I'm experiencing something similar. I have my sub-2 output connected to bass shakers on my sofa, and the wiring picks up an incredible amount of RF on 20. As my wife found out when she was taking a nap in the room while I was contesting. As soon as I switched to 20 she was getting rumbled to the pattern of CQ TEST. That was an interesting conversation, and something I will look at this summer.
As for your low frequencies getting into your left and right main, why not switch them to "small" in the AVR menu, and let the sub do all the work below 80 Hz? I have had some luck putting ferrites just before the speaker terminals in the past. I sadly cut all my speaker cable to length so there's no room to wind around a core, so these will need to be clamp-ons for me. I get into my center and surrounds on 40 and 20. Or I can tell my XYL to nap in the living room, since there's just the two of us in the house. - pjd -----Original Message----- From: [email protected] <[email protected]> On Behalf Of Nicklas Johnson Sent: Saturday, May 23, 2020 12:38 PM To: elecraft <[email protected]> Subject: [Elecraft] ferrites for subwoofer: before or after isolation transformers? The backstory as briefly as I can make it: I wanted to place my home theater subwoofer in the corner of our living room; doing so required running two speaker wires and a coaxial cable under the house and plugging the subwoofer into a different outlet than the AV receiver; this in turn resulted in ground-loop hum (because of a tiny difference in potential between the two outlets) which I worked around with a set of 1:1 low-frequency audio isolation transformers. The subwoofer is of a type that produces a signal based not only on the LFE channel, but also on the left and right speaker channels, thus the two speaker wires along with the coaxial cable. Now the subwoofer is picking up common mode noise on 20m, which isn't terribly surprising, as this happens a good bit with consumer-grade electronics. I'm hoping to mitigate this with some substantial ferrite clamps for all three connections and as many turns as I can get through them. My hunch is that the best place in the path to clamp them on will be immediately before the connection to the speaker itself, on the speaker side of the isolation transformer, but I wanted to get the opinions of folks who have solved this problem in the past to see if there's any reason the ferrites should come before the isolation transformers. Thoughts? Nick -- *N6OL* Saying something doesn't make it true. Belief in something doesn't make it real. And if you have to lie to support a position, that position is not worth supporting. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
