BillFitzmaurice.info

I am currently putting together a system for the church I attend and was hoping I could get some help designing a stage that would fit 4 -27" titan 48s underneath. The room is 100'x80' the side walls are 16' tall and the gable height is approximately 30'. The room will be used for sports so thats why they want them under the stage, even though they could handle a basketball. The only restrictions are a height max of 40" keep in mind we are using 2x10 for floor joists, The stage depth max is 20'. And the stage length max is 40'. They are going to put a room at each end of the stage each room will be 20' wide x 16' deep. How should we incorporate these subs in to the stage design. I would like to achieve the best performance given these stipulations. I can build a sealed compartment under the stage and line it with something absorptive as peavy suggests, but I not sure what How far from the back wall to make it, the dimensions or materials to use. Any help would be greatly appreciated.

Lance

Building a compartment around the subs is unnecessary, as long as the opening is relatively tight around the perimeter of the subs. You're going to have another problem though, with reflections off the back wall of the stage. At 20' deep, you're going to have some reflections that will result in cancellations primarily right in front of the stage. If you must place the subs on the floor, with a 40' wide stage, you just have to add 5'-10' on each side in order to have a split sub arrangement that wouldn't have nearly as many reflection problems, and probably would cover the room better.

Gymnatoriums are no fun from a sound perspective, because the expectation usually is to cram a performance or worship space into a room not designed for it.

If I were designing this for a customer, I'd probably fly the sub cluster at the gable crest, and fly a line array on either side of the stage at near ceiling height with at least three cabinets (DR200 or DR250), power shaded for near/mid/far field coverage. This arrangement should be basketball resistant and would cover the room pretty well. You'd lose a LF little level up front compared to the same cabs at floor level, but LF coverage would be more consistent throughout. You'll need a good DSP, like the built in DSP on Crown XTI, or a nicer processor like the dbx Driverack 260, Ashly 24.24 or Symetrix Solus. There will be some delay work that needs to be done to align the system, and each box in the array will need to be tuned and amped individually.

All that said... if you're going to fly anything and you've never done it before, consult with or hire someone who does rigging professionally, and do what they say to do.

As for the stage, try not to make it a square box. You want to avoid parallel surfaces. If it's built a couple of feet wider at the stage front than the rear and had a slanted ceiling (higher at the front), you will find that it helps ot keep standing waves to a minimum in the stage area. Acoustic tile would be better than sheetrock for the ceiling, and if you can afford some absorption and diffusion on the walls, you should have a nice performance environment.

Another thing that will help immensely is acoustic absorption in the rest of the room. Gyms are loud and reflective. The more you dampen and diffuse that reflectivity, the better it will sound (and the quieter it will be for sports events).

Thanks for the quick reply. If possible I would like to keep the titans on the floor so I can use them for special events with some omnitop12s. I wish I would have talked to you first because I just finished building 8 omnitop12 jarrays and leland just shipped part of my order, so I will make them work. I was planning on putting 4 per side and power shading as you have stated.Also Some more info about the room The ceiling is vinyl backed insulation (It might as well be called paperbacked), the floor is concrete, the walls will be smart board siding the first 12' up and the last 4' will be insulation and the gable ends will be insulation above 12' as well. I also have access to as much tectum as I need and can place it around the room if necessary. Since placing the titans under the stage will create issues, what if we were to place 2 in each corner of the rooms we are building on the ends of the stage for storage. I could even set them back in the walls we build if that would not hurt anything to keep them off the court. that would put them about 80' apart. I will have the stage changed to have an angled front thanks for the tip!


Lance

Nothing wrong at all with the OTops. i keep forgetting there's a JArray version now.

Two Titans in each corner would be a reasonable compromise.

For a 100' deep by 80' wide room, 3 stack of OT12s, dividing the width into 3rds (@ 20', 40', & 60') would give better coverage. But, your sub to top ratio might be a bit light in the subs. In a room that large, with 184000 cubic feet, I think your going to be anemic on the bottom.

I tried to match sub to top ratio according to their suggested audience size. How many more do you think I will need? How high should the tops be flown? Sorry for so many questions.

lancemhorsley wrote:I tried to match sub to top ratio according to their suggested audience size. How many more do you think I will need? How high should the tops be flown? Sorry for so many questions.

most find that 1.5-2 subs per top is about right. Fly the tops as high as possible without having any obstacle to line of sight like light fixtures and ductwork.

thanks you have been a big help! I will just have to build more subs in the near future to add to this system.

That's the ticket. You may find that four is all you need. Eight Otops would normally run away from 4 T48s without a problem, but flying the tops does induce a bit of overall SPL loss with the tradeoff being more even coverage thanks to the inverse square rule. Between that and the fact that you probably won't push those Otop arrays to their max, you may be OK with what you have.

With the subs on the floor and the tops flown, you may find that you're a bit bass heavy up front regardless of how many of them you have, also thanks to the inverse square rule. You may end up needing to put a couple of sub-only delay stacks in to evenly cover the room... but then again you may find it acceptable. There's no limit on how many cabs you build for your own use once you have purchased the plans, so go wild!

lancemhorsley wrote:I tried to match sub to top ratio according to their suggested audience size. How many more do you think I will need? How high should the tops be flown? Sorry for so many questions.

The problem is the super high walls & ceiling. That kind of room volume will need a bit more subs to cover the bottom. My SWAG would be 6 to 8 subs total. YMMV.