How can I isolate humming from sub?

[czynot]

I just notice a very low humming noise coming from the sub at night time when it is very quiet. It seems like the cause of the humming is from the power outlet. Hum is still there when the sub and amp is off. All device is connected to the same outlet. Anyone know how can I get rid of this noise?

 

[djreef]

Ground loop hum. Is it a 3 prong (grounded) plug?

DJ

 

[Adam]

Question - are you saying that you hear the hum when the amps are completely off, or when they are in standby? I have an amp that hums in standby because the transformers inside the amp vibrate.

If you had a hum when things were on, then a ground loop would have been my first guess, but you say it happens when everything is off.

 

[timoteo]

I have the same issue with my Martin Logan Grotto sub as czynot does. When all is off even the sub itself (not on standby) i noticed a light buzz or humm. Took my sub to a ML dealer, tested, all is good.

Then one night i noticed that the humm went away when a had my floor lamp off. Then the humm came back when i turned it on. The weired thing is that the lamp has 2 brightness settings, dim & bright. The humm is there when its on dim but the humm goes away when either bright or off.

So its most likely an issue with your outlet or another object plugged into the same outlet. Czynot...try plugging your sub into another outlet or even another room...worst case, a friends house. If the problem is still there then you may have another problem.

Let us know how it goes & if you dial in the prob!
Hope all goes good for you!!

 

[czynot]

The sub is not plug into the amp. but the system is all plug into the same outlet. This outlet do not have ground. Maybe that is why?
Humming is there no matter amp is standby or unplug. I think it is the outlet because it does not have ground to it. How can I bypass this. there is no metal pipe around the area to add ground to the outlet. other outlet are too far away.

 

[djreef]

There really isn't any real way around a true ground. You'll have to ground it to the outside somehow - that prob means going through your wall and setting a grounding post in the earth with a wire connecting it to the ground screw on your plug. Sounds like you're in an older home. If that's the case then it shouldn't b real big deal.

DJ

 

[czynot]

If it is a ground problem? easiest way to gound it is to any water pipes. My house is new but that outlet to the tv and amp have no ground. I know this outlet have no ground because i wired it. I guess i have to find a pipe to ground it to. Will post if clear the problem.

 

[j_garcia]

IMO, if the sub is not connected to a source and it hums, it isn't ground loop. It could be normal transformer noise (or the amp could be dying?) or line noise. Have you tried a different outlet? What other devices are on the same circuit? Definitely should not have any fluorsecent lighting on the same circuit.

 

[timoteo]

czynot you can change the "guts" of the outlet and put in a new three prong outlet. Im in construction and that is only a matter of 2 screws and some wire disconnecting and reconnecting. Just make sure to turn the power off at the fuse panel!!! The new outlet will cost bout $8 at home depot and you can ad a ground wire once the outlet plate is off. If this doesnt make sense to you then have a local electrician do it. It wont be expensive!

If that does not work then the electrician will give you advice and or do it for you. This problem can be solved a hand full of ways but first you do need to try other outlets to help diagnose the problem source. Its most likely the ground because that is the case with mine & i would get the humm even with the sub2reciever cable disconnected.

I hope this is helpful and hope you get it fixed!!

 

[AnthemAVM]

Ground loops drive me nuts.