high frequency intermittent noise

james1969 OP
246 posts 11-13-2017 12:15pm

@jea48 Funny you should mention socket outlets, I just changed my socket outlet from a generic to a Furutech outlet (audiophile brand). When I opened up the original socket, there were only 2 connections made with no ground. That is how I know there is no ground. I looked in the socket for a ground wire and did not find one, so when I swapped out the outlets, I simply mirrored the previous installation - no ground wire to connect.

Just because there was not a ground wire in the box that does not mean the equipment ground is not present. If rigid conduit was used per NEC code the conduit is an acceptable grounding means. The conduit is the equipment grounding conductor. (Of course the rigid conduit must be electrically continuous from the outlet box all the way back to the electrical panel. It can be connected to other metal boxes and conduit bodies in it’s travel.)

Note. Just because NEC allows rigid conduit to be used as an equipment grounding conductor that does not mean your city electrical inspection department does. The AHJ (Authority Having Jurisdiction) has the final say.

Buy one of these.
https://www.homedepot.com/p/Power-Gear-3-Wire-Receptacle-Tester-50542/206212329?cm_mmc=Shopping%7cTH...
It will tell you if the receptacle outlet is grounded and if the Hot and neutral AC polarity is correct. It will not tell you the conductivity integrity of the equipment grounding conductor to carry ground fault current back to the electrical panel in the event of a ground fault event though. Not matter if the conduit is used as the equipment grounding conductor or a ground wire is used.

@jea48 Thank you for all your expertise.  I will pick up that receptacle tester and check it out.

@james1969

If the tester indicates the equipment ground is present then you will know it is not doing anything to help with your noise problem.

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. 

@kosst_amojan  

My interconnects are all shielded, but they could be under-shielded.  If I turn everything off in my system except for my amps, I can still hear the noise.  So in that case we would look at the speaker cables, they are shielded too.  When I turn on my pro-audio monitors plugged into the same circuit or a different circuit, they exhibit the noise too (that rules out my system).  Keep in mind, these pro-audio monitors are self powered with class AB amps built into the speaker enclosure, so it's a self contained amp/speaker.

I do not have the noise on my TV or computer.

I did think about the tubes picking up the noise because on my amps, all the tubes are out in the open?  But then I had a solid state phono preamp in my system just recently, and that picked up the noise as well, so that rules out the tube theory.