Passive splitter for in-ear monitor rig, ideas for how to approach physical cabling.

[Mikdu]

I am in the design phase of building an In-ear monitor rig, consisting of a X32 rack mixer and an audio interface for backing tracks, with a passive, transformerless splitter.
Setup is as follows:
1. 16ch mic in chassis XLR panel, wired directly into the male 16ch XLR panel on the back (to FOH), as well as Male XLR connectors that connect to the X32 mixer. (one mic channel in mixer will be unused, to fit in click)
2. 6ch (+1ch click only to in ear mixer) of backing tracks from the audio interface TRS connectors, wired into panel on the back to FOH, as well as TRS for our in ear mixer.
3. 10ch output from mixer TRS and XLR directly to XLR panel on the back. (no worries here)

The question is:
How and where would you physically implement the splitting of the signal?
The problem i'm imagining is that the cups on the XLR connectors only really fit one cable in them properly, but wiring a seperate splitting point for the signal would be another potential point of failure, not to mention a lot of work. If going for this method, how do you approach wiring them in the XLR connector, just twist the pair up before hand? Using two shields at least does not fit, would you just trim the shield and use the drain connector?

I thought of using wire jointers, but that is again a point of failure and physically hard to implement, as there would need to be a place to mount them.


An extra question about grounding:
Would you rather keep all grounds seperate, or connect the in and outgoing grounds?
also physical space doesn't allow for a seperate ground lift for each channel, but is there any use in adding a switch to seperate the outgoing split from the ground?

Thanks a lot!

 

[sodderboy]

There are no issues multing single wires on XLR's, either cable or panel mount. It's easier on the panel because you have no strain/boot dictating your stripback length. I do not twist, I simply tin 3mm and hold two wires at the contact instead of 1. Plenty of room for three wires on Neutrik. The skill needed here is strong fingers or you can cheat with small lengths of shrink that help hold the wires together. Good panel strain relief will protect the xlr connections and you "Y" out to the different equipment.
You are multing mic signals, so that gets a bit tricky with potential P48 useage. Traditional just uses a trafo splitter and one of the split loads is dedicated to providing the P48. Going trafoless is doable, but adds complications. You want to disable P48 on the x32 any way possible to prevent double powering, I don't know the equipment. Cable lengths after the split are important, 10 m or less for each should not invite spectres, but 100 m and more invites issues, hence the use of trafos in live situations.
In your case, can you steal line-level signal post-pre from the FOH mixer? That is another way to feed the in-ear add-on mixer. The FOH inserts are a potential, but that could complicate the FOH user's world.
We mult mic pre's all the time in the studio where you want to use some mojo pre and steal P48 from a console pre. They just get multed at the bay. You would do the same on the rack panel. The major issue would be excessive loading of certain microphones.
I would NOT entertain switches or relays for mic signals or shields. "On the fly" routing changes can be made with better designs.
Mike

 

[Chrisfromthepast]

I recently supported a band that used a homebrew solution that made me laugh at first, and then after I thought about it a bit, its totally fine!
I’ve let perfection stop me in my tracks for years for no good reason.
This engineer came through a bare bones venue and I was supplying just a projector and screen.
They had a little in ears setup, and needed to split the signal with FOH. There was no house split, so the engineer grabbed this contraption which accepted stage box inputs and split them to FOH and Mons using an old 2x4. Even the bottom plate of the “enclosure” is made of wood.
In a pinch, given the parts already arrived, you could build 24 channels of passive split in a day.
I didn’t ask, but I would ground the monitor rig and leave FOH floating personally.