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Author Topic: Distributed Sound In High School Gym  (Read 9226 times)

Daniel James

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question about those 70 V's
« Reply #10 on: February 02, 2006, 03:36:06 pm »

about that 70 V system.  I understand why there is a need for that higher potential difference on a school's PA system.  THis must mean that there is a solenoid at each speaker?  Is there a standard 8 ohm or 4 ohm driver at each of those speaker boxes, and if this is the case, could I essentially just have those drivers swapped out for a higher quality one?
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Tom Young

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Re: question about those 70 V's
« Reply #11 on: February 03, 2006, 06:45:35 am »

Yes, there is a transformer (not a solenoid) on each loudspeaker in a 70V system.

You certainly could replace the loudspeakers with higher quality devices. But chances are that the quality of the transformers, themselves, in your existing system would limit the frequency response and power handling of the new loudspeakers. Better to replace the existing loudspeakers with better devices that also have better transformers. Tannoy, EAW, JBL and a few others make very good 70V loudspeakers.

You need to also look at the power amplifier and determine whether it provides enough power and has a decent output transformer. You could replace this with a more appropriate amp that may or may not need an output transformer.

Less of a concern is the cable from amp to loudspeaker to loudspeaker. But it may be a concern and therefore needs to be evaluated.

Finally; as is the case with any type or configuration of loudspeakers, you need to provide equalization (plus high-pass filter, alignment delay and limiting) and have the system measured and optimized in order to achieve the best response.
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
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www.dbspl.com

Daniel James

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Re: Distributed Sound In High School Gym
« Reply #12 on: February 03, 2006, 12:20:23 pm »

We're actually gonna go up there in a couple of weeks to evaluate the equipment, i just need to wait until i have time and I can bring a lift in (it's busy teaching full time AND trying to do the extra-curricular stuff).  

I didnt' even consider the quality of the transformer..that's a good point I'll look into.  Chances are, they are of poor quality.  

It just seems like it may be easier to install a couple of speakers at the front, and rear fill, then trying to make what's already there work.  I hate retro-fitting.

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Rick Johnston

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Re: Distributed Sound In High School Gym
« Reply #13 on: February 03, 2006, 03:57:03 pm »

The existing speakers are part of the original school paging/intercom system, correct? I would be surprised if the transformers were tapped higher than 5 watts, or if the speakers themselves could handle more than ten watts each. Those speakers are definitely not designed for anything but voice paging.

At the head end, the line(s) terminate in switchbank "ports" that are also limited in the wattage they can handle, usually between 12 and 30 watts per switch.

If you break the lines to add a local amp, you may run into a code issue: The school's paging system may be required to take priority over local systems in the event of a building emergency. (a.k.a. "Take-over")

IMO it would be much better to install a separate system for your concert events (distributed or not) than to try and make the school's voice-only paging system serve two masters.

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Daniel James

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Re: Distributed Sound In High School Gym
« Reply #14 on: February 03, 2006, 06:20:51 pm »

thank you for the insight. This was my biggest concern with the distributed system proposed by the consultant: that he wanted to use the exising pa system.  You're right, they're 8 W each.  The consultant claimed this would be plenty.  This was my largest concern.

The fact that the exising PA needs to take priority during an emergency is the reality, another one of my major concerns.  I don't want announcements coming over my system.

Thank you again,

Many of you have been very helpful in reminding me of major concerns as well as explaining new things to me
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Ivan Beaver

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Re: Distributed Sound In High School Gym-Horns and a tip
« Reply #15 on: February 04, 2006, 09:45:55 am »

As stated earlier, a distrubted system in a gym only works if the room is fairly "dry"-most are not.

The problem with simply doing a center cluster or exploded clusters is using a speaker that does not have enough pattern control to a low enough freq.  That means big horns. Often times small speakers are used-because of budget-and they just spray everywhere.

My current favorite approach for a limited budget is to use the Atlas Ap series of outdoor horns.  they have a 15" and a 1" and have a fairly large horn and are "basketball proof".  They have a decent amount of low end and do require a fair bit of "radical" eq to get them to behave, but can work fairly well.

A little trick here when doing the system setup.  After you have the system slignment to as flat as you want-do a RT60 frequency dependent test and find the major  (hopefully there is only 1 that really sticks out) cause of the Reverb.  Yes this will change with bodies in there, but you have to start somewhere.  Then put a notch in the response at that point-how wide and how deep depends on your RT60 measurements.  This will help to keep from energizing the room so much at that freq.  Music does not sound quite as good, but intelligability is often quite higher.
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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?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

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Re: Distributed Sound In High School Gym
« Reply #16 on: February 08, 2006, 09:01:09 am »

Another option to consider is the widely-used Community R-series, including the R1 and R2 series speakers. The R2 uses two 12" woofers and is similar in design to Community's T-Class touring array systems. My high school had a suspended scoreboard in the middle of the room, above which would have been the perfect place to install a center cluster. Is there any reason your school can't just put together a decent, loud portable system and then move it into the room whenever it's needed?
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matt oskay

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Re: Distributed Sound In High School Gym
« Reply #17 on: March 19, 2006, 04:19:16 pm »

Your gym sounds a lot like the gym in indy I did a couple years ago.

 I have 8 passive JBL AE 4212/95 series speakers independently hooked into the eight outputs of the DBX 482 (no controls on the front for kids to screw with the settings) obviously amps in between Crown CTS series 9 mounted in a rack up on the stage.

There are three of the JBL AE speakers on each side of the basketball court evenly spaced facing the bleachers.  The other two are L/R of the stage at the end of the court shooting down the court.

Every speaker has a custom mounting bracket that allows it to rotate 360dg. by taking a genie lift and turning it.  You can also adjust the tilt.  

The DBX 482 is in a rack with a cd player and a little mackie  mackie mounted on the wall in the gym that feed input 1 of the DBX.

All the sport teams have their own preset in the DBX.  They know how to turn the system on and get to their asigned preset.  i.e: basketball preset 1, volleyball preset 2 etc....  Each preset is designed specificly for that event and has been time aligned.  Basketball has music and speach that needs to be loud to get over the crowd.  Wrestling isn't that big so only the center speakers on each side are turned on and the two shooting down the court.

You cannot set the mutes for each preset but you can turn off the routing to certain speakers in the gui software for the DBX.

For Musicals and speacial events the speakers are turned creating a distributed delay system for the gym.  The Drama department has their own mixer and FOH gear that gets patched into the system through a snake routed from the back of the gym to the stage.  There is an xlr input jack on the side of the  gym rack that feeds input 2 of the DBX which goes into effect when they hit their preset.  Normally they have the gym for awhile and it only takes 10 minutes to turn all the speakers.  I trained the theatre teacher on how to do this.  

It works really well and handles music seamlesly.  There are even subs that can roll out and hook into the system ( just a different preset on the DBX where two speakers are turned off to make room for the subs.)

Overall it's a great system for their application which is a Catholic High School that does everything from sports, plays, mass etc... in the gym.  I have never really seen another like it.

Good luck....



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