I feel that many might argue it is not proper to count on that ground path for safety purposes. BUT, I imagine the path over the RCA and HDMI is relatively high resistance, compared to the grounds directly back to the outlet. Clearly it does carry ground because it's creating a loop. If it is safe to lift ground on my subwoofer, or alternatively on my projector, as long as they are connected via a cable that will carry ground, i.e. I just know that elsewhere, people are adamant that I should never lift ground on a device as more than a test.
#HUM X GROUND ISOLATOR FREE#
The first did have some unrelated issues that justified a free replacement, which is why I was able to try with two.Ĭlick to expand.You're not wrong that I'm hesitant, because I'm unfamiliar with ground issues and don't consider myself experienced enough or knowledgable enough to make a fix without confirmation that it'll be fine. I have tested with two of the same model from the same brand, both brand new. NOTE: I know this is not an issue with just my receiver unit. Of these solutions, which would you suggest, and why? Include some details on the "how" if applicable. I replaced some capacitors just over 3 years ago to good results, with help from this forum actually. It wouldn't be the first time I've gone inside it. I have considered opening the sub up in the back to find a ground point internally. If I touch some speaker wire, connected on one end to the phono grounding post on the receiver, to any of those additional interconnects while the LFE is connected, I hear an ever so slight reduction of hum but it is clearly not doing anything useful to resolve the ground loop. I also can't find anything conductive on the outside of my subwoofer, other than the outer ring of the RCA interconnects. And why don't the Denon receivers I've owned have ground prongs anyway? How would I ground the receiver? The phono input has a ground post, though I am not sure if that can be used to ground the whole system, or just the phono preamp. If Klipsch doesn't think they have to ground their subs, why should it be so critical that I don't lift the ground on my other one? Especially if it is already connected to a power conditioner.īut I'd assume the best solution would be to ground the receiver. Though to play devils advocate a bit, I have a Klipsch subwoofer in another room that doesn't have a ground prong. I have also heard of people "lifting" the ground on the subwoofer, which has been firmly discouraged for safety issues. I also feel that isn't a true solution to the problem, but a bandaid to treat the symptom.
Now, what would be the best way to resolve this? I have heard of ground loop isolators I could put inline between the sub and receiver, but I've heard they reduce quality and that is one more thing to buy. If I plug the subwoofer into an outlet on another circuit, the hum is reduced moderately, but still there. If I plug the subwoofer into a different outlet, there is no change. When the projector is turned off, the hum stops. I have tried 3 HDMI cables and 2 RCA cables, all of which have carried the hum but interestingly one longer thinner hdmi cable seemed to attenuate it a bit. If the HDMI or RCA are unplugged, the hum in the subwoofer goes away.
ONLY ONCE THE PROJECTOR IS TURNED ON, the hum starts in the subwoofer. All components are plugged into the same Furman power conditioner. The loop is between an ultra short throw projector (grounded), a Denon AV receiver (UNgrounded, connected via hdmi), and a Subwoofer (grounded, connected via shielded RCA cable). I just set up a new home theater and ran into what I believe is a ground loop which I can hear in my subwoofer.
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