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Dynamic Entertainment
22-07-2009, 04:25 PM
Right then. Im looking for cable for making up DMX leads, and looking on Terralecs website i can only find 5-core. Is 5-core the standard and you just dont use the spare 2 cores? or can you specifically buy 3 core?

Also, how do your wire it with a plig. Does it not matter which colour of the core you use for which pin, as long as you keep it uniform.

i.e. Pin 1 all red core, Pin 2, all blue, pin 3 all white?

TonyB
22-07-2009, 04:54 PM
Just had a look at the DMX cable on Terralec and it looks like install cable. Foil shielding doesn't stand up to the rigors of mobile use too well and if it gets kinked, the kink won't come out.

Any AES/EBU digital cable will do with an impedance of 120 ohm +/- 10 Ohm.

Van Damme do a digital cable, only problem is that it is green.

What I have been using is digiflex http://www.connectronics.uk.com/digiflex.htm . Pin one is the ground (connect the shield to it). Pin 2 is the data component (-), usually blue or black and pin 3 is the data true (+) usually red or white.

Dynamic Entertainment
22-07-2009, 05:16 PM
Cheers Tony :beer1:

So the piccy below shows the shield (the wires that wrap round the outside), the blue is Negative and the white positive?

TonyB
22-07-2009, 05:38 PM
Yes that is correct. I suppose it doesn't overly matter what way around you connect the blue and white wires as long as you do the same at both ends.

Tony Scott
22-07-2009, 06:48 PM
I use standard 0.5mm black 3 core power cable and always have, never had an issue.
I know you are supposed to use shielded but I have 6, 9 & 12mtr looms containing power and dmx cables and all my trusses are prewired the same way. Never had a single glitch..:)

Excalibur
22-07-2009, 06:56 PM
I use standard 0.5mm black 3 core power cable and always have, never had an issue.
I know you are supposed to use shielded but I have 6, 9 & 12mtr looms containing power and dmx cables and all my trusses are prewired the same way. Never had a single glitch..:)

Hmmm, interesting. And how many times have you seen the advice to use proper DMX cables, cos (shielded) mic cables aren't good enough? ;) :confused:

BTW, some of my DMX cables bear the legend " mic cable", so I'm not perfect.

Tony Scott
22-07-2009, 07:05 PM
.......how many times have you seen the advice to use proper DMX cables, cos (shielded) mic cables aren't good enough? ;) :confused:

Yeah that's always puzzled me, I'm sure that if you are running hundreds of fixtures as in a stage show then the amount of digital info being carried by the cables dictates the use of the proper stuff.

I run a maximum of 20 fixtures (including 8 LED par cans) so that's probably why I can get away with using what I do? :confused: :)

Vectis
22-07-2009, 07:11 PM
DMX512 runs over RS485 protocol at 250Kbaud which any IT bod from the 80s onwards will remember is an asynchronous serial analogue protocol with an extended range compared to the more usual RS232 used for attaching VDUs and printers etc. to mainframes, then minis, then micros in due course.

So "digital" cable is probably overkill.

Just get the right impedance and job done. Over relatively short runs like mobile jocks use, even the wrong impedance cable will probably not be an issue as the impedance imbalances will be pulled up with the frequent short hops between devices.

Dynamic Entertainment
22-07-2009, 07:21 PM
I use standard 0.5mm black 3 core power cable and always have, never had an issue.
I know you are supposed to use shielded but I have 6, 9 & 12mtr looms containing power and dmx cables and all my trusses are prewired the same way. Never had a single glitch..:)

That sounds like a plan. Cheaper too. Im only wanting to make up cables for uplighting.

Cheers :)

Excalibur
22-07-2009, 08:07 PM
DMX512 runs over RS485 protocol at 250Kbaud which any IT bod from the 80s onwards will remember is an asynchronous serial analogue protocol with an extended range compared to the more usual RS232 used for attaching VDUs and printers etc. to mainframes, then minis, then micros in due course.

So "digital" cable is probably overkill.

Just get the right impedance and job done. Over relatively short runs like mobile jocks use, even the wrong impedance cable will probably not be an issue as the impedance imbalances will be pulled up with the frequent short hops between devices.
Vectis, for a person born on the wrong side of the Pennines, you're a lovely lad, but please please please can you post in English? :confused: :confused:


That sounds like a plan. Cheaper too. Im only wanting to make up cables for uplighting.

Cheers :)
FWIW I'd use mic cable. ( Then again what do I know, I'm only a Dinosaur ):o :o

Jiggles
22-07-2009, 08:21 PM
I use mic cable... Even though the paper band round it said DMX!

Paul James Promotions
23-07-2009, 08:58 AM
The difference between the mic and DMX cable is the resistance. For DMX ideally you need around 110-120 ohm.

Some mic cable is conveniently manufactured to a similar specifiaction anyway, and therefore is ideal.

As has been mentioned, for a small number of lighting effects, you should be ok with standard mic cable, but for more than maybe 6/8 fixtures I would look at using proper DMX cable. The bonus is that DMX cable can be also used for audio.

Issues would usually be in the form of gobos/colours losing position, movement juddering etc due to poor transmission of signal from the controller.

J