Help me eliminate my sub hum

[darien87]

Hey all,

I did a search and didn't find the information I was looking for.

I bought an Earthquake MKIV-10 to augment the bass in my home theater system. It sounds great, but I'm getting what seems like a ground loop hum that I CANNOT get rid of. It's not loud, but it's just audible enough to annoy the hell out of me. Earthquake tells me that my Denon 2805 receiver is notorious for causing ground problems.

I'm almost positive that the hum is ground related, because I took the sub upstairs and plugged it in, and the hum almost completely goes away. Here's what I've tried so far:
1. ground isolator plug - Didn't help
2. Ran ground wires from the back of all my components to the back of the Denon - Helped a little.
3. Hooked the sub up using high level connections - Didn't help

Now Earthquake is telling me to try buying a noise eliminator from Radio Shack. Guess I'll try that one next. Anyone else have any ideas?

 

[A/VUSMCSGT]

Maybe something from this article will help you.

http://www.axiomaudio.com/tips_eliminate_hum.html

 

[mtrycrafts]

Hey all,

I did a search and didn't find the information I was looking for.

I bought an Earthquake MKIV-10 to augment the bass in my home theater system. It sounds great, but I'm getting what seems like a ground loop hum that I CANNOT get rid of. It's not loud, but it's just audible enough to annoy the hell out of me. Earthquake tells me that my Denon 2805 receiver is notorious for causing ground problems.

I'm almost positive that the hum is ground related, because I took the sub upstairs and plugged it in, and the hum almost completely goes away. Here's what I've tried so far:
1. ground isolator plug - Didn't help
2. Ran ground wires from the back of all my components to the back of the Denon - Helped a little.
3. Hooked the sub up using high level connections - Didn't help

Now Earthquake is telling me to try buying a noise eliminator from Radio Shack. Guess I'll try that one next. Anyone else have any ideas?

I don't see any mention of cable TV. Is it somehow connected through the receiver? The sub would have been removed from that upstairs if you just tried it out there on its own.
Is the hum there when you just power the sub and remove all connections to it with RCA connections?

 

[dirtraven]

AC Outlet

Is your Sub AC cord plugged into the same outlet as the receiver? If not try that, most of the time it will fix the GL problem.

 

[3db]

bingo

Is your Sub AC cord plugged into the same outlet as the receiver? If not try that, most of the time it will fix the GL problem.

I had the same problem with subwooofer hum until I plugged all components into the same plug using a power bar. Mytrs also raises a good point about the cable TV. Does the hum go away when disconnecting the cable?

 

[darien87]

OK. Lemme answer your questions.

1. Cable has audio only going to the Denon 2805 via fiber optic cable.

2. Hum does not go away when I unplug the cable box.

3. Yes, I do get the hum with NO connections made to the sub.

4. No, my sub isn't hooked up to the same outlet as the receiver. It's on the other side of the room.

I just bought a Monster HT800 power center today. It didn't fix the hum, but the sub still isn't plugged into the same outlet. Maybe I'll try that next.

 

[dirtraven]

hum

OK. Lemme answer your questions.

2. Hum does not go away when I unplug the cable box.

Unplugging the power to the cable box is not gonna do anything cause their is still power coming in from the Coax itself.

4. No, my sub isn't hooked up to the same outlet as the receiver. It's on the other side of the room.

I had the same setup

I just bought a Monster HT800 power center today. It didn't fix the hum, but the sub still isn't plugged into the same outlet. Maybe I'll try that next.

The PowerCenter isn't gonna fix the hum problem since the sub is not plugged into the Powercenter (i've tried that also), just as a test just run an extention cord from the sub to the Monster (Amp Outlet)

Curious though that you tried a cheater plug and that didn't work, I used a cheater and it got rid of my hum, but not really a safe alternative even though I used it for like 3 years. But I've since replaced my sub and the one I have now is a 2 prong AC plug.

 

[darien87]

The PowerCenter isn't gonna fix the hum problem since the sub is not plugged into the Powercenter (i've tried that also), just as a test just run an extention cord from the sub to the Monster (Amp Outlet)

Curious though that you tried a cheater plug and that didn't work, I used a cheater and it got rid of my hum, but not really a safe alternative even though I used it for like 3 years. But I've since replaced my sub and the one I have now is a 2 prong AC plug.

I tried running an extension cord to the Monster Power Center and that didn't help.

Dirtraven - Sorry I wasn't more clear. When I said I unplugged the cable box, I meant I disconnected the coaxial cable.

However, I think I have one more thing to try. When I grounded the components to the back of the receiver, I think it might not be getting a good ground because it's painted black. I'll try switching the ground to the bottom of the chassis. I'm pretty sure that's bare metal. We'll see.

 

[mtrycrafts]

I tried running an extension cord to the Monster Power Center and that didn't help.

Dirtraven - Sorry I wasn't more clear. When I said I unplugged the cable box, I meant I disconnected the coaxial cable.

However, I think I have one more thing to try. When I grounded the components to the back of the receiver, I think it might not be getting a good ground because it's painted black. I'll try switching the ground to the bottom of the chassis. I'm pretty sure that's bare metal. We'll see.

If your sub is humming audibly when nothing is plugged into it, just its amp, no interconnect cable. that is interesting. That would indicate something in that plug or most likely the sub. But, the sub worked much better upstairs.
Have you called Earthquake back with the news that the sub still hums when nothing is connected to it?

 

[darien87]

Thanks for the advice guys, but I seem to have finally figured out the problem. I called Denon today and they told me there is a ground screw on the back of the unit to use. I switched my grounds to that screw and now the hum is almost completely gone! Thank God. That damn hum was driving me nuts!!! For the hell of it, I tried plugging the sub back into it's original wall socket, and the hum came back. So I guess I need to leave it plugged into the Monster power strip.

Thanks again.