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DMX vs AUDIO cables


sunray

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The risk you take is, when there is a problem with the audio, which may be nothing to do with you using one line for DMX, yours will be the first to get disconnected. Then you have no DMX line. Be safe and run your own, or perhaps look at one of the better wireless DMX solutions, if it really is problematic running a cable.
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It will work fine - unless it doesn't.

Ah come on,  if the cable works for sound it'll work for DMX over 50m.

Indeed and I have done so with 3 full 100m of standard mic cable, most likely Proel knowing where it was sourced from. I don't know if it's relevant but this long run started at an opto isolated splitter and fed into another similar splitter as a buffer. We we were not aware of any glitching but we weren't exactly watching the remote display, it wouldn't have been a problem as long as there was some sort of sensible activity.

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It will work fine - unless it doesn't.

Ah come on, if the cable works for sound it'll work for DMX over 50m.

Indeed and I have done so with 3 full 100m of standard mic cable, most likely Proel knowing where it was sourced from. I don't know if it's relevant but this long run started at an opto isolated splitter and fed into another similar splitter as a buffer. We we were not aware of any glitching but we weren't exactly watching the remote display, it wouldn't have been a problem as long as there was some sort of sensible activity.

 

Well if we are having a distance competition, I have run it down 1km of Van Damme install cable with no problem...

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I managed to NOT make it work on a 2m cable, pack to pack - and the cable tested fine - the fault was rust! the screen and both cores had been exposed on a sharp edge drilled between two racks, and the copper was green, and presumably hi res or possibly a partial short between the pair.
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The risk you take is, when there is a problem with the audio, which may be nothing to do with you using one line for DMX, yours will be the first to get disconnected. Then you have no DMX line. Be safe and run your own, or perhaps look at one of the better wireless DMX solutions, if it really is problematic running a cable.

That may be an issue I hadn't thought of, thanks.

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I regularly do this for small-scale shows as most of the audio guys I work with are friendly and helpful.

 

Provided the multicore has individual screens per channel then it should be fine, if it's a cheap multicore with an overall screen only then the audio feed will pick up a lot of digital noise from the DMX.

 

For bigger shows I tend to use one of the ethercon cables in the audio guy's multicore - definitely no noise issued with that!

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Well if we are having a distance competition, I have run it down 1km of Van Damme install cable with no problem...

Absolutely not a competition, I only mentioned 300m of mic cable, and probably cheap stuff at that, to indicate that sometimes things work which are predicted to be troublesome.

By install cable, I assume you mean Beldon 9500 or equivalent. Officially this is the proper cable for the job as RS 485/DMX and the cable were designed around each other, or so I believe.

 

Going back a few years (ouch 30 or more) I was working at the nearest Telephone exchanges to Brands Hatch and providing phone lines and private wires for the F1. We had totally run out of spare pairs and we had WB900 racks laying all over the floor to increase capacity. Suddenly BT's IT department turned up expecting to find 2 pairs to run Kilostream so BT could have a computer terminal on site. I laughed.

Then I asked the maximum run of the RS485 between terminal and hub, I think he said 500m and it needed 2.5 pairs. We used 9504 for the job and he had enough on the van to cover the 3.5Km. We tested with 9 drums (4.5Km) and it worked so ran it down the side of the country lanes, across farm fields, etc, even crossed 2 roads and the M20 motorway. As soon as he got it up and running I had 2 more phone lines on the spare pair. Fortunately the scrap metal merchants didn't discover it until after the event was over.

Elsewhere we gave temporary telephone service to a farm after his cows rubbed right through a telephone pole. We used his barbed wire fences, some 1/4 mile across his land.

 

Anyway back to the OP, last night there was a problem with a DMX line running in a tie circuit. at each end of the tie is a short gender bender lead with the XLR's nicely labelled DMX one end & Audio at other. I replaced both with straight barrels (from his kit) and the problem went away. Sure enough the leads have a flip incorporated, it looks like one had been pulled as the tight wiring had broken.

Edited by sunray
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Depends how well you get on with the audio guy. Perhaps I'm lucky who I work with...

 

In my experience most are pretty good as we all have the events interest at heart. It's the occasional idiots who spoil it.

 

I was only joking about competition.
I guessed as much but one has to be careful.

Vd install cable is like skinny mic cable, not 120 ohm.

Good work with the barbed wire telephone.

I you're talking about this sort of thing: https://cpc.farnell.com/van-damme/268-002c/vandamme-1-pair-blue-100m/dp/CB04658 then it will be as close as dammit to 120ohms.

I have always found opportunities for solutions to be satisfying. in those days it probably took 3 weeks to get the surveyor on site, 2 weeks for his report, 2 weeks for planning then on to the in tray for the pole erection unit.

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Well if we are having a distance competition, I have run it down 1km of Van Damme install cable with no problem...

Absolutely not a competition, I only mentioned 300m of mic cable, and probably cheap stuff at that, to indicate that sometimes things work which are predicted to be troublesome.

By install cable, I assume you mean Beldon 9500 or equivalent. Officially this is the proper cable for the job as RS 485/DMX and the cable were designed around each other, or so I believe.

 

Going back a few years (ouch 30 or more) I was working at the nearest Telephone exchanges to Brands Hatch and providing phone lines and private wires for the F1. We had totally run out of spare pairs and we had WB900 racks laying all over the floor to increase capacity. Suddenly BT's IT department turned up expecting to find 2 pairs to run Kilostream so BT could have a computer terminal on site. I laughed.

Then I asked the maximum run of the RS485 between terminal and hub, I think he said 500m and it needed 2.5 pairs. We used 9504 for the job and he had enough on the van to cover the 3.5Km. We tested with 9 drums (4.5Km) and it worked so ran it down the side of the country lanes, across farm fields, etc, even crossed 2 roads and the M20 motorway. As soon as he got it up and running I had 2 more phone lines on the spare pair. Fortunately the scrap metal merchants didn't discover it until after the event was over.

Elsewhere we gave temporary telephone service to a farm after his cows rubbed right through a telephone pole. We used his barbed wire fences, some 1/4 mile across his land.

 

Anyway back to the OP, last night there was a problem with a DMX line running in a tie circuit. at each end of the tie is a short gender bender lead with the XLR's nicely labelled DMX one end & Audio at other. I replaced both with straight barrels (from his kit) and the problem went away. Sure enough the leads have a flip incorporated, it looks like one had been pulled as the tight wiring had broken.

The organisers have been using this guy(in OP) for a few years but he's never got to grips with the intercom, so we went in for that part only. However as we have been working with them and demonstrated our abilities it looks like we have the job next time round.

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The organisers have been using this guy(in OP) for a few years but he's never got to grips with the intercom, so we went in for that part only. However as we have been working with them and demonstrated our abilities it looks like we have the job next time round.

 

Now confirmed, next show is in May and we have the whole job. The thing that sealed the deal was his unavailability to fix the problem when the DMX stopped working, they called us and we attended to sort out his kit.

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