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Laptop + USB audio interface = annoying ground loop noise Audio Interfaces
Old 9th March 2013
  #32
Gear Head
 

ZOMBIE THREAD!!!!!

I'm having digital noise come through my interface via a usb ground loop. The interface manufacturer said that it's cause by my computers power supply (Corsair HX650) being poorly grounded. I'd rather not change the PSU since it is a rather nice PSU so I will try first:

Ebtech Hum-X
Many posts suggest that this is a solution to these sorts of issues


if that doesn't work


Multi-Purpose USB Isolator
This seems more logical since it's breaking the loop where the noise is being transmitted, but the Hum-X is available locally so I shall try that first
Old 10th March 2013
  #33
Gear Head
 

Ebtech Hum-X connected to the computer power solved the insanity
Old 11th March 2013
  #34

Common mode chokes are good too.



-tINY

Old 4th September 2013
  #35
Gear interested
 

I hate the fact that this problem exists. So frustrating. I got my computer, I got my audio interface, I've got my DAW.. now I can finally be creative and make music! NOPE... usb ground loop interference, you need to drop another $100 on some stupid little adapter.
Old 4th September 2013
  #36

Or try running on battery....



-tINY

Old 5th September 2013
  #37
Lives for gear
 
Richard Crowley's Avatar
 

@charlesurich, don't blame the USB. The problem is the COMPUTER, and specifically the power supply brick. Portable computers are NOT designed to play nice when integrated into larger systems. They are designed for portable, isolated use. If you want to connect them to other gear, then you must deal with the nature of the beast.

You could try the $20 stereo line-level isolation transformer from Radio Shack.
Ground Loop Isolator : Isolators | RadioShack.com
I see they also sell one of the Nady iso transformer products
Nady HE-1 Hum Eliminator : Hum Eliminators | RadioShack.com
Old 5th September 2013
  #38
Gear interested
 

I usually do run on battery. Not fun trying to finish your session up before the battery dies. It also works when I use an extension chord and plug it into another outlet on the other side of the room.. obviously these aren't permanent solutions. Just another annoying little unforeseen problem to solve.
Old 5th September 2013
  #39
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LeeYoo's Avatar
 

Quote:
Originally Posted by ZardozMusic View Post
The interface manufacturer said that it's cause by my computers power supply (Corsair HX650) being poorly grounded.
Bovine Excrement!
Old 5th September 2013
  #40
Lives for gear
 
LeeYoo's Avatar
 

Quote:
Originally Posted by Richard Crowley View Post
@charlesurich, don't blame the USB. The problem is the COMPUTER, and specifically the power supply brick. Portable computers are NOT designed to play nice when integrated into larger systems. They are designed for portable, isolated use. If you want to connect them to other gear, then you must deal with the nature of the beast.

You could try the $20 stereo line-level isolation transformer from Radio Shack.
Ground Loop Isolator : Isolators | RadioShack.com
I see they also sell one of the Nady iso transformer products
Nady HE-1 Hum Eliminator : Hum Eliminators | RadioShack.com
Sorry Richard. I do not fully agree. And isolation transformers are second grade solutions.

In case of a laptop, I would break the USB ground with a USB isolator.
http://www.amazon.com/Multi-purpose-...780693-8554447
You might have to power the interface with a dedicated brick if you were running it on laptop power before.
Ebtech Hum-X is fine for grounded PCs, but might not work with 2-pin laptop powerplugs.
Leo..

AFAIK, laptop bricks have a cap between laptop ground and power neutral (for safety reasons). That gives problems with other grounded gear in your setup.
That gives them a bad name. Maybe someone can confirm this..
Old 5th September 2013
  #41
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Richard Crowley's Avatar
 

Not all isolation transformers are "second grade solutions". For example Jensen IsoMax products are top-drawer.

I have had to deal with too many unruly laptop power bricks which are congenital offenders. BOTH those that had 2-wire or 3-wire (grounded) power mains cords.

IME, isolation transformers are equally effective with both grounded and ungrounded power bricks. Indeed, there are some "isolation" products that use other schemes, and they are not universally effective.

I have had no direct experience with USB isolation products, but I can easily believe that they can be equally effective with USB-connected external audio interfaces. Of course, if they interrupt the ground connection, you can use only externally-powered USB devices.
Old 5th September 2013
  #42
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LeeYoo's Avatar
 

Quote:
Originally Posted by Richard Crowley View Post
Not all isolation transformers are "second grade solutions". For example Jensen IsoMax products are top-drawer.
True, but I prefer a straight wire over any transformer.

Quote:
Originally Posted by Richard Crowley View Post
Of course, if they interrupt the ground connection, you can use only externally-powered USB devices.
Some do have an inbuild isolated DC/DC converter.

Maybe time that interface builders start integrating isolators by default.
ADuM4160: First Single Package USB Isolation Solution - YouTube

Leo..
Old 6th September 2013
  #43
Quote:
Originally Posted by LeeYoo View Post
True, but I prefer a straight wire over any transformer.


ADuM4160: First Single Package USB Isolation Solution - YouTube

Sometimes, galvanic isolation is required. Transformers are usually the best, simple solution...

I've got an "A-Dumb" device on a measurement isolation board on it's way to me. I'll let you know how well it works....



-tINY

Old 6th September 2013
  #44
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LeeYoo's Avatar
 

I think it's all about strategy.
Draw or visualise all the dirty ground paths, and break the one(s) that are easy and have the least impact on the sound.
USB isolation must be big in the medical and industrial field, but uncommon for audio.
Love to hear from people with practical experience.
Leo..
Old 16th September 2013
  #45
Gear interested
 

Quote:
Originally Posted by Wavebourn View Post
You just power your notebook and USB connected device from different sources, isolating them galvanically. Should work, why not, it is one more possible solution, to break a ground loop in one more place.
A lot of USB audio interfaces are bus powered, so as the USB isolator breaks the electrical connection between the laptop and the interface, I can't see this working for bus powered devices. Shame - it seemed the perfect solution!
Old 16th September 2013
  #46
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LeeYoo's Avatar
 

Quote:
Originally Posted by Pengman View Post
A lot of USB audio interfaces are bus powered, so as the USB isolator breaks the electrical connection between the laptop and the interface, I can't see this working for bus powered devices. Shame - it seemed the perfect solution!
As said, some also have an isolated DC/DC converter on board.

More info for people who like to solder...
adum4160
Old 16th September 2013
  #47
PRH
Gear addict
 

Quote:
Originally Posted by LeeYoo View Post
As said, some also have an isolated DC/DC converter on board.

More info for people who like to solder...
adum4160
Probably worth flagging that this device is limited to the lower usb 2.0 speeds: Low Speed (1.5Mbps) and Full Speed (12 Mbps).

I believe that other similar devices are the same in that regard.
Old 16th September 2013
  #48

The pulse transformer they use in that part will never be able to do 1.2Gb, let alone 5Gb...

There are two ways to get there, currently. Gigabit Ethernet has galvanic isolation. Optical links require no ground connection. Neither of these is popular or has a wide-spread standard for remote power, though.



-tINY

Old 22nd October 2013
  #49
Gear interested
 

Guys this is my first post and this thread helped me come to a really simple solution, for my set up anyway, so it's only polite for me to share it.

I have had this issue for years , plugging in certain USB devices and getting that ridiculous annoying noise which was rendering my recording channels useless, especially with a compressor on the inserts. Today I decided to tackle the problem once and for all and found this thread.

I had no idea of the earthing issues USB devices picked up but to cut a long story short it may not necessarily be the USB device you think that's causing the issue. By chance I found that my external LCD apple monitor, although not causing much when plugged in on it's own, was the source of USB noise when my interface was also plugged in. The Apple LCD does not even use USB, it's a mini DVA, hence the lack of previous association.

This solution worked for me (in the UK): To remove the ground I simply plugged my LCD monitor power supply into a European adapter, then plugged the Euro adapter back into a UK adapter to remove the earth pin. Years of annoying noise gone, just like that! Cannot believe it! Didn't have to rewire anything, lose any warranties, buy new power supplies, nothing.

I understand that this may not work for everyone but if you've got some Euro-UK and UK-Euro adapters knocking about it's defo worth a go.

Thanks for your previous experiments which lead me to this solution :-)
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