[MKHTTJ]

Hey guys, I have a serious ground loop issue I cant figure out
 
I run audio from my PC through a USB DAC (powered by the usb cable) to an MKIII Little Dot headphone amp (with its own power cable) and then to my Grado RS-1's.  Unfortunately theres an incredibly annoying buzzing sound that I can't get rid of, even if i turn the amp off.  I never had this problem on my laptop and I can't figure out what to do :/
 
I won't pretend to completely understand how ground loops work but I was hoping someone could give me some productive (and safe) advice on how to fix the problem.  I've heard of just cutting off the third prong on the power cable but that sounds like a bad idea so..... I'm asking you guys lol
 
edit: also the buzzing sound gets louder if i turn up the volume on the amp so I assume the problem begins with my pc if that helps

 

[Dalamar]

Cutting the ground will help, putting everything on the same surge protector should help. Pick your poison.
 
As far as non-grounded, back when I hadn't realized the incompetent who wired this house didn't connect the ground wires to the outlets, my pc case had a charge in it that could make a noise if I touched headphones to it, but it never seemed to adversely affect anything. Honestly grounding is mostly about safety.

 

[batphink]

You need a ground loop isolator.  Xitel's product page does a pretty good job of explaining what ground loops are and what causes them.  The reason why you've never has this problem with your laptop is because laptops use far less power (less than 20 watts) than desktops (more than 350 watts).

 

[Dalamar]

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=265-012
^ much more sane price than Xitel's product.
 
Ground loop isolators aren't a fix, they're a workaround.

 

[leeperry]

you need an ADuM4160 dongle, it will provide USB galvanic isolation.

 

[ROBSCIX]

Quote:

Hey guys, I have a serious ground loop issue I cant figure out
 
I run audio from my PC through a USB DAC (powered by the usb cable) to an MKIII Little Dot headphone amp (with its own power cable) and then to my Grado RS-1's.  Unfortunately theres an incredibly annoying buzzing sound that I can't get rid of, even if i turn the amp off.  I never had this problem on my laptop and I can't figure out what to do :/
 
I won't pretend to completely understand how ground loops work but I was hoping someone could give me some productive (and safe) advice on how to fix the problem.  I've heard of just cutting off the third prong on the power cable but that sounds like a bad idea so..... I'm asking you guys lol
 
edit: also the buzzing sound gets louder if i turn up the volume on the amp so I assume the problem begins with my pc if that helps

Yes cutting off the ground plug is for idiots...or rather dead idiots.  The groiund is there for a reason to keep you from getting fried.  If you removed the ground an stray electricity will go right into you instead of the ground.  Try and put everything on the same power circuit, this should fix the trouble.  If not then perhaps your issue is elswhere.

 

[Nebby]

There is an important distinction between disconnecting a ground pin vs a device that is made without a ground pin. Devices that don't have a ground pin are required to be Class II insulated (double insulated) preventing the possibility that a deadly shock can reach the user. Disconnecting an existing ground pin means that you are removing the safety ground from a Class I insulated device and isn't recommended.
 
The safety ground is there to prevent the worst case scenario of line voltage reaching the user. I don't think you can overstate the importance of preventing the possibility of that happening.

 

[ROBSCIX]

Quote:

There is an important distinction between disconnecting a ground pin vs a device that is made without a ground pin. Devices that don't have a ground pin are required to be Class II insulated (double insulated) preventing the possibility that a deadly shock can reach the user. Disconnecting an existing ground pin means that you are removing the safety ground from a Class I insulated device and isn't recommended.
 
The safety ground is there to prevent the worst case scenario of line voltage reaching the user. I don't think you can overstate the importance of preventing the possibility of that happening.

Exactly.  Thank you.
Not to mention the guy already dismissed the idea and wants only SAFE advice.

 

[MKHTTJ]

I tried putting everything on the same surge protector and that helped but it was still really annoying.  This might have to do with the fact that my computer runs at about 800 watts, with a 1000watt power supply.
 
So after that didn't work I grabbed a $20 ground loop isolator from radioshack and it worked perfectly.  My amp is completely silent at any volume and I can listen to music again
 
 
Thanks for the advice, you guys are always helpful!

 

[ROBSCIX]

Great you got it fixed.  Enjoy.

 

[brymuse]

Hi
Sorry to reopen an old thread, and I hope I'm not recovering old ground. Im pretty new to headphones as a main system, having been a speaker/amp guy. Now, mostly due to a change of address, I'm turning back to headphones. My stock HD595/Project headbox mk2 isnt good enough and  I'm thinking of going up to this Little Dot 3 with HD650s. However I'm worried about this 'ground loop' noise I keep reading about. Is it purely because people are running it through laptops? Ill be using my Meridian 506 CD player and Isotek Minisub mains filter. Will these counteract the problem? I mostly listen to classical, so hum would be a killer...
Thanks in advance for your answers
Bryan