Multicore cable run to FOH

[stillwave]

Hi All,

 

Have the current dilemma of touring company's multicore runs from stage to FOH control position (rear centre stalls). Previously this was achieved by simply following the skirting boards & up & over doorways along the side of the auditorium... management do not want multicore runs through the auditorium after our restoration.

 

The only other way I can see is a concrete service duct (approx 3ft wide 2ft tall) which runs down prompt side of the auditorium under the floor, we have drawn up rough plans to have a 8" internal diameter approx PVC or similar pipe to run through this duct, with a smooth interior surface finish (to reduce friction). this service duct runs in a stage to FOH direction we would then need to dig a pit to concrete in a further section of this pipe. to complicate matters this 2nd section of pipe would be of the metal air duct variety as is being put in by the contractors (IIRC spirally type metal air ducts are not smooth internally), sorry air ducts are beyond my expertise!

 

 

I'm concerned about the 90 degree bend that the pipe would go through in order to get to the control position and the amount of friction it would introduce to the arrangement? it has also been suggested to use 2 x 45 degree bends (I understand it still adds up to 90!). my thoughts are to have a hatch in the floor of the auditorium at this corner & not have a corner in the pipe instead have an air gap where someone can gently 'assist' the multicore down second pipe / duct

 

Has anybody had any experiences with similar multicore systems (rabbit run?) elsewhere?

If you were presented with this arrangement for your audio multicore what would you do / say?

 

Regards,

 

Ben Wainwright

 

 

Mods: please move to another forum if not correct forum (mainly deals with audio multicore, but any cable inc. DMX)

[dan slv-tech]

well interesting problem,

 

my 1st thought would be how long is it going to take me to feed my multi through that v how long to hang up around doors etc.

and what feeds the cable through?

Time frame would be ur biggest obstical I suspect.

If your telling me it would take me like an hour to feed my multi through it I wouldnt be happy!

however if it was like 20 mins then Id do it.

you could consider some way of a pully system inside so you can tie the end of the cable and pull it through?

 

dan

[Matt Riley]

Just install a multi...

[Andrew C]

Just install a multi...

Won't work for touring shows. Nor for that matter will having a 90 degree bend. Two 45s might, but I would go for the inspection pit idea; much more likely to work. Ensure that you have AT LEAST two ropes in there, as some idiot is bound to forget to draw the line back in at the end of the gig. I'd be inclined to insist on a smooth-bore pipe, you don't want to be heaving on a 120 pin multi that gets stuck, only to rip the end off!

[cedd]

The install method does sound easiest, but as somebody who does a lot of work pulling cables through ducts, can I suggest the following.....

 

No matter how much you lecture incoming techs, somebody will at some point forget to tie the draw rope back onto their multi when pulling out, leaving you with no way of getting the next multi in without using rods. Never a good state to be in.

 

I'd go for the inspection hatch idea over the bend, it'll slow down the pulling in procedure, but will decrease the possibility of jams.

 

Providing that the multicore ends are suitably taped/bagged, the rough surface on the new ducting shouldn't be too large a probem.

 

Make sure there are loads of spare draw ropes in there, and a proper place to tie them off. Label them too to speed things up.

 

 

If you're trenching the concrete floor anyway, depending on distances would it not be easier to make the run using a trench with a lift off top? You can get properly designed lids and trench systems which can be carpeted to match your flooring.

 

In my experience, there's nearly always an extra cable you forgot to pull in. With a pulled duct system you're now in a tricky position. Pulling a second cable may well mean it getting stuck and tangled with the cabling already in the duct. I'm pretty sure anything that got forgotten will still end up going across the doorways!

 

If you do install a permenant multi, can I suggest lots of cat5 runs to go with, along with DMX, comms, coax and possibly some 10-or-so core cabling connected to terminal strips at either end. Always useful for pyro's, cue lights, remote control, whatever!

[Jack-handy]

How about fixing 2 pulleys & an endless rope in each leg of the ducting, with a carabiner/spring clip as an attachment point?

A bit more fiddly than draw ropes, but the buggers couldn't lose the end!

[stillwave]

thanks for the many replies,

 

what has been said about having a trench with lift up lid was my first suggestion but was quickly turned down because of cost? & that you would see the cut in the carpet (& they don't want to cut the carpet... a custom made/printed one) I have already suggested that if they had the trench lid so that it hinged into the auditorium & the trench hugged the sidewall there would be no need to cut the carpet as it would hinge with the lids, but this also was turned down.

 

the previous method (through auditorium, up & over doors) took around 5 minutes for 1 person to sort (total about 10mins including taping down etc). this method I am estimating will take a minimum of 2 people 15 minutes to install, they will need to drag multi length into corridor below stage (start of service duct), drag through 1st pipe into 2nd then up through hatch in floor at control position (will get away with this hatch as it's in 'technical area', hatch down to inbetween 1st pipe & 2nd pipe would be on aisle).

 

Comms, DMX & Cat5e will be going down a 2nd duct for semi-permanent / permanent install. Excellent suggestion about tying off the draw ropes, I hadn't thought about that.

 

There will be an installed multi for house sound, but I would very much doubt any medium / large touring shows would use a house multi (strange how the lampies don't mind? ) before you get into the problem of different connectors (XLR, jacks, phonos, multipins...)

 

<rant> I favour the trench idea but that would mean cutting the custom carpet so may get turned down purely on that basis, in which case what are the H&S implications of crawling down said service duct (3ft wide, 2ft tall 20 Metres long?) full of dust on a regular basis (3-6 one night shows per week)? </rant>

 

type of rope we were thinking about was polythene rope (similar to washing line) based on cost & the breaking strain.

 

 

Regards,

 

Ben Wainwright

 

P.S. sorry for semi-metric / semi-imperial measurements... I work out mileage as Miles Per Litre!

[dbuckley]

My most used venue has done this to me and others.

 

There is now a pair of runs of four inch plastic sewer pipe from the two useful FOH positions to the orchestra pit. At the orchestra pit end its a hole in the wall with a hatch over the pipe, at the FOH end its a gutted small floorbox on the floor surface, and the pipe a couple of inches down. Theres a drawstring mechanism anchored at both ends with the drawstring at twice the length of the run. The sewerpipe consists of sections that push into each other, so there are a number of bumps in the run when you're pulling the cables.

 

It's OK, but getting multicores with fanouts of XLRs on the end through is a bit of stress. I'm thinking of having a pulling bag made to make it easier.

 

For another hall user the string became disconnected; they used a garden hose to restablish the string.

 

Not my favorite thing, but it verges on workable.

 

They installed some permanent wired cable at the same time; a couple of runs of Cat5 from both FOH positions to SM corner, along with a couple of XLR runs, and a couple of 3.5mm circuits. Yes, you read that right, 3.5mm stereo headphone type circuits.....