So i want to bring a little light into a more professional way to handle all kind of noises from the stage and studio points of view.
If i understand it right, you use almost exclusively unbalanced consumer level (-10dB) line signals and want to have them splitted for mainly live use i.e. gear to FoH mixer/recording mixer/monitor mixer.
The pro version of what you want would cost you a big amount of money. The highest level would be an active transformer splitter box with every channel having a transfomer with a primary 600 Ohm (line level? check your gear for this in the manual) impedance winding (mics would be rated 150 Ohm normally) and optimally THREE secondary windings (all 600 Ohm to match line or 150 Ohm). I really don’t know a standard splitter transformer having more than 2 secondary windings. But nothing is impossible…
just didn’t heard of. You can buy lams and bobbins and stuff and end up winding yourself (diy!) - resulting in a bad sounding 100 tons heavy box…
Other option: get a 2x splitter transformer, standard model with one primary 600 Ohm to 2 secondaries 600 Ohm per channel (leaving out either monitoring or recording) and pay around 50-60$ (per channel) without mounting hardware and stuff.
Last option: an active transformerless splitter. (search the net for this and “diy”, you will find various options for this, many of them quite professional!) May be opamp based or even discrete transistor tech. fairly easy circuits but must be made with a good will of perfection as you will route all your signals at the earliest stage thru them.
BTW, a fairly pro level splitter is for example available from whirlwind (with trafos i think). Costs: approx. 350 to 450$ for 4 channels to split. A pro 24ch split (complete small console) is rated at 3k$ normally…
Other question: Steel rack for shielding your signals…
My opinion: nearly useless to think about that…it’s the least important factor for noise rejection (otherwise all live racks would be steel racks i think ;D).
Gear placed into racks is almost EVER shielded by it’s own casing. Most sensible part is the cable works in the rack and proper grounding. Each device has to be checked for hums due to a ground loop (most evil in a live situation). For decent description read the AN’s of Jensen Transfomers Inc. . Lots of info about that. In fact one could write books about this, really…
Organize your psu and signal cables on the backside of your rack to avoid noises (keep both types AWAY from each other as far as you can and fix them).
Use good and stable wallwart psu’s (if you have to). Often reduces noise ALOT.
And last but not least think about using symmetrical signals when leaving the rack! Get a decent DI box. Again, a good (and i mean good = pro *usable*) DI Box is transformer based and *really* expensive (100 EURO per channel is absolutely a kind of standard, the trafo itself normally cost 60 Euro without the active electronics, mounting, etc…).
On the other hand especially in live applications symmetrical/BALANCED signals tend to be a milestone for a good noise rejection. (signal is doubled with diametral phase, at the receiver phases are paralleled again, so (nearly) all noises from external influences are killed when the signals were summed again - just in short and bad english).
A cheapy recommendation is the exeptionally cheap and small (1 rack unit) Etek 16x DI Rack unit. More awful than behringer in terms of solidity and inside electronics but i was really surprised - it’s fairly usable! (Maybe i would buy a decent single DI for bass signals…)
I hope it helps you a little with your decisions…
Kind regards
and happy DIY
Martin
