Two Inoperable Subwoofers That Constantly Hum, Need Help

[DIGITALBATH]

Hello everyone. I've recently run into a problem I can't solve. First I'll tell you the equipment, receiver Onkyo 605, sub-Velodyne VA-1012-B, Infinity HTS-20-sub. Speakers are Paradigm Monitor 7, CC290.

While trying to get my antenna signal optimized I bumped into the rca line inputs of my Velodyne Sub, the sub immediately started buzzing. I unhooked everything and figured I'd plug in the Infinity, which was a gift, and I don't use it because it's not very good at all, but for testing sake I figured I would try it out. Same thing loud humming no music. On both subs, they will be quiet if I don't have an rca connected, but as soon as I do, they start loudly humming. The other speakers are having no issues.

So far I've tried unhooking all plugs, hdmi cables and hooking back in, tryed different subwoofer cables, tried cheater plugs, tried different outlets, the same outlet. I'm really frustrated, to the point where do I just have to buy a new sub and receiver? I'm thinking about buying a multimeter, and perhaps a sound islation transformer and the Humkiller AV-HK1, and a Panamax M4300.

One thing I wanted to add is that if I place my hands on the amp back plate, I can get the sub to almost quit humming(or 90%).

I would be grateful for any help. I don't want to have to spend $2000 to fix this problem.

 

[slipperybidness]

So, it was working fine, you bumped it, not working for either sub? Which end did you bump?

It really sounds like a cable issue to me, with the limited info that you've given us. Are you using a shielded cable?

 

[DIGITALBATH]

I'm using some older monster cables, I tried a rocketfish and an acoustic research cable, so I'm not positive.

My sub sits on a riser so I kind of knocked it off, and caught it at the same time, my hand bumping into the rca line inputs.

 

[markw]

Both subs started humming when you bumped the Velo?

Do the subs still hum when nothing is plugged in to them?

 

[DIGITALBATH]

With nothing plugged in there is no humming, as soon as you put and rca into line in, humming begins, and not a slight humming, a lou
d humming.

 

[DIGITALBATH]

Both subs started humming when you bumped the Velo?

Do the subs still hum when nothing is plugged in to them?

To be honest, in my haste to solve the problem, I think I had the sub on when I plugged it In because it made a loud thump, that being the infinity.

 

[markw]

Well, when you plug and unplug things when they are powered up they ARE gonna make nasty noises.

Try this three step method:

1) Power EVERYTHING down

2) Now do all your plugging/unplugging

3) When you're done with step 2, then turn everything back on.

You may, no, you WILL, find this prevents many, many problems.

 

[DIGITALBATH]

I've tried that, still no change.

 

[j_garcia]

Are you talking about an external antenna that you were working on? Sounds like it is not properly grounded if so. I would disconnect the antenna and CATV feed from the system and see if the problem goes away. Good chance it is a ground loop issue and possibly has nothing to do with "knocking" the connectors on the sub since it happens with both subs.

http://forums.audioholics.com/forums/beginners-audiophytes/5667-ground-loops-eliminating-system-hum-buzz.html

 

[DIGITALBATH]

I unhooked the antenna from my tivo and put the coax cables and antenna in a different room unplugged, did not change.

 

[j_garcia]

Hmmmm... that is usually the culprit. You did all the unplugging/plugging already. How about if you disconnect all the sources you have going to the receiver? CD/DVD/BD, etc... and turn on the system - basically just the speakers/sub connected to the receiver. If you get hum, then you may have a problem with the receiver itself. If no hum, then (turn off each time) connect each one until you have the hum.

 

[DIGITALBATH]

I have unplugged every single appliance in my apartment, but when plugging the subwoofer in as soon as I plug in the rca it makes the loud humming sound. This doesn't change no matter what I do.

 

[j_garcia]

Can you plug the sub into another outlet? Maybe that outlet is damaged now?

 

[PHANofPHUNK]

Alright, there are some red flags here.

FACTS
1. tried 2 subs both buzzed

2. tried 2 sub cables both buzzed

3. bumped and caught sub by the rca input. most likely bending the input causing it to contact something in the sub. therefore sending current back to receiver sub output.

another theory is by catching the sub by the input you bent the rca cable causing some separation of the wiring in the plug itself. and maybe your second and 3rd cable are bad.

 

[j_garcia]

Does your receiver have preamp outputs for any other channels? If so, try one of those. That will tell you if the sub-preout is damaged. If not, I'd be looking at that outlet or checking your house ground.

 

[panteragstk]

Yep, check the sub RCA connectors, then hunt for ground loop. Good luck. Hopefully if it is a damaged RCA, you have a second input to use.

 

[lsiberian]

You sure it's the right plug on the sub and receiver that you are using.

 

[mtrycrafts]

I have unplugged every single appliance in my apartment, but when plugging the subwoofer in as soon as I plug in the rca it makes the loud humming sound. This doesn't change no matter what I do.

It could be that the grounding side of that RCA connector on the sub itself may be open and it hums as when you put your finger on the center pin only on a connected IC cable.

 

[Adam]

It could be that the grounding side of that RCA connector on the sub itself may be open and it hums as when you put your finger on the center pin only on a connected IC cable.

Seems odd that both subs would act that way if that was the cause, though.

 

[j_garcia]

Seems odd that both subs would act that way if that was the cause, though.

He said he tried a few other cables, so I don't think the IC is the cause.