# Humming in Sub and out of ideas



## Dale Rasco (Apr 11, 2009)

Alright everybody, I thought I had a handle on this, but apparently I was wrong. I noticed a humming in both of my subs about a week or so ago. I figured out that I had not properly grounded my rack so I did that and it went away. Sometime over the weekend, a less audible hum came back to one of the subs. I have done a couple of things to troubleshoot and am kind of stuck and need some ideas.

So far:


Replaced the sub cables between the receiver and the Behringer and between the Behringer and the sub.
Replaced the splitter on the Behringer that is servicing the two subs.
Verified that when I turn off the Behringer, the hum goes away.
Verified that when I unplug the Behringer from the receiver, the hum goes away while the sub is still plugged in.
Verified that when I turn off all of the other devices on that electrical circuit, except for the Behringer, Onkyo and sub, the hum is still there.

Any and all ideas are welcome and appreciated.


:fireworks3:*UPDATE: RESOLVED!!*:fireworks3:
Switching the X-Over from bypass to active shut it right up! Thanks for the help everybody!


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## Zeitgeist (Apr 4, 2009)

You're going to call me crazy, but do you have a cable receiver or satellite box in the mix?

I spent too much time hunting down a hum only to figure out it was due to the coax running into my cable receiver. I was getting a ground loop via the HDMI connection to the cable box. HDMI disconnected no hum, coax disconnected, no hum.


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## Dale Rasco (Apr 11, 2009)

That's crazy Jim! Sorry, couldn't resist. I have Uverse and run Cat6 to the device however; I think I'll start unplugging the HDMI as you suggested and see what happens from there. Grounding loop makes sense and removing each device HDMI sounds like a good way to isolate it. Thank you sir!


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## koyaan (Mar 2, 2010)

I've had that fustration also.
Have you tried using a "cheater plug" on the sub?
Have you tried taking the splitter out altogeather?
Good luck in finding the problem.:dontknow:


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## benbo (Jul 27, 2010)

I noticed that you are running an Onkyo receiver. I owned the Onkyo 804 and experienced hum from day one thru my sub, Velodyne. I visited various web sites and found that a common factor was the use of Direct TV ( use of HDMI connects) and the Onkyo receiver. It seemed to be a ground loop issue and people tried all types of fixes, some went as far as to break the ground to the subs. My Direct TV dish was on the opposite side of the house from the grounding rod for the rest of the house. I finally re-did the ground for the Direct TV and the hum was greatly reduced, to the point that I did not ditch my receiver. You might want to start there as it is a cheap fix if it works


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## Gregr (Nov 2, 2010)

Bummer,

This sounds like the old 60 cycle hum we would always have to deal with when setting up band equipment. Well most of the time it was a matter of getting of the fluorescent light circuit or just turning out the light. But then there is the electric motor problem..., on and on. On the guitar/organ amps there was always a reverse polarity switch on most subs today there is a reverse phase switch. Try switching phase 180 degrees if that helps or if there is not a reverse phase switch try running an extension cord from another breaker hopefully something closer to the 220v line in than the circuit you are on now. First try the receiver on the other circuit if that works you could actually change any other component but any test should probable start with the receiver/amp.

If that does not work in any way then I would suggest checking all power cords to make sure they cross one another @ 90 degree angles only and "DO NOT" run parallel to each other. Next if the cords lay on carpet or concrete floor lift them at least 8" above the floor. Or you can swap out cords for shielded power cords such as Furutech and/or Neotech..., try soniccraft.com or revolutionpower.com. You could also try a ground directly of of the sub itself. :hsd:

I hope I've actually helped and not just given you more work. But grounding is the issue.:T

Greg


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## Dale Rasco (Apr 11, 2009)

Hey Greg, you know all I have been able to think about is how my amp used to buzz at clubs back in the early 90's and didn't even think about the reverse polarity. I tried switching the phase and that didn't work however; switching the X-Over from bypass to active shut it right up. I have the crossover set to max so it shouldn't interfere with the receiver. Thanks for the brain shake, hopefully it will hold. I'll have to run some
Sweeps later to see if everything is still good, but for now it's gone.


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## Gregr (Nov 2, 2010)

Alright! Glad you got it. Sometimes you gotta try it all in order to shake something loose to give you a hint. Sounds like you've changed the circuit enough to make a real difference. 

Happy Tunes!

Greg


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## caliberconst. (Dec 10, 2009)

Hey dale I was just going to suggest that. Your problem sounds the same as mine, except I could actually hear my internal radio/tuner threw the sub. I went a and turned the radio off in my receiver's menu, but still had a hum. Finally I flipped the x over switch on the sub and viola no more buzz. Glad to hear you got it all fixed up!


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## Dale Rasco (Apr 11, 2009)

Thanks for all the input you guys. Sometimes it's hard to see the forest through the trees and y'alls ideas really helped me pull my head up and look from a different angle. Very much appreciated!


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## Gregr (Nov 2, 2010)

Ya Man..., ain't it the truth !


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