The basic placement strategy for Churches and meeting
rooms is really quite simple based on two facts...                                      
1- The lower area of the room is absorbed by the furnishings
and people for the most part and,
2- The speakers are always at the front firing to the back of
the room. The side walls can echo between them from the
people but the side walls will only be "grazed" with energy
from the speakers while most of the energy of the sound
system will eventually reach the back wall. Therefore, keep
the absorbers approximately 7 ft. above the finished floor
height and space them from 2 to 4 feet apart on the back wall
and 3 to 6 feet apart on the side walls. This will give some
side to side control but most of the energy will be absorbed
when it reaches the back wall. A few on the platform or stage
back wall at approximately 5 feet above the finished floor
height and 2 to 4 feet  apart will help keep monitors from
reflecting off the back platform  wall into the microphones.
This will help you to control feedback problems.
To learn more about acoustics, go on line and get Jay
Perdue's books on acoustics. They are short, sweet, and to the
point, and very inexpensive. One is about Church Acoustics
and the other is about educational acoustics, but they both
speak to acoustics in general and will shed light on any
acoustical situation.
One box treats a home theatre or recording studio with a 14' X
20' room. Two boxes treats a room that would be large enough
to seat 25 people, three boxes for a room large enough to seat
50 people, four boxes to treat a room that would seat 100
people, and one box per 50 people after that. Remeber it's
about how many the seating capacity would be not how many
are actually in the room at the time. For more, on this see the
installation and instruction page.
A box contains 8 specially built 2' X 4' x 1" acoustial absorbers,
8 patented "Black Hole Acoustics"tm Mounting Systems, all
necessary mounting hardware, mounting instructions and
placement suggestions for only $840.00 or we will sell a 4
panel box of acoustical absorbers for $545.00
2" thick absorbers can be purchased for extra low end
absorption as well as  25% more overall absorption for