Grounding and output jacks

[MNA]

I am putting together a shopping list for my Green Pre project. I found some cheap stereo 1/4" jacks to use as outputs, and then I realized that these jacks are not isolated from the chassis (no isolation between the sleeve and the chassis). I guess that means that there is no way to star ground the outputs? Does that matter? I realize that there is no absolute answer to this, except maybe "try it, and you'll find out", but if I rephrase the question: would you order isolated or non-isolated 1/4" output jacks? (the isolated ones cost four times as much, that's why this is even an issue)

Thanks!

/martin.

 

[nacho459]

You should be fine, just make sure you also attach the sleeve conductor to the star ground. Also, they do make TRS jacks that are isolated.

 

[MNA]

[quote author="nacho459"]You should be fine, just make sure you also attach the sleeve conductor to the star ground. Also, they do make TRS jacks that are isolated.[/quote]
OK, I should be fine? But wouldn't making a connection from the sleeve to the star ground form a ground loop (the sleeve being connected to the star ground via the chassis AND the cable)?

And I do know that there are isolated 1/4" jacks, that's why I was asking this question. They cost quite a lot more, though.

Thanks!

/martin.

 

[PRR]

> no way to star ground the outputs? Does that matter?

If your load is a proper differential ("balanced") input, it should not matter except in extremely high EMI fields (which would probably corrupt your mike signal before you ever get to the amps).

If your load is unbalanced.... it depends what other crap is flowing in the chassis. If only the jacks and the safety power ground, and the load shares the same power-strip and the power ground isn't too trashy, it may be fine. A lot of stuff works this way.

> "try it, and you'll find out"

There is a right way, and often a cheaper way that works perfectly in nearly all situations.

Myself, I use naked-metal jacks a LOT. Cheaper, but also often more rugged.

 

[BYacey]

Spae-Nauer makes a shouldered fibre washer that fits a 7/16 hole with a 3/8 opening for the jack; this works well and I have seen them on commercial equipment from the past.

http://www.spaenaur.com/