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Author Topic: Center hung system in gym  (Read 5064 times)

Josh Hoevelmann

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Center hung system in gym
« on: August 15, 2008, 03:32:17 pm »

There is a large gym(11,000) seats, yet it is very intimate.  The idea proposed is a center hung system of speakers.  There would be a center hung octagon shaped truss on motors with about a 30ft span to any side.  Speakers would be hung on their respective side facing that side with a sub on each side as well.  

With the backs of that many speakers facing each other, are their potential problems with frequencies interfering?  At first I thought their would be but then I realized there are "in the round"  concerts that pull it off all the time.  there is acoustical baffeling in the ceiling?

Any info would help

Thanks
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Ivan Beaver

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Re: Center hung system in gym
« Reply #1 on: August 15, 2008, 05:18:59 pm »

The biggest problem with a setup like that is the fact that you are going to be energizing a  lot of area where there are no people.

I like to do gyms where you put the loudspeakers closer to the people so the intelligability is much higher.  Of course this costs a good bit more-but also works much better.  You also do not need as much "horsepower" from each loudspeaker because of the distance decrease.

An exploded mono rig if you will.
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Caleb Dick

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Re: Center hung system in gym
« Reply #2 on: August 16, 2008, 11:20:35 pm »

I would be worried about the LF interference.  From box to box, assuming one per side of the octagon, and possible cancellations from box/ceiling interaction.  Maybe some sort of super- or hyper-cardioid setups (there goes the budget!).  

Should be obvious, but excellent acoustical treatment gets a big vote from me.  

Caleb
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Tom Young

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Re: Center hung system in gym
« Reply #3 on: August 17, 2008, 08:18:54 am »

Not sure if I interpretted this right or not:

How was the octagon with 8 loudspeakers with subs determined to be appropriate, coverage-wise ?

This is way over kill.

Was it "designed" by an architect or the art teacher ?
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Tom Young
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Josh Hoevelmann

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Re: Center hung system in gym
« Reply #4 on: August 18, 2008, 02:56:15 pm »

The positioning of the speakers was determined based on sight lines to video boards, point of reference and minimizing number of cabinets needed.  Also trying to stay out of outside events fly space.

The ceiling is acoustically treated.  this rig plus the acoustical treatment sits about 20ft below the actual roof with the actual ceiling beams that shows and anything else if flown from.

Also, it is worth noting this is the current location of the speakers now.  Just with a bad coverage pattern for the space.  When in the coverage pattern it sounds pretty good.  No specific frequencies sound excited by the current arrangement.
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Sam York

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Re: Center hung system in gym
« Reply #5 on: August 18, 2008, 03:12:47 pm »

Josh Hoevelmann wrote on Mon, 18 August 2008 19:56

The positioning of the speakers was determined based on sight lines to video boards, point of reference and minimizing number of cabinets needed.  Also trying to stay out of outside events fly space.



So, everything was considered apart from whether the audience will be able to hear what's coming out of the speakers?  Laughing
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Brad Weber

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Re: Center hung system in gym
« Reply #6 on: August 18, 2008, 04:50:23 pm »

Josh Hoevelmann wrote on Mon, 18 August 2008 14:56

The positioning of the speakers was determined based on sight lines to video boards, point of reference and minimizing number of cabinets needed.  Also trying to stay out of outside events fly space.

So no consideration was given for the resulting performance of the audio system?  I would think that the audio system designer would be modeling the system for that type of application and size of room and that should show any resulting interference.

You mentioned the room seats 11,000 and the ceiling is 20' above the rigging, but can you tell us anything else about the project like the shape and overall size of the room or what the sound system is used for or any specific performance requirements?
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Brad Weber
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Josh Hoevelmann

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Re: Center hung system in gym
« Reply #7 on: August 19, 2008, 09:13:06 am »

It's very difficult to convince an athletic department and graduation committee that it would be better to hang the speakers somewhere else when they've been in the same spot(not same speakers)since 1972.  With the recent addition of video boards, that has become a concern, dealing with sight line issues.  To the graduation committee, the current system is just fine and athletics wants more "punch" or "impact."

These are the two main things the system would be used for.  For seating 11,000 it is very compact.  The speakers would be hung no higher than 45 ft above court.  The very farthest seat is only about 120 ft from court side(measured diagnaly....the very top set of bleachers would be covered by a delay ring.   Well, here's a picture.

index.php/fa/17485/0/

This is from 2004, so the center hung scoreboard is not there but the speakers just above it are.  There are two video/scoreboards at each end, one where the American flag is and directly opposite of there.  This picture makes it look huge but it's not!
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Josh Hoevelmann

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Re: Center hung system in gym
« Reply #8 on: August 19, 2008, 09:23:58 am »

Here's another pic.   Again it's old and blury but you can see the current speaker set up.  I don't have problems with the quality of audio just the coverage.

index.php/fa/17486/0/
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Jason Lavoie

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Re: Center hung system in gym
« Reply #9 on: August 19, 2008, 10:20:46 am »

Josh Hoevelmann wrote on Tue, 19 August 2008 09:13

It's very difficult to convince an athletic department and graduation committee that it would be better to hang the speakers somewhere else when they've been in the same spot(not same speakers)since 1972.



ask them what their car looked like back in 72?
what did their "home theatre" look like back in 72?
so much has changed since then, that it deserves a fresh re-design just out of principle to make sure you're not missing out.

that long ago, the only way to get enough volume was probably with horns, which would have projected nicely, but with less frequency range. today you're trying to use completely different technology and the approach needs to change.


Quote:

 With the recent addition of video boards, that has become a concern, dealing with sight line issues.  To the graduation committee, the current system is just fine and athletics wants more "punch" or "impact."


so, graduation committee needs it once, maybe twice per year, and athletics needs it how many times??
this is no contest who should be driving the cart here. as long as it doesn't negatively impact graduations

Jason
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Brad Weber

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Re: Center hung system in gym
« Reply #10 on: August 19, 2008, 12:59:11 pm »

Here's another picture: http://www.mtsu.edu/murphycenter/images/arena_e.jpg

Josh Hoevelmann wrote on Tue, 19 August 2008 09:13

It's very difficult to convince an athletic department and graduation committee that it would be better to hang the speakers somewhere else when they've been in the same spot(not same speakers)since 1972.  With the recent addition of video boards, that has become a concern, dealing with sight line issues.

Why did they need to change anything, it was just fine wasn't it?  So get rid of the video boards or try to get them to understand that both the space and the audience's expectations have changed as demonstrated by the other changes in the space and that this also applies to audio.

You keep mentioning coverage being the problem with the existing system and the audience coverage is a factor of both the speakers and their locations.  Perhaps you can find speakers that meet all of your other requirements and can provide acceptable coverage from the existing locations, but it may be far from the most effective approach or possibly not even practical.

Quote:

The very farthest seat is only about 120 ft from court side(measured diagnaly....the very top set of bleachers would be covered by a delay ring.

Would be covered or are covered or might be covered?  Maybe others are not as confused as I am, that happens a lot, but I am not clear on what is in place or what is being added or where you are in the process.  I thought you only had a center cluster type system but in your pictures I also see a totally separate cluster for graduation type events and it is not clear how that plays into the current situation.  The pictures also make it seem the room is rectangular and with mostly glass walls, making a symmetrical center cluster appear less than ideal for a number of reasons (including that you would probably need different coverage for the sides than for the ends where the seating is further away).  It also seems that it is possible to use the arena with the upper bleachers closed and only partial seating, something which could affect the coverage desired.

Beyond the physical issues, I am also not clear on the general situation.  Is this system currently in the design process or has a specific system already been proposed?  Are you the system designer or reviewing someone else's design or what?  This may seem to be getting way off your original question but I think the relevancy is that your question was something you should be addressing with your system designer and if you are wanting comments on someone's design then we need to know all the facts in order to be able to respond appropriately.
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Brad Weber
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Josh Hoevelmann

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Re: Center hung system in gym
« Reply #11 on: August 19, 2008, 04:29:30 pm »

This is in the very early stages.  Yes, athletics gets the most use out of the system, however, more than likely the money will not come from them.  If you're not familiar with University politics, graduation ceremonies trump all other events through out the year in priority, importance and finances.  We have 2 ceremonies in May, 1 in August and 2  more in December.  We are also home to 6 high school graduations in 4 days in May.  We have about 10,500 for each ceremony and about 1700 graduates each time.  In short, our total for the graduations throughout the year come close to matching our basketball total attendance.

The other speakers you see are used for graduation only, but it has been requested that speakers hung in that location be reconsidered.  There currently is not a delay ring, but there would be one with a new system, for various reasons.  Yes, there are many events when those bleachers are not used and are pushed in.

Please be aware I am playing devil's advocate with you all somewhat to better answer the questions posed to me by the audio illiterate.  Again no system has been designed, no company even hired yet.  However, the folks that would be cutting the check and those organizations that the system would effect have expressed these concerns.  
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Ivan Beaver

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Re: Center hung system in gym
« Reply #12 on: August 19, 2008, 07:29:50 pm »

Less than a year ago we did a good sized University basketball arena.  While not as large as yours (only 6000 or so seats) the concepts remain the same.  And with you, graduation was the PRIMARY concern.  This was at an expensive private school and they wanted the parents to hear their kids name when called.

The system is an exploded ring witht he loudspeakers just in front of the front row of bleachers.  There is also another couple of loudspeakers positioned above where the front of the graduation stage is set that cover the floor where the students sit-during graduation.

THere are various presets in the system that allow different parts of it to be turned off if people are not in those particular seats-in order to keep the clarity up.

For graduation the floor loudspeakers are turned on and the ring of loudspeakers is signal aligned (in the preset)to the floor cluster so as to have a system that operates as a single unit.

It works quite well.  It took awhile to align properly, but that is just part of the job.
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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

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Brad Weber

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Re: Center hung system in gym
« Reply #13 on: August 20, 2008, 03:33:43 pm »

Josh Hoevelmann wrote on Tue, 19 August 2008 16:29

Yes, athletics gets the most use out of the system, however, more than likely the money will not come from them.  If you're not familiar with University politics, graduation ceremonies trump all other events through out the year in priority, importance and finances.
Quote:

The other speakers you see are used for graduation only, but it has been requested that speakers hung in that location be reconsidered.

Do you mean that the speakers hung in the separate array were going to be deleted and they have asked to consider keeping that array (or something similar) or that they are wanting to consider not having a separate array?


Quote:

Again no system has been designed, no company even hired yet.  However, the folks that would be cutting the check and those organizations that the system would effect have expressed these concerns.

What are you trying to do at this time?  Are you trying to establish what you need the system to do and/or a budget or are you actually trying to define the system?  If you do not have someone with expertise in this type of audio system design onboard, I suggest staying focused on the functionality and approaching the actual technology and system in as general terms as possible until you have a system designer onboard.  Not only does defining specific solutions potentially limit your designer's options, but if you present those solutions to faculty and administrators then they also may develop expectations based on what is presented and you may experience resistance to varying from that later on.

While speakers at the scoreboard might actually work pretty well in that space for basketball and other sporting events, such a system would pretty much be dedicated to that use.  And you could add a dedicated array for graduation type events similar, basically the same concept apparently currently in use (in fact if the current array works for them you could probably just keep it).  However, in order to support a wider variety of events and to try to provide better intelligibility, many arenas use a distributed satellite type system as Ivan described.  With multiple speakers located closer to the listeners and each covering a smaller area you can potentially achieve better intelligibility while another advantage of this approach is that it often allows using programmable routing and processing to configure the system to support different applications and events.
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Brad Weber
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