Posted by thylantyr [ 66.35.226.228 ] on October 03, 2006 at 10:30:51:
In Reply to: Ported Enclosure for line array posted by JP Haggar on October 02, 2006 at 09:42:03:
Use the same rule of thumbs as you would any ported enclosure.
Don't stuff the box in such a manner that hinders port performance,
usually loose fill. You can experiment by adding/removing fill
and taking note of how it works. A more exotic method is to make
sound conditioning pillows. I used ordinary poly batting with
Acoustastuf {substitute polyfill to save money} inside, folded
to make it like a pillow, use 3M spray glue to secure the pillow
and use the glue to attach it to each cabinet wall.
see pic; [looking inside chamber through rear 6" port]
http://home.pacbell.net/lordpk/robarray/Rear_chamber-2.JPG
This works very well. The large hole and pillows gives me the open
airspace for proper port function and the rear sound wave has a nice
big 6" hole for some of the sound to exit. The sound is smooth,
uncolored by the box.
You don't need a fancy 1/2" - sand - 1/2" recipe, you can do
a simpler recipe if you have proper bracing to deaden the cabinet.
I used 3/4" plywood {except front baffle}, then installed 12" x 12"
MDF panels on each chamber wall [except the front side], four chambers. The chambers are seperate/isolated by a wood brace, then
each chamber has a 1" dowel securing the side panels. This is more
than enough to solve the problem.
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