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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => Lighting FUD Forum Archive => Topic started by: Kemper Watson on November 10, 2010, 08:36:13 am

Title: DMX cables
Post by: Kemper Watson on November 10, 2010, 08:36:13 am
What is the real difference in 3 pin DMX cables vs mic cables? Should I use only DMX cables? Thanks for your time
Title: Re: DMX cables
Post by: Rob Timmerman on November 10, 2010, 08:44:34 am
Kemper Watson wrote on Wed, 10 November 2010 08:36

What is the real difference in 3 pin DMX cables vs mic cables? Should I use only DMX cables? Thanks for your time


First off, the DMX standard calls for 5-pin XLR connectors, not 3 pin.  Secondly, the RS485 (which is what DMX is based on) standard recommends cable with a 110 ohm characteristic impedance.  Most mic cable has neither 5-pin XLR nor a 110 ohm characteristic impedance.
Title: Re: DMX cables
Post by: Matt Melberg on November 10, 2010, 09:51:16 am
My rule of thumb is, mic cables can work in a pinch, but if failure is not an option, use real DMX cables.  And a terminator at the end of the chain.
But the big difference is that DMX cable is intended for digital signals and has the proper impedance for those signals.  They are usually a little better shielded, but that all depends on the quality.
Title: Re: DMX cables
Post by: Thomas Bishop on November 10, 2010, 09:55:31 am
... and 3-pin DMX is perfectly acceptable for microphone cable.  I have 1000' spool of DMX cable on order to replace all my mic cables, and it's only pennies more than mic cable.
Title: Re: DMX cables
Post by: Silas Pradetto on November 10, 2010, 11:53:39 am
Read the article in this thread. It explains what happens to the leading edges of a digital signal that is transmitted over a high-capacitance cable.
Title: Re: DMX cables
Post by: Kemper Watson on November 10, 2010, 06:45:04 pm
Thanks.
Title: Re: DMX cables
Post by: Micky Basiliere on November 11, 2010, 12:07:06 am
I have always used 3 pin mic cables and NEVER had ANY issues! i really think its all cable hype!!! five pin is a different story...any high quality xlr 3 pin would be just fine. AND, using a DMX splitter eliminates the need for terminators
Title: Re: DMX cables
Post by: Rob Spence on November 11, 2010, 12:10:31 am
Thomas Bishop wrote on Wed, 10 November 2010 09:55

... and 3-pin DMX is perfectly acceptable for microphone cable.  I have 1000' spool of DMX cable on order to replace all my mic cables, and it's only pennies more than mic cable.

But DMX cable may not be ok for audio.

Different cable for different uses.

Audio cable works ok for DMX use for short runs. Long runs or reliability should use DMX cable.
Title: Re: DMX cables
Post by: Rob Spence on November 11, 2010, 12:13:16 am
Micky Basiliere wrote on Thu, 11 November 2010 00:07

I have always used 3 pin mic cables and NEVER had ANY issues! i really think its all cable hype!!! five pin is a different story...any high quality xlr 3 pin would be just fine. AND, using a DMX splitter eliminates the need for terminators

Option I assume. There is no science in your statements.
Connector type is simply a choice you make for the instruments you are using. The cable types are different. Terminators are important. Some times you can get away with out them for short runs.
Title: Re: DMX cables
Post by: Marlow Wilson on November 11, 2010, 09:12:18 am
Kemper Watson wrote on Wed, 10 November 2010 08:36

What is the real difference in 3 pin DMX cables vs mic cables? Should I use only DMX cables? Thanks for your time


The best affordable DMX cables I have found are the ADJ Accu Cable line.  They are obviously not top shelf quality, but the soldering appears to be okay (Better than I can do, I'm ashamed to say)and the cable is generally workable.  The connectors are not perfect, but for the price they are very serviceable.

At these prices, there is no excuse not to use the correct cable (and buy the terminator while you are at it):

http://www.godirectmusic.com/advanced_search_result.php?keyw ords=accu-cable&x=0&y=0

(That's where I ordered from and I was happy with the service).

If you want I can try to take some pics of the connectors and soldering later today.
Title: Re: DMX cables
Post by: Micky Basiliere on November 11, 2010, 10:33:33 am



Rob Spence wrote on Thu, 11 November 2010 00:13

Micky Basiliere wrote on Thu, 11 November 2010 00:07

I have always used 3 pin mic cables and NEVER had ANY issues! i really think its all cable hype!!! five pin is a different story...any high quality xlr 3 pin would be just fine. AND, using a DMX splitter eliminates the need for terminators

Option I assume. There is no science in your statements.
Connector type is simply a choice you make for the instruments you are using. The cable types are different. Terminators are important. Some times you can get away with out them for short runs.


Using the splitter creates shorter runs...eliminating the need for terminatore.


Title: Re: DMX cables
Post by: Shane Presley on November 11, 2010, 03:41:06 pm
The best difference it makes for me is the lighting patch cables are not taken for audio use, and visa versa... I ordered all my DMX in purple, so it's VERY distinct.  This makes trouble shooting, or patching a lot easier than following 2 black mic cables, one audio and one dmx.... As others have said it's a minimal cost difference to use the "correct stuff". Also I've found using a termintor is not needed unless it's needed - if that makes sense... If your fixtures are behaving without termination then don't bother. If they are erratic, then terminate.  

I'll also throw one out to the "no dmx on audio lines" guys... 9 times out of 10, I run the lighting sends, up my audio snake (250ft), before it hits the opto splitter.  Yes the 10th time, it makes noise on the audio, but for the most part it works like a charm... when it doesn't I run 2 x 100ft dmx lines...but that's rare...
Title: Re: DMX cables
Post by: Rob Timmerman on November 11, 2010, 08:11:26 pm
Rob Spence wrote on Thu, 11 November 2010 00:10

Thomas Bishop wrote on Wed, 10 November 2010 09:55

... and 3-pin DMX is perfectly acceptable for microphone cable.  I have 1000' spool of DMX cable on order to replace all my mic cables, and it's only pennies more than mic cable.

But DMX cable may not be ok for audio.

Different cable for different uses.

Audio cable works ok for DMX use for short runs. Long runs or reliability should use DMX cable.



Why would DMX cable not be ok for audio?
Title: Re: DMX cables
Post by: Micky Basiliere on November 11, 2010, 09:47:32 pm
Shane Presley wrote on Thu, 11 November 2010 15:41

The best difference it makes for me is the lighting patch cables are not taken for audio use, and visa versa... I ordered all my DMX in purple, so it's VERY distinct.  This makes trouble shooting, or patching a lot easier than following 2 black mic cables, one audio and one dmx.... As others have said it's a minimal cost difference to use the "correct stuff". Also I've found using a termintor is not needed unless it's needed - if that makes sense... If your fixtures are behaving without termination then don't bother. If they are erratic, then terminate.  

I'll also throw one out to the "no dmx on audio lines" guys... 9 times out of 10, I run the lighting sends, up my audio snake (250ft), before it hits the opto splitter.  Yes the 10th time, it makes noise on the audio, but for the most part it works like a charm... when it doesn't I run 2 x 100ft dmx lines...but that's rare...


I do the opposite...From FOH,from opto splitter(6 sends) out through 150' lighting ONLY snake to stage...NO TERMINATORS(they only cause problems!) I would not recommend sending DMX through an audio snake??? just my 2 cents... Smile
Title: Re: DMX cables
Post by: Tom Bourke on November 11, 2010, 11:47:48 pm
Micky Basiliere wrote on Wed, 10 November 2010 23:07

I have always used 3 pin mic cables and NEVER had ANY issues! i really think its all cable hype!!! five pin is a different story...any high quality xlr 3 pin would be just fine. AND, using a DMX splitter eliminates the need for terminators

and
Quote:

I do the opposite...From FOH,from opto splitter(6 sends) out through 150' lighting ONLY snake to stage...NO TERMINATORS(they only cause problems!) I would not recommend sending DMX through an audio snake??? just my 2 cents... Smile


All of this is wrong in my experience.  Audio cables work ok for short run and few instruments.  Once you hit any kind of length or instrument counts signal breaks down.  Worse yet is mixing audio and data cable types in one system.  If a terminator makes things worse you have a problem or 2 some place else.

Every time there is a change in cable type there is a reflection of the signal from that point.  If you have several such changes you have lots of interactions.  A terminator is meant to act as a substitute for an infinite line.  The reason they may or may not cause a problem in a mixed or audio only cable environment is they change how the reflections interact.  Some times they make it worse, some times better. Depends on how the reflection from an unterminated line interacts.  Every output of a splitter should have its own termination.  Don't even think of Y cables.

It is understanding these reflections that explains the erratic nature of DMX problems.  I have seen them on a scope and in video setups.
Title: Re: DMX cables
Post by: Rob Spence on November 12, 2010, 06:58:54 pm
Rob Timmerman wrote on Thu, 11 November 2010 20:11

Rob Spence wrote on Thu, 11 November 2010 00:10

Thomas Bishop wrote on Wed, 10 November 2010 09:55

... and 3-pin DMX is perfectly acceptable for microphone cable.  I have 1000' spool of DMX cable on order to replace all my mic cables, and it's only pennies more than mic cable.

But DMX cable may not be ok for audio.

Different cable for different uses.

Audio cable works ok for DMX use for short runs. Long runs or reliability should use DMX cable.



Why would DMX cable not be ok for audio?

Well, for one thing it is the wrong impedance. Why do you think there are multiple kinds of cable?
Heck, my main power feeder has twisted conductors but that doesn't make it ok for mic cable.
So, shielded twisted pair for mic cables is a different impedance than that for DMX because DMX is a digital signal and audio is analog.

An electric circuit such as the input of a mixer is made up of 3 main components. There is the mic, the cable, and the mixer preamp. Together they make a circuit that takes sound waves, generates electricity, transmits it over the wires and into the mixer. For it to work right (meaning get the audio into the mixer without distorting it), all the impedances should be correct. Same goes for other kinds of circuits like TV antenna or WIFI antenna.
Title: Re: DMX cables
Post by: Rob Spence on November 12, 2010, 07:02:17 pm
Micky Basiliere wrote on Thu, 11 November 2010 10:33




Rob Spence wrote on Thu, 11 November 2010 00:13

Micky Basiliere wrote on Thu, 11 November 2010 00:07

I have always used 3 pin mic cables and NEVER had ANY issues! i really think its all cable hype!!! five pin is a different story...any high quality xlr 3 pin would be just fine. AND, using a DMX splitter eliminates the need for terminators

Option I assume. There is no science in your statements.
Connector type is simply a choice you make for the instruments you are using. The cable types are different. Terminators are important. Some times you can get away with out them for short runs.


Using the splitter creates shorter runs...eliminating the need for terminatore.




Micky, if you are going to quote me, don't put your thoughts in my quote!

If I understand what you meant, yes, the splitter makes shorter runs but it doesn't "eliminate" the need for terminations, you are simply lucky it works without them.
Title: Re: DMX cables
Post by: Rob Spence on November 12, 2010, 07:05:41 pm
Micky Basiliere wrote on Thu, 11 November 2010 21:47

Shane Presley wrote on Thu, 11 November 2010 15:41

The best difference it makes for me is the lighting patch cables are not taken for audio use, and visa versa... I ordered all my DMX in purple, so it's VERY distinct.  This makes trouble shooting, or patching a lot easier than following 2 black mic cables, one audio and one dmx.... As others have said it's a minimal cost difference to use the "correct stuff". Also I've found using a termintor is not needed unless it's needed - if that makes sense... If your fixtures are behaving without termination then don't bother. If they are erratic, then terminate.  

I'll also throw one out to the "no dmx on audio lines" guys... 9 times out of 10, I run the lighting sends, up my audio snake (250ft), before it hits the opto splitter.  Yes the 10th time, it makes noise on the audio, but for the most part it works like a charm... when it doesn't I run 2 x 100ft dmx lines...but that's rare...


I do the opposite...From FOH,from opto splitter(6 sends) out through 150' lighting ONLY snake to stage...NO TERMINATORS(they only cause problems!) I would not recommend sending DMX through an audio snake??? just my 2 cents... Smile

I submit that correct termination of the DMX line would not cause problems. Explain please.

I don't recommend sending DMX down audio cables either but I do it when I have to knowing I am taking some amount of risk.
Title: Re: DMX cables
Post by: Rob Timmerman on November 12, 2010, 07:32:18 pm
Rob Spence wrote on Fri, 12 November 2010 18:58

Rob Timmerman wrote on Thu, 11 November 2010 20:11

Rob Spence wrote on Thu, 11 November 2010 00:10

Thomas Bishop wrote on Wed, 10 November 2010 09:55

... and 3-pin DMX is perfectly acceptable for microphone cable.  I have 1000' spool of DMX cable on order to replace all my mic cables, and it's only pennies more than mic cable.

But DMX cable may not be ok for audio.

Different cable for different uses.

Audio cable works ok for DMX use for short runs. Long runs or reliability should use DMX cable.



Why would DMX cable not be ok for audio?

Well, for one thing it is the wrong impedance. Why do you think there are multiple kinds of cable?
Heck, my main power feeder has twisted conductors but that doesn't make it ok for mic cable.
So, shielded twisted pair for mic cables is a different impedance than that for DMX because DMX is a digital signal and audio is analog.

An electric circuit such as the input of a mixer is made up of 3 main components. There is the mic, the cable, and the mixer preamp. Together they make a circuit that takes sound waves, generates electricity, transmits it over the wires and into the mixer. For it to work right (meaning get the audio into the mixer without distorting it), all the impedances should be correct. Same goes for other kinds of circuits like TV antenna or WIFI antenna.



So I take it you wouldn't mix'n'match Canare L4-E6s (Z=44 ohms), Belden 8412 (Z=67 ohms), or snake cables (Z ranging from 40 through 70 ohms depending on the cable) in the same run for a mic cable?  (Connecting 8412 to the StarQuad is the same amount of mismatch as connecting the 8412 to a 110 ohm DMX cable).


The reality is that cable impedance only really becomes important once the cable is long enough that it needs to be treated as a transmission line (~1/10 wavelength).  For audio frequencies, this is around 1km, or rather longer than we typically encounter.  For DMX runs, this 1/10 wavelength is around 150', or well within what may be encountered in typical environments.
Title: Re: DMX cables
Post by: Rob Spence on November 13, 2010, 11:56:40 am
Rob Timmerman wrote on Fri, 12 November 2010 19:32

Rob Spence wrote on Fri, 12 November 2010 18:58

Rob Timmerman wrote on Thu, 11 November 2010 20:11

Rob Spence wrote on Thu, 11 November 2010 00:10

Thomas Bishop wrote on Wed, 10 November 2010 09:55

... and 3-pin DMX is perfectly acceptable for microphone cable.  I have 1000' spool of DMX cable on order to replace all my mic cables, and it's only pennies more than mic cable.

But DMX cable may not be ok for audio.

Different cable for different uses.

Audio cable works ok for DMX use for short runs. Long runs or reliability should use DMX cable.



Why would DMX cable not be ok for audio?

Well, for one thing it is the wrong impedance. Why do you think there are multiple kinds of cable?
Heck, my main power feeder has twisted conductors but that doesn't make it ok for mic cable.
So, shielded twisted pair for mic cables is a different impedance than that for DMX because DMX is a digital signal and audio is analog.

An electric circuit such as the input of a mixer is made up of 3 main components. There is the mic, the cable, and the mixer preamp. Together they make a circuit that takes sound waves, generates electricity, transmits it over the wires and into the mixer. For it to work right (meaning get the audio into the mixer without distorting it), all the impedances should be correct. Same goes for other kinds of circuits like TV antenna or WIFI antenna.



So I take it you wouldn't mix'n'match Canare L4-E6s (Z=44 ohms), Belden 8412 (Z=67 ohms), or snake cables (Z ranging from 40 through 70 ohms depending on the cable) in the same run for a mic cable?  (Connecting 8412 to the StarQuad is the same amount of mismatch as connecting the 8412 to a 110 ohm DMX cable).


The reality is that cable impedance only really becomes important once the cable is long enough that it needs to be treated as a transmission line (~1/10 wavelength).  For audio frequencies, this is around 1km, or rather longer than we typically encounter.  For DMX runs, this 1/10 wavelength is around 150', or well within what may be encountered in typical environments.

For Audio, I would not be bothered by the mis matches as I am unlikely to hear the resulting distortion.
For DMX, the distortion may result in bright lights pointing where they should not.
Your call.
Title: Re: DMX cables
Post by: Kemper Watson on November 13, 2010, 05:39:07 pm
So the higher the ohms the better to transmit data?
Title: Re: DMX cables
Post by: Rob Spence on November 13, 2010, 05:49:14 pm
Kemper Watson wrote on Sat, 13 November 2010 17:39

So the higher the ohms the better to transmit data?

No.

The impedance (not resistance) of the cable needs to match to the circuits in each device and the final termination such that there are no disruptions to cause reflections which will corrupt the digital data. Note that "matching" doesn't mean same impedance. It means the correct number for the design. This is true for all digital transmission.

DMX design specifies a specific cable. Simple. It is only the popularity of inexpensive DMX devices with 3 pin connectors that has led people to use microphone cable because it looks right visually. The fact that it works much of the time for small configurations has led people to make all sorts of erroneous assumptions.
Title: Re: DMX cables
Post by: Bob Goodwin on November 14, 2010, 02:04:49 pm
I'm afraid to ask but here goes:  If I just want to link 2 LED pars together so that they fade and change colors together (Slave and Master???) without a controller, what kind of cable do I use?
Title: Re: DMX cables
Post by: Rob Timmerman on November 14, 2010, 03:22:29 pm
Bob Goodwin wrote on Sun, 14 November 2010 14:04

I'm afraid to ask but here goes:  If I just want to link 2 LED pars together so that they fade and change colors together (Slave and Master???) without a controller, what kind of cable do I use?


What does the fixture manufacturer recommend?
Title: Re: DMX cables
Post by: Rob Spence on November 14, 2010, 03:55:22 pm
Bob Goodwin wrote on Sun, 14 November 2010 14:04

I'm afraid to ask but here goes:  If I just want to link 2 LED pars together so that they fade and change colors together (Slave and Master???) without a controller, what kind of cable do I use?

If they are DMX, then the "right" answer is DMX cable.
That said, if they are close together (under 100'), it likely that an XLR cable will work.
Rob is right, what does it say in the manual? You did read it, right?
Title: Re: DMX cables
Post by: Bob Goodwin on November 14, 2010, 05:14:09 pm
I presently don't have any lights. I happen to read owners manuals when I get them. Thanks for the help!
Title: Re: DMX cables
Post by: Micky Basiliere on November 14, 2010, 09:14:44 pm
Rob Spence wrote on Sun, 14 November 2010 15:55

Bob Goodwin wrote on Sun, 14 November 2010 14:04

I'm afraid to ask but here goes:  If I just want to link 2 LED pars together so that they fade and change colors together (Slave and Master???) without a controller, what kind of cable do I use?

If they are DMX, then the "right" answer is DMX cable.
That said, if they are close together (under 100'), it likely that an XLR cable will work.
Rob is right, what does it say in the manual? You did read it, right?



Just use a G.D. Mic cable and be done with it! this IS NOT rocket science... Very Happy
Title: Re: DMX cables
Post by: Bob Goodwin on November 14, 2010, 09:34:03 pm
Micky Basiliere wrote on Sun, 14 November 2010 21:14

Rob Spence wrote on Sun, 14 November 2010 15:55

Bob Goodwin wrote on Sun, 14 November 2010 14:04

I'm afraid to ask but here goes:  If I just want to link 2 LED pars together so that they fade and change colors together (Slave and Master???) without a controller, what kind of cable do I use?

If they are DMX, then the "right" answer is DMX cable.
That said, if they are close together (under 100'), it likely that an XLR cable will work.
Rob is right, what does it say in the manual? You did read it, right?



Just use a G.D. Mic cable and be done with it! this IS NOT rocket science... Very Happy




Gee, I'm sorry I asked. I thought this was a good place to ask a question. I'll try another Forum next time.
Title: Re: DMX cables
Post by: Micky Basiliere on November 14, 2010, 11:38:09 pm
[quote title=Bob Goodwin wrote on Sun, 14 November 2010 21:34]
Micky Basiliere wrote on Sun, 14 November 2010 21:14

Rob Spence wrote on Sun, 14 November 2010 15:55

Bob Goodwin wrote on Sun, 14 November 2010 14:04

I'm afraid to ask but here goes:  If I just want to link 2 LED pars together so that they fade and change colors together (Slave and Master???) without a controller, what kind of cable do I use?

If they are DMX, then the "right" answer is DMX cable.
That said, if they are close together (under 100'), it likely that an XLR cable will work.
Rob is right, what does it say in the manual? You did read it, right?



Just use a G.D. Mic cable and be done with it! this IS NOT rocket science... Very Happy



Sorry man...This topic is just out of control! you will NEVER notice a difference between Mic and "DMX" cable in the 3 pin config. 5 pin would definetly be of the "dmx" type...Have a great night. Smile
Title: Re: DMX cables
Post by: Mac Kerr on November 14, 2010, 11:45:01 pm
Micky Basiliere wrote on Sun, 14 November 2010 23:38


Sorry man...This topic is just out of control! you will NEVER notice a difference between Mic and "DMX" cable in the 3 pin config. 5 pin would definetly be of the "dmx" type...Have a great night. Smile


Why would 3 pin be different than 5 pin? It is only using 3 pins. The signal is also impedence sensitive and should have 110Ω cable. Mic cable usually works, but not always. When it doesn't work, do you want to trace where on the truss the problem is?

Mac
Title: Re: DMX cables
Post by: James Feenstra on November 15, 2010, 09:05:05 am
put up a rig with more than 4 lights in it and you will

they wouldn't make 110ohm cable the standard for dmx (and aes/ebu as well) if it wasn't necessary, cause it's definitely not cheaper
Title: Re: DMX cables
Post by: Silas Pradetto on November 15, 2010, 11:06:41 am
James Feenstra wrote on Mon, 15 November 2010 09:05

put up a rig with more than 4 lights in it and you will

they wouldn't make 110ohm cable the standard for dmx (and aes/ebu as well) if it wasn't necessary, cause it's definitely not cheaper


For AES it is absolutely necessary; I've had problems pushing AES 50 feet over mic cable...

I don't know why some "pros" on here keep insisting "their way" (which is the wrong way) is perfectly fine, just because of "their experience."   Rolling Eyes

The one time that "experience" will be wrong will be the biggest, most critical show you've done, and it will bring you back to earth in a hurry.
Title: Re: DMX cables
Post by: Micky Basiliere on November 16, 2010, 12:08:26 am
Silas Pradetto { wrote on Mon, 15 November 2010 11:06

James Feenstra wrote on Mon, 15 November 2010 09:05

put up a rig with more than 4 lights in it and you will

they wouldn't make 110ohm cable the standard for dmx (and aes/ebu as well) if it wasn't necessary, cause it's definitely not cheaper


For AES it is absolutely necessary; I've had problems pushing AES 50 feet over mic cable...

I don't know why some "pros" on here keep insisting "their way" (which is the wrong way) is perfectly fine, just because of "their experience."   Rolling Eyes

The one time that "experience" will be wrong will be the biggest, most critical show you've done, and it will bring you back to earth in a hurry.


No need for a "pissing contest" here! i've run 12 movers , 8 led pars , and fiber curtains..aswell as a plethra of colors changers and p64's with NO problem all on mic cables. I've seen alot of "dumb" threads on here from "other pros" to... Laughing
Title: Re: DMX cables
Post by: Micky Basiliere on November 16, 2010, 12:14:36 am
Mac Kerr wrote on Sun, 14 November 2010 23:45

Micky Basiliere wrote on Sun, 14 November 2010 23:38


Sorry man...This topic is just out of control! you will NEVER notice a difference between Mic and "DMX" cable in the 3 pin config. 5 pin would definetly be of the "dmx" type...Have a great night. Smile


Why would 3 pin be different than 5 pin? It is only using 3 pins. The signal is also impedence sensitive and should have 110Ω cable. Mic cable usually works, but not always. When it doesn't work, do you want to trace where on the truss the problem is?

Mac



Hi Mac, I was referring to the # of conductors needed in the cable for 5 pin...DMX Cable is "no doubt" different but,Mic cable(9 times out of ten)works just fine...Thx Smile
Title: Re: DMX cables
Post by: Bill Hinds on November 16, 2010, 07:53:06 am
What is going to happen to his show that 1 out of 10 times?  I will admit I am guilty of using the wrong cable but I also understand the risk.  The OP is asking for advice so, the right answer is he should be using the correct 110 ohm DMX cable. Using anything else may compromise performance. Now the OP knows the risk.

Title: Re: DMX cables
Post by: Tom Bourke on November 16, 2010, 08:21:35 am
Micky Basiliere wrote on Mon, 15 November 2010 23:08

Silas Pradetto { wrote on Mon, 15 November 2010 11:06

James Feenstra wrote on Mon, 15 November 2010 09:05

put up a rig with more than 4 lights in it and you will

they wouldn't make 110ohm cable the standard for dmx (and aes/ebu as well) if it wasn't necessary, cause it's definitely not cheaper


For AES it is absolutely necessary; I've had problems pushing AES 50 feet over mic cable...

I don't know why some "pros" on here keep insisting "their way" (which is the wrong way) is perfectly fine, just because of "their experience."   Rolling Eyes

The one time that "experience" will be wrong will be the biggest, most critical show you've done, and it will bring you back to earth in a hurry.


No need for a "pissing contest" here! i've run 12 movers , 8 led pars , and fiber curtains..aswell as a plethra of colors changers and p64's with NO problem all on mic cables. I've seen alot of "dumb" threads on here from "other pros" to... Laughing

I have seen that one time happen at at least twice.  One time it was a 30 can LED rig.  We had the LEDs on and were sending signal as we wired the rig.  Every thing was fine till the last light bar.  We also were running out of real DMX cables.  So the last run was done with mic cables.  The first clue we had a problem was the fact we needed to leave the terminator off. It also worked to leave off an instrument or 2 at the end. We got the rig stable enough to make it threw programming and a rehearsal.  Show night it all broke down.  The whole thing started glitching.  All it was suppose to be was lights up, lights down.  Not disco!

Point is 1 or 2 less cables and it "worked just fine"  But the rig was close enough to the edge that when it counted, it fell off the edge.  Shortly after that they bought a DMX distribution amp, terminators for each branch and more DMX cables.  Since then they have added more LEDs and the rig has stayed stable.
Title: Re: DMX cables
Post by: John Strzalkowski on December 03, 2010, 03:24:56 pm
I have run 44 LEDs with 8 movers and 8 scanners with mic cable...I had no problem.

Different night I was running 20 LEDs with mic cable, got a bunch of glitches/twitchy lights. Replaced a bunch of cable with working mic cable, and still had glitches. Frustrating as hell seeing as how i ran so much before...

Another night I was using a DMX distributor box with mic cable. The distributor DID NOT work. Any signal that went THRU the device worked fine, when trying to use a distributed line, no DMX was present at the lights. I ended up having to run a long line around the damn venue to patch in the lights that could not be distributed.

Whoever says mic cable is fine has yet to experience problems, however with the problems I have faced using mic cable, I think the extra money spent on DMX cable is FAR FAR FAR more worth it than cheaping out and 'POSSIBLY' have an annoying headache of a time trying to get something to work.
Title: Re: DMX cables
Post by: John Livings on December 04, 2010, 04:06:24 pm
For anyone wanting more Basic information on DMX, Have a look at this;

http://www.elationlighting.com/ProductDetails.aspx?ItemNumbe r=1560&MainId=1&Category=26

Regards,  John
Title: Re: DMX cables
Post by: len woelfel on December 07, 2010, 10:41:20 am
The short answer is that mic cable will GENERALLY work in MOST small rig situations.  However, if you're doing long dmx runs, using a lot of fixtures, splitters, etc., then you should be spending the money on proper data cable.  The thing is that even tho a mic cable hasn't "failed" it might add in bad data, etc. due to improper shielding, etc. and cause lights somewhere in the rig to misbehave.  The best reason to use twisted pair shielded cable for data is that tracking down a bad signal in your cabling is a tedious, time-consuming job and it's just more cost effective in the long run to get good cable than to spend the time trouble shooting.  That time could better be spent with a pint of Guinness and a hockey game.  
As for those who say mic cable is fine in larger lighting rigs, they are just lucky to have avoided failure yet.
Title: Re: DMX cables
Post by: Gian P. Portanova on December 08, 2010, 11:15:49 am
So for those who want to use the proper DMX cables, what is a good recommended source for purchasing?  Low cost install up to high end mobile applications?
Title: Re: DMX cables
Post by: Silas Pradetto on December 08, 2010, 11:56:51 am
Gian P. Portanova wrote on Wed, 08 December 2010 11:15

So for those who want to use the proper DMX cables, what is a good recommended source for purchasing?  Low cost install up to high end mobile applications?


Elation's Accu Cable has proven to be excellent, and it's cheaper than buying cable and putting ends on yourself. Even if you have to replace the generic Neutrik-style ends eventually, it's still cheaper than buying and making your own originally.

Call me...
Title: Re: DMX cables
Post by: James Feenstra on December 08, 2010, 02:40:56 pm
Gian P. Portanova wrote on Wed, 08 December 2010 11:15

So for those who want to use the proper DMX cables, what is a good recommended source for purchasing?  Low cost install up to high end mobile applications?

belden 1696a + neutrik ends in either the 3 or 5 pin variety, whichever you prefer

or for strictly 5 pin, belden 9729

there's very few lights that actually use pins 4+5, and generally the ones that do also run over cat6
Title: Re: DMX cables
Post by: John Livings on December 08, 2010, 04:47:19 pm
[quote title=Marlow Wilson wrote on Thu, 11 November 2010 08:12]

The best affordable DMX cables I have found are the ADJ Accu Cable line.  They are obviously not top shelf quality, but the soldering appears to be okay (Better than I can do, I'm ashamed to say)and the cable is generally workable.  The connectors are not perfect, but for the price they are very serviceable.

At these prices, there is no excuse not to use the correct cable (and buy the terminator while you are at it):

 http://www.godirectmusic.com/advanced_search_result.php?keyw ords=accu-cable&x=0&y=0

(That's where I ordered from and I was happy with the service).


Thanks Marlow, We ordered some DMX cables from "Go Direct Music" Great Price, Great Service.

Regards,  John


Title: Re: DMX cables
Post by: Rob Timmerman on December 08, 2010, 06:14:38 pm
Gian P. Portanova wrote on Wed, 08 December 2010 11:15

So for those who want to use the proper DMX cables, what is a good recommended source for purchasing?  Low cost install up to high end mobile applications?


For installs, CAT5 cable is fine.
http://srforums.prosoundweb.com/index.php/t/59916/108/

Title: Re: DMX cables
Post by: Graham Wakefield on December 08, 2010, 10:50:06 pm
I like the LEX stuff, coils well and is extremely rugged. A bit on the pricey side however
Title: Re: DMX cables
Post by: Tom Bourke on December 21, 2010, 12:25:04 am
Found this while working on a different project.  DMX used the RS485 wiring specs.  Here is what Maxim-IC has to say on cable and termination.  The cool thing is there are pics of what each configuration does to the wave form.

http://www.maxim-ic.com/app-notes/index.mvp/id/763
Title: Re: DMX cables
Post by: Geri O'Neil on December 21, 2010, 06:37:06 am
That's good reading, even if a little over my head. But it makes the basic point.

The assertion that advocating the use of DMX-spec cable only amounts to marketing hype and un-necessary expense can be equated to the argument that advocating the use of seat belts in vehicles only amounts to marketing hype and un-necessary expense to the consumers.

We will take our chances with the DMX-spec cable (and oh, yeah, the seatbelts, too!)

Geri O
Title: Re: DMX cables
Post by: Duane Massey on December 22, 2010, 03:07:54 am
Considering the price drop on off-the-shelf dmx cables I am finally going to stick with them for my installs.

To be honest I've rarely had an issue, but I can't deny that I have been lucky, as well as having the luxury of fairly non-demanding and non-critical applications.

I rarely make my own cables anymore, except for the home runs where the length cannot be pre-determined and/or the cables have to go thru conduit. Used to spend hours making up cables to length for installs, just not cost-effective anymore.