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USB earth

post #1 of 11
11/9/12 at 5:40am
Thread Starter 

Will removing the earth (pin 4) from my USB cable which hooks up to my external sound card work as a solution for my digital noise/ground loop woes?

 

Also, is it safe to do so?

 

Many thanks :)

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post #2 of 11
11/9/12 at 10:26am
Quote:
Originally Posted by kar1zma View Post

Will removing the earth (pin 4) from my USB cable which hooks up to my external sound card work as a solution for my digital noise/ground loop woes?

 

Also, is it safe to do so?

 

Many thanks :)


Google for Ebtech Hum X, works wonder.

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post #3 of 11
11/9/12 at 10:37am
Thread Starter 
Quote:
Originally Posted by Andrew_WOT View Post


Google for Ebtech Hum X, works wonder.

Hi bud. Thanks for the reply.

 

Sadly I live in the UK so this isn't an option for me. I spoke with their tech guy Scott who said it can't be sold in Europe.

 

I did find some on eBay but I would have to buy a US to UK plug adapter, plus a US to UK "Stepdown 240/120v Transformer", frankly I'm not sure how the Hum X would cope with all that.

 

So... I need to find another solution. Any ideas? I've been looking at USB Isolators, I came across this: https://www.olimex.com/Products/Modules/Interface/USB-ISO/  Olimex USB-ISO.

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post #4 of 11
11/9/12 at 10:45am

There are USB DACs powering the USB receiver but often the USB receiver is powered by the PC. Sometimes using only data lines work, sometimes it is complete silence.

Take a al cheapo cable and try

If it is a grounding issue try connecting PC and DAC to the same power outlet.

If it is a noisy PSU disconnect it (assuming laptop).

Try another PC

Etc.

Try to isolate the problem

 

Success

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post #5 of 11
11/9/12 at 10:54am
Thread Starter 
Quote:
Originally Posted by Roseval View Post

There are USB DACs powering the USB receiver but often the USB receiver is powered by the PC. Sometimes using only data lines work, sometimes it is complete silence.

Take a al cheapo cable and try

If it is a grounding issue try connecting PC and DAC to the same power outlet.

If it is a noisy PSU disconnect it (assuming laptop).

Try another PC

Etc.

Try to isolate the problem

 

Success

I've tried many plug combinations to no avail. I even ran a 30m extension lead to another room downstairs, that did dampen the noise quite a lot but it's not a practical solution.

 

I have a tower computer so it's earthed at the wall, as is my DJ mixer (xone32). As soon as a ground loop is present, I get the noise. It doesn't matter if the computer is hooked up to the amp directly via phono cables, or through the external sound card via USB cable. As soon as there is a physical connection between mixer and computer the digital interference is there.

 

Taping over the earth pin in the USB cable did remove the interference, but it made a popping sound every now and then. I'm a bit worried I'm damaging my computer or the external sound card so I've stopped using the doctored cable.

 

Has anyone used the Olimex USB-ISO and had good results? Would this adapter cause any problems using an audio interface, e.g. the Traktor Audio A6?

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post #6 of 11
11/9/12 at 12:25pm

Before I got Hum-X I was just lifting earth on both computer and amp using cheater plug. I know it might not be the safest option but served me well for years. As long as they share the earth there is very little you can do, ground loop breakers like Hum-X and such do work though.

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post #7 of 11
11/9/12 at 12:32pm

If you soundcard uses a 3-prong plug ( grounded ) you may want to try a 2-prong ungrounded plug and allow your PC to the be primary ground.  That may be an easy option to try if your external soundcard allows you to swap to a 2-prong plug.

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post #8 of 11
11/9/12 at 12:42pm
Thread Starter 
Quote:
Originally Posted by NA Blur View Post

If you soundcard uses a 3-prong plug ( grounded ) you may want to try a 2-prong ungrounded plug and allow your PC to the be primary ground.  That may be an easy option to try if your external soundcard allows you to swap to a 2-prong plug.

External sound card is USB powered. That's why I want to know if it's safe taping over the ground pin?

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post #9 of 11
11/9/12 at 12:42pm
Thread Starter 
Quote:
Originally Posted by Andrew_WOT View Post

Before I got Hum-X I was just lifting earth on both computer and amp using cheater plug. I know it might not be the safest option but served me well for years. As long as they share the earth there is very little you can do, ground loop breakers like Hum-X and such do work though.

I'm not happy lifting grounds on my power supplies, I'm a bit on the cautious side :)

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post #10 of 11
11/10/12 at 8:16am

Here are a couple of products similar to the Hum-X which are available in the UK.

 

http://www.studiospares.com/mic-accessories/stageline-fga-102-stereo-line-transformer/invt/255290/

 

http://www.studiospares.com/di-boxes/art-cleanbox-ii/invt/325300/?htxt=%2FUvRjc0xAaKk26JwgsxcsV6E2gjpK53ITJCPcypNRrR6jhjYX3SDlEUFWaOdTpLU0xVcTayKYYOc%0Aw4t9gBa9qg%3D%3D

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post #11 of 11
11/10/12 at 12:22pm

Removing the ground pin wont work, Ive tried it before, the data pins need it as a reference for zero  or something like that. I wonder how just putting a resistor that in the usb ground cable would work, one that would still allow an electrrical connection but reduce the rf in the ground?

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