i love this stuff... heres my take. remember in a live and studio guy, ive toured lots and done lots of ob's JJJ live at the wireless and live recordings etc.. ive been all these people below.
from the PA company's thinking
in a normal show the "system" it prepped or put together from a single source as in one company usually owns the whole pa FOH, MONS, cables core/splits set. it goes in and up every day and "works".
when you add anything they will blame whoever "added" the stuff.. its your bla bla bla thats causing the issue. it wanst like that last night without you and your toys..(you will later find the real issue, or maybe not).
from the OB people. the cores stuffed, noise everywhere, you need ISO's/transformers, they start de earthing bla, bla BANG..
both sides blame the other. its usually power earth from different locations causing the "noise", and a few bad cables as no one had enough leads to do a 3 way patch and everyone has used their last cables from the bottom of the packer that are sus anyway.
now im not taking into account the load with a third console/system connected and some gear really freaks out.
in the 90's i did lots of JJJ live at the wireless shows as i had old yamaha consoles with transformer balancing on the ins and outs for both the FOH and MON consoles. i had simple passive splits and used 2 of them for a 3 way split (foh, mons and radio.) we were the only pa campany thay wanted to use as the radio feed was clean with our system and other pa companies with newer "Better" gear had lots of issues.. their consoles were not transformer on in 's and outs.
today we have "much better" equipment and most live consoles are NOT transformer balanced.. so theres no isolation. everything talks to each other and at least 1 of not all 3 systems will be digital without any master clock, but with analogue interconnects (the multicore).
so again most PA companies will blame the third split (even if they provide it, its your stuff hanging off our split thats causing the issue, its you not us, it was fine last night, bla bla bla..)
what to do. you will be blamed no matter what.
most PA companies already have all the splits they need (1 for FOH, 1 for MONS) and they are now usually straignt, no trsansformers, no earth lift (some older cores had the ability to lift all the earth from at least 1 side with 1 switch).
you need to provide 2 x splits and if you want to be safe make 1 straight and the other transformer isolated. the best way is to take the inputs out of the main core (if they will let you, i bet they will all be sacred) and you give them back the STRAIGHT split. so mics into your core, your straight split to their core, you them use the transformer iso split for recording. you cant effect them and they are effectively connected as normal..
if they say no, take the monitor split (their tails) into your core, you take the transformer end and give the mon system the passive/straight split.
or just use a straight passive split
.
BTW these things are quite good and inexpensive if you dont want to make one yourself.they do use DB25's which some people love, some hate. ive used them and a system i use regularly with digital consoles uses them
http://www.violetaudio.com/index.php?op ... view&id=25