondescript - no signs indicating ownership or contact info.  All I see on the towers are WARNING labels everywhere.
That is an outstanding post you found on ProSoundWeb.  Thank you very much with all of your attention on this thread.  You are a real asset to the community.
james1969's avatar
james1969 OP
345 posts
 
Thank you EVERYONE who has participated on this thread for that matter.  I really do appreciate your ideas and posts.
james1969's avatar
james1969 OP
345 posts
 
Something I’ve been looking at to correlate the noise to the cell tower:

https://www.amazon.com/gp/product/B007L09DLY/ref=s9u_simh_gw_i2?ie=UTF8&fpl=fresh&pd_rd_i=B007L09DLY&pd_rd_r=68bbfce7-caf8-11e7-8cdf-51a46fae6b0a&pd_rd_w=4szrl&pd_rd_wg=JjucN&pf_rd_m=ATVPDKIKX0DER&pf_rd_s=&pf_rd_r=T88X159BY8J205PDCWS2&pf_rd_t=36701&pf_rd_p=8f696f0a-3abd-4660-b9bd-1931764e0008&pf_rd_i=desktop

Here is an example of cell phone noise:

https://www.youtube.com/watch?v=s99i0H-nBw4

If I had the tool, I would be able to correlate with certainty.

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