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Potentially huge issue with my setup?

post #1 of 7
Thread Starter 
Hey guys,

I posted this in the sub forum, but since you guys have helped me out so much lately, thought I would ask here as well.

So here's the deal. I have wired my home theater so that from the receiver, there's an RCA cable that plugs into the wall behind it (the gold plated connectors from PE on wall plate). Then there's a wire in the walls that runs to a corner in the room with another wall plate. There, I have my sub plug into the wall "outlet" via another RCA. Problem is, in the middle of the night, every now and then, there is a giant constant hum that eminates from the sub, i'd say give or take like 60hz and extremely loud. I have to unplug the sub or touch the sub amp to get it to stop.

Furthermore, every time I touch the connector on the RCA that's plugged into the sub, the music mutes for a second and then goes back on.

So today, I decided to fiddle around with it a bit and changed the wire so that I have only one wire directly from the receiver to the sub. Now, there's no stop in the music when I touch the end of the connector where it's plug into the sub. Instead, every time I touch the amplifier at all, I get a very miniscule zap and the music mutes for a second and then continues!

Does anyone have ANY idea what the heck is going on?

Also, strangly enough, there are certain switches in the house that when I turn them on and off, they mute the stereo for a second and then it continues.

What to do?!
post #2 of 7
Better check those grounds on the outlets and switches. You probably have a switched wire somewhere in the house, or a floating ground. That means black hooked up where white should be. or a ground wire not attached to the grounding screw or mains.
post #3 of 7
Are there electrical wires run next to your speaker wire in the wall? I don't have a lot of practical experience with speaker cables, but I can tell you about getting funky errors across long network cables or serial cables strung in the ceiling and walls. Every time you flick a light on or off the sudden electrical current causes a bad electrical field that causes a lot of distortion and can really screw up data streams. I would assume the same type of thing can apply to the speaker.

As for what HT Nut said, that also seems very probable. Just speculating here, but if the ground isn't actually grounded that may cause charge to build on the amp, and then when you touch the amp it discharges through you. Obviously a small charge, but you said it happens at night, so I would assume that would mean it has ample time for it to build a big enough charge and cause the hum. Just speculating.

post #4 of 7
Thread Starter 
Hey guys,

So I did some fiddling around and here's what I found.

As far as the system going mute for a second when switches go on and off, my CD player was plugged into the receiver. I plugged it into my monster surge component instead and that no longer happens.

As far as the sub, I unplugged the RCA from the wall and held it in my hand. With the sub plugged into the wall, I touched the tip of the RCA that was connected into the sub and it made the same LOUD humming noise.

Does that mean anything regarding the electrical? This eliminates the electrical crossing the RCA in the wall since I was holding this test one in my hand.

Oiy, maybe it's just a problem with the amp in the sub or something?!
post #5 of 7
It's expected to make that sound when you touch the cable. You can do the same thing with a guitar amp for instance (touch the cable that plugs into the guitar). I guess the outside of the RCA plug is actually part of the cable! That would explain why it would make those sounds when you touched it. Perhaps it contributes to the humming you're getting. Try swapping the RCA cables with some other ones if you happen to have any others (even cheapies).
post #6 of 7
Thread Starter 
Yeah, but the strange thing is that it's the exact same sound that comes in the middle of the night, so something tells me it has something to do with the wires and some kind of interference of some sort?

There's so many potential places for issues because when I plug in the sub into the wall, there's the wire that goes from the sub to the terminal, the terminal itself, then the internal wire that goes to the terminal behind the reciever, then that terminal and finally another wire that goes from that terminal to the reciever!

Yikes, what to do?!
post #7 of 7
Try running the cables straight from the receiver to the sub (not through the wall). If you still get the same problem run different cables. If you're still having problems after that you need to test your amp, and after that the receiver. To do that just hook up another sub to it and see what happens. If you determine that both of those are good, then you have limited it down to the subwoofer.
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AVS › AVS Forum › Audio › DIY Speakers and Subs › Potentially huge issue with my setup?