XLR socket question...

[Light Console]

Hi folks,

Am just starting to design a side lighting system using "pods" in the school where I work. The brief means that each pod will have a cheap dimmer inside, and run off a 13A plug, using existing ring mains in the Dance Studio or the Hall. The problem is floor level DMX sockets. The plan is to make eight of the pods to be able to have four on each side of the stage. However in the Studio, they may use any combination of pods.

 

Simple plan is to make a DMX ring around the Studio at existing socket height - that isn't the problem!

 

What is the problem is devising the way to keep the ring intact no matter which pods are pluged in where, without using switches, panel socket and cable plug, or link cables, as all of these could be fiddled with.

 

My ideal solution came to me on the way home! 1/4" jack sockets can have two sets of contacts which connect when no plug is present, but seperate when a plug is there. Then one set of contacts will make contact with the plug and the other set go nowhere.

 

Does anybody know of an XLR socket that can do this? Or come up with a better idea for the ring sockets which is fiddle proof? (have just thought of key switches as a second option, and just using 1/4" sockets and making up jumper leads to XLR.)

[dunk_1984]

This is just a suggestion, hopefully someone who who knows more can confirm/deny.

 

If you solder the in and the out DMX line into the back of the socket, obviously daisy chained all the way to the end. I know this has been discussed before but can't remember if this is acceptable or not, however if you placed a terminator in all the vacant sockets would this rectify the issue?

 

Apologies if this isn't correct.

 

Alternatively could you not individually cable all the sockets and run this back to a patch/distro?

[johnhuson]

Have you already ruled out a star wiring configuration and using a DMX splitter?

[bruce]

It may sound like a sensible idea today, but a few years down the line, people (who don't know all the facts) will be saying "which idiot designed this...".

 

Rather than faff about with non-standard connectors, who not do the job properly and get an 8-way splitter...

 

A concurrent post has been automatically merged from this point on.

 

This is just a suggestion, hopefully someone who who knows more can confirm/deny.

 

If you solder the in and the out DMX line into the back of the socket, obviously daisy chained all the way to the end. I know this has been discussed before but can't remember if this is acceptable or not, however if you placed a terminator in all the vacant sockets would this rectify the issue?

 

Apologies if this isn't correct.

 

It's not correct, for lots of reasons. Please, don't speculate.....

[johnhuson]

This is just a suggestion, hopefully someone who who knows more can confirm/deny.

 

If you solder the in and the out DMX line into the back of the socket, obviously daisy chained all the way to the end. I know this has been discussed before but can't remember if this is acceptable or not, however if you placed a terminator in all the vacant sockets would this rectify the issue?

 

Apologies if this isn't correct.

 

This would create a Y-Split when a pod was plugged in which is not good practise although it may work, it shouldn't be relied on.

 

EDIT Beaten to the draw once again...

[bruce]

This would create a Y-Split when a pod was plugged in which is not good practice although it may work, it shouldn't be realied on.

 

Not only that, it would mean you would have too many terminators, some in the middle of the line.... trying to model what would happen gives me a sore head, but at it's simplest level, think about all those resistors in parallel...

[johnhuson]

Fair point, I missed the terminator part the first time round.

[MarkPAman]

One (not so cheap) way would be to get proper DMX splitters. Something along the lines of two like this. Put a terminator in each pod & you'll only need an output socket in each of your locations.

 

Edit : Wow - That's a lot of posts while I was writing that!

[Dmills]

That is what I did for DMX distribution to the fixed pipe grid at work, two 8 way splitters with each output feeding a single socket.

It makes fault finding much simpler as well as faults are isolated to whatever bar has the problem.

It works well.

 

Regards, Dan.

[gareth]

Don't think about fannying around with fancy custom wiring arrangements. Your successors *will* hate you for it. There are two simple ways to do it - either make each output its own buffered DMX socket fed from a buffer ; or keep it all as a ring with a plug and socket at each outlet, a send and return cable going to each tower and a jumper to link plug and socket together when a connection point isn't in use.

[dosxuk]

I think the only solution here is, as other have suggested, to use a splitter / buffer. Only solution? Because when you've got a pod pluged in, if you're not splitting the DMX, you're going to need to pass the DMX back to the wall socket, increasing the numbers of cables & connectors needed to get it working and to keep it working (i.e. when some iquisitive pupil decides to unplug a pod, some of the rest will stop working also.

[peternewman]

This has kind of been alluded to, but if you go down the XLR with switch route, you'd need both males and females, because you need to continue the DMX chain, otherwise when you plug your first pod in, it would activate its plunger/switch and all the ones downstream of it would loose DMX. Of course you could add a buffer in each panel, but then you don't need the clever switching sockets as its buffered already!

 

You could possibly go for some wierd and convoluted system from Harting or similar, with power and data in one big connector, with suitable/safe/relevant isolation in all the right places, but I'd agree with others people will hate you in the future when they have to make wierd adaptor leads up, it would also probably be more expensive than a cheap DMX splitter.

[Brian]

Does anybody know of an XLR socket that can do this?

Neutrik NC5MAV-SW and NC5FAV-SW have switch outputs although sadly only a single CO set. I guess you could do something with relays.

[Light Console]

Right-o, a few spliters will be worked into the budget - I simply hadn't thought of that! As most of you say, a simple way to do it.

I don't want to piss off any future people, there are enough quirks in the hall as it is - mostly to do with limited power!

 

Peternewman - the plan is that each pod has an in and out DMX cable regardless of which pod it is, so they are all the same. The wiring idea was that the in signal went to the contacts that mate with the out plug, the contacts that don't mate were connected to the ones that don't mate with the in plug. The contacts that did mate with the in plug would go to the next socket box, but as you have all told me, this is a silly way of doing things, so I wont!

 

I have a budget of £4,000 to do this, so we are already going down the used kit route for lanterns...the problem comes when the head of dance wants me to reinstate the old school hall lighting rig in the same budget - a couple of DMX splitters will help keep it side lighting only!

 

E2A - Thanks Brian, good to know there is something like this about, even though I wont be going down that route now.

[JDP]

Why not have a Panel with an XLR 5 Socket on it, and have these at every point.

 

The Panel has an XLR5 Female on it and a 10cm cable with a plug on it. Then, plug the little cable in when not in use, or when in use, plug the dimmer in, and using the DMX Out on the dimmer plug the 10cm cable in. That way you always have a chain - and if you need to plug the dimmer in, you link the rest of the chain back out from the dimmer... This also gives you the DMX input anywhere into the system!!