Tom Baldwin Posted April 13, 2004 Share Posted April 13, 2004 this goes against the specification.. but couldnt you just wire all your extensions 5 pin socket, 3 pin plug? then they would fit into both 5 and 3 pin devices either way wouldnt they?No. 3 pin DIN plugs will fit in 5 pin DIN sockets, which might be what you're thinking of, (and the pin numbering remains unchanged - for the first 3 pins, obviously). 3 and 5 pin XLR connectors have different diameter pins, for starters, the pins wouldn't line up physically, even if they were the same diameter, and pins 1, 2 and 3 certainly don't line up between the two connectors. (Blame Jono) I've used mains flex instead of XLR before for coms with no probs over about 50m of cable so I cant see any reason for not doing the same with DMX.Somebody shoot the troll. Link to comment Share on other sites More sharing options...
TomLyall Posted April 13, 2004 Share Posted April 13, 2004 the main two reasons why you can not (and at least should not) use mains flex for DMX is that: DMX spec calls for a twisted pairDMX spec specifies sheilding and the last time I looked most mains flex has neither of these... (ok dont kill me about the twisting) Link to comment Share on other sites More sharing options...
paulears Posted April 13, 2004 Share Posted April 13, 2004 I've used mains flex instead of XLR before for coms with no probs over about 50m of cable so I cant see any reason for not doing the same with DMX.Once you've had your first DMX nightmare, the very thought of passive splits, 'mains cable', cheap screened cable, etc etc simply makes no sense whatsoever. If your desk has multiple DMX outputs - USE THEM! The fewer number of 3pins, 5 pins, 3 to 5 convertors, odd short mic XLRs of budget construction you have in each universe - the fewer problems you'll have. Trying to isolate problems in long, drawn out DMX cable routes is next to impossible if you want to remain sane. One recently was eventually traced to a flown truss - about a third of the way down the DMX run. If all of the moving heads were pointed forwards at the same time, the shift in the C of G was enough to just put a little extra strain on a short 'mic type XLR 3pin plug to socket, used to loop two heads together. The non-neutric XLRs were a slightly loose fit, and when they flexed, two rows of stage level movers suddenly did a little dance all of their own. If you want to see what's happening stick a scope on the end of the run at look at what the square waves actually look like. RF engineers are quite aware of the problems of reflected power. Hence why passive RF splitters that are well designed cost upwards of 30 times the price of a domestic splitter, and use better designed connectors. Don't forget that data distribution is a whole new black art. 110 ohm impedance cable wouldn't have been designed if it could be replaced with something cheaper. Link to comment Share on other sites More sharing options...
Brian Posted April 13, 2004 Share Posted April 13, 2004 I've used mains flex instead of XLR before for coms with no probs over about 50m of cable so I cant see any reason for not doing the same with DMX. Why not just use wet string? It works.Seriously though, yes mains cable will probably work, as will mic cable, as will bell wire, as will just about anything which will conduct electricity. They will work some of the time. The problem is that you will never be able to predict when they will and when they won't work. If the fact that your DMX signal might get corrupted doesn't matter then by all means use the cheapest cable you can find. If, one the other hand, you care about what you are doing then use the proper cable. Link to comment Share on other sites More sharing options...
TomLyall Posted April 13, 2004 Share Posted April 13, 2004 would it be sensible to get 2 pair cable and conect both, rather than jus the one in new DMX cables or should I just connect the one? Link to comment Share on other sites More sharing options...
Brian Posted April 13, 2004 Share Posted April 13, 2004 would it be sensible to get 2 pair cable and conect both, rather than jus the one in new DMX cables or should I just connect the one?If you mean should you parallel them then the answer is no.If you mean should you use the second pair to connect up the second data pair on the 5-pin XLR then I'd probably still not bother, not much kit uses the second pair. If you are a hire company then it's probably worth doing. Link to comment Share on other sites More sharing options...
TomLyall Posted April 13, 2004 Share Posted April 13, 2004 the latter brian, I was thinking of future proofing as I guess they may become used in the future... slightly off topic, but if I were to construct a DMX multicore, would I tbe a bad idea to keep it on a drum? I was also thinking of inverting the usual way of wiring multicores and having the females pull off the drum so they could be taken straight up onto a truss etc, leaving the drum and the rest of the cable at the control end... any ideas? [edit, spelling] Link to comment Share on other sites More sharing options...
P. Funk Posted April 13, 2004 Share Posted April 13, 2004 no soz - I mean, if you have 3 pins, they will (?) fit in 3 pin and 5 pin sockets, and thus can be used in both situations, and if you have 5 pin sockets, 3 and 5 pin plugs can fit in, and seeing as only pins 1, 2, and 3 are used, it shouldnt be a problem should it? of course ou'd run into problems if any of the devices decided to use pins 4 & 5... Link to comment Share on other sites More sharing options...
Stu Posted April 13, 2004 Share Posted April 13, 2004 Well a standard 3 pin XLR plug / socket ain't gonna fit in a 5 pin 'DMX' XLR plug or socket - so it'd mean re-engineering the 3 pin XLR, then the 3 pin sockets on the Movers etc... Don't think it'd work Stu Link to comment Share on other sites More sharing options...
TomLyall Posted April 13, 2004 Share Posted April 13, 2004 3 and 5 pin XLR's are not interchangeable in that way (ie: a 3 pin male will not fit into a 5 pin female). for one the pins are much finer on a 5 pin... [edit: jus had a look at some XLR's] the pins dont line up anyway... well they do, sorta, but all to the wrong ones... if you see what I mean 3M - 5F1 - 12 - 33 - 5 Link to comment Share on other sites More sharing options...
P. Funk Posted April 14, 2004 Share Posted April 14, 2004 hmm thats a shame.. oh well. Link to comment Share on other sites More sharing options...
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