Hey guys.....I tried searchin so as not to dredge up an oft discussed topic. But....I must have forgotten how to use the date range? I keep getting a "broaden search criteria" message? At any rate, I have an apparent ground loop hum. I can't remember the exact process but could probably fumble through ok. If anyone has an old post that would be great - and a piece of advice - are the standard Radio Shack isolaters sufficient or should I look elsewhere?..........Rob

Rob, setting the search at newer than 3 years and older than 1 day for "ground loop"(use the quote marks in the search term)brings up 204 posts, so start reading. Or, first read Alan's hum tips . Also, why don't you describe the symptoms in some detail to see if we have some thoughts.

You can just clear out ALL the fields in the newer than and older than fields (all 4 of them) and search across all years, you don't have to be restricted to 1 year searches.

I have had the hum for some time - just ignoring it. I notice it most from my QS8's during normal listening when there is a quiet moment like the breaks between commercials. Alan's article leans heavily towards the sub being the culprit. I'll do the search, do some reading, and do some checking tonight to see what I can come up with. Thanks for the responses.

Do you have any dimmer switches on the same circuit? That's what caused the buzzing that came out of all my speakers. Got rid of the dimmer, and it fixed everything.

Yup. I believe those switches, much like the remote activated ones I have in my house, have their own transformer box (or something of the sort) that causes the issue.

The remote ones that communicate over powerline purposefully put noise on the lines, that's how they send data. It isn't supposed to interfere with other things plugged in, but I've heard of many cases where audio gear will pick up the noise.

Great suggestion, Neon. Those dimmers radiate all kinds of garbage because many are unshielded. I had a friend in Toronto who was devoted to a CBC radio station on the AM band and he complained to me about a terrible buzzing he was getting, making the station unlistenable. He'd just had his place renovated with all kinds of dimmers, so I used a portable radio as a kind of signal tracer and as you got closer to the dimmer switch the buzz increased. Once the dimmers were gone, AM reception was clear.

Argon should also unplug the cable-TV feed (or satellite feed) where it enters the cable box or satellite receiver and see if the hum goes away. Those are most often the source of ground voltage differences causing ground loop hum.

Alan

The light switch in my room emits a very quiet buzz, but it's really only noticeable when the room is quiet, and the moment it's switched on.

Thanks, group - Alan I read your article and a couple of others and am going to check it out tonight. I do have a dimmer that operates by remote control. If it (the hum) is not the cable, is there a way to check the dimmer without removing it? I really like the dimmer - is ther no way to eliminate the hum if the dimmer is the source - other than removing it?

If the dimmer is on a separate circuit, you could probably turn that breaker off, or remove the fuse.



Depending on the brand of the dimmer, I would suggest giving Smarthome.com a call and see if they have any suggestions. I've purchased all of my home automation products from them, and they have very knowledgeable, helpful, customer service.

What kind of surge suppressor are you using? You might try one with a bit more filtering. While I dislike suppressors with transformers or chokes, because of their current limiting, in this case it may be the lesser evil.

Try a Tripp Lite ISOBAR-ULTRA. Even if it doesn't fix the problem, you'll have an excellent surge suppressor.

OK.....first thing I surmised is that the hum that I noticed on the QS8's was also evident on the M60's but only from the tweeter. Next thing I tried was unplugging the cable from the wall. No affect - still hummed. The hum did not change with the volume control on the receiver. Next I unplugged the sub cable and the hum vanished. So I pulled the sub out and to my dismay the cable snagged on the tv stand and the input jack broke off the sub panel - completely off. I can stick it back on but....Would it do any good to super glue it back on?? Luckily (or maybe unluckily) I have replaced the amp several times and I remembered JC telling me the Input and Output Jacks were linked. I plugged the cable back into Output Jack and, Voila, the sub still worked but the hum was still there. Reading Alan's article, I removed the chassis ground screw and that killed the hum. So....Hum gone, input jack gone, Dimmer stays....

How remiss of me....of course thanks to the regulars for their suggestions and patience to help and thanks to Alan for his article.......Rob

Sounds like you've had a very productive night.

Very good, Rob; those comments about possible problems caused by dimmers are correct, of course, but it turns out that it was instead the suspected ground loop.

Yes, much simpler than I had imagined. The dimmer switch - I could not recall exactly the brand at work today - is a Lutron that I bought at Lowes HI.

Lutron is probably one of the better brands of dimmers, as those things go.

In theory the power supply in the audio gear should filter out noise. In practice that isn't always true.

The funny thing is the noise was getting into my system via the Pioneer Elite DVD player with it's fancy dual power supplies (one for the analog components and one for the digital, the later can be shut off in "Pure" mode). I'd only get the buzzing when playing back through this player. My PS3 and receiver were immune.

I take it no one has experience in breaking off the sub jack? It is like my 500 had 2 lives but is now down to 1....The dimmer is an IR Remote and I do like sitting on the couch - being able to dim or raise the lights without getting up, walking to the wall and touching the switch?? HOW primitive is that?

Hi Argon,

Great--I'm glad my article and everyone's suggestions helped you out and you've been able to keep your dimmer.

The broken sub input jack is not uncommon. Owners pull out the sub to vacuum or whatever or step on the coax cable and the input jack breaks. It's one of the reasons we switched to the combo XLR/phone-jack input with the RCA adapter, although that generates its own set of problems (owners lose or can't find the adapter that's shipped with the sub) or are perplexed by what sort of inputs the sub has.

Regards,
Alan