Shielded cables inside plastic case or plain wires inside a shielded case, or both?

[EB1000]

Hi


I always wondered if using shielded cables inside a shielded case has any added benefits to using wires as far as noise immunity goes. I hope someone tests this by taking measurements...


Attached is a picture comparison for a simple RCA splitter. Which one is better? What about combining both (shielded cables and case)? And finally, what would be the answers to the same questions is the signals were balanced (in such case I only use twisted pair unshielded with shielded case and twisted+shielded with plastic case)

What do you think is best?

Thanks

 

[egellings]

If source and input impedances are relatively low, then there'd be little difference, if any. For the bare-wired version, I'd separate the wires to minimize crosstalk.

 

[Cbdb2]

The case should grounded. Why not do both?

 

[egellings]

It certainly does not hurt to do both. It's just that you may not gain anything by doing so.

 

[Rock Rabbit]

Plastic case all the shields must be connected at one point to common RCA gnd (probably best at the output), plastic case cheaper and easy for drilling. Metal case better for pro use EMI fool proof (it can protect even the selector), earth at single point. UTP good for minimal crosstalk. For balanced lines there's only metal case option, case must be tied to mains gnd. By design metal case always makes contact with XLR (chassis male and female has a fourth metal contact to chassis), bear in mind that signal gnd is not equal to chassis gnd (many diagrams on internet are wrong) and even with "ground lift" option the case on connectors are at chassis potential

 

[Rock Rabbit]

Combo XLR/TRS balanced chassis connector