Installs - Gymnasium Speaker Problem

[MNicolai]

Our gymnasium just got revamped, they knocked down a wall and made it probably about 2.5x as long as it was, and now are calling it a field house. It's still under construction, won't be done until August. I was just walking around with the electrician the other day though and noticed that inside of there, they installed all of the speakers so they are mounted directly on the I-Beam and pointed straight at what will be a wood floor, and there's nothing in there aimed at where the bleachers will be at all.

Is it just me, or does this sound like a really bad idea? In addition, can anybody provide me with a diagram or article to explain the physics of this?

I thought I had some system design manuals sitting around that explained this but I've been unable to find any. I want something that's easy to take to the project managers though so that the issue can be addressed appropriately.

[highdesertpirate]

After working as both a mobile DJ and in a number of clubs, I have had some experience with speaker placement. One detail you did not include was the height of the I-beams from the floor. The higher they are, the more likely the sound is to carry to the bleachers. One problem with the set up you described is you lose some of the stereo definition (assuming that matters at all) if you are broadcasting music. I think you would be far happier with the quality if some of the speakers were directed at the bleachers. The acoustics of the room also have an effect on the sound quality. If the room is really bright (reflects sound) you may end up with some annoying echos, but unless its Carnegie Hall, you're probably in for some acoustic challenges regardless. One last thing, are there any speakers directly over the bleachers, or are they all in the middle of the room? Good luck.

[MNicolai]

Originally Posted by highdesertpirate

After working as both a mobile DJ and in a number of clubs, I have had some experience with speaker placement. One detail you did not include was the height of the I-beams from the floor. The higher they are, the more likely the sound is to carry to the bleachers. One problem with the set up you described is you lose some of the stereo definition (assuming that matters at all) if you are broadcasting music. I think you would be far happier with the quality if some of the speakers were directed at the bleachers. The acoustics of the room also have an effect on the sound quality. If the room is really bright (reflects sound) you may end up with some annoying echos, but unless its Carnegie Hall, you're probably in for some acoustic challenges regardless. One last thing, are there any speakers directly over the bleachers, or are they all in the middle of the room? Good luck.

A rough estimation puts the speakers at around 30-35' off the floor, and primarily in the center, not over the bleachers. Stereo definition is irrelevant. It's the usual gym, finished wood floors, concrete walls, exposed steel I-Beams with a hard ceiling. The speakers are not regular two-way cabs, they are square-shaped and don't appear to have much to them for angling the sound waves outward.

[SHARYNF]

Probably not going to work for much more than the players hearing the announcements. Some of the worst installs seem to be done in gyms, the designers seem to think that they can use the same technique for hall ceiling mount pa speakers.,


Are their bleachers on both sides of the gym? Some arrangement where there are three elements one pointing to the bleachers one pointing down and the other pointing to the opposite bleachers. For a rough idea take the center line, and draw a line from it to the top of the bleachers on each side, take these degrees and divide it by three, typically you are going to want some sort of horn for mids/high and speaker for the lows, and try to get a horn dispersion that approximates the degrees divided by 3 (usually around 40-60 degrees)

This is just a rough guess, someone should really design the system properly.

Sharyn

[museav]

Since this is the same situation you posted on another forum, I'll post that same response here. The general idea is simply that you may have a valid concern but you should probably do a little confirmation first since you don't seem to actually have been involved up to this point and the installation may not be complete. You may also want to consider if there are any factors such as what is being installed being the same thing that is in other district school gyms or the result of a low bid or Value Engineering situation. This is very sensitive to me as I have had this happen, even having one school ask us to completely change my design to match what the electrician said he could install cheaply to make up for cost overruns elsewhere on the project (we refused to provide a design we know would not work, but not everyone may do that). Anyways, here is what I posted elsewhere:

I have done a number of gyms with speakers directly over the court in addition to the speakers covering the stands. The court speakers are typically a separate zone with a separate mix, processing, amplifier, etc. These court speakers are used for graduation, mass and other special events, maybe even for pep rallies and halftime to get direct coverage of the floor for music.

There may be a problem with the speaker locations and aiming but there also may not and I think you need to do more investigation. The Electrical Contractor said there was a reason, so maybe you need to follow up on that. Have you talked to the designer or reviewed the system drawings? If the room is not to be completed for another 4 to 8 weeks, are you even sure all the speakers are in? They may have had to get everything installed over the court proper so they can finish and paint to court or they might be waiting for the bleachers to be installed in order to coordinate the installation and/or aiming of the speakers covering the bleachers. I would suggest getting a little more information before you assume that it is wrong and start making an issue of it. If what you find confirms your fears, then raise the issue.

[MNicolai]

Originally Posted by museav

Since this is the same situation you posted on another forum, I'll post that same response here. The general idea is simply that you may have a valid concern but you should probably do a little confirmation first since you don't seem to actually have been involved up to this point and the installation may not be complete. You may also want to consider if there are any factors such as what is being installed being the same thing that is in other district school gyms or the result of a low bid or Value Engineering situation. This is very sensitive to me as I have had this happen, even having one school ask us to completely change my design to match what the electrician said he could install cheaply to make up for cost overruns elsewhere on the project (we refused to provide a design we know would not work, but not everyone may do that). Anyways, here is what I posted elsewhere:

I have done a number of gyms with speakers directly over the court in addition to the speakers covering the stands. The court speakers are typically a separate zone with a separate mix, processing, amplifier, etc. These court speakers are used for graduation, mass and other special events, maybe even for pep rallies and halftime to get direct coverage of the floor for music.

There may be a problem with the speaker locations and aiming but there also may not and I think you need to do more investigation. The Electrical Contractor said there was a reason, so maybe you need to follow up on that. Have you talked to the designer or reviewed the system drawings? If the room is not to be completed for another 4 to 8 weeks, are you even sure all the speakers are in? They may have had to get everything installed over the court proper so they can finish and paint to court or they might be waiting for the bleachers to be installed in order to coordinate the installation and/or aiming of the speakers covering the bleachers. I would suggest getting a little more information before you assume that it is wrong and start making an issue of it. If what you find confirms your fears, then raise the issue.

Though I imagine audio is as done as it will be, because new speakers are already in and I wouldn't imagine an audio guy coming out twice to rig equipment up, it's possible that there are circumstances I'm not foreseeing. I will talk with the electrician tomorrow, who is an employee of the school district, overseeing the project, not a subcontractor to it, and see if he is aware of anything that is being added. If he isn't aware of anything, then I will move on to the system drawings and check those out.