Axiom Home Page Forums General Discussion Technical Questions EP500 Magnetic Interference

Thanks again for the help. Unfortunately, looks like you're on the mark real80sman. The line bending will hopefully turn out to be an issue for fix via the tv's service menu. Sadly, the issue with the video distortion is turning out to be problematic. Based upon your feedback, I tried video switching for the first time, and the distortion was severe, again when the sub kicked in. I tried switching my sub cable, but the distortion is caused using either balanced or coaxial connections, and also occurs when I switch the connection to the tv between composite and component. Have contacted Outlaw to see how to proceed, as it does seem that therein lies the issue, rather than with the EP500.

Hi. My EP500 is right next to my Sony 32XBR CRT, approximately 1.5 ft to the lower righthand corner. I have never noticed any interference.

Thanks for the feedback maphiker. Yes, it appears that I was confusing two separate problems I'm experiencing in my system. The line bending appears to be a calibration issue with the tv itself - whether or not something is causing drift over time is unclear, but I'm now confident that the sub has been far enough away to not be the root cause. I had assumed that it might be as I have also experienced noticeable distortion of the video picture on my crt when the sub kicks in, and having ruled out cable issues, it appears to be a problem with my outlaw pre/pro.

Hi,

Real80sman is correct. It would be impossible for the EP500 at that distance to cause magnetic interference to a CRT set, because the inverse square ratio law applies. All this means is that when you start moving a source of magnetic interference away from the CRT set, the magnetic field dissipates extremely rapidly.

In all my experience with large unshielded floorstanding speakers and subwoofers close to a CRT, a separation of 2 to 3 feet from the speaker or subwoofer and the CRT set completely removes the interference.

I also have a gut feeling that there may be a ground-loop issue operating between the Outlaw, the Sony CRT, your cable-TV input and the subwoofer.

Have you tried using a ground-isolation transformer between the cable input and your set-top box? Try disconnecting your cable-TV input from the box and see if the issue with the subwoofer disappears. . .

Regards,

Thanks for the suggestion Alan. Will try that after work today. Would this still explain the distortion seen with other inputs, such as my dvd?

Yes, because if there is a low-level ground-loop issue, it will operate between any interconnected components, whether or not they are powered on or off. The "ground loop" voltage differential is conducted through the shield connection of the incoming RF cable from the cable-TV supplier, the outer shield of any RCA cables, the chassis grounds of the TV, the AV receiver, DVD player, subwoofer, etc. and your ground connection of the house wiring, to which every component is also connected through their AC power cords.

Ground loops are frustrating and difficult to track down and are pervasive in their effects on audio and video performance. But all such grounding issues can be resolved with persistence and/or isolation transformers.

Thanks Alan. Looking forward to checking it out after work today.

Alan, you're the Man! Unplugging all the cable tv connections and power didn't solve the issue, but plugging the sub into the same surge protector as the tv and other a/v components did. The sub was originally on the same circuit but a different outlet and surge protector. So the question now, given the sub's power cord length, is whether there is a method of isolating this voltage differential so that I can again move the sub further away if better frequency response dictates. I'm not familiar with the isolation transformer electronics - is there a type that can be put in the path of either the coax or balanced cable that might do the trick?

Mark, there're isolation transformers that'll do the job, but the simpler solution would appear to be extending the sub power cord(the EP500 cord is impressively thick, but it's unnecessary for the extension to match it; common cords have more than enough capacity).

Awesome, I didn't realize that was an acceptable solution. Thanks so much for everybody's help - was so glad to solve the issue I cranked the Cream DVD to insane levels and it was great to watch and hear at the same time. Aloha.