bernmart Posted April 20, 2006 Share Posted April 20, 2006 With the help and advice of many here (mostly followed; not always), I built up the following system, with which I'm well-pleased: Klipsch Forte speakers HK 430 dual-powered receiver PS Audio SL3 DAC Rotel CD player About a month ago I started getting a loud hum through the speakers, which would disappear if the receiver was turned off and then turned on again after a minute or two. Now the hum is constant and loud, no matter what components I turn off, whenever the receiver is on. Do I have a defective receiver, or should I be looking at some other culprit? As always, thanks in advance for any and all advice. Bernie Quote Link to comment Share on other sites More sharing options...
tpg Posted April 20, 2006 Share Posted April 20, 2006 It could be that the power caps in the receiver are failing or have failed. This often produces a loud, annoying hum... If that is the case, you'd have to open the amp up and replace the caps. Wait for a second opinion before doing anything, though... 1 Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 20, 2006 Share Posted April 20, 2006 You should disconnect all feeds to your receiver. That will leave just the speakers and the power connection. If the hum is still there, it is the amp. Some people try reversing the power connection at the wall socket. This might or might not be possible if there is a polarized plug and socket (one blade wider than the other. I've never had to try that. So I can't speak to it. Gil Quote Link to comment Share on other sites More sharing options...
wuzzzer Posted April 21, 2006 Share Posted April 21, 2006 If your 430 is like my 730 the plug-in isn't polarized. Like Gil said, unplug the receiver and try plugging the cord in opposite of how you had it. I had some bad hum when I moved the cords around for my Nintendo and PS2. Took me a while to figure it out. [:$] Quote Link to comment Share on other sites More sharing options...
NOSValves Posted April 21, 2006 Share Posted April 21, 2006 If the receiver still has this hum with all other sources disconnected chances are you have a intermittent caps in the PS going bad. One thing that makes me wonder about this is you would think that the hum would only omit from one channel since the HK is the twin power supply design. So this kind of makes me think its some other gremlin. Craig Quote Link to comment Share on other sites More sharing options...
bernmart Posted April 22, 2006 Author Share Posted April 22, 2006 All of these posts have been enormously helpful. Here's an update. I isolated all the various components, and found that the culprit seems to have been my old B&O Beogram turntable. At first I noticed that the ground wire, which connects to the receiver, was loose. Tightened it, and this reduced the hum to an intermittent state. However, a hum would sometimes begin just by walking in front of the cabinet! The whole area seems "live." I then unplugged the turntable from the wall and plugged it into the "switched" outlet on the receiver itself. For no reason I can come up with, this seems to have worked--no more hum! Remaining questions: WHY would such a change work? Does anything more remain to be done? Should I place a matting of some kind underneath the stack of components to isolate them from the vibes which set off the hum in the first place. All observations and suggestions welcome, and thanks for your help. Bernie Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 22, 2006 Share Posted April 22, 2006 I don't have any very constructive suggestions. It does not seem to be anything which would be solved by putting padding under the system. That I'm pretty sure of. Let me point out that re-plugging the power cord may have jostled something else which was the real problem. Grounding or the neutral connection could be part of the issue. I take it that the problem occured even thought the truntable was not switched as an input to the system. Is that right? Even when I fooled with turntables long ago I never experienced hum modulated by distance. Maybe, maybe, maybe, the walking around stressed the floorboards which affected some electical connection? That could be in the amp set up or the wall socket. A buddy had a circuit in his den go dead. I brought in a multimeter to check. But first I tested it by plugging the probes into an outlet down the hall. The den suddenly came alive, just by this. This was a bad connection in the daisy chain of romex wired though the hall outlet. So I'd look at that outlet you're using. The field thing is very odd, again. Is there any electronics in the basement below? A dog fence? I know, too wacky. At least you don't have to replace your receiver. That is good news. Smile, Gil Quote Link to comment Share on other sites More sharing options...
bernmart Posted April 24, 2006 Author Share Posted April 24, 2006 Saturday night I was at a party. Some wonderful audio equipment in the house, so I discussed my problem with the host. He suggested that plugging the turntable into the receiver might have completed a "negative ground." I've no idea what this means! Also, I detect better sound coming from my system than before the hum made it unlistenable. Cleaner highs, especially. I'd chalk this up to placebo effect, but it's my wife, who care nothing about equipment, who first pointed out the improvement. Maybe there was a slight hum there all along? Dead silent now. Quote Link to comment Share on other sites More sharing options...
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