IB in an auditorium?

[jud]

My brother-in-law and I have been working on designing a sound system for our new church auditorium, and we were talking yesterday about the feasability of an infinite baffle installation instead of traditional pro-audio subs.

Our auditorium is about 100 feet wide by 70 feet deep by 35 feet tall, and has two nice big empty chambers in the front corners where rear projectors are installed. Probably enough space for a total of 8 18" drivers per side in a line array.

The priority is being able to generate clean, loud bass without displeasing the "aesthetic" committee. Depth of bass is not as important since it will be a music-only application.

Anyone have any experience in this area? Is this feasible given the large space, or are we better off to stick with more traditional sub cabinets?

[ThomasW]

Me thinks that horns or ported cabs are the best bet...

[rgvivace]

"My brother-in-law and I have been working on designing a sound system for our new church auditorium, and we were talking yesterday about the feasability of an infinite baffle installation instead of traditional pro-audio subs.

Our auditorium is about 100 feet wide by 70 feet deep by 35 feet tall, and..."

That's 245,000 cubic feet, about 2/3 the size of Vienna's Musikvereinsalle (!!!). At that size, bass quality -- especially issues of room acoustics -- will predominate over issues of extension and spl. You will need to get the woofers relatively close to the main drivers or you will have serious issues of phasing and time arrival over that broad a listening area. There are real, preactical reasons of size that leads the pro-sound people to ported cabinets in this kind of installation (the Meyer Sound cabs seem to be the popular choice these days).

In any case, you will almost certainly need some sort of "speaker management device" like the Behringer, BSS MiniDrive dBX DriveRack or siminar digital XO/EG/Time Delay units to time align the woofers and your main arrays.

To get the clarity benefits of IB would require a ginormous array -- 16 total 18" drivers might not be enough to drive that large a cubic capacity space.

[poormanq45]

Perhaps instead of using the space you're talking aobut for an IB, you could seal off about 20~50ft^3 of it. Then use 8 18" drivers with a couple of 6" ports tuned to ~25hz.