Using a passive direct box to kill ground loop noise?

[Glowbug]

This was recommended to me by a friend who's into hi-fi as well as pro audio.

I'm getting a ground loop, using unbalanced connections, using cheater plugs "fixes" it but I know that's no permanent solution. Would a passive direct box solve the issue? If so, which ones are good? I see ones by ART, ProCo, and others...is this a "get what you pay for" kind of thing, or is one pretty much like all the rest? Since all the audio's going through this one box, it better not impart anything of its own or take away anything 🙂

http://www.partsexpress.com/webpage.cfm?webpage_id=3&SO=2&CATID=27&ObjectGroup_ID=683

 

[leadbelly]

You need to say what your application is. A DI box is built for a specific range of input and output impedances. Are you trying to mate an instrument to an amp?

 

[Speedskater]

I just read that the Radio Shack, Audio Ground Loop Eliminator is surprisingly good! Especially when you consider the budget price.

 

[Glowbug]

You need to say what your application is. A DI box is built for a specific range of input and output impedances. Are you trying to mate an instrument to an amp?

Nope, this is going between my preamp and my power amps...

 

[cerrem]

For audio you really need the best....and that is Jensen..
The reason is because you need the exceptional bandwidth with exceptional balance.... There is only one choice...

http://www.jensen-transformers.com/

cerrem

 

[leadbelly]

Nope, this is going between my preamp and my power amps...

Then stay away from a DI box. The transformer inside them is wound for very different impedances and signal levels than found in line level home audio gear.

Although a little dated, have a look here: http://www.diyaudio.com/forums/showthread.php?postid=408789#post408789

 

[Glowbug]

So what's the solution for breaking a ground loop like this?

 

[hotbottle]

You need an isolator, usually made from a pair of good quality 1:1 transformers. I see Speedskater earlier in the thread mentioned one.

 

[Glowbug]

Eek. $177 for that Jensen one pre-built.

Wonder if there's a cheaper solution...

 

[imix500]

Isolation Transformers

We use the Sescom IL-19 on Broadway for that purpose. I have run one on our AP rig and they really are ruler flat. Excellent transformer for about $50.

 

[cerrem]

Read the "white papers" on Jensens's website....it may be of some good information with isolation grounding issues....

Chris