I don't understand why you can't just make a
Y cable or a splitter box. Isn't the signal split that way in every lighting
fixture that it is daisy chained through?
I like to hope that in most, if not all, gear the full
DMX packet is received, buffered, and re-transmitted down the
line. At least, at the price
point I'm paying for my intelligent gear, I should hope someone had the foresight to
throw an extra RS485 chip in there. Or at the bare minimum, optically isolate the output from the input.
(The fact that I'm certain there's cheap gear out there that does, literally, Y the signal... Notwithstanding)
Going back to the OP... It boils down to this:
Yes, simply splitting the
DMX signal with a few dollars worth of components will work... Sort of.
However, it will work unpredictably, and do nasty things including (but not limited to)
voltage drop, signal
reflection and increased 'noise' in the signal.
And it will fail (oh boy, you can count on it) and when it does, you can bet every last dollar that you didn't spend on a proper
opto-splitter that it will be at the
absolute worst possible moment.
DMX devices are 'dumb' recievers... They hear a start code, and then listen to 512 bytes... Paying attention to the ones they think they need.
Reflections can cause havoc, because they'll transpose data from somewhere else in the packet overtop of the correct data... Or there may simply not be enough signal by the time it reaches the device for it to be read properly... Or it could just be riddled with noise... Or, Or, Or...
To put it bluntly: Your moving heads will wig out unexplainably, your scrollers will get the shakes, and your
hazer may just decide to not
haze.
(Anyone who's worked with
DMX has likely seen any and all of these symptoms occur with proper gear that has had a component within the
DMX transmit/recieve module start to fail... And wouldn't, voluntarily, wish this on anyone.)
For $100 you can save yourself (and everyone who inherits the space from you) a world of
DMX gremlins, unexplainable random errors, and nastiness...
Sidenote: you probably shouldn't Y audio cable either.
Why Not Wye?