DMX vs Cat6

ACTSTech

Active Member
Joined
Nov 13, 2019
Location
USA
We have basically been evicted from our venue and are looking for a new home. There’s already a few possibilities but none are ready, everything will have to be installed. I pulled our dimmer racks today and we’ll be reusing as much as we can since this was an unforeseen occurrence that’s going to be expensive, but I ran into some issues and hope some people might share thoughts.

Our light board will need to go eventually. Currently, the board sits in the rear of the old venue and the 5-pin DMX cable runs to the dimmer rack. We’ll probably do the same to start, but if we upgrade the board, should I run DMX from the new booth to the rack, to a splitter, or run Cat6 as well? I’m not up to speed on the new lighting systems, but I’m reading as many posts as I can. I originally thought just 2 DMX lines, one to the racks then one for a second universe (I think I’m using that right) in case we get movers for FOH. Eventually the dimmer racks will be retired I’d assume, so would it be worthwhile running Cat6 at the same time? I’m already planning on buying a spool for runs from the sound booth to the rack, so I’ll have it. We don’t have any lighting equipment that uses it at the moment, but if I’m running one cable I might as well run 8.

And I know wireless DMX seems to be popular, but I’m terribly old school and fearful of wireless technology. I’ll be reading, but any help is welcome!
 

DrewE

Well-Known Member
Joined
Mar 18, 2019
Location
Vermont
If you pull cat 6 cable, you can use it for a few universes of normal DMX512 and then swap it over to some Ethernet-based alternative when the need for that comes up. In other words, Cat 6 cabling will be fine for standard DMX512 signaling; there's no particular reason I can see to pull anything else for a new installation. It would, in my opinion, be worth pulling a few Cat6 cables while you're at it, or at the very least leave a pull string in place to be able to pull more in the future, should the need arise--say for digital audio distribution. I guess it partly depends on how much pain it is to do the cable pull; I try to always leave a string in place if it's at all tricky in any way, since mason line or similar is really cheap compared to one's time and skinned knuckles and mental health.
 

DavidJones

Well-Known Member
Joined
Jun 7, 2017
Location
Touring
Just use Cat6. Look up TMB sneak snake. A bunch of companies make the same things. These are completely passive, just using the twisted pairs for DMX signal. You can get 1, 2 ,3 universe versions over one Cat5/6, and 4 universes with Shielded cable. Sounds like a single Cat to 5-pin barrel at each end will be all you need for now. You can even just make some of these adapters yourself for a single universe. For multi-universe breakouts, I'd recommend the professionally built ones, because they are much nicer and it would be a hassle to get all the parts and make them yourself.
 

ACTSTech

Active Member
Joined
Nov 13, 2019
Location
USA
If you pull cat 6 cable, you can use it for a few universes of normal DMX512 and then swap it over to some Ethernet-based alternative when the need for that comes up. In other words, Cat 6 cabling will be fine for standard DMX512 signaling; there's no particular reason I can see to pull anything else for a new installation. It would, in my opinion, be worth pulling a few Cat6 cables while you're at it, or at the very least leave a pull string in place to be able to pull more in the future, should the need arise--say for digital audio distribution. I guess it partly depends on how much pain it is to do the cable pull; I try to always leave a string in place if it's at all tricky in any way, since mason line or similar is really cheap compared to one's time and skinned knuckles and mental health.
We’re an extremely small group, so I’m having a hard time imagining how many universes we’d ever use. Of course I live in the dark ages, but I’m trying!

My first instinct is to run two lines of cable from the booth to wherever the dimmer racks are located, one for use, one for redundancy. In the old venue, I was thinking of running two lines from the racks back to a front of house location to a distribution box, but from what I’m reading I could skip that and run a line (or 2 because I’m neurotic) straight to the FOH to a distribution box and call that a new universe.

Since I’ll be using shielded cable, I’m assuming that it will protect against interference. I’ll still use conduit, separate it from my audio runs, and pull strings go in the same time as cable regardless. Jim, what are the big sources of interference for wireless DMX you’ve seen? We’re not large, but our old home had unique problems, like the plaster and lathe walls were wire reinforced, so it was like an enormous faraday cage. No cell service, but any bad wire, circuit, fluorescent light, curling iron, refrigerator, etc wreaked havoc on wireless mics regardless of the frequency. Plus we were close enough to the one radio station that if we opened to fire door and they were broadcast a high school football or basketball game, we could pick it up on old toasters. Like I said, I’m not against learning because this is all new to me.

We’re moving fast and furious trying to save next year’s season, so instead of a little pressure I’m on defcon 6.

Thanks for the input everyone. I search but I’m not sure what I’m searching for most of the time.
 

RickR

Well-Known Member
Joined
Sep 18, 2009
Location
Spokane, WA the great "Inland Northwest"
Cat5e or 6 cable is cheap and does a lot. Pull some everywhere, left right, high, low, front, racks, booths, etc! I suggest pulling in a star pattern with everything joining in one place, and creating a DMX patch bay until you go network. You will want networking someday. Wireless can be great but wire is usually far cheaper and more reliable.

No need to use shielding in conduit.
 

macsound

Well-Known Member
Joined
Jun 15, 2018
Location
San Francisco, CA
Something to be aware of that I wasn't. Some shielded Cat6A has larger wires inside and a larger exterior jacket. This means - even for the well versed - crimping RJ45s is a nightmare and will require larger boots and larger gauge RJ45s.
Although I'd definitely recommend pulling the wire now, because now is always better than later, pull a few Cat5e and a couple more Cat6A for the future.

I'm trying to scare you because I was gutsy once and screwed myself. I've made 1000s of Cat5 cables and stripping and crimping usually takes me 1 minute. Putting one connector on a 23AWG Shielded CAT6A took me about 15 minutes of complete grief.
 
Joined
Nov 10, 2019
Location
Finland
If you actually need CAT6 performance, it really doesn't make a ton of sense to crimp yourself any more. I used to make all my own cables back in the day, but they've gotten so much cheaper and the quality standards have gone up so much that I wouldn't dream of it any more now. In particular, if you think you're ever going to run anything other than DMX over them (and chances are pretty good that you will), I'd strongly recommend just running machine-crimped CAT6 or CAT7 — you don't want to find out in ten years that you're going to have to go digging in the walls because you can't get a GigE link to work.
 

RonHebbard

Well-Known Member
Premium Member
Joined
Jun 12, 2004
Location
Waterdown, ON, CA
If you actually need CAT6 performance, it really doesn't make a ton of sense to crimp yourself any more. I used to make all my own cables back in the day, but they've gotten so much cheaper and the quality standards have gone up so much that I wouldn't dream of it any more now. In particular, if you think you're ever going to run anything other than DMX over them (and chances are pretty good that you will), I'd strongly recommend just running machine-crimped CAT6 or CAT7 — you don't want to find out in ten years that you're going to have to go digging in the walls because you can't get a GigE link to work.
@Eleanor Saitta If you intended to pull multiple runs through existing empty conduit, and didn't have space to pull pre-crimped ends through, even if staggered, would you buy cables with only one end pre-crimped and crimp the blank ends post installation OR would you buy pre-terminated cables and cut one end off for pulling, then crimp your blank ends?
In my mind, this would come down to purchase costs, perhaps buying pre-manufactured cables and cutting one end off is the more economical route to go due to mass production rather requesting a "special" cable?
Toodleoo!
Ron Hebbard
 

ACTSTech

Active Member
Joined
Nov 13, 2019
Location
USA
Something to be aware of that I wasn't. Some shielded Cat6A has larger wires inside and a larger exterior jacket. This means - even for the well versed - crimping RJ45s is a nightmare and will require larger boots and larger gauge RJ45s.
Although I'd definitely recommend pulling the wire now, because now is always better than later, pull a few Cat5e and a couple more Cat6A for the future.

I'm trying to scare you because I was gutsy once and screwed myself. I've made 1000s of Cat5 cables and stripping and crimping usually takes me 1 minute. Putting one connector on a 23AWG Shielded CAT6A took me about 15 minutes of complete grief.
Oh, I’m well aware of the differences, but it’s good to note. There’s subtle differences in brands too, some jackets are thicker, some insulation is a hard plastic, almost rigid. And even with the right crimped,
@Eleanor Saitta If you intended to pull multiple runs through existing empty conduit, and didn't have space to pull pre-crimped ends through, even if staggered, would you buy cables with only one end pre-crimped and crimp the blank ends post installation OR would you buy pre-terminated cables and cut one end off for pulling, then crimp your blank ends?
In my mind, this would come down to purchase costs, perhaps buying pre-manufactured cables and cutting one end off is the more economical route to go due to mass production rather requesting a "special" cable?
Toodleoo!
Ron Hebbard
Since I’ll be pulling all new wire through all new conduit, I’d prefer running my own wire and cutting it myself. Especially as whatever venue we move to will be all new installation. However, I know the benefit of pre-made cable. To me, it really comes down to where it’s going, pitfalls, and sweat labor. The venue I just removed things from was mostly simple, because I cut off ends. The conduit was full, and even with pull line, it would have been difficult to get any wire through, let alone terminated wire.

If, going into this, I can anticipate so many wires going where, plus leave room for future expansion, I’ll pick a large enough conduit. In that case, I’d consider per-terminated. If I didn’t have a choice and had to pull in old conduit, especially if it’s got some bends, unterminated.

I’ve seen enough mic cable stuck when an overzealous “techie” thinks they can just pull a 100’ cord through conduit.
 

DavidJones

Well-Known Member
Joined
Jun 7, 2017
Location
Touring
I'm not sure I've ever heard of anyone pulling pre-terminated cable in a conduit. Even if you did, where do you order a specific length of install grade cable pre-terminated? Plus it's a PITA to pull cable that is not coming right out of the box. Yes, Cat6 RJ45 connectors are different than the ones for Cat5e, so it is important to get the right connectors and crimpers. If you have not terminated these before, there is always YouTube. Also, ask around, there is a good chance you know somebody that can help.
 

RonHebbard

Well-Known Member
Premium Member
Joined
Jun 12, 2004
Location
Waterdown, ON, CA
I'm not sure I've ever heard of anyone pulling pre-terminated cable in a conduit. Even if you did, where do you order a specific length of install grade cable pre-terminated? Plus it's a PITA to pull cable that is not coming right out of the box. Yes, Cat6 RJ45 connectors are different than the ones for Cat5e, so it is important to get the right connectors and crimpers. If you have not terminated these before, there is always YouTube. Also, ask around, there is a good chance you know somebody that can help.
@DavidJones Every now and again, the company I free-lanced with would purchase pre-terminated RJ cables, I'd stagger the ends by approximately 1" per cable, tape them along side a metal or fiberglass fish and haul them through conduit, typically metal, 1 or 1.25" ID EMT. (Electrical Metallic Tubing) as we refer to it here in Canada. I recall it commonly being referred to differently within Donnie's walls.
Toodleoo!
Ron Hebbard
 
  • Like
Reactions: macsound

RonHebbard

Well-Known Member
Premium Member
Joined
Jun 12, 2004
Location
Waterdown, ON, CA
@RonHebbard People call it 'conduit' when they aren't being specific. That metal stuff you describe, designed for wires and cables? yea, we call that EMT too. We've also got Schedule 40 PVC and Schedule 80 PVC in common use for conduit.
@eadler You also have '"Seal-Tite / Liqui - Tite Nylon coated, tightly woven, Flex.

On the strip in the heart of downtown 'Vegas, I was totally ASTOUNDED by the number and sizes of pre-manufactured Flex-El's my IBEW brethren installed in labor saving preference to bending anything larger then 3/4" I.D.

I was also startled by the number of cordless, hand-held, saws equipped with TRULY VICIOUS looking Piranha blades in common everyday use to cut EMT where I'd still be using my trusty, fine-tooth, Armstrong powered hacksaw.
Toodleoo!
Ron Hebbard
 

RonHebbard

Well-Known Member
Premium Member
Joined
Jun 12, 2004
Location
Waterdown, ON, CA
I too am amazed Ron at how some electricians would rather bend 10 1/2" EMT than buy one prebent 4". Some have told me it can be done but they'd rather use the 1/2"
@macsound I began my IBEW Installation and Maintenance apprenticeship in June 1967 and spent my entire first year to the day installing literally miles of 2.5" and 4" ID fibre duct underground joining 11 new poured concrete manholes together.
During my 1st year I also bent 4" Blue 'Genel' - Coat schedule 40 steel rigid with a Blackhawk segment bender.
In my second or third year, I progressed to bending 4" rigid 90's and offsets with a hydraulic Greenlee 'One-shot'. Once I'd met and mastered the one-shots, I rarely went back to Blackhawks and / or manually operated Chicago benders again.

Oh how those Greenlee 4" one-shots spoiled me.
Some years post my apprenticeship, electrically powered 'Clock style' benders appeared; I've never used a 'Clock' bender but definitely bent my share of 1.25" EMT by hand (and foot) with EMT hand-held / arm-strong powered manual benders with the two position foot rest.
Thanks (and no thanks) for the memories.
Toodleoo!
Ron Hebbard
 
Last edited:
Joined
Nov 10, 2019
Location
Finland
From my perspective, every high-bandwidth connector you don't have to terminate yourself is one you can't screw up. But yes, if you're pulling long enough runs, or enough of them, connectors are going to be a pain. It may be worth borrowing one of the Fluke network bandwidth testers for a day once everything is done to make sure you're getting the full expected performance of the cables. The day you suddenly find yourself needing to run 4k video over an HDbaseT transceiver you'll be very happy you did.