Oh that ground loop hum!

[Jim R]

Can anyone give me a few clues regarding how to isolate and eliminate ground loop hum in my audio (only) system? Thanks.

 

[agarwalro]

http://www.audioholics.com/home-theater-connection/ground-loops-eliminating-system-hum-and-buzz

TL;DR: Unplug everything, except amp, on the same circuit breaker. Now plug things back one at a time (the amp and only one AV device, appliance, lamp, charger, etc.). Cycle through everything that's unplugged. One that causes the hum to return is the culprit. There may be more than one.

 

[slipperybidness]

Great advice above ^^^

If you have a cable TV as part of your system, I would start by disconnecting the coax cable only and see if the hum disappears. Cable companies are notoriously idiots when it comes to establishing a good ground in their system.

 

[highfigh]

Can anyone give me a few clues regarding how to isolate and eliminate ground loop hum in my audio (only) system? Thanks.

Do you have a subwoofer that's not near the rest of the system? Unplug that and see if it stops. If it does, it might be easier to use a wireless transmitter/receiver than rewiring and it won't mess up the sound the way some ground loop isolators do.

 

[Cos]

My guess is it isn't your amp and your pre/pro, that 90% of the time it is the Cable/Direct TV as stated above. I never had the problem with my cable TV until the past year.

It is an easy problem to fix if it is the Cable TV/Direct TV; I used the Viewsonics one and it worked perfectly.

http://www.amazon.com/Viewsonics-VSIS-EU-Cable-Ground-Isolator/dp/B0017I3K9M/ref=pd_sim_sbs_229_1?ie=UTF8&refRID=1MWGEABQMSZSBRS086C2

or if you want the pro Audio version...don't even know if there is any difference

http://www.jensen-transformers.com/product/vrd-1ff/

 

[brombo]

You need a single point ground. If you are powering components from different circuits (circuit breakers) and assuming all are grounded plugs (separate ground terminal) you can break the ground where it runs into the AC outlet and run the ground from that piece of equipment to a plug strip that the rest of your equipment is pluged into. I simply use a grounded plug with only the ground wire connected. I have equipment on three different circuits (two different 120 VAC circuits and one 220 VAC circuit for a big emotiva power amp). Doing this got rid of the hum on the speakers driven by the emotiva and hum on my sub-woofer (second 120 VAC line). All my other components are pluged into a 120 VAC power strip with grounded plugs. Note that these components contain an htpc with tuner card so a coax is plugged into the htpc. Also note that the htpc, emotiva upc-200 preamp, and my projector are on UPS's plugged into the power strip (the UPS's are needed since if there is even a short power glitch the htpc, preamp, and projector would not automatically restart after the glitch goes away and it also takes about 30 sec for the computer to boot up).