D-sub connector, trigger ground and shielding question

[Rovalo]

I plan to fit my MD with sub-D connectors 25 pins to connect break-out boxes or wires. I want to use a bunch of 1 to 1 PC cables I have. Initially I planned to use only 23 pins for trigger signals and 2 pins for ground (double wires to MD for safety, because all triggers depend on the same reliable ground connection to MD).

The PC cables have a common shield connected to the metal part of the D-sub connectors. Initially I planned not to use the shield as common ground for the triggers, see above.

However, all trigger cables typically use sleeve=ground/shield and tip/ring the pair of 2 wires, so the shiled is actually used as ground for the trigger.

So my question is: is it OK to use the shield from the PC cable as the ground, same as the trigger cables?

That case I would have 2 more signal pins (so all 25) on the D-sub connector for trigger signals.

[Rovalo]

I found this article on wiring a piezo, also using the shield of the cable as ground for the piezo.

http://www.drummagazine.com/plugged-in/post/diy-drum-triggers/P2/

So I guess using the shield of a multicore as a common ground for all piezo's should be OK.

[dmitri]

Yes, it will be ok provided each signal wire is shielded individually.

[Rovalo]

No, not exactly so this could be a show stopper...

My plan in short:
1. From MD box to the break-out box the common outer shield of the multicore (PC cable) would be the ground for all 25 signal wires.
2. On the break-out box all stereo jacks sleeves are connected to the multicore shield (ground), alle 25 wires connected to jack tip/ring.
3. All cables from the break-out box to triggers have 2 signal wires with shield (ground).

Is that not possible?

[dmitri]

Most likely it will be ok.

[Rovalo]

Dmitri, that would perfect.

I understand though that you still have little concern about 25 trigger pulse wires in the multicore affecting each other? If so, I'm interested why in order to reduce trigger disturbances to the minimum.

[dmitri]

I presumed that this 25 core cable is very short, i.e. less then ~30cm.

[Rovalo]

Thanks, I can work with that!