Hi David I'm using Y cables without any problems, but you have to know what you're doing to avoid problems. The real issue is that most people are just using a simple resistor as termination to avoid reflections. It works but at the same time they really suck up a lot of your signal. Usually an RS485 transceiver has in input impedance of around 12kOhm (if it isn't a quarter-load type allowing up to 128 devices). If you terminate a cable with a 120ohm resistor the load seen by the driver is comparable to attaching 100 lights with 12kOhm to the bus. As a 120ohm termination at both ends double that figure, so you can see that it's really the termination resistors loading your bus. If you add a Y-cable you have 3 ends and need 3 120ohm terminations in parallel equal to a 40ohm load. Many transceivers are not specified for a load much below 60ohm (maybe 50ohm or so - it varies by type). The good news is that to kill the reflections you only need to have 120ohm at the frequency of your signal. By adding a capacitor in series with your 120ohm termination you reduce the DC load on your RS485 transmitter by a factor of 7,25 (375ohm with 32 lights versus 375ohm||60ohm = 52ohm). Suddenly your RS485 transmitter has a much easier time transmitting a full amplitude signal and you're still killing all the reflections. It's simple and cheap. :) Another thing is that cables vary and not all cables perform according to the impedance printed on the sleeve, sadly. I use 100ohm in series with a 10nF capacitor on my setup to minimize reflections. If you've got an oscilloscope you can find the correct termination value by attaching a variable resistor to the end of a cable and transmit a square wave. Tune for minimum reflection and use a resistor with similar value in series with a 10nF capacitor. If you have really long cables you might need a 15nF or a 22nF capacitor instead. My cables are about 100ft or 30m so 10nF is sufficient for me. Another benefit is that you can add more fixtures because you take away the 60ohm DC load which is comparable to about 200 fixtures at DC. Now you can't add 200 fixtures because each transceiver also has an input capacitance, but you will get a lot more headroom in terms of bus loading.
Good Morning, I love your videos thank you for your work :) I'm looking for a NX 1 and NX P case but can't find any in europe... can you ship to europe?? i found no option on your website..
Might be a dumb question but having multiple different types of fixtures connected to the dmx splitter. Would I still be able to control one group of fixtures independently without messing with the other different fixtures? I hope that makes sense
What is the easyeast software do you think? I only have a little Info about soundswitch and onyx for the first time from you. I so want to do lightworks with music. So what should i do, start?
Hey man. Great video, I'm just resetting up a system. The DMX was going out of the computer system with a LSC dongle, thru and old dimmer pack, then to a splitter. I took the dimmer pack out of the system as we are on all LED lighting now. But every now and then the movers play up. Do you think going through the dimmer pack would provide any other service to the DMX chain. Like protection from power surges or anything? I'm gonna hit subscribe on your channel, I've got a lot to learn lol😅
Can you use a splitter AFTER some daisy chained lights? DMX cable comes in on one side of truss, into 10 lights, and then a splitter at the end of truss to continue to backlights. Or do I need to run a separate dmx cable across truss?
i'm not sure I get the don't "double up" on the splitter that you mentioned. I have the same splitter in your video and I'm using the 5 pin out to connect a group of lights and I'm also using the 3 pin out to connect another group of lights. Is that "doubling up" and an incorrect use of that splitter?
Great lessons for an old timer like me who has been playing for a long time, but never considered the importance of lighting positioning.
Hi David
I'm using Y cables without any problems, but you have to know what you're doing to avoid problems. The real issue is that most people are just using a simple resistor as termination to avoid reflections. It works but at the same time they really suck up a lot of your signal.
Usually an RS485 transceiver has in input impedance of around 12kOhm (if it isn't a quarter-load type allowing up to 128 devices). If you terminate a cable with a 120ohm resistor the load seen by the driver is comparable to attaching 100 lights with 12kOhm to the bus. As a 120ohm termination at both ends double that figure, so you can see that it's really the termination resistors loading your bus.
If you add a Y-cable you have 3 ends and need 3 120ohm terminations in parallel equal to a 40ohm load. Many transceivers are not specified for a load much below 60ohm (maybe 50ohm or so - it varies by type).
The good news is that to kill the reflections you only need to have 120ohm at the frequency of your signal. By adding a capacitor in series with your 120ohm termination you reduce the DC load on your RS485 transmitter by a factor of 7,25 (375ohm with 32 lights versus 375ohm||60ohm = 52ohm). Suddenly your RS485 transmitter has a much easier time transmitting a full amplitude signal and you're still killing all the reflections.
It's simple and cheap. :)
Another thing is that cables vary and not all cables perform according to the impedance printed on the sleeve, sadly. I use 100ohm in series with a 10nF capacitor on my setup to minimize reflections.
If you've got an oscilloscope you can find the correct termination value by attaching a variable resistor to the end of a cable and transmit a square wave. Tune for minimum reflection and use a resistor with similar value in series with a 10nF capacitor. If you have really long cables you might need a 15nF or a 22nF capacitor instead. My cables are about 100ft or 30m so 10nF is sufficient for me.
Another benefit is that you can add more fixtures because you take away the 60ohm DC load which is comparable to about 200 fixtures at DC. Now you can't add 200 fixtures because each transceiver also has an input capacitance, but you will get a lot more headroom in terms of bus loading.
Good Morning, I love your videos thank you for your work :)
I'm looking for a NX 1 and NX P case but can't find any in europe... can you ship to europe?? i found no option on your website..
Great info for a newbie ty!
Might be a dumb question but having multiple different types of fixtures connected to the dmx splitter. Would I still be able to control one group of fixtures independently without messing with the other different fixtures? I hope that makes sense
Hello 👋 can you do video of patching lights connected to splitter but using avolites console
What is the easyeast software do you think? I only have a little Info about soundswitch and onyx for the first time from you. I so want to do lightworks with music. So what should i do, start?
Hey man. Great video, I'm just resetting up a system. The DMX was going out of the computer system with a LSC dongle, thru and old dimmer pack, then to a splitter. I took the dimmer pack out of the system as we are on all LED lighting now. But every now and then the movers play up. Do you think going through the dimmer pack would provide any other service to the DMX chain. Like protection from power surges or anything? I'm gonna hit subscribe on your channel, I've got a lot to learn lol😅
Nope
Can you use a splitter AFTER some daisy chained lights? DMX cable comes in on one side of truss, into 10 lights, and then a splitter at the end of truss to continue to backlights. Or do I need to run a separate dmx cable across truss?
It will work after some fixtures. It’s no problem.
Is it possible to take an output from 1 splitter and give it to the input of another splitter
Yes
i'm not sure I get the don't "double up" on the splitter that you mentioned. I have the same splitter in your video and I'm using the 5 pin out to connect a group of lights and I'm also using the 3 pin out to connect another group of lights. Is that "doubling up" and an incorrect use of that splitter?
Yeah, basically only use each output once, even if there are two connection points. Decide 3 or 5 pin and use adaptors if you must.
How can I split my DMX signal using Donner wireless transmitters and receivers?
It's not technically really splitting, but one transmitter should be able to broadcast to multiple receivers, in essence, splitting the signal :)
So does each output of the splitter give me up to 32 devices?
Theoretically, yes. As long as it's a solid splitter it will amplify the signal at the splitter similar to as if it just came out of a console.
A triangle DMX splitter like a PRISM 😅