# How to eliminate ground loop hum?



## RobertR (Jan 23, 2007)

I've read threads on here about how to eliminate ground loop hum, and I traced my problem to my 12 volt trigger connection. My question is, how do I eliminate the ground loop while keeping the 12 volt trigger? Would one of the aftermarket devices such as the Radio Shack do it? The 12volt trigger uses 1/8 inch mini plugs.


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## tenzip (May 4, 2007)

The 12V trigger cable may be the conduit for the ground loop, but it's not the cause of it. By definition, the 12V (DC) signal is not hooked up directly to the outlet and electrical ground of your house wiring.

What are all the devices in your system?

And what other troubleshooting steps have you taken?


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## salvasol (Oct 31, 2006)

RobertR said:


> ... I traced my problem to my 12 volt trigger connection. My question is, how do I eliminate the ground loop while keeping the 12 volt trigger? Would one of the aftermarket devices such as the Radio Shack do it? The 12volt trigger uses 1/8 inch mini plugs.


I have never used a 12Volt trigger ... so take my advise with a grain of salt :yes:

You can try the Radio Shack ground isolator, and for the 1/8 mini plug ... just get an adapter form 1/8 to RCA's :yes:

Does the 12V trigger has audio connections??? ...:huh:


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## RobertR (Jan 23, 2007)

salvasol said:


> I have never used a 12Volt trigger ... so take my advise with a grain of salt :yes:
> 
> You can try the Radio Shack ground isolator, and for the 1/8 mini plug ... just get an adapter form 1/8 to RCA's :yes:
> 
> Does the 12V trigger has audio connections??? ...:huh:


No audio connections. The sole purpose of the 12v trigger is to switch other equipment on and off.


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## tenzip (May 4, 2007)

Unfortunately, that won't work, as there are only 2 conductors in the 12V trigger cable, so if you cut or lift one, you'll never get the signal. Pesky electrons insist on having a path to follow back home.


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## salvasol (Oct 31, 2006)

RobertR said:


> No audio connections. The sole purpose of the 12v trigger is to switch other equipment on and off.


That's what I thought :yes: (as a newbie, I wasn't sure) :bigsmile:

What is the 12V triggering??? ... like tenzip said; if you can describe what you have connected you'll get more suggestions :yes:

Have you added anything new before the hum??? ... I remember that when I added my buttkicker amp I got the famous hum, so I added the ground isolator between that amp and the receiver :yes:


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## RobertR (Jan 23, 2007)

Sounds like I'd have to use an audio connector ground loop eliminator. The 12v trigger switches my surround and bass amps.


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## RobertR (Jan 23, 2007)

tenzip said:


> The 12V trigger cable may be the conduit for the ground loop, but it's not the cause of it. By definition, the 12V (DC) signal is not hooked up directly to the outlet and electrical ground of your house wiring.
> 
> What are all the devices in your system?
> 
> And what other troubleshooting steps have you taken?


Two surround amps, subwoofer amp, front L/R amp, front active crossover, HDDVD player, satellite receiver, BFD. I've tried disconnecting sources one at a time. I can't reverse any a/c plugs. Can't think of anything else...


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## tenzip (May 4, 2007)

Is all the equipment on a single circuit, or is it spread around on 2 or more? If spread over 2+, can you connect it all to 1 circuit for testing purposes?

I assume you disconnected the satellite cable from the satellite rec'r?

Can you verify that the ground wires to the outlets running your equipment are connected correctly and securely?

Does the hum come from all speakers, or just some?

You may need an iso transformer, but don't give up yet.


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## RobertR (Jan 23, 2007)

tenzip said:


> Is all the equipment on a single circuit, or is it spread around on 2 or more? If spread over 2+, can you connect it all to 1 circuit for testing purposes?
> 
> I assume you disconnected the satellite cable from the satellite rec'r?
> 
> ...


Everything is connected to the same 2-outlet electrical box. I did disconnect the satellite cable. I just thought of a few other things I have connected that I forgot about: An X-10 controller, a Monoprice HDMI switcher, and a Buffalo IR repeater. I'll see if that makes a difference. The hum is confined to the midrange ribbons of my front L/Rs (I have a biamped system with an active crossover).


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## RobertR (Jan 23, 2007)

I made some good progress today. The hum is GONE from the right channel. Now I just need to track down the left channel source....

Edit: Looks like it's a bad left cable.


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## tenzip (May 4, 2007)

It's good you're making progress. I assume you mean the interconnects? I had a problem with my interconnects between my pre/pro and amp, caused a hiss, not a hum. I swapped them out for some better quality cables from Monoprice, problem solved. Even worse with Klipsch, as they're so efficient. I hooked up some speakers that didn't have horn mids and tweets, no hiss unless I stuck my ear right against the front of the speaker, with the Klipsch, I could hear it from the listening position.


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## RobertR (Jan 23, 2007)

> I assume you mean the interconnects?


Yes. The surprising thing is that it's an XLR cable. I'm going to get some new ones from Monoprice.


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## E-A-G-L-E-S (Sep 15, 2007)

I don't know what causes it, but this afternoon when I hooked up my freshly finished DIY sub, I haf the loudest, most aweful hum from just my sub not the speakers.
Luckily I had someone build me aRCA to XLR cable with a ground attatched.
I connected the ground to my AVR and the RCA end, then the XLR to my Behringer EP2500 amp.

No hum 'at all' anymore. So I didn't find and eliminate the cause but I completely maske dit which is good enough for me as it is the same as being gone.


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