Low level HUM, driving me CRAZY!

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marpow

2K Club - QQ Super Nova
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I am embarrassed to say I have been chasing a problem for months now and am at my wits end. I have read and watched more than you can imagine.
I have done everything. Ask me a question and I will likely respond "I've done that".
According to these two articles PSA Audio #1 and PSA Audio #2 I have a 120Hz hum/buzz typical of ground loop problems. There is an actual sound bite near top of article to verify what I am saying.

I call it low level because when I increase volume the hum does not increase.

I love my rig, it sounds and works fantastic, except for this hum, that shows up if the music takes a dip in sound or a movie gets silent for a moment, stuff like that. All 9 speakers, 1 pre/pro, 3 amps are equal in this. All I have to do is mute the source and there it is. When music or movie is playing I do not hear.

Without telling you every little thing I've tried these are a few significant things.
1. Yesterday at the expense of $400.00 I had an electrician drive a 5' copper stake in ground and grounded the specific circuit breaker panel dedicated to my room. The entire system was of course already grounded when built in 1981, with grounded rebar in the foundation, but what the heck, let's try. No help.
2. Cables, Cables, Cables, sick of changing them. Money, money, money. I have AudioQuest. I would call them there mid level priced?
3. Removed/unplugged every single item in room and adjacent room. Plug in wall outlet only Pre/Pro and 2 channel amp in another outlet. No help. Even ran an extension cord to another room, no help.
4. XLR Balanced vs RCA Unbalanced. I started with all XLR's, as an experiment I switched some of the channels to RCA's this actually helped, cut it down to only hearing a very minor noise when ear is right on speaker. This does not make sense as the XLR's are specific to noise reduction.
5. Disconnected all DirecTV input to house (Coax). No help.
6. I was absolutely convinced it was my pre/pro to the point where I ordered a new updated version, willing to pay the restocking fee if no change, my heart sunk when there was no change.
7. My 5 floor speakers, not my heights, are Bi Wired, single positive/negative at amp and Bi Wired to four terminals at speakers. I disconnected the top two, midrange/treble drivers and speaker went dead silent, connected the jumpers and came right back. Am I on to something here?
8. I have a Niagra power conditioner, no help, I have tried Fuhrman power supply's, no help.
9. I tried cheater plugs and Hum X. No help.
10. I would like to say it is cross cabling interference behind my unit at wall, but when only doing as #3 above, this again not the answer.
11. It has nothing to do, with Blu Ray, DVD, external DAC, PC, Fire Cube, DirecTV, power conditioner and Subs. Whether these are plugged in, connected, whatever, makes no difference.
12. Trigger cables, no trigger cables. No help.

#4 and #7 above are the only two items where I have noticed change whether positive or negative.


As @GOS would say, when asking these type of gear questions you really open yourself up to an ass whooping, but if that is what it takes, bring it.

I should be able to hear dead silence with nothing playing, right? My room is dead quiet, so I am susceptible to this more? Certain signal to noise ratio that I have to live with?

What am I missing?

There is an answer, I know, but what? Today I am going to pull apart, AGAIN, and go cable by cable, one at a time. I have no faith.
 
It's there for every source?
Doesn't change with the preamp volume?
Still there when muting inputs?
All 9 channels?

Are all 9 channels coming from the same amp unit? Like an AVR style unit?

If 'yes' to that last one, it has to be coming in at the power amp(s). Check the power supply for a failed diode or drying out or bursting (and thus changing value) caps.

It sounds like you have investigated ground loops and gone through permutations of looking for that. I'd verify that of course.

Do you have any other amplifier units available to A/B against?

That's where I'd start.
 
It's there for every source? YES
Doesn't change with the preamp volume? NO
Still there when muting inputs? YES
All 9 channels? YES

Are all 9 channels coming from the same amp unit? NO Like an AVR style unit? NO, 3 Amps. 4 heights coming from 1 amp, FL/FR coming from 1 amp, C& L/R Surround coming from 1 amp.

If 'yes' to that last one, it has to be coming in at the power amp(s). Check the power supply for a failed diode or drying out or bursting (and thus changing value) caps.

It sounds like you have investigated ground loops and gone through permutations of looking for that. I'd verify that of course. YES

Do you have any other amplifier units available to A/B against? NO

That's where I'd start.
Thank you.
 
wow that sounds like a tough one, I feel your pain, if it's possible can you take #4 and #7 to another persons system and see if those results occur?
 
It sounds to me like your amps are not liking something within your speakers crossovers when Bi-amping that’s feeding back to the amps and, in turn, effecting the rest of your speakers. Do you really need to Bi-wire your speakers?
Great question, and my experience is in flaw here. When I did the removal of speaker Bi Wire from top two terminals the hum was GONE.
But when I left those two speaker wires off and used the jumpers it came back.
Don't I either need to Bi Wire or use jumpers? I will gladly not do that.
But my heights are just positive/negative with good quality spool wire only. They pick up the same noise.
 
wow that sounds like a tough one, I feel your pain, if it's possible can you take #4 and #7 to another persons system and see if those results occur?
Yes, the audio sales tech suggested that, saying just take a few blocks away, to determine if it is my house power and if so, not much can be done if it is silent somewhere else. The audio stores are no help as they are in commercial buildings where there is a lot of electrical noise.
 
I still think the problem is a crossover within one or more of your loudspeakers. I would swap out some low cost budget speakers to see if that fixes your issue.
OK, I have a pair of B&W bookshelves down stairs and a pair of Definitive Towers in the garage, good idea. I know my B&W's hooked up to my NAIM streamer are dead quiet.
 
I still think the problem is a crossover within one or more of your loudspeakers. I would swap out some low cost budget speakers to see if that fixes your issue.
You really got me thinking, before I grab a bunch of speakers, maybe I have my crossovers, set WRONG in my setup menu? I am going to open up the settings and take a couple pictures for your feedback.
 
You really got me thinking, before I grab a bunch of speakers, maybe I have my crossovers, set WRONG in my setup menu? I am going to open up the settings and take a couple pictures for your feedback.
No. I’m talking about the passive crossovers inside your speakers. It’s possible that one of them could be wired incorrectly, some solder from one part to another is touching, or there could be a bad component such as a cap.
 
try some of these, I use 4 in my system. I used to have some different hum issues and now my system is completely silent after adding them.

one reason it worked for me is I have 7 dedicated power lines in my theater, multiple power conditioners to keep analog from digital and power amplifiers safe. As you can see on these ipurifiers You can use some speaker cable and plug a banana plug into them to run them all together if to get all your grounds connected.

AC iPurifier by iFi audio | Mains Audio Noise Eliminator only $99 bucks so worth a try,
 
No. I’m talking about the passive crossovers inside your speakers. It’s possible that one of them could be wired incorrectly, some solder from one part to another is touching, or there could be a bad component such as a cap.
OK, I'll still try the speakers but here are two pictures of my crossover settings which I am clueless as to why I set them there.
IMG_1140.jpg

IMG_1141.jpg
 
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