DIY Digital cable question

@auxinput - RE:

@williewonka - he’s talking about a single-ended S/PDIF coax cable

The original posts stated...

There is a double braid on this cable. The inner braid is the signal return. The outer copper braid is for additional shielding.

In which case the outer braid can be used as a "floating screem/shield" - i.e. it should be connected at only one end

IF both components are "grounded" then that end of the cable should be connected to the source.

IF only one component is grounded then that end should be connected to the "grounded" component

IF neither components are grounded then connect that cable in either direction

BTW,

• floating shields can be applied to both single ended and balanced cables - its how the wire is made and not related to the type of connection. 
• and it provides benefit to both digital and analogue cables

@corelli - you can leave it "floating" at both ends and it will provide "some" benefit, but grounding at one end is better

Regards - Steve

@williewonka - he's talking about a single-ended S/PDIF coax cable, so it will not have a 3-pin XLR plug.  However, this is not the same as a XLR analog interconnect.

RE:

I would connect outer shield to ground at the source (transport) side only

That is correct provided that the transport has a grounded three pin plug

If the transport has an isolated power supply then the grounded end of the cables should be plugged into the amp/Pre

• assuming they have a three pin plug also
• otherwise it makes no difference.

Regards

Thanks for the responses.  Confirms what I thought, but I was not aware of the minimum length suggestion.  Good info. 

I would connect outer shield to ground at the source (transport) side only.

Minimum length for a coax digital cable is 1.5 meters. Less than that and problems can arise from reflections within the cable.

A cable which has a floating braid will add capacitance and basically "choke" the current.  You need to ground the braid on at least one end.