Low level HUM, driving me CRAZY!

QuadraphonicQuad

Help Support QuadraphonicQuad:

LuvMyQuad

2K Club - QQ Super Nova
QQ Supporter
Joined
Aug 12, 2010
Messages
4,401
Location
Western NY
Another Success: My interference between PC and Sub. This was a different issue than the Hum in speakers, that was solved by RCA cables.
Took 3 cheater plugs and added as below.
1. Power cord sub to wall.
2. PC to Fuhrman supply.
3. Ethernet switch to Fuhrman supply.
No Noise coming out of sub.
Now disconnect cheater plugs one at a time.
1. Power cord back in wall, no cheater. No Noise.
2. PC back in Fuhrman, no cheater. Noise.
3. Ethernet switch back in Fuhrman, no cheater, PC back in Fuhrman with cheater. No Noise.

Well, that is the answer, PC has a ground something it does not like with Sub being in same something?
Now, I have used cheater plugs my whole life being in construction, never a problem.
So unless someone has something overwhelmingly positive to remove this one cheater plug on PC or some other new fangled device, (maybe I will try my Hum X that failed everywhere else), I will just leave it be and go on so I can forget this months of madness.
I hope you found it. It only affected the sub and not the woofers on the mains eh?
 

4-earredwonder

2K Club - QQ Super Nova
QQ Supporter
Joined
Jan 9, 2013
Messages
20,768
Another Success: My interference between PC and Sub. This was a different issue than the Hum in speakers, that was solved by RCA cables.
Took 3 cheater plugs and added as below.
1. Power cord sub to wall.
2. PC to Fuhrman supply.
3. Ethernet switch to Fuhrman supply.
No Noise coming out of sub.
Now disconnect cheater plugs one at a time.
1. Power cord back in wall, no cheater. No Noise.
2. PC back in Fuhrman, no cheater. Noise.
3. Ethernet switch back in Fuhrman, no cheater, PC back in Fuhrman with cheater. No Noise.

Well, that is the answer, PC has a ground something it does not like with Sub being in same something?
Now, I have used cheater plugs my whole life being in construction, never a problem.
So unless someone has something overwhelmingly positive to remove this one cheater plug on PC or some other new fangled device, (maybe I will try my Hum X that failed everywhere else), I will just leave it be and go on so I can forget this months of madness.

I'm assuming, Markie, that your electrician installed DEDICATED plugs throughout for your system.....that no other extraneous electrical devices are causing interference?
 

gene_stl

900 Club - QQ All-Star
QQ Supporter
Joined
Nov 3, 2019
Messages
937
Location
St.Louis

Absolutely amazing you can buy these things from WalMart. No one mentioned them yet that I noticed. They may not help but won't hurt and may reduce the level if its interference pick up.

The post about transformer or capacitive ground loop breakers is probably what and where you will find the solution to your problem but I would not want any of these in my signal path permanently. Use them as a diagnostic tool.

This one is even called "Mpow"

Did you have any luck grounding chasis together with a strand of wire?


Oh problem solved. Someone mentioned keys. You always find them the last place you look.;):cool:
 

audiomaster

Active Member
Joined
Jul 14, 2019
Messages
79
Location
SC
Another Success: My interference between PC and Sub. This was a different issue than the Hum in speakers, that was solved by RCA cables.
Took 3 cheater plugs and added as below.
1. Power cord sub to wall.
2. PC to Fuhrman supply.
3. Ethernet switch to Fuhrman supply.
No Noise coming out of sub.
Now disconnect cheater plugs one at a time.
1. Power cord back in wall, no cheater. No Noise.
2. PC back in Fuhrman, no cheater. Noise.
3. Ethernet switch back in Fuhrman, no cheater, PC back in Fuhrman with cheater. No Noise.

Well, that is the answer, PC has a ground something it does not like with Sub being in same something?
Now, I have used cheater plugs my whole life being in construction, never a problem.
So unless someone has something overwhelmingly positive to remove this one cheater plug on PC or some other new fangled device, (maybe I will try my Hum X that failed everywhere else), I will just leave it be and go on so I can forget this months of madness.
Most devices that use a "wall wart" type power supply (two prong plug) have no ground to "earth" and only a ground thru any interconnect cables to other connected devices. Sometimes adding a single conductor wire connected between chassis of these devices quiets them down also.
 

audiomaster

Active Member
Joined
Jul 14, 2019
Messages
79
Location
SC

Absolutely amazing you can buy these things from WalMart. No one mentioned them yet that I noticed. They may not help but won't hurt and may reduce the level if its interference pick up.

The post about transformer or capacitive ground loop breakers is probably what and where you will find the solution to your problem but I would not want any of these in my signal path permanently. Use them as a diagnostic tool.

This one is even called "Mpow"

Did you have any luck grounding chasis together with a strand of wire?


Oh problem solved. Someone mentioned keys. You always find them the last place you look.;):cool:
Ferrite cores usually work at radio (RF) frequencies to filter it out of wiring. So the wire doesn't act like an antenna. Unless near a transmitter (or maybe cell phone) I wouldn't expect it to help with audio range noise.
 

gene_stl

900 Club - QQ All-Star
QQ Supporter
Joined
Nov 3, 2019
Messages
937
Location
St.Louis
The spikes from 60 Hz modulated hash can be the source of noise. I don't think it would be a high probability but he has been thrashing this problem for a long time and I would try everything. As I said "they may not help but won't hurt". They are inexpensive and when I discard cabling that has them they always go into my junk box.
no-mqa.jpg.jpg
 

marpow

2K Club - QQ Super Nova
QQ Supporter
Joined
Jul 9, 2015
Messages
5,735
Location
San Mateo CA

Absolutely amazing you can buy these things from WalMart. No one mentioned them yet that I noticed. They may not help but won't hurt and may reduce the level if its interference pick up. I tried those a couple months ago, but a multi pack and put them everywhere including one at each end of my pre/pro power cable, did nothing anywhere at any combination.

The post about transformer or capacitive ground loop breakers is probably what and where you will find the solution to your problem but I would not want any of these in my signal path permanently. Use them as a diagnostic tool.

This one is even called "Mpow"
I see it but, where and how would it connect to?

Did you have any luck grounding chasis together with a strand of wire? Never tried, yet.


Oh problem solved. Someone mentioned keys. You always find them the last place you look.;):cool:
 

gene_stl

900 Club - QQ All-Star
QQ Supporter
Joined
Nov 3, 2019
Messages
937
Location
St.Louis
I would be willing to bet that if you drill down into the instruction manuals of your amplifiers and your pre processors you are likely to find that they are using two different conventions for the wiring diagram of the XLRs three conductors.

A funny thing about "lifting the ground conductor at one end only" is it is exactly the opposite of grounding chasis s to together with a ground cable (which has solved problems for me in the past several times). The fact that switching to RCA solves the problem makes me think that the grounding schematics may be the problem. The + and - conductors and ground need to be mapped to the same numbers on both ends.

XLR is generally better than RCA but in most listening rooms with cable runs of twenty feet or less the difference won't be much, probably not audible.
 

marpow

2K Club - QQ Super Nova
QQ Supporter
Joined
Jul 9, 2015
Messages
5,735
Location
San Mateo CA
Thanks everyone for your help. I have learned a lot and going to close this chapter. Still some things for me to investigate as to why RCA cables where the fix, but my problem has been solved.
I did swap out the cheater plug at PC and replaced with a HumX plug, a little safer I guess, plus it was just laying around doing nothing.
As I close this chapter, at least fo me, I have to laugh, the first bit of music I pick this morning is from the Joni Mitchell Archives Disc 4, Home Demo, oh my, listening to a 1960 something home mono recorder with tape hiss, you just can't win sometimes.
:LOL: :cry:
 

~dave~~wave~

1K Club - QQ Shooting Star
QQ Supporter
Joined
Jun 7, 2016
Messages
1,627
Location
Lincoln, NE USA
.. If you have a meter, see if pin one is connected at both ends....
I don't have a meter, but very interesting.
$12 at Lowes. Use ohms scale for continuity of cable. I don't know what I would do without mine.

Stuff like this makes me feel old.

I couldn't function without a meter, as basic and necessary as a philips screwdriver for me since I started my own toolbox after high school.

Is it like someone owning a nice bicycle and no tire pressure gauge? 🚴‍♂️ ;)
Not a great example, except they're not expensive or difficult to learn on a basic go / no-go level.

More like a tach and dwell meter for tuning the distributor on a car?
Used to be necessary and common, now an antique curiosity for elderly hobbyists? 🏎 👴

So what's the world coming to?
If there's no app for it on a smartphone, what use could it possibly be? 📱:ROFLMAO:
 

MidiMagic

1K Club - QQ Shooting Star
Joined
Jul 5, 2010
Messages
1,531
I got those ferrites from Walmart.

They remove FM radio interference from LED lamps when on the lamp cords near the bulbs.
 

THX1136

Well-known Member
Joined
Oct 9, 2011
Messages
127
Location
Iowa
Just to clarify the ground shield connection has nothing to do with whether or not a cable is unbalanced vs balanced. The balance refer to the two signal wires in opposite polarity. This allows for common mode rejection (CMR). The shield is for RFI.
Thanks for the clarification. I mis-spoke in my comment and my statement was not accurate. That's why I posted the links out to 2 other sources that explained things better than I. I was reacting to the implication that all studios/professional spaces lifted pin 1 on all cables regardless of whether there were noise/grounding issues present. It is only applies if one is dealing with noise/grounding issues. I failed to keep in mind the context of the discussion and reacted from a (my) false premise. My apologies to all.
 
Top