AK has been my go-to for advice for many years, but this is the first time I've not found an answer by searching. Big Yamaha/Bose nerd, and have an large assortment of investment-grade pre-1993 odds and ends ... but the question pertains to a rarely/barely-used entertainment system in the family room.
Yamaha RX-V459 with AM10, purchased a long time ago used but months old, never a hiccup with infrequent use. A few weeks ago: disconnected the subwoofer to wax the floor; I'd like to think I disconnected the AC first. What I didn't do was disconnect the receiver from AC ... now remember from reading here that it's not "off" unless unplugged, not the case with the vintage toys. After reinstalling, after light cleaning: the dreaded subwoofer hum. Most pronounced with both powered on, somewhat diminished with receiver off, then absent with receiver unplugged; ditto with both on and LFE unplugged.
Yes, sounds like a ground loop, but why now all of a sudden? Not averse to buying a GL device, but skeptical that's the issue? They're on separate circuits, no phase errors possible, I don't think? I have systematically tried every remedy posted elsewhere on AK - TY
Yamaha RX-V459 with AM10, purchased a long time ago used but months old, never a hiccup with infrequent use. A few weeks ago: disconnected the subwoofer to wax the floor; I'd like to think I disconnected the AC first. What I didn't do was disconnect the receiver from AC ... now remember from reading here that it's not "off" unless unplugged, not the case with the vintage toys. After reinstalling, after light cleaning: the dreaded subwoofer hum. Most pronounced with both powered on, somewhat diminished with receiver off, then absent with receiver unplugged; ditto with both on and LFE unplugged.
Yes, sounds like a ground loop, but why now all of a sudden? Not averse to buying a GL device, but skeptical that's the issue? They're on separate circuits, no phase errors possible, I don't think? I have systematically tried every remedy posted elsewhere on AK - TY
