Head-Fi.org › Forums › Equipment Forums › Computer Audio › USB Isolator and PC noise
New Posts  All Forums:Forum Nav:

USB Isolator and PC noise

post #1 of 13
Thread Starter 

I recently bought a tube amp for my PC (Litte Dot MKIII). I am using an USB DAC.

The problem is that there is ground loop related noise. There is a buzzing noise on high volumes. When I scroll a web page there is more noise. And when I play a game there is a lot of buzzing. Anyway, the cause is that the amp does not have isolated inputs and it's the PC's noisy ground that differs from the amps ground that is causing the noise. I tested using the amp with a cheater plug (no ground in power cable) and the noise is gone.

Since cheater plugs are not really safe, I am looking for a better fix.

Would a USB isolator work?
I found these two:

https://www.olimex.com/Products/Modules/Interface/USB-ISO/

 

http://electronicsshop.dk/isolated_usb_hub.htm?currency=EUR

Any experience on these? Which one is better?

post #2 of 13
Thread Starter 
Anyone?
post #3 of 13

You might try:

 

http://www.ifi-audio.com/en/iUSB.html

 

Dont know if it will solve your problem but I am very happy with the improvement.  

 

 

Good luck!

post #4 of 13
Quote:
Originally Posted by tuoppi View Post

I recently bought a tube amp for my PC (Litte Dot MKIII). I am using an USB DAC.

The problem is that there is ground loop related noise. There is a buzzing noise on high volumes. When I scroll a web page there is more noise. And when I play a game there is a lot of buzzing. Anyway, the cause is that the amp does not have isolated inputs and it's the PC's noisy ground that differs from the amps ground that is causing the noise. I tested using the amp with a cheater plug (no ground in power cable) and the noise is gone.

Since cheater plugs are not really safe, I am looking for a better fix.

Would a USB isolator work?
I found these two:

https://www.olimex.com/Products/Modules/Interface/USB-ISO/

 

http://electronicsshop.dk/isolated_usb_hub.htm?currency=EUR

Any experience on these? Which one is better?

Pulling the ground isn't actually particularly dangerous, I had to pull the ground to my amp because of a hum, no adverse effects. Unfortunately with computers having ground loop issues is fairly common unless you have good isolation between the signal path and the computer power.

post #5 of 13

Apparently Little dot have ground issues

 

There are a few solutions posted

http://www.compudio.ca/2007/06/little-dot-mk-iii-exclusive-review.html

post #6 of 13
Thread Starter 
Quote:
Originally Posted by 65535 View Post

Pulling the ground isn't actually particularly dangerous, I had to pull the ground to my amp because of a hum, no adverse effects. Unfortunately with computers having ground loop issues is fairly common unless you have good isolation between the signal path and the computer power.
There is no adverse effects when everything works. But when something goes wrong and the amp starts looking for a ground it will most likely use the user (me) as the ground which is pretty dangerous. Seeing as the amp is sitting at my desk and I sometimes use it with headphones I rather not take that risk unless I really have to. Pulling ground is the absolute last option I will use if nothing else works.
Quote:
Originally Posted by squallkiercosa View Post

Apparently Little dot have ground issues
There are a few solutions posted
http://www.compudio.ca/2007/06/little-dot-mk-iii-exclusive-review.html
The recommended solution in there is an RCA isolator. However I read that those lessen the sound quality, especially those cheap ones. It makes sense too because they work in the analog domain and breaking the ground loop is not a simple task.
That's why I am looking at USB isolators so the ground loop would be broken when the signal is still digital thus leaving the sound quality intact.
post #7 of 13

I use one of the Olimex USB isolators. For me it wasn't so much a sound issue or hum issue, there was a potential difference between the AC outlet that my PC was plugged into and where the USB DAC and other nearby USB things we connected to the AC line.  Maybe one of the outlets had ground and neutral reversed, I don't know.  (There is some dodgy wiring in my flat.)

 

What would happen is the printer and the scanner would repeatedly reset. Also, if you turned a light on it would cause the printer to reset and cycle and the scanner to home up.  Damned annoying.  So I put an Olimex isolator in line with the USB from my PC and that solved the issue.

 

So, the Olimex isolators DO work; they galvanically isolate one side from the other.

post #8 of 13

The isolators only support full speed (12 Mbit/s) and not high speed (480 Mbit/s). Even though full speed in theory should be enough, some USB devices require high speed to function properly (eg. M2tech Hiface Two).


Edited by Anda - 1/14/13 at 11:42am
post #9 of 13
Thread Starter 
I went ahead and ordered the Olimex isolator. I will see how well it works.
post #10 of 13
Thread Starter 
The isolator works perfectly.

All the noise is gone and the noise floor is completely quiet.
post #11 of 13
Quote:
Originally Posted by tuoppi View Post

The isolator works perfectly.

All the noise is gone and the noise floor is completely quiet.


Cool! Which DAC are you using?

post #12 of 13
Thread Starter 
Quote:
Originally Posted by Anda View Post


Cool! Which DAC are you using?
SMSL SD-022+
post #13 of 13
Quote:
Originally Posted by tuoppi View Post


SMSL SD-022+

 

Thanks. Good to know that the TE7022L works with an isolator :)

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Computer Audio
Head-Fi.org › Forums › Equipment Forums › Computer Audio › USB Isolator and PC noise