| Ported Enclosure for line array [message #23211] |
Mon, 02 October 2006 08:42  |
JP Haggar
Messages: 20
Registered: May 2009
|
Chancellor |
|
|
How much stuffing and wich kind is better for absorbing standing waves in a ported line array ?
I'm building the enclosures with double layer 1/2 " MDF with 1/2 " sand filling in between to avoid any enclosure resonance , with horizontal braces between the 8 Mid/Woof. Is the port better on the back panel or the front panel? Only have 30 cm clearance to the rear wall ?
Thanks
|
|
|
|
| Re: Ported Enclosure for line array [message #23212 is a reply to message #23211] |
Tue, 03 October 2006 09:30  |
|
|
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.
|
|
|
|
|
|
| Re: Ported Enclosure for line array [message #23218 is a reply to message #23216] |
Tue, 03 October 2006 15:40 |
|
|
I'm not familiar with your project but big cabinets can get noisy.
Thick walls plus bracing is needed. My cheap array has 1 3/8" wall
thickness throught out the design. Even so, more cross bracing was
needed. This was determined while building by using the old school
hammer trick on the cabinet - thunk - lol .. {same trick used by
Wilson Audio to demo their fancy materials - lol}, hit the cabinet in different areas and fix the problems as they happen, but you need
to start with a good plan first. Just analyze your box while
building and fix the problem spots. Don't think about it too much,
just couple the walls with wood or dowels to make the box dead.
I don't think the port placement is going to be critical. Place it
in the rear so it's not an eye sore and you don't hear any wind
noise.
|
|
|
|
Posting Rules
Members
Search
Help
Register
Login
Get a T-Shirt!
