Film-Tech Forum ARCHIVE: Unusual speaker setup

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Posted by Gunnar Johansson (Member # 1661) on 03-20-2003, 04:53 AM:

Hello!
Just registered, so this is my first post. I just love to find a forum for people who are freaks like me, if not more so. I´ve read through most of the posts, but I have a really unusual question.
We´ve built a new cinema, one room, where we show films twice a week, usually some older films, since students don´t get the best of everything. But we´ve got good equipment, Ernemann projector, CP650 EX and JBL 3632 for front, and 8330A for surround.
The problem is this. We share the room with a conference-center, so we can´t have the speakers there all the time. Another problem is that we didn´t get a perforated screen, at least not yet, so the speakers are placed under the screen (not to good, but it´s cheap to get in, and engineering students aren´t too concerned with that, as long as the technology is cool). We´ve got the cables coming down from the ceiling, and would like to put the speakers on a bar which can be lowered for showtime, but there doesn´t seem to be a standard for mounting the 3632 in such a way. We´re right now thinking of building them in to boxes and hanging the boxes for security and stability reasons, and my question is if anybody has ever had a solution to this kind of problem? Probably not, but if you don´t ask the question you don´t get the answer. Please advise, and I´ll be back for more...

//Gunnar

Posted by Kenneth Wuepper (Member # 1174) on 03-20-2003, 07:42 AM:

Hello, Gunnar,

Welcome to this forum. Everyone here is interested in the success of motion picture presentation. You will not find a more cooperative or resourceful group anywhere.

The system you describe is very interesting. You are in need of "rigging" information for the speaker systems you intend to hang. There is a company dealing with rigging www.sapsis-rigging.com
where you can find assistance and materials for your project.

You are in an engineering environment? That is very good since you will need to understand the structural strength of the ceiling from which the speakers will be suspended. You will need to suspend the loads from the structure and not just the ceiling.

Your screening room sounds very interesting. Can you post some pictures for everyone here to see?

Welcome and best regards

KEN

Posted by Mark Gulbrandsen (Member # 72) on 03-20-2003, 07:56 AM:

None of the JBL Cinema series is capable of being hung/flown right out of the box. The cabinets are not constructed in a way that allow it. JBL does manufacture professional type speakers that are capable of being flown in or out though. FOrm this ort of thing a structural frame usually has to be built around the speaker, and the frame may well cost much more than the speaker costs. Consult with a professional rigger in your area to get them properly installed.
Mark @ CLACO

Posted by Gunnar Johansson (Member # 1661) on 03-20-2003, 08:25 AM:

Thanks!
There´s already a motordriven bar hanging from the ceiling, and I´ve gotten instructions and inspections for how much weight I can hang (which unfortunately aren´t all the speakers yet... [Frown]

) but I probably don´t have to calculate structural mechanics too much (not my strong side...).
We will probably have to construct some kind of "custom"/"customer"-made rigging.
Thanks for the link, I´ll look into it, and check for local rigging companies as well.
I´ll gladly post some pictures, as soon as I post them. Now it´s about time to get ready for todays presentation: Hero, advertised as a secret film, so hopefully nobody will be disappointed.

//Gunnar

Posted by Philippe Laude (Member # 79) on 03-21-2003, 03:22 AM:

Hmm, it seems quite easy to me to build some steel frame to support the speaker, especially in an engineering environment.
there must be all kind of workshop facilities around, for sawing, welding, etc.

Posted by Jean-Michel Grin (Member # 1360) on 03-21-2003, 05:19 PM:

By the past we had in the Alhambra theater in Geneva a system such like this to hang the three screens speakers behind the screen on a horizontal bar (used as light fixture) moved by a powerfull motor, up above the theater stage. The screen was a Rooll-on horizontal type, but perforated.
The three speaers was heavy 3x JBL4638 and 3x4675 horns!
On the first experiments, the tech used just various pieces off rope to hang the speakers ! one year later the system was modified and metal fixture was added on speaker's boxes, and all will be hangin with a more safe material.
One another idea: Maybe you could inspire you off the "clusters" collum system used by bands in tourning, Or make some "rolling tables" to move easelly the speakers...

Good luck, and sorry for my weak English !

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-21-2003, 06:50 PM:

If you ever intend on operating the speakers while they are suspended strictly by wire make sure they are either tied off to the ground or tied so that they are slightly pulled towards the wall. A freely suspended speaker can start swaying by itself, which while fun to watch can lead to some serious damage.

You might also want to look at possibly mounting the speakers on the wall beside the screen.

Posted by Phil Hill (Member # 371) on 03-21-2003, 07:33 PM:

Mark is absolutly correct. Those speaker cases are not meant to be hung by themselves and will pull apart and fall. Either build a frame around them or suspend them from a flying platform so the speakers sit on the platform. AND don't forget to secure them to the frame/platform.

If they are suspended over where people will be or walk, be sure to use additional safety wires directly around the speakers in case the support fails.

>>> Phil

Posted by Kenneth Wuepper (Member # 1174) on 03-24-2003, 07:01 AM:

Whenever attaching anything above the floor, seek professional assistance as there is great liability from injury due to falling of improperly mounted weight.

Have your liability insurance updated to include the new risk. This is especially true if other people who do not have the skills to operate the rigging will have access to your equipment.

Posted by Steve Kraus (Member # 476) on 03-24-2003, 07:07 AM:

Or put the whole operation in your wife's name. [Wink]

Posted by Gunnar Johansson (Member # 1661) on 03-24-2003, 03:37 PM:

Thanks for all the great advise...
It´s not my responsibility to make sure it´s safe, but I´m not that stupid that I don´t make sure that the responsible people (who often are more than stupid) fix something even worse... So I have my own version of letting my "wife" a.k.a. the University have responsibilty. It´s also a stage, with place put on in not so regular intervals, meaning I don´t have to have 8-fold security, just 5-fold, but I´m going for all that I can. I will let a proffesional inspect it, and let a proffesional build it. Personally I can almost not trust my calculations, so I certainly don´t trust my welding... [Smile]

This whole construction has been a nightmare in most aspects. The right stuff being bought for the wrong plays, and the wrong reasons. I´m coping though, and hopefully all will be fixed after this summer (I won´t "leave office" until it´s done, ususally it´s a one year asignment, and I´m soon coming up on one year). Surround speakers is our next thing, and you´ll probably fall over if you see it when it´s finished, but I do the best with what I got.
Tomorrow night we´ve got Gangs of New York, and I´ll try to take some pictures of what it´s like, what I´m aiming to do, and a picture of me to post here. Hopefully you´ll see some good things and some innovative things, and I´ll gladly take all advise I can get...
Daryl: I´ll make sure they have enough points to be stable, and mounting them on the back wall is unfortunately not an option. Over three meters away (~10 feet) and we still don´t have a perforated screen... Any tips on how to solve that? Shotgun? A needle and lots of time?
I´ll probably construct separate boxes for tops and mids as they don´t fit under the screen if they´re on top of each other.

Thanks for all the good advise so far... I´ll get back soon..

//Gunnar
PS The secret movie was Hero (Ying Xiong (2002))http://us.imdb.com/Title?0299977 which was pretty good, and we were the first ones to have the print... [Smile]

Posted by Gunnar Johansson (Member # 1661) on 03-26-2003, 02:42 PM:

Here are now some pictures of the theatre, and hopefully at least one that shows my problem. Enjoy, and I´ll get back to you as soon as it gets better...
I´ll try to get some pictures posted for the picture tour of my theatre. These are just of speakers and the speaker setup.

The back of the screen showing the speakers standing.

This is what it looks like from the front (masking below screen was put up again after the picture was taken)

Hope this helps you understand. And I´ll gladly show you what I did to make it work, if I ever do.

//Gunnar