Grounding xlr combi jack

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rjuly

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In my efforts to design a small tracking console, I am looking at options for the line inputs, and deciding to use a combi jack and connect the switched 1/4" (line) connections normalled with a DB25 connector, so that I could insert a plug into any input and break that connection coming from the multi-pin connectior. In looking at the available panel/chassis mounted Neutrik offerings I find two that differ in terms of having a switched ground connection for XLR (top without, bottom with):

Screenshot 2021-09-17 at 10.48.10.png
What is the practical difference between the two, and under what circumstances would I choose one over the other?

- Richard
 
Last edited:
Clearly the ground normalling contact isn't good for anything but detecting the presence of the XLR shell like abbey said. So you're not going to be able to normal the XLR into the DB25. Only the 1/4". And due to the physical construction of the XLR, there is no version of an XLR jack with normalling contacts on the pins. You would have to use the ground normally contact to switch a relay that takes it's signal from either the 1/4" or XLR. Pin 1 of all three would just be shared I guess.
 
I am not sure, I have only seen ground switches used in battery powered guitar efx 1/4" jacks to turn off power when unplugged but I could imagine a combo line/mic input using different circuits for mic path and line path.
neutrik faq said:
We also offer an additional switching ground contact (NCJ10FI-*), which is closed to the XLR chassis ground and opens when connecting a XLR cable connector.

Perhaps it is desirable in some cases to only connect the XLR ground at one end. Of course the switch can be defeated by shunting across it.

JR
 
Perhaps it is desirable in some cases to only connect the XLR ground at one end. Of course the switch can be defeated by shunting across it.
Not sure I'm following that. I would think that G, which is the shell of the XLR, and 1 would just be hardwired together at the pins. Then you put a pull-up resistor on GN. When the shell is inserted, the downstream side of the pull-up goes high and turns on the transistor or PIC input or whatever to signal that the XLR is inserted.
 
I am not talking about using it for signaling tally, but different input grounding schemes.

I have never seen or used one. Some manufacturer probably asked neutrik if they could do it, and they could.


JR
 

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