Aloha. Trying to diagnose a problem in my system that seems to be a 990 issue. Have had the unit now for ~ 2 months. First noticed the problem out of the box when using the OSD to my CRT tv, but didn't think much of it. Tonight I experimented with video switching for the first time and also experience the problem with video inputs. The specific problem is visible distortion of my tv whenever the subwoofer kicks in. My subwoofer is also new, the Axiom EP500. I've tried two different cable connections to the subwoofer, a balanced XLR (new from bluejeans) and also coaxial (but not at the same time of course). Distortion happens in either case, and also when I change the video cables between 990 and the CRT (component or composite). The distortion is similar in appearance to what happens to older tv's when a vacuum cleaner is close to the tv - frizzy white lines all over the place. Wondering if any other 990 owners have experienced similar problem, or someone might know the nature of the problem. Any help would be sincerely appreciated. I've contacted tech support, but want to make sure that I've ruled out all competing explanations...

Hmmm.. It appears with both component and composite connections from 990 to TV, it affects any video source routed through the 990, and it only occurs when the subwoofer is on. Is that a pretty accurate summary? How close are the video cables from the 990's monitor outputs to the audio cable running to the sub?

Here's an interesting test that might give us some good input. Try the following with the subwoofer, just to help trouble-shoot (and you may have already done some or all of these):
- Turn the sub off and see if you get distortion.
- Unplug the sub cable from the 990 and pull it clear from behind the equipment rack (so it isn't in proximity to the video cables) and see if you get distortion. Make sure that you are doing something that produces a subwoofer signal from the 990 (movie with active LFE track, perhaps).
- Plug the sub cable back into the 990 but unplug it from the sub and see if you get distortion.
This will help confirm whether it is the subwoofer, the subwoofer cable, or simply the subwoofer output involved in producing the distortion.

Thanks for your help Gonk. Between your suggestions and those of Alan Loft over at Axiom, I was able to detect a ground loop problem. The sub was on the same circuit as the other a/v components, but a different outlet and surge protector. Moving the power cord to the same outlet and surge protector seems to have cleared up the problem. Wondering now if there is some format of isolation transformer that will enable me to again move the sub further away should best frequency response dictate ?

Muttsinparadise, I had a similar problem recently and I purchased the following based on info on this forum. I purchased the Jensen, model VRD-1FF cable tv rf isolator. It cost $50.00 and got rid of 90% of the problem. 6th photo down - Jensen, model VRD-1FF.

Also, you might want to try brickwall below for high power audio applications such as an amp and subwoofer, model PW2RAUD, cost $235.00.

Thirdly, again excellent advice from this forum, I purchased a Belkin PureAV PF60 and it seems to be doing the trick for $169.99. Excellent price for this as it cost $300.00 on almost all other web sites.

I wish you luck as I know how annoying ground loop hum and buzz can be.

http://www.jensen-transformers.com/iso_vid.html

http://brickwall.thomasnet.com/item/audi...raud?&forward=1

http://www.ecost.com/ecost/shop/detail.asp?dpno=501009&store=ecost&source=ECOSTDEAL&srccode=cii_13736960&cpncode=07-20334864-2&adcampaign=email,ECOSTDEAL

The Jensen's a good choice for ground loop problems originating at the cable service entrance. For ground differences between outlets, however, it's not really going to help. If you need to move your sub out of reach of the main system's surge protector, you may want to consider a device like the Belkin that AARONMADLER mentioned (or a smaller-scale option, since you'll just be dealing with the sub).

Thanks guys, will look into the Belkin.