Too many options to go into here. Do a site search on "ground loop" and "hum". Many threads and loads of good ideas/solutions. BTW, my suggestion is to float the ground (using a 2 prong plug converter) as a last resort.
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There are several Isolation Transformers to do this, ranging in price from $4 to $50 depending on the company. I am unaware of the actual video quality differences, as I ran into the same issue and my local HIFI dealer sold me the $50.00 device. Nearly any mid - hifi dealer should stock these devices as the problem is common...
Here is some info:
- Mondial has a device called MAGIC. Mondial Antena Ground Isolation Circuit.
- Sonance RFGI1 is another device. Sonance has a web site.
Hope this helps..
Please refer to my archived threads on this subject; there are two easy solutions both of which have been appplied successfully by members here.
Many thanks to Bob_bundus.
I researched the Forum and found a solution which works for me. I grounded the incoming CATV line to an isolated ground near the house ground. It was poorly grounded to the outside electrical box cover, which introduced paint into the ground path, and and this connection was further degraded because the ground path now includes the mounting screws of the box, more paint. I then floated all the system AC grounds to allow the interconnects to carry the ground... no ground loops, no hum, no 'hardness' in the sound and picture. (Grounding the amp in this configuration causes a definite hum). Using the MAGIC, I lost some of the baseband and premium channels. Note, there is a very small resistance between the house ground and the isolated ground, and this this is simply the soil resistance between the 2 grounds... verified by poking the voltmeter probes into the soil near the 2 grounds. However, there is no voltage difference. The code says to ground the CATV to the house ground at the point of entry, and if I could get direct access to the house grounding rod, I would prefer to use it instead.
Sorry to jump in. I have a question for Bob_bundus and Fpeel. I have experienced "ground Loop" and I think I have tamed it by MAGIC and/or chater plug (MAGIC lost some channel resection and did not completely got rid of the constant baxx). This means that the system is now very quiet at volume zero. However, I still have another buzz which emerges and increases with the volume-up. At maximum volume with no source, the buzz (definitely NOT humm or hiss) is audible from about 2 feet away. Was the buzz some of you have solved this sort? And, Bob, would using "Grounding Block" and connecting Cable TV's ground to AC outlet ground solve this? My system is tube power (70 wpc) and passive pre drivnig 87 db sensitivity speakers, using very shielded IC between power and pre. The buzz is the same level from both channels. It exists even with no source connected. The manufacturer (CJ) claims that "the noise which varies with volume is not amp problem. If it's not audible at normal situation, that should not be a problem." I half agree. But it still concerns me.
Thank you for your help. Ken