My speakers are humming and its not the type of music I like.

[Kruppy]

Ground loops (I think)….I’m so depressed.

Potential Problem:
Over the past couple of months I noticed a slight hum coming from my right SL3 only. It’s louder when I have my amp on and my preamp off. As soon as the pre is turned on the hum volume is reduced to the point where it’s quite acceptable. Basically you have to be within about a foot of the panel to hear it. So I haven’t really bothered with it, but it may be contributing to the problem below.

Serious Problem:
Earlier this week I came across an extremely good deal on a Yamaha AV receiver to replace a failing Adcom GDD-1 Dolby Digital processor. I’m using the receiver’s pre –outs since I have separates already. My PS Audio PCA-2 preamp has a HT bypass (which input channel is user selectable). So I had everything hooked up, powered up all my cr@p, selected the bypass channel and Holy Bejesus there’s a 60+ dB hum coming from BOTH channels. Totally unacceptable! I started wantonly farting with the interconnects and coax cable connections with the hope of finding the needle in the hay stack, but no success. Unfortunately, I have a rat’s nest of cables, power cords and components to mess with and no time to do it.

Other than systematically eliminating every connection/component does anyone have any advice?

I was so looking forward to watching a movie with the kids tonight. Now I’m contemplating tearing the whole rig down. Sometimes this hobby can bite.

 

[roberto]

Ground loops (I think)….I’m so depressed.

Potential Problem:
Over the past couple of months I noticed a slight hum coming from my right SL3 only. It’s louder when I have my amp on and my preamp off. As soon as the pre is turned on the hum volume is reduced to the point where it’s quite acceptable. Basically you have to be within about a foot of the panel to hear it. So I haven’t really bothered with it, but it may be contributing to the problem below.

Serious Problem:
Earlier this week I came across an extremely good deal on a Yamaha AV receiver to replace failing Adcom GDD-1 Dolby Digital processor. I’m using the receiver’s pre –outs since I have separates already. My PS Audio PCA-2 preamp has a HT bypass (which input channel is user selectable). So I had everything hooked up, powered up all my cr@p, selected the bypass channel and Holy Bejesus there’s a 60+ dB hum coming from BOTH channels. Totally unacceptable! I started wantonly farting with the interconnects and coax cable connections with the hope of finding the needle in the hay stack, but no success. Unfortunately, I have a rat’s nest of cables, power cords and components to mess with and no time to do it.

Other than systematically eliminating every connection/component does anyone have any advice?

I was so looking forward to watching a movie with the kids tonight. Now I’m contemplating tearing the whole rig down. Sometimes this hobby can bite.

Hola Kruppy...you are right thinking a ground loop problem. You have to track which component of from where the hum is produced. My first guess is tv cable. Sometimes, a different ground potencial from the post outside of your house to your place, this ground loop is the problem. First, disconnect the tv antenna from the VCR or tv...and listen. Sometimes also with the aid of a cheater plug at the power amp, might work...but first, we have to find from where this unwanted 60 Hz is coming from...
Roberto.

 

[Taz]

You can also try a product called HumX I had a very bad ground loop I could not get rid of short of cheater plug which can cause its own problems this product from evtech worked perfect. I plugged it in to the pece of gear causing the problem and the hum was gone. It wa a loud hum and it was gone.

 

[dyazdani]

Narrowing it down to one component is the easiest way to go. I've had a couple of problems similar to yours that were easily solved with a little testing and logic. Found a bad ground connection on an RCA plug one time. The tough one was a cold solder joint on one channel of my power amp's line level connection.

 

[Kruppy]

Thanks guys.

With my frustration level so high last night, I knew I was going to end up a bull in a china shop, so I left every thing alone. The weather looks like it's going to be rainy all day, so I'm probably going to dig into it this afternoon.

 

[Kruppy]

So on Sunday morning I decided to get some of my aggression out before digging into my ground loop issue by working out. A hour and a half later I sat down for lunch. The power flickered on and off about 20 times in a 1/2 hour and then decided to stay off for the next.....15 hours. We had some high winds in the metro Detroit area that took down power lines. Unfortunately, yesterday was the perfect day to be farting around with my set up without the kids pestering me. Oh well, maybe some time this week I can mess with it. (With my fist in the air) Curse you evil ground loop Gods! (Insert stink eye look).

 

[Jeff Zaret]

Kruppy,
As a wild guess in to the air, what about flouresent lights? Is there a lamp or an aquarium on the same circuit? I believe this may create a 60 cycle hum if I guessed right. Maybe somewhat can enlighten me on that but can be a cause of noise within the system

Just a thought

Jeff

 

[Kruppy]

Oooooh, that's a good one Jeff.

There is a flouresent light right over my rack just to the right of the center of my system . I don't know if it's on the same circuit or not, but I'll check it out and power up with the lights off.

 

[Kruppy]

Ok, I think my stink eye scared off the ground loop Gods.

After a short time goofing around with things I've discovered that my problem is the result of my coax cable connection from the vcr and cable box running to the TV. The TV is connected to the AV receiver/processor. If I remove the cable connection to the cable box or the TV to processor the dreaded hum goes away. Wahooo! Thanks to Roberto's post!

Now that I've diagnosed the problem what's the cure, besides completely eliminating cable tv from my HT?

 

[roberto]

Hola Kruppy...it is good to know that you did find the problem. All what you need is go to yahoo and seach for ground loop. There are several brands that offers a transformers. It is a little expensive (some up to $100.00). What you do is place this special device between your cable antenna and your vcr. It's a special tranformer and only have about three inches long...I use tributaries cable brand and here in Costa Rica works just fine!
Happy listening,
Roberto.

 

[Taz]

That was my problem. I used the HumX from ebtech and it disappeared. The other thing I like it is not in the signal path. It sits between the plug and the outlet. I picked it up for $50.

 

[Kruppy]

Taz,
I did a little search on the HumX the other day, although I need to read up more. What do I plug into it, the power for the cable box, the vcr, or does it not matter?

Roberto,
I'm assuming from Taz's post that the transformer you're suggesting is connected directly to the coax cable.

I've been dealing with the kids tonight while my wife is out. I've only been able to spend a couple of minutes here and there online. When they're in bed I'll be able to research a little more.

Thanks for the input.

 

[Spike]

Now that I've diagnosed the problem what's the cure, besides completely eliminating cable tv from my HT?

Here are some URLs to ground loop information:
http://www.smr-home-theatre.org/Ground-Loops/
http://www.epanorama.net/documents/..._isolators.html
http://www.altavistaaudio.com/hum.html

Do a search on this site. Here are a few cheap fixes...
Parts Express - Video Isolation Transformer
Parts Express - Dual Isolation Transformers
Ground Loop Isolation Transformers
Hum Buster thread on ML board

Good luck with your system
Spike

 

[roberto]

Taz,
I did a little search on the HumX the other day, although I need to read up more. What do I plug into it, the power for the cable box, the vcr, or does it not matter?

Roberto,
I'm assuming from Taz's post that the transformer you're suggesting is connected directly to the coax cable.


I've been dealing with the kids tonight while my wife is out. I've only been able to spend a couple of minutes here and there online. When they're in bed I'll be able to research a little more.

Thanks for the input.

Hola...this is the address for the hum eliminator: http://www.tributariescable.com/catalog_view.php?id=172
This device solved my problem with cable antenna ground loop. Hope this can help!
Cheers,
Roberto.

 

[Kruppy]

Roberto, Taz and Spike,
Thanks for all of the help, this has been a big learning experience for me.

 

[Taz]

You will have to try. Mine ended up on my AVR.

 

[Kruppy]

The Ground Loop Gods have been exorcised from my coax

Isolation transformer installed, problem fixed. My ears are happy...

Thanks guys

 

[roberto]

Isolation transformer installed, problem fixed. My ears are happy...

Thanks guys

Hola Kruppy, it is good to know that you are now enjoying again your sound...please tell us what kind of isolation transformer you got...there are some out there and the prices are very different, so we can learn through you!, ...happy listening, and regards from Costa Rica,
Roberto.

 

[Kruppy]

I ended up using the in-line cheap-o $9 video isolation transformer from Spike's link to Parts Express. I was hoping to find something at Radio Shack because I wanted an immediate fix, but they were not very helpful. I figured I'd start out with the low cost version and move up the cost ladder if required.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=180-075

I'm not so worried about how this affects the video signal right now, due to my cheap tv I'm using. Once I've upgraded to a HD tv, blah, blah, blah I may need a higher quality solution. But right now the noise in my audio rig has been squelched.

 

[roberto]

I ended up using the in-line cheap-o $9 video isolation transformer from Spike's link to Parts Express. I was hoping to find something at Radio Shack because I wanted an immediate fix, but they were not very helpful. I figured I'd start out with the low cost version and move up the cost ladder if required.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=180-075

I'm not so worried about how this affects the video signal right now, due to my cheap tv I'm using. Once I've upgraded to a HD tv, blah, blah, blah I may need a higher quality solution. But right now the noise in my audio rig has been squelched.

Thank you Kruppy...good price and please tell me if you have any problem with the higher channels, do you have snow, low signal at the screen?...here is Costa Rica, the problem with ground loops is very common...thanks again!
Roberto.