empyfree Posted July 24, 2015 Share Posted July 24, 2015 Sorry guys. Speed reading failed me again! Link to comment Share on other sites More sharing options...
mattcoomber1 Posted July 24, 2015 Author Share Posted July 24, 2015 Thanks all again for your replies, I can't move the movers any more towards the centre, they are as far as they will go without interfering with the projection. I cant raise the bar to get them above the projection as I only have about 30 cm to the roof. As the old saying goes, a picture says 1000 words http://i300.photobucket.com/albums/nn12/mattcoomber1/IMG_20150724_152145_zpsgf2bgbhk.jpgThis is how the movers are at present, the SLs are only up as we have a show on this week which is using them, when the cinema is in use, they all come down. Proposed speaker location is right next to the mover as close I can get to it without it failing the mover which puts it just to the left of the 1st 15amp socket. Matt Link to comment Share on other sites More sharing options...
Dave m Posted July 24, 2015 Share Posted July 24, 2015 If it isn't a silly question, Why fit the speakers at all with the ones on the wall there? Link to comment Share on other sites More sharing options...
mattcoomber1 Posted July 24, 2015 Author Share Posted July 24, 2015 Not a silly question, they are part of the cinema surround sound, the ones I want to rig are for theatre use :) Matt Link to comment Share on other sites More sharing options...
GR1 Posted July 24, 2015 Share Posted July 24, 2015 Put some ballast just inside the 2 centre hanging points such that it evens out the loading along the bar and falls within the 250Kg loading limit. Doughtys make Pipe Sling Weight Bags which are available from Flints amongst others. PS : For an auditorium that size you could use smaller speakers like Nexo PS8 which will weigh less and make it easier to balance the loading on the bar. Link to comment Share on other sites More sharing options...
Ynot Posted July 24, 2015 Share Posted July 24, 2015 OK...So next silly question - are these additional speakers to the main house PA then, or are you looking at these AS the main PA?If they're secondary, I'd ask the question why you'd need them unless they're a one-off for a certain effect...If they're your main PA, it does look an odd place to position them as they're behind the first few rows of audience seats... Link to comment Share on other sites More sharing options...
mattcoomber1 Posted July 24, 2015 Author Share Posted July 24, 2015 No silly questions here :) They are fill for the back half of the auditorium, I have my main FOH just in front of the stage. Due to the quite steep rake of the seating, it needs some fill at the top or there is a huge difference in level between top and bottom of auditorium. If you boost the main PA to fill the top, its too loud for the bottom of the auditorium. Matt Link to comment Share on other sites More sharing options...
paulears Posted July 24, 2015 Share Posted July 24, 2015 I'd just hang them, I think looking at the modern IWB. Mainly because its clearly been designed to have the load spread across, and 250Kg is a decent figure. 17KG on each end of that wouldn't worry me at all, but I'm not you. I doubt the bar would even bend. I'd trial hang it and see if anything moves. Link to comment Share on other sites More sharing options...
trussmonkey Posted July 25, 2015 Share Posted July 25, 2015 just a point of clarification. on an evenly distributed bar you do not divide the load by the number of pickups. i.e. 100kgs evenly distributed over 4 pick ups is not 25kgs per pick up. 2 points = 50kgs per point 3 points = 18.8kg/62.5kg/18.8kg4 points = 13.3kg/36.7kg/36.7kg/13.3kg5 points = 9.8kg/28.8kg/19.5kg/28.8kg/9.8kg and so on. :) Link to comment Share on other sites More sharing options...
J Pearce Posted July 26, 2015 Share Posted July 26, 2015 For clarity, I was not suggesting that the load would spread in this manner, but that a rating defined as UDL ought to be interpretable as a load per metre of bar. How the suspension points take that load is a matter for the designing engineer. Link to comment Share on other sites More sharing options...
chrisdwalker2002 Posted July 29, 2015 Share Posted July 29, 2015 As others have said, I would say you're going to have no problem with the weight of a speaker cantilevering on either end. One would assume a socket on the IWB means a load is allowed for on the cantilever. I work in entertainment rigging, and this really wouldn't worry me, but its not my theatre, and not my bar. If the speakers are going to be a permanent install, why not have two new PA points installed. You say the bar is fixed to steel beams above the ceiling. If the beams run north-south of the auditorium, have a PA point just behind the IWB. If they run east-west, at the end of the IWB, or add another pickup to support the cantilever? Lots of options. A new PA point made out of abit of unistrut and allthread to the beam above, easy 50KG< point for a multitude of applications. Link to comment Share on other sites More sharing options...
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