Can anyone identify this grounding hum problem?
July 15, 2010 8:19 AM Subscribe
I'm having (sort of) intermittent grounding-hum type problems with a set of powered speakers and need some advice.
I've searched everywhere but can't find information pertaining to this precise set of symptoms, and am hoping that there's an easy fix.
I've got a set of Harman/Kardon powered speakers which take their source from a subwoofer which for the last few weeks have started buzzing/humming as if getting a grounding problem.
The thing is, if I switch them on they're fine for anything up to an hour before the hum starts up again. Sometimes on the other hand they manage about 5 minutes. I can't find any real source of info for grounding hums that aren't constant.
I've tried switching out the fuse, using a different set of sockets, changing the plug itself (as it's using a euro to UK socket converter) and unplugging a number of other devices on the offchance they were the problem, but nothing seems to clear it up. Also I've tried both running it from another audio source or none at all, confirming that the speakers aren't just amplifying an existing source problem.
They're really good speakers used with my main setup, and I really don't want to have to try and replace them. Any ideas?
I've searched everywhere but can't find information pertaining to this precise set of symptoms, and am hoping that there's an easy fix.
I've got a set of Harman/Kardon powered speakers which take their source from a subwoofer which for the last few weeks have started buzzing/humming as if getting a grounding problem.
The thing is, if I switch them on they're fine for anything up to an hour before the hum starts up again. Sometimes on the other hand they manage about 5 minutes. I can't find any real source of info for grounding hums that aren't constant.
I've tried switching out the fuse, using a different set of sockets, changing the plug itself (as it's using a euro to UK socket converter) and unplugging a number of other devices on the offchance they were the problem, but nothing seems to clear it up. Also I've tried both running it from another audio source or none at all, confirming that the speakers aren't just amplifying an existing source problem.
They're really good speakers used with my main setup, and I really don't want to have to try and replace them. Any ideas?
Usually problems that appear as a device sits for a while are due to heat. A component sits on the board while the device is "cold", but due to warming, warps slightly and lifts from the board, breaking the circuit. Sometimes you can verify this by hitting the device -- if it is a loose component, moving it or hitting it will momentarily put it back into place, and you'll hear it.
My guess is that you have a loose solder joint internally, and it's flexing with the heat of the board warming up. If you or a friend are handy with a soldering iron, you can go in and look for cold solder joints.
posted by fake at 9:12 AM on July 15, 2010
My guess is that you have a loose solder joint internally, and it's flexing with the heat of the board warming up. If you or a friend are handy with a soldering iron, you can go in and look for cold solder joints.
posted by fake at 9:12 AM on July 15, 2010
My guess is it's a bad capacitor in a power supply somewhere.... look for the ooze.
posted by MikeWarot at 9:42 AM on July 15, 2010 [1 favorite]
posted by MikeWarot at 9:42 AM on July 15, 2010 [1 favorite]
Here is the blog of someone who fixed a hum in a pair of Harman Kardon powered speakers by replacing a bad electrolytic capacitor in the "filter"-- probably a part of the power supply, as MikeWarot suggests.
posted by jamjam at 11:47 AM on July 15, 2010
posted by jamjam at 11:47 AM on July 15, 2010
This probably isn't the answer you were hoping for, but I will put in my recommendation.
Ground lifter.
I've been dealing with these issues for ~16 years now, have multiple $$$$ power conditioners, and finally decided that short of rewiring my house i was not going to be able to fix the problem. a $0.79 ground lifter on one powered monitor eliminated the hum everywhere. If that's an option for you, I do think it's worth saving yourself the headache.
posted by Señor Pantalones at 11:15 PM on July 15, 2010
Ground lifter.
I've been dealing with these issues for ~16 years now, have multiple $$$$ power conditioners, and finally decided that short of rewiring my house i was not going to be able to fix the problem. a $0.79 ground lifter on one powered monitor eliminated the hum everywhere. If that's an option for you, I do think it's worth saving yourself the headache.
posted by Señor Pantalones at 11:15 PM on July 15, 2010
Response by poster: Thanks all. All great responses. I will take it apart soon and have a look for ooze (eek), dodgy joints and the like.
And I will definitely look into ground lifters, as it might just help me with a very faint hum I'm getting in one of my audio setups.
I'll resolve it with whatever worked in case anyone ever stumbles across this at a later date.
posted by opsin at 7:39 AM on July 21, 2010
And I will definitely look into ground lifters, as it might just help me with a very faint hum I'm getting in one of my audio setups.
I'll resolve it with whatever worked in case anyone ever stumbles across this at a later date.
posted by opsin at 7:39 AM on July 21, 2010
This thread is closed to new comments.
posted by samsara at 8:33 AM on July 15, 2010