Thoughts on this light... World's smallest RGB DMX light

[beardedbil]

To all members,
I am working on a haunted attraction project for a client and he desperatly wants to use these Precision DMX lights which are marketed as the worlds smallest RGB DMX light:

Precision DMX: RGB Theatrical Light

My question and potential problem is the way the light is manufactured. It shows only one DMX input on a 3.5mm TRS jack. When I spoke to the vendor he suggested using a headphone splitter to direct the DMX signal onto the next light for ease of wiring. Then we could use simple 1/8" headphone extensions to go from light to light.

The website does show a setup diagram (seen below) using bare wires but he shows the signal T-ing at every light. It is my understanding that the DMX protocol does not allow this type of wiring. Am I completely wrong? I would think the headphone splitter would not work as well either.

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When speaking to the vendor about this he said he did a lab test using headphone extensions as wire and it worked perfectly for the 5 lights he setup. We will be using over 75 lights between 2 universes of DMX which makes me worry. We will also be using a DMX splitter from Blizzard lighting to hopefully cut down on any errors and length of DMX legs . I am writing today to get the members feelings and thoughts on this light... Hope everyone is having a great day!
Best,
Bill Rod.

 

[DuckJordan]

It will work until it won't. Your right in thinking dmx doesn't like being split like that.

Sent from my ADR6300 using Tapatalk

 

[jfleenor]

Hey there Bill! I was pointed in this thread's direction [Thanks Dave!], and I got Milton to take a look at it for you. Here's his response:

I have avoided Control Booth as I would spend all day doing nothing but that. As a consequence, I have no login. So, here's my response to this thread:

The use of a 3.5mm TRS connector and the cable typically associated with such connectors is definitely outside of the DMX512 and DMX512-A specifications. "T", "Y", and star wiring topologies are also not allowed. The fact that someone did a test with 5 fixtures and it "worked perfectly" is only because the tester is lucky and/or the test was performed over a very fairly short cables (under 25 feet). We have made DMX work perfectly over barbed wire laying on the ground, but if you try that over a 500 foot run, you will quickly discover why we always emphasize proper cable and connectors.

All that said, the real question is what you can do to make these non-compliant fixtures work reliably in a medium sized installation. Your first response was correct. Using a proper DMX splitter at least isolates the out-of-spec situations from the rest of the world. I would use as many splitters as possible. Each one can have proper cabling going to its input. In an ideal world, you would have one splitter output for each of these lights. Each output would be located as close as possible to the fixture so as to minimize the cable length from the fixture to the splitter output. On very short runs, you can even *get away with* using a "Y" adaptor. Please note that I am not endorsing the use of such adaptors; I am only pointing out that it is possible to bend the rules if you know what you are doing and why you are doing it. Things may still break, but on short runs, it's less likely.

The first sign of problems due to cabling issues is typically flickering when you are supposed to be in a static color. The other is interaction between channels or fixtures. Let me know if you need any other input on this. My contact information is shown below.

Regards,

Milton Davis, Engineer, ETCP-CEE-RT
Doug Fleenor Design, Inc.
396 Corbett Canyon Road
Arroyo Grande, CA 93420
e-mail: [email protected]
web: www.dfd.com
phone & FAX: 805-481-9599

I hope he was able to answer your questions. Have a great day!

 

[beardedbil]

Hey there Bill! I was pointed in this thread's direction [Thanks Dave!], and I got Milton to take a look at it for you. Here's his response:



I hope he was able to answer your questions. Have a great day!

Thank you very much for the response. I understand what you mean by using as many DMX splitters as possible. I doubt my client with go for that solution but that will always be an option I can present him.

One thing my client did purchase was custom 3.5mm TRS to XLR cables. So that the pinout of the TRS matches that of a 3 pin dmx signal. Whether that makes this more stable of a system, I doubt it, but maybe it will help the slightest. I guess at this point I am going to cross my fingers and just hope it works, but in reality I am pretty sure running these lights over long distances will have issues.
Thank you again...
Best,
Bill Rod.

 

[xander]

Personally, I would avoid using this product. Trying to get 75 of them all working flawlessly (all at the same time) might turn into a real nightmare. What exactly is the application that requires such a small unit? It's only 3 watts and has a 120deg beam angle. I can't imagine it is really going to accomplish what your client wants it to. You could probably get just about as much light out of something like LED tape. Is it possible to go a little bit larger in order to get a more appropriate product?

-Tim

 

[beardedbil]

Personally, I would avoid using this product. Trying to get 75 of them all working flawlessly (all at the same time) might turn into a real nightmare. What exactly is the application that requires such a small unit? It's only 3 watts and has a 120deg beam angle. I can't imagine it is really going to accomplish what your client wants it to. You could probably get just about as much light out of something like LED tape. Is it possible to go a little bit larger in order to get a more appropriate product?

-Tim

Hi Tim,
My client likes it because it is so small making it easy to hide in the rafters or sometimes right above the customer as they walk through the haunted attraction. I advised against the product but he went ahead and purchased 75 of them anyways. I believed he really liked it as well because it offers a "flicker" setting, and he likes to make many fixtures flicker which is a pain to do through DMX, as we will be using an DMX playback module for the entire attraction. It basically needs to light small scenes in a walk through attraction. I wouldn't mind at all going larger for a more stable system, but I couldn't seem to locate anything within a similar price range, with similar or higher output... Do you know of anything?
Best,
Bill Rod.

 

[beardedbil]

Also here is the diagram the vendor gave me, which made me very suspicious...

 

[KGDJ]

I use the RGB Pinball from Blizzard Lighting and it has the 1/8" jacks for DMX. However, it has a seperate input and thru on it. I made a DMX to 1/8" adaptor and then just daisy chain them. 9 times out of 10, though, I just use the internal programs.

PinBall

It's stupid small too. About the size of a softball.

 

[dj41354]

another small LED fixture, The BrickBlaster PRO:
LED Fixtures | The Black Tank
4x4x4" cube, RGBW, 50W, 1200Lumens, adjustable beam angle (15 to 60degrees) $780MSRP

 

[len]

Not a fan of yet another cable connection. It may be fine if you're using this in permanent installation, but for those of us who are going in and out of places on a regular basis, it'd be pretty low on my wish list just because of that.

 

[chausman]

Also here is the diagram the vendor gave me, which made me very suspicious...

View attachment 5302

As far as I know, those splitters, wouldn't work like that. Unless it is some proprietary splitter, they split the male end, and send that to the female end. As in, having the same pin-out on each end. Not, having an in on one side and an out on the other.

 

[derekleffew]

As far as I know, those splitters, wouldn't work like that. Unless it is some proprietary splitter, they split the male end, and send that to the female end. As in, having the same pin-out on each end. Not, having an in on one side and an out on the other.

They're like these

Amazon.com: GLS Audio 6 Inch Patch Y Cable Cords - 1/4" TRS Male To Dual 1/4" TRS Female Cables - 6" Home Series Y-Cable Cord Splitter - 4 PACK: Electronics
and will work fine, unless/until they don't. Oh, and this:

Splitting

Never split a DMX signal with a "wye" cable. Use a splitter device that buffers each line separately or daisy chain from device to device.

The problem with splitting the signal with a wye cable is that the signal going up one leg of the wye is reflected back down and corrupts the signal going down the other leg. The longer the legs of the wye, the worse the problem. A wye where each leg is 10 feet may work fine but may fail if the legs are increased to 100 feet. A lot has to do with the quality of the cable, the strength of the signal at the wye point, and your relationship with God.

If you must split the signal, and you don't have a buffered splitter, do it as close to the source as possible, i.e. at the console. If you have an isolator available, place the wye at the output of the isolator. If you have two isolators available, place the wye at the input to the two isolators (which is like making your own splitter).

from Doug Fleenor Design - DMX Primer .

 

[Chris15]

We're talking here about putting spurs on the DMX line, not generally a wise move.
BUT we're talking about spurs that are 6 inches long, maybe 8 once you add everything up...
I'd hazard a guess that there is more than one DMX product out there that has a straight link between input and thru connectors and then a cable coming off that PCB to connect to the motherboard - is that not also a spur that's probably at least 8 inches long?

I presumed that the vendor in quesion was suggesting the use of the rigid 1/8" double adapters, rather than a cable based Y per Derek's pics. Ultimately that's moot, both legs of that are the main DMX trunk, not the spur.

I'd probably be looking to break the system up into a few runs and isolate each one off but my gut reaction is that a run of 10 or 15 is probably going to behave OK. Wer'e not talking about vast distances from what I can gather.
You could use an actual data cable in lieu of the headphone cables - that will help things along, particularly for the trunk line between splitter and 1st fixture.

 

[thrilltainment]

Hey there Bill! I was pointed in this thread's direction [Thanks Dave!], and I got Milton to take a look at it for you. Here's his response:
[...]
I hope he was able to answer your questions. Have a great day!

Dear All,

I noticed this discussion about our product and wanted to comment. Indeed, the TRS plug that we use for DMX signal is non-standard. This was a design trade off we had to decide on in the early stages of product development. We had customers needing extremely compact lighting solutions with DMX control --- using an XLR cabling system was just too large for the design as a single XLR plug is about the size of the light fixture, let alone two plugs. In the applications that called for our product, distance wasn't as big of an issue as size.

That being said, we definitely understand the concern of signal degradation over splitting and longer distances. Therefore, we are developing signal repeaters that offers a DMX through output. These repeaters can be directly plugged into our Precision DMX lights to pass the DMX In signal to the light while repeating a pass-through signal for the DMX Out connection down to the next fixture. If trying to follow DMX standards (other than the plug form factor), each fixture would be attached to one of these repeaters --- but practically speaking, using a single repeater for several fixtures is quite reasonable.

I have included a video of us successfully controlling 32 individually addressed fixtures over 525ft of audio extension cable using only Y splitters.

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We certainly appreciate any feedback the lighting community can offer us as we're continuously innovating to meet our customers' demands.

Sincerely,

Quan Gan
President, Darklight: Precision Lighting System

 

[beardedbil]

Dear All,

I noticed this discussion about our product and wanted to comment. Indeed, the TRS plug that we use for DMX signal is non-standard. This was a design trade off we had to decide on in the early stages of product development. We had customers needing extremely compact lighting solutions with DMX control --- using an XLR cabling system was just too large for the design as a single XLR plug is about the size of the light fixture, let alone two plugs. In the applications that called for our product, distance wasn't as big of an issue as size.

That being said, we definitely understand the concern of signal degradation over splitting and longer distances. Therefore, we are developing signal repeaters that offers a DMX through output. These repeaters can be directly plugged into our Precision DMX lights to pass the DMX In signal to the light while repeating a pass-through signal for the DMX Out connection down to the next fixture. If trying to follow DMX standards (other than the plug form factor), each fixture would be attached to one of these repeaters --- but practically speaking, using a single repeater for several fixtures is quite reasonable.

I have included a video of us successfully controlling 32 individually addressed fixtures over 525ft of audio extension cable using only Y splitters.

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We certainly appreciate any feedback the lighting community can offer us as we're continuously innovating to meet our customers' demands.

Sincerely,

Quan Gan
President, Darklight: Precision Lighting System

Thank you to all who responded about my original post. There has been great insight and I appreciate Quan (the owner of Darklight systems and the light we are discussing) coming on here and re-assuring me about the Precision DMX light.

Chris15, your right I will be splitting the DMX legs into as few lights as possible. I have a 8output DMX splitter so I will run a few lights of each output to cut down on any signal errors and also isolate any problems that may exist in the system. From seeing Quan's video it does give me confidence that it will work with the audio extension cables and my 6in "y" cables, much like the ones pictured above.

I will be installing these lights in September and will be happy to report back how they work. My experience with Darklight Systems has been a good one and Quan seems to want to do whatever he can to make sure his system works, and works properly, and I really appreciate that.
Best,
Bill Rod.

 

[KeeperoftheKeys]

- I hope I won't be strung up for this one, playing devils' advocate here -

Though on the one hand their wiring scheme does look really bad (and lets not even talk about the cabling recommendation), and gave me the same close to alergic reaction as most people above.
The Y-splits here are actually more like the 'normal' EIA-485 bus since every Y serves 1 fixture (which is in essence what also happens inside of any fixture), this is of course on the condition that you use no more then 1 fixture per Y and have 1 'bus' and that the tail from the fixture is not too long (no longer then 3 feet/1m IIRC).

Obviously obeying standards is important and situations with lots of different plugs and polarities for the same signal are just annoying for the users but DMX-512 does allow other plugs when the fixture is unable to accommodate full-size XLR plugs due to size restrictions.

 

[derekleffew]

... but DMX-512 does allow other plugs when the fixture is unable to accommodate full-size XLR plugs due to size restrictions.

Interesting. Would you show where in ANSI E1.11 - 2008 this is stated?

 

[ScottT]

Interesting. Would you show where in ANSI E1.11 - 2008 this is stated?

It's located here:

DMX512 1990 specifies that where connectors are used, the data link shall use five-pin XLR style electrical connectors (XLR-5), with female connectors used on transmitting (OUT) ports and male connectors on receiving ports. DMX512-A (E1.11) requires the use of an XLR-5 connector, unless there is insufficient physical space on the device, in which case an XLR-5 adapter shall be supplied. DMX512-A (E1.11-2008) allows the use of eight-pin modular (RJ-45) connectors for fixed installations where regular plugging and unplugging of equipment is not required.

 

[DuckJordan]

But that requires that there be an XLR-5 Adapter meaning going from the device there should be a tail ending in the five pin XLR, for connection not substituting the connector for a different one.

 

[ScottT]

But that requires that there be an XLR-5 Adapter meaning going from the device there should be a tail ending in the five pin XLR, for connection not substituting the connector for a different one.

I wasn't commenting on the original problem, only on derekleffew's request.