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Author Topic: Question about Gymnasium Speaker Placement  (Read 10988 times)

Jeff Jenkins

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Question about Gymnasium Speaker Placement
« on: January 24, 2012, 11:13:11 pm »

Hello everyone, thanks for taking a sec to read this --

I operate an av business, mostly focusing on residential audio, but occasionally working nightclub/bar installs and more recently schools. I have installed in several standard style gymnasiums, but never one like the one I am set to start on next week.
All the other gyms I have worked with have been setup with the court centered between two sets of stands opposite of one another and bare walls on either end, with either tile ceilings or open ceilings.
This gym has the stands located on only one side, with a bare brick wall opposite. Behind the goal on one end is a small stage that will be used for performances, graduation, guest speakers, etc. The back wall of the stage is solid glass floor to ceiling. Behind the other goal is a bare wall. The ceiling is finished (drywall), and sits at 25'. I attached a rough drawing of the room layout.
The school has purchased (4) JBL JRX115i Speakers for installation. They currently have (4) small ART cabinets which they want integrated as well. We have Crown XLS Amplifiers to power.
My question is what would you recommend for placement to ensure a full sound for sporting events as well as stage events? My plan is to fly the (4) ART cabinets at stage front, and designate their use to stage events only, as they provide sufficient vocal coverage for the room during low noise conditions. Since the gymnasium is used primarily for sporting events and athletic practices, I plan to devote the new JBL cabinets to these events. I was thinking of clustering the JBL's into 2 clusters and flying on the far wall at 1/4 court each way. Do you think is the best placement? Should I cluster all four together in one and place at center court on the far wall? Should I fly them each individually?
I would like to know what your opinions are. I'm always learning in this business, and this is one of those times. Any input is good input.
Thanks alot.
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Brad Weber

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Re: Question about Gymnasium Speaker Placement
« Reply #1 on: January 25, 2012, 07:32:18 am »

Hello everyone, thanks for taking a sec to read this --

I operate an av business, mostly focusing on residential audio, but occasionally working nightclub/bar installs and more recently schools. I have installed in several standard style gymnasiums, but never one like the one I am set to start on next week.
All the other gyms I have worked with have been setup with the court centered between two sets of stands opposite of one another and bare walls on either end, with either tile ceilings or open ceilings.
This gym has the stands located on only one side, with a bare brick wall opposite. Behind the goal on one end is a small stage that will be used for performances, graduation, guest speakers, etc. The back wall of the stage is solid glass floor to ceiling. Behind the other goal is a bare wall. The ceiling is finished (drywall), and sits at 25'. I attached a rough drawing of the room layout.
The school has purchased (4) JBL JRX115i Speakers for installation. They currently have (4) small ART cabinets which they want integrated as well. We have Crown XLS Amplifiers to power.
My question is what would you recommend for placement to ensure a full sound for sporting events as well as stage events? My plan is to fly the (4) ART cabinets at stage front, and designate their use to stage events only, as they provide sufficient vocal coverage for the room during low noise conditions. Since the gymnasium is used primarily for sporting events and athletic practices, I plan to devote the new JBL cabinets to these events. I was thinking of clustering the JBL's into 2 clusters and flying on the far wall at 1/4 court each way. Do you think is the best placement? Should I cluster all four together in one and place at center court on the far wall? Should I fly them each individually?
I would like to know what your opinions are. I'm always learning in this business, and this is one of those times. Any input is good input.
Thanks alot.
Looking at your drawing it looks like the audience in the bleachers would have a very restricted view of the court due to four huge columns and a recessed corner.  Is that correct?  If so, that is also going to affect the speaker quantity and placement to cover the bleachers.

What are the ART speakers?  As far as I know, Applied Research & Technology or ART has never offered speakers and ARTcoustic offers some home theater speakers that would have no place in an install like this.  So I have no idea what those speakers are.

The JRX115i is an entry level, MI grade speaker.  Its nominal 90x50 pattern isn't applicable until about 5kHz and above, at 2kHz the JRX115i pattern is apparently closer to 80x85 and at 4kHz around 100x80.  So it is not what you want to put on the wall 72'+ opposite from the listeners in a room such as you described, at least not if you want to understand what is being said.

If the only purpose of the athletic event system is to cover the stands, not the court, then you might look at whether speakers could be flown closer to the bleachers so they cover the listeners but also cover just the listeners.  You'd have to look at where speakers could be flown and whether the speakers they are providing would work or if you'd need something else.

For the stage, that depends greatly on what types of performances are envisioned and the actual audience area.  For example, would commencement use the bleachers in addition to seating on the court floor?  Are they thinking the system will support live bands or DJs for dances?

On a more general issue, why aren't you selecting the appropriate speakers, addressing acoustics, etc.?  We don't know what you plan for mics, mixer, system processing, etc., but you apparently plan to use whatever speakers and amps the school has seemingly randomly supplied rather than your guiding them on appropriate choices.  Since you don't mention it, I don't know if you have thought about how you plan to address any cabling and the possible need for conduit and/or plenum cable when you are dealing with a sheetrock ceiling and glass and brick walls .  And you have a room with at least one glass wall (behind the stage) and one bare brick wall, a sheetrock ceiling (flat?) and a court floor that is apparently going to be used for athletic events, commencement, live music performances and so on but haven't even mention addressing the acoustics.  If you want to best serve your clients for professional/commercial installs then addressing these types of issues along with business aspects such as appropriate licensing and insurance are recommended practice.
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Ivan Beaver

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Re: Question about Gymnasium Speaker Placement
« Reply #2 on: January 25, 2012, 07:38:31 am »

Hello everyone, thanks for taking a sec to read this --

I operate an av business, mostly focusing on residential audio, but occasionally working nightclub/bar installs and more recently schools. I have installed in several standard style gymnasiums, but never one like the one I am set to start on next week.
All the other gyms I have worked with have been setup with the court centered between two sets of stands opposite of one another and bare walls on either end, with either tile ceilings or open ceilings.
This gym has the stands located on only one side, with a bare brick wall opposite. Behind the goal on one end is a small stage that will be used for performances, graduation, guest speakers, etc. The back wall of the stage is solid glass floor to ceiling. Behind the other goal is a bare wall. The ceiling is finished (drywall), and sits at 25'. I attached a rough drawing of the room layout.
The school has purchased (4) JBL JRX115i Speakers for installation. They currently have (4) small ART cabinets which they want integrated as well. We have Crown XLS Amplifiers to power.
My question is what would you recommend for placement to ensure a full sound for sporting events as well as stage events? My plan is to fly the (4) ART cabinets at stage front, and designate their use to stage events only, as they provide sufficient vocal coverage for the room during low noise conditions. Since the gymnasium is used primarily for sporting events and athletic practices, I plan to devote the new JBL cabinets to these events. I was thinking of clustering the JBL's into 2 clusters and flying on the far wall at 1/4 court each way. Do you think is the best placement? Should I cluster all four together in one and place at center court on the far wall? Should I fly them each individually?
I would like to know what your opinions are. I'm always learning in this business, and this is one of those times. Any input is good input.
Thanks alot.
Since the school bought the loudspeakers-I would go to whoever recommended them and ask them what the design was and where they thought they should be placed.

OH WAIT- there was not DESIGN-just that somebody sold them a bill of goods and expects somebody else to somehow make it work.  At least that is probably what happened.

You don't have enough loudspeakers to begine with.   Yes you can "cluster" them, but in a reverberant room all they will do is make noise and excite the room.

What I have found that works well is to move the loudspeakers closer to the people, and you don't excite the room as much so you have a higher "sound to reverb" relationship.

But that takes wide pattern loudspeakers (if you care about covering all the seats) or more more loudspeakers (because the pattern is no narrower because they are closer to the audience.

WIth what you have-something is going to have to be compromised-sound quality (exciting the room with speakers that don't have pattern control) or some seats not being covered.

It amazed me the people who will buy gear and not consider how it will be used or the best application first.
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Jeff Jenkins

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Re: Question about Gymnasium Speaker Placement
« Reply #3 on: January 25, 2012, 08:32:39 am »

Looking at your drawing it looks like the audience in the bleachers would have a very restricted view of the court due to four huge columns and a recessed corner.  Is that correct?  If so, that is also going to affect the speaker quantity and placement to cover the bleachers.

What are the ART speakers?  As far as I know, Applied Research & Technology or ART has never offered speakers and ARTcoustic offers some home theater speakers that would have no place in an install like this.  So I have no idea what those speakers are.

The JRX115i is an entry level, MI grade speaker.  Its nominal 90x50 pattern isn't applicable until about 5kHz and above, at 2kHz the JRX115i pattern is apparently closer to 80x85 and at 4kHz around 100x80.  So it is not what you want to put on the wall 72'+ opposite from the listeners in a room such as you described, at least not if you want to understand what is being said.

If the only purpose of the athletic event system is to cover the stands, not the court, then you might look at whether speakers could be flown closer to the bleachers so they cover the listeners but also cover just the listeners.  You'd have to look at where speakers could be flown and whether the speakers they are providing would work or if you'd need something else.

For the stage, that depends greatly on what types of performances are envisioned and the actual audience area.  For example, would commencement use the bleachers in addition to seating on the court floor?  Are they thinking the system will support live bands or DJs for dances?

On a more general issue, why aren't you selecting the appropriate speakers, addressing acoustics, etc.?  We don't know what you plan for mics, mixer, system processing, etc., but you apparently plan to use whatever speakers and amps the school has seemingly randomly supplied rather than your guiding them on appropriate choices.  Since you don't mention it, I don't know if you have thought about how you plan to address any cabling and the possible need for conduit and/or plenum cable when you are dealing with a sheetrock ceiling and glass and brick walls .  And you have a room with at least one glass wall (behind the stage) and one bare brick wall, a sheetrock ceiling (flat?) and a court floor that is apparently going to be used for athletic events, commencement, live music performances and so on but haven't even mention addressing the acoustics.  If you want to best serve your clients for professional/commercial installs then addressing these types of issues along with business aspects such as appropriate licensing and insurance are recommended practice.
Thanks for the reply. I am licensed, insured and bonded...for the record. I was contacted by the school several weeks ago, they were having problems achieving their desired volume levels in the gym when they had a full house. The system they had in place was by far inadequate. They have (2) ART Amplifiers, an ART 418 8x2 Mixer and the (4) small cabinets. The staff electrician had told me the speakers were by the same company (ART), but he was wrong, they are Atlas SM82-B cabinets. The cabinets look to hold nothing bigger than an 8" woofer. Under the current setup, they have one speaker at 1/4 court on either side of the far wall, and one on each end of the stands. This is what they have used for years.
The pillars are an obstruction. The ceiling over the stands is also dropped 6 feet from the ceiling over the court, and there is an eve of 3ft over head if you are sitting in the stands looking at the court. The original gym was built in 1929, and has been added on to several times over the years. One of the additions is the area where the stands are. I could fly the JBL speakers on this eve, individually behind each beam. This would adequately cover the stands I would think, right? I could then mount the existing speakers at stage front for coverage of the court? Your thoughts?
They are on an extremely low budget. $4,000 to be exact. Thats all the board would and will approve, regardless of what I tell them they need. I'm trying to simply give them all that I can for their money. They want a specific set of Shure mics and a mixer for their auditorium included as well, so technically I have $3,000 to work with. They have the JRX115i cabinets already, so that I can not change. Apparently they had intended to make an upgrade themselves, but decided against it. I am providing the Crown Amplifiers and all the necessary cabling. This alone eats up a chunk of what money I have to work with, and if I expect to make anything, I can't include any additional speakers.
I realize its insufficient, but I can't help it. I just needed a little help trying to make the most of it. Thanks alot.
« Last Edit: January 25, 2012, 09:09:47 am by Jeff Jenkins »
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Brad Weber

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Re: Question about Gymnasium Speaker Placement
« Reply #4 on: January 25, 2012, 10:47:39 am »

I'll start by offering the potential downside.  You go into this trying to help and do what you can for the money.  You know the results will be less than ideal and tell your contacts that.  The results are less than ideal, everyone forgets you told them that would happen and instead of being thanked for trying, you are blamed for it being less than what some 'expected' and they badmouth you to everyone they can.  The "no good deed goes unpunished" approach.

Another consideration is that if you 'make things work' with less than appropriate equipment and budgets then in their minds you may establish those as being accepted practices.  I'm not saying you shouldn't do it, but I would make it as clear as possible that what you are providing is what you can do within the conditions they've imposed and not what should be done or following industry standard practices.

Situations like this where the solution rather than the desired results are dictated to you can require a good deal of  'expectation management' and you might want to try to minimize the possibility of their expectations exceeding what you know you can realistically provide.  The best way I've seen to avoid these issues coming back to haunt you is to be sure to document your understandings and concerns.  Document in writing the goals as you understand them, what you see potentially limiting achieving those goals and what you think will actually be possible, then get them to 'sign off' on that.  If you feel they need to treat the room acoustically to get the desired result, include that recommendation and note that the results may be compromised without it.  Basically, do what you can to make sure they know what to expect and what you see limiting the potential results and document that they agree to that.   


On the more technical side, the Atlas SM82-B is apparently discontinued, the SM82T-B with an internal transformer now includes a direct 8 Ohm 'bypass' setting thus eliminating the need for a separate non-transformer model.  But it is not a bad small speaker with a nominal 65x65 horn that is limited by the size of the box but larger than many other similar boxes.  Response is 65-20kHz (+/-3dB), sensitivity is 92dB@1W/1m and power handling is 150WRMS(?) and 225W peak.  They come with a supplied 'U' bracket, which is nice because you probably wouldn't have to purchase other hardware. 

It would be preferred in that type of space and acoustical environment to cover the listeners from as close to them as possible, maximizing the direct sound to the listeners while minimizing the interaction of the speakers with the room.  For the stage, to cover the main court area I might consider a speaker or array overhead at the front edge of the stage and then overhead delayed fills covering further back.  Keep the level on the first speaker high and run the the fills at a lower level with a delay that supports precedence to keep the localization to the stage.  For the bleachers, some speakers mounted at or just behind the 'bulkhead' aimed down at the bleachers.

Because the stage speakers would be used for live music and would need to provide localization to the stage for the longer dimension of the room, I would consider using the JBLs for the stage and the Atlas boxes to cover the bleachers.  However, with what looks to be 120'-130' of bleachers with an 18' ceiling over the bleachers, and a 'bulkhead' down to 15' at the front, you'd probably need more than four of Atlas speakers to get proper coverage of the bleachers.  You'd probably need something like either four minimum 90 degree horizontal pattern speakers or a larger number of speakers with a tighter horizontal pattern.  Unfortunately, the same basic issue applies if you inverted that approach and used the Atlas speakers for the stage and the JBLs for the bleachers, you'd be hard pressed to get one SM82-B speaker to cover the width of the court from a 24' ceiling, not to mention providing enough sound to cover one quarter of the court for a music performance.

So you apparently simply don't have enough of the right type of speakers to support having them close to the listeners and provide good coverage for all of the listener areas.  But if you move the speakers further away to allow them to each cover a larger listener area then the room becomes more of a factor and both the direct level and intelligibility will drop.

I'm sure it's not what you want to hear but my recommendation would be to really try to get them to come up with some more money, maybe just enough so that you can provide a few more Atlas speakers and some appropriate processing.  Otherwise they seem likely to be treading into that area of decisions made regarding products and budget without proper planning leading to them applying that budget and equipment ineffectively.
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Jeff Jenkins

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Re: Question about Gymnasium Speaker Placement
« Reply #5 on: January 25, 2012, 12:40:46 pm »

I'll start by offering the potential downside.  You go into this trying to help and do what you can for the money.  You know the results will be less than ideal and tell your contacts that.  The results are less than ideal, everyone forgets you told them that would happen and instead of being thanked for trying, you are blamed for it being less than what some 'expected' and they badmouth you to everyone they can.  The "no good deed goes unpunished" approach.

Another consideration is that if you 'make things work' with less than appropriate equipment and budgets then in their minds you may establish those as being accepted practices.  I'm not saying you shouldn't do it, but I would make it as clear as possible that what you are providing is what you can do within the conditions they've imposed and not what should be done or following industry standard practices.

Situations like this where the solution rather than the desired results are dictated to you can require a good deal of  'expectation management' and you might want to try to minimize the possibility of their expectations exceeding what you know you can realistically provide.  The best way I've seen to avoid these issues coming back to haunt you is to be sure to document your understandings and concerns.  Document in writing the goals as you understand them, what you see potentially limiting achieving those goals and what you think will actually be possible, then get them to 'sign off' on that.  If you feel they need to treat the room acoustically to get the desired result, include that recommendation and note that the results may be compromised without it.  Basically, do what you can to make sure they know what to expect and what you see limiting the potential results and document that they agree to that.   


On the more technical side, the Atlas SM82-B is apparently discontinued, the SM82T-B with an internal transformer now includes a direct 8 Ohm 'bypass' setting thus eliminating the need for a separate non-transformer model.  But it is not a bad small speaker with a nominal 65x65 horn that is limited by the size of the box but larger than many other similar boxes.  Response is 65-20kHz (+/-3dB), sensitivity is 92dB@1W/1m and power handling is 150WRMS(?) and 225W peak.  They come with a supplied 'U' bracket, which is nice because you probably wouldn't have to purchase other hardware. 

It would be preferred in that type of space and acoustical environment to cover the listeners from as close to them as possible, maximizing the direct sound to the listeners while minimizing the interaction of the speakers with the room.  For the stage, to cover the main court area I might consider a speaker or array overhead at the front edge of the stage and then overhead delayed fills covering further back.  Keep the level on the first speaker high and run the the fills at a lower level with a delay that supports precedence to keep the localization to the stage.  For the bleachers, some speakers mounted at or just behind the 'bulkhead' aimed down at the bleachers.

Because the stage speakers would be used for live music and would need to provide localization to the stage for the longer dimension of the room, I would consider using the JBLs for the stage and the Atlas boxes to cover the bleachers.  However, with what looks to be 120'-130' of bleachers with an 18' ceiling over the bleachers, and a 'bulkhead' down to 15' at the front, you'd probably need more than four of Atlas speakers to get proper coverage of the bleachers.  You'd probably need something like either four minimum 90 degree horizontal pattern speakers or a larger number of speakers with a tighter horizontal pattern.  Unfortunately, the same basic issue applies if you inverted that approach and used the Atlas speakers for the stage and the JBLs for the bleachers, you'd be hard pressed to get one SM82-B speaker to cover the width of the court from a 24' ceiling, not to mention providing enough sound to cover one quarter of the court for a music performance.

So you apparently simply don't have enough of the right type of speakers to support having them close to the listeners and provide good coverage for all of the listener areas.  But if you move the speakers further away to allow them to each cover a larger listener area then the room becomes more of a factor and both the direct level and intelligibility will drop.

I'm sure it's not what you want to hear but my recommendation would be to really try to get them to come up with some more money, maybe just enough so that you can provide a few more Atlas speakers and some appropriate processing.  Otherwise they seem likely to be treading into that area of decisions made regarding products and budget without proper planning leading to them applying that budget and equipment ineffectively.

Thank you very much for your input. They are a small private school, with a small operating budget. I am simply trying to help them as best I can given the situation. They don't have lofty expectations and just want to improve what they have as much as the money will allow.
Your advice has me leaning toward flying the JBL cabinets at stage front and doing the best I can with the Atlas cabinets over the bleacher area. Would you think a single 4 cabinet array at center stage would be best, or dual cabinet array stage left and stage right?
Thanks again for your advice and input, I really appreciate it.
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g'bye, Dick Rees

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Re: Question about Gymnasium Speaker Placement
« Reply #6 on: January 25, 2012, 01:00:38 pm »

Thank you very much for your input. They are a small private school, with a small operating budget.

Brad has given you the hard realities of the situation.  Here's another basic truth which you should never forget:

Any organization/person will never have a budget which encompasses their needs.  They will, however, have a budget that'll get them what they want........
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Brad Weber

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Re: Question about Gymnasium Speaker Placement
« Reply #7 on: January 25, 2012, 02:26:55 pm »

Your advice has me leaning toward flying the JBL cabinets at stage front and doing the best I can with the Atlas cabinets over the bleacher area. Would you think a single 4 cabinet array at center stage would be best, or dual cabinet array stage left and stage right?
The JRX115i are a) not intended to be arrayed and b) a nominal 90 degree horizontal pattern and wider than that for much of their response.  Especially with them at one end of the room, I would not array them as you do not need 180 degree coverage.  I would also forgo stereo since it wouldn't really be stereo except for maybe a few listeners.

In a room those dimensions and finishes I would be hesitant to try to cover the entire court from the stage.  You could certainly get sound out to all of the listeners but the level would probably vary significantly throughout the listener area and with the amount of energy likely to be hitting the ceiling and walls the resulting intelligibility might be poor.  In general, for that type of space and use I tend to not worry about things such as stereo and to instead focus on factors like coverage and maximizing the direct/reverberant energy ratio (e.g. maximizing the direct sound and minimizing the indirect sound for the listeners).

Just to clarify, there can be a big difference between getting some sound out into the room for a dance and everyone being able to understand what is being said during the valedictorian's speech or by the announcer during a game.  At the same time, there can also be significant differences between dealing with only speech and needing to support full range music.  If the school said the priority was understanding the announcer during games then I might take a very different approach than I would if the priority were music performances or commencement.  You may have the situation where they want all of those, in which case you have a much greater challenge especially with the budget provided.

Because of the nominal 90 degree horizontal and 50 degree vertical pattern of the JRX115i, my thought was more along the lines of four speakers mounted in a row down the centerline of the ceiling over the court.  One located at the front edge of the stage and then the others at something like 25', 50' and 75' in front of that, with each then covering down and in front of them.  That's not going to cover the entire floor properly but it might provide acceptable coverage with reasonable intelligibility and gain before feedback on stage.  You could then play with the level and delay for the individual speakers to make it seem as though everything comes from the stage.  Of course I'd want to quickly model that arrangement and the room just to see what the coverage and intelligibility might be like before making a final decision.

If you don't care about localization to the stage then each speakers mounted at the ceiling in the center of each about a 50'x35' quarter of the court (with the 90 degree horizontal pattern for the 50' dimension and the 50 degree pattern for the 35') and the speaker aimed straight down may even work.

There are probably other options that might be even better than those, that's just a couple of preliminary approaches you might want to consider.
« Last Edit: January 25, 2012, 03:50:23 pm by Brad Weber »
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duane massey

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Re: Question about Gymnasium Speaker Placement
« Reply #8 on: January 25, 2012, 03:14:42 pm »

Jeff, this sounds like the bulk of the type of clients that I deal with, clients that the bigger companies won't work with (for very good reasons). As long as you know going in that the results are not going to be optimum (which you obviously do) and you communicate your concerns to the client (in writing) you can only do as well as the limitations allow you.
I think Brad's idea of firing the JBL's as straight down as possible makes a lot of practical sense if they are primarily for the bleacher crowd and not for the floor area.
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Duane Massey
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g'bye, Dick Rees

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Re: Question about Gymnasium Speaker Placement
« Reply #9 on: January 25, 2012, 03:25:02 pm »

Jeff....

My ideal resolution of such a situation would be to select a proper delivery system and components, present the plan to the school and have them sell or return the inappropriate stuff they purchased.  In other words, back to square one.  If they are not willing to bite the bullet and do it right, I'd respectfully decline.  You're going to be stuck with "why it doesn't work" forever after.......

DR
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