does using XLR cables instead of DMX cables screw up your lights? and how?

**DJ Matt** · 03-05-2018, 07:04 AM

iv been told by people working in local sound rental stores that you can use XLRs for this, and they do all the time.

but i remember hearing somewhere that it was not good to do this and will f* up your lights.
anyways, i decided to give this a try the other day, i tried to daisy chain 4 LED fixtures together using xome XLR cables (normally used for my speakers) set one light to a program, and then the others to slave, the first light followed the master light fine but once i got past the first light, the second one was just going bananas flickering like mad, so i decided to give it a miss untill i consult you guys.

perhaps this was because i used XLRs , or perhaps its for another reason

what are your thoughts?

**inthedirtagain** · 03-05-2018, 08:04 AM

Just had this happen to me last week. Purchased some inexpensive RGB par lights and ADJ Inno Pocket Fusion. None of them would respond to my usb/dmx interface with a standard xlr cable. I decided to try a 2-pack (25ft) xlr cable set from Amazon and the lights are now responsive. Been told that dmx cable are meant for data streams and are shielded better than xlr that are meant for music. Sorry, but can't explain it any better than that.

**conanski** · 03-05-2018, 09:57 AM

Originally Posted by DJ Matt

iv been told by people working in local sound rental stores that you can use XLRs for this, and they do all the time.

OK I have done a LOT of testing with this and here are my results.

I lined up 8 LED uplights on the floor in my basement and connected them all with standard 3' mic/interconnect cables and another longer 10' cable between the first fixture and the DMX controller. The first 3 or 4 fixtures followed commands no problem but the last 4 were slow, intermittent, and did some random flashing.

I changed out all the cables with proper DMX cables and got pretty much the same result, it was a little better maybe 6 of the 8 fixtures worked OK but there was still some random flashing and irregular behaviour.

Next I installed a DMX terminator in the last fixture and this cured all problems, solid reliable performance. The interesting thing is the terminator produced the same reliable results with the mic cables, and since that I have run several hundred feet of mic cable around ballrooms connecting lighting of various types with no problems as long as there is a DMX terminator at the end of the line.

**light-o-matic** · 03-05-2018, 11:00 AM

It won't screw up your lights. The consequence of using the wrong cable, when problems do pop up, is that you will get flaky, weird response from the lights, blinking etc.. or no response at all.

It will pretty much always work in setups where the number of lights are small and the total distance of cable is relatively small. The more length you have and the more lights you have, the greater the chance that you will have a problem. The reason is because DMX is designed for a cable and connectors with a consistent characteristic impedance of 120 ohms.. and regular mic cables do not have this, so you get a less clean transmission of the signal with more errors. Same thing if you don't use a DMX terminator. When you use the right cable and terminator, DMX can run reliably for over 1000 feet... When I worked in theatre I always used the right cable because the console was further from the lights/dimmers and I could not afford to have any nonsense in control of the lights on a live show.. it had to work perfectly, always. In a DJ situation with a short run and less precise lighting you can get away with using mic cables.

**DJ Matt** · 03-05-2018, 12:35 PM

Originally Posted by conanski

OK I have done a LOT of testing with this and here are my results.

I lined up 8 LED uplights on the floor in my basement and connected them all with standard 3' mic/interconnect cables and another longer 10' cable between the first fixture and the DMX controller. The first 3 or 4 fixtures followed commands no problem but the last 4 were slow, intermittent, and did some random flashing.

I changed out all the cables with proper DMX cables and got pretty much the same result, it was a little better maybe 6 of the 8 fixtures worked OK but there was still some random flashing and irregular behaviour.

Next I installed a DMX terminator in the last fixture and this cured all problems, solid reliable performance. The interesting thing is the terminator produced the same reliable results with the mic cables, and since that I have run several hundred feet of mic cable around ballrooms connecting lighting of various types with no problems as long as there is a DMX terminator at the end of the line.

i wonder if the reason for the erratic behaviour was due to where they are plugged in.... a bit like a DMX version of 50Hz hum ?

what is a DMX terminator exactly? i did a search for it and its just turning up basic 3 pin XLR/DMX connectors.

**conanski** · 03-05-2018, 12:49 PM

Originally Posted by DJ Matt

i wonder if the reason for the erratic behaviour was due to where they are plugged in.... a bit like a DMX version of 50Hz hum ?

Not sure what you mean by that, there is only 1 DMX in and 1 DMX out on each fixture so regardless what cable is used they all plug in to the same place. The erratic behavour is because of noise in the signal, the terminator dampens this.

Originally Posted by DJ Matt

what is a DMX terminator exactly? i did a search for it and its just turning up basic 3 pin XLR/DMX connectors.

Yeah that is it pretty much.. but they do have a 120ohm resistor soldered across pins 2 and 3 which makes them easy to DIY.

**DJ Matt** · 03-05-2018, 01:24 PM

Originally Posted by conanski

Not sure what you mean by that, there is only 1 DMX in and 1 DMX out on each fixture so regardless what cable is used they all plug in to the same place. The erratic behavour is because of noise in the signal, the terminator dampens this.

Yeah that is it pretty much.. but they do have a 120ohm resistor soldered across pins 2 and 3 which makes them easy to DIY.

ok, interesting, i have played around with my lights here and it seems that certain cables set it off for some unknown reason,maybe the cables in question are damaged somehow.
wierdly, the next light in the chain doesnt even need to be turned in, in fact once the "bad" cable is plugged into the output of a light the light goes nuts.
i found a combination of cables that seems to work fine now (incidentally they are DMX cables anyways, just one of them seemed to give problems) so i will store those cables with the lights.

**conanski** · 03-05-2018, 06:11 PM

Originally Posted by DJ Matt

i found a combination of cables that seems to work fine now (incidentally they are DMX cables anyways, just one of them seemed to give problems) so i will store those cables with the lights.

You will need a terminator sooner or later so it's worth it to buy/make one to have on hand.