Wayne Parham Messages: 18756 Registered: January 2001
Illuminati (33rd Degree)
Use R11 or R13 lining the line the top, one side and the front up to the woofer. You'll also want two pieces of insulation to span the cross-section. These are conveniently placed, resting on cross-braces inside the cabinet. This breaks the cabinet into three partitions, and midrange energy cannot pass through, only bass. The cross-section insulation impedes standing waves from setting up inside the cabinet.
Bracing is important in that it keeps panel vibrations to a minimum. It is important that the cabinet not add sound of its own, and you should be able to strike the cabinet with your knuckles and not hear a resonant "drum head" sound. As mentioned above, the braces also serve to hold cross-section dampers, one a third of the way up and another a third of the way down. They should be cross braces or window braces and they should double as a place to hang partitioning pieces of insulation across the cross-section of the cabinet.
You can find this damping materials around. Another equivalent is rock wool (instead of glass). Similar properties of different materials are available like this one, COPOPREN by Recticel of 2cm thickness, a sound barrier/foam available from "Leroy Merlin" that I am going to use this year. Pay attention that the speaker was tuned already by Wayne with the first fiberglass insulation solution. I like also another (to) fluffy material used in sofas and pillows that is Polyester Fiber, available at "Mosqueteiros", etc.(many other places).