Need suggestions please! Electrical noise in my system and it's driving me crazy!

I've had similar issues more than once -  the first time - I narrowed it down to the cable tv box -  so I just don't have it hooked up anymore -  but to nail it down - I removed every component from the system one at a time - power as well as any ground or interconnect that connects any single component to the system - this at least identified the culprit component.  

The second time was a lot more complicated -  i had an annoying hum in one speaker ( ml Clx ). I switched my mono blocks from left to right - hum stayed with the speaker -  i switched boards from one speaker to the other - stayed with the speaker -  removed all Inputs from the amps - still had the hum - now I was convinced that I needed to buy a new panel - and was going to swap the hf panel from left to right to see if it moved with the panel - or stayed with the speaker - I had just bought a new rack - so was plannning on tearing it all down and rebuilding the layout -  getting rid of any redundant wiring connections -  example - having one source hooked up to two different dacs -  or to the same Dac in different ways - USB as well as spdif etc. so I go rid of a lot of redundant cabling -  I took each component into my workshop - took the covers off - blew everything off with an air compressor -  then spent time cleaning every connection on the outside of the chassis with deoxit and pipe cleaners - then again using the gold version of deoxit - do this on all your IC's and power cords as well 
 
Put it all back together -  and the hum was completely gone -

im just suggesting that although it's a lot of work - cleaning the connections is necessary maintenance at some point anyways - and by doing this - you can pull out - and put back in - each component one at a time to nail down the culprit ( if it happens to be a single component -  and benefit from knowing every component now has no oxidation issue that might be contributing -  and when putting it back together 
 

I also recently eliminated a hum by disconnecting my CATV from my system. After 
re-grounding it, removing the ground and trying power conditioners, I could not eliminate it until I unhooked the coax from the system. 

N

nutty
1,212 posts 09-03-2017 1:29pm

I also recently eliminated a hum by disconnecting my CATV from my system. After
re-grounding it, removing the ground and trying power conditioners, I could not eliminate it until I unhooked the coax from the system.

By re-grounding it I assume you are referring to the CATV coax cable grounding block. Please explain in detail how you re-grounded it.

Sometimes even though the grounding block is well grounded to the main grounding system of the electrical service a difference of potential, voltage, may still exist between the shield of the coax cable and the wall receptacle outlet safety equipment ground where the audio/video equipment is located, and plugged into.

"Well grounded"? The least resistive path, best conductivity path, possible?
The connection made at the grounding block must clean and tight. Both the wire and the inside of the lug of the grounding block must clean and free of any corrosion. Corrosion can add series resistance. The best place for the other end of the ground wire to be connected is as close as possible to the electrical service main disconnecting means equipment. Sometimes that may be on the outside of the house or on the inside the house, on an outside wall. NEC code requires that the ground rod/s, for the earth connection of the electrical service, be driven outside the house in close proximity to the main service panel. So whether the main electrical service panel is outside or inside you should see a bare copper, #6awg minimum (maybe #4) wire that exits the metal enclose and goes down into the ground where it connects to the ground rod/s. Connect the ground wire from the CATV grounding block to this bare ground wire where ever it is convenient above earth grade. At least a foot or so if possible. To make the connection to the bare ground wire use what is called a split bolt.
Example: http://www.elecdirect.com/split-bolts-grounding-products/split-bolt-connectors/copper-alloy-2-conduc...
This one has a max conductor size for #6 copper. If your bare ground wire is #4 go to the size for #4 copper.
Note: Clean the bare copper wire with sand paper first to a new shiny copper color.

You’re not done yet.... Every "F" connector from the CATV grounding block to the one that finally screws on the CATV cable box must be free of corrosion and tightened wrench tight. (Snug) Everyone of them. Again, to eliminate any series resistance in the coax cable shield conductor from one end to the other.

After all that you still experience ground loop hum.

That can be due to the continuity, conductivity, integrity, of the in wall receptacle outlet branch circuit wiring safety equipment grounding conductor, wire.
If the branch circuit is a standard 15 amp convenience outlet branch circuit every outlet box the branch circuits passes through the wires were cut and then connected together again in "some fashion" to feed the next outlet. Every equipment grounding wire connection could be adding just a little series resistance to the equipment grounding conductor. Not a problem if the wall receptacle outlet for your audio/video system is closest to the feed end, but if it’s closer to the end of the run that could be a problem.

The only way to find out for sure is to open up every single outlet box and inspect the wiring connections. Not only receptacle outlet boxes but there may be ceiling lights on the same branch circuit.

Or you could buy one of these,
http://www.jensen-transformers.com/product/vrd-1ff/

Jim

+1 on the drop isolator recommended by @jea48

I don’t have the Jensen, but I do have an Extreme. When I traced a hum to my cable line, the cable company (Cablevision, Long Island) installed an Extreme drop isolator http://www.extreme-broadband.com/hardware.html and the hum was completely gone.

Edit: My cable company provided the part and installed it free. Also, I was told there is no degradation of the picture/sound quality, nor did I detect any degradation. I think this is one of those "can't hurt and can only help" kind of parts.