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Old 1st December 2003, 11:33 AM   #1
michael is offline michael  Australia
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Default Fast answer needed.. subwoofer cabinet foam

i am finishing construction of my subwoofer tomorrow and so will not have access to the insides after tomorrow, i have some foam at home here that i would like to use inside the box, please tell me if the substance is suitable for a subwoofer and tell me how and where in the box it should be applied.

i have enough offcuts to line alot of the box, but i would have to cut the foam because some of the pieces are 70mm thick.

it is the sort of foam that is used in office chairs, i know this because i used some to replace some old chair padding. anyone please help, i can give pictures of the foam if that helps any.

thanks
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Old 1st December 2003, 11:51 AM   #2
Volenti is offline Volenti  Australia
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That kind of foam will be suitable for lining a sub enclosure, glue it to the walls if possible (contact adhesive ect)

[edit] line as much of the inside of the inside of the enclosure as possible, ie;everywhere about 30-40mm thick is optimal.
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Old 1st December 2003, 11:53 AM   #3
michael is offline michael  Australia
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evenly on walls? reflecting driver and or port opening, on bracing or just walls?
i just gotta get the info b4 tomorrow, and is it worth not putting together and getter better foam
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Old 1st December 2003, 11:56 AM   #4
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I used foam like that directly behind my drivers, with pillow stuffing in the rest of the box...
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Old 1st December 2003, 11:57 AM   #5
Volenti is offline Volenti  Australia
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Well something better would be that thick underlay/sound proofing that most cars have under the carpets, made from shredded cloth type material, I'll take a pic...
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Old 1st December 2003, 12:07 PM   #6
michael is offline michael  Australia
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ok but i only have this foam stuff, the only other thinf i have is a bit of old wetsuit material but not enough for a 100L enclosure.
so if i put this foam on some of the walls and where it looks like the sound may reflect i will be fine...yes?
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Old 1st December 2003, 12:08 PM   #7
Volenti is offline Volenti  Australia
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This is what I use, can't remember what it's called, most carpet places should have it, or something similar.
Attached Images
File Type: jpg soundproofing.jpg (69.4 KB, 164 views)
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Old 1st December 2003, 12:12 PM   #8
Volenti is offline Volenti  Australia
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Quote:
Originally posted by michael
ok but i only have this foam stuff, the only other thinf i have is a bit of old wetsuit material but not enough for a 100L enclosure.
so if i put this foam on some of the walls and where it looks like the sound may reflect i will be fine...yes?
First priority is the wall directly behind the driver, then the side walls, don't limit yourself to just one type of material, use the foam, and when you run out use the wet suit material, or vise versa. Doesn't matter if their different,infact it'll be better because their different
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Old 1st December 2003, 12:51 PM   #9
sreten is online now sreten  United Kingdom
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First off stuffing of a subwoofer box theorectically is not strictly
necessary as its cutoff point is usually well below the resonant
modes of the box airspace.

For sealed box subwoofers the effective volume can be increased
by stuffing completely with a light filling, e.g. BAF (bonded acetate
fibre), this will also suppress the higher box resonant modes.

For a reflex subwoofer its important to keep the airspace around
the end of the port clear, but other than this the rest of the space
can be stuffed with BAF or similar.

Chair foam - which you seem to have is far too dense to stuff the
box - and can only be used to damp the resonant modes.

I found this out the hard way - completely filling a box with foam,
the results were terrible.

Its not necessary to apply to every wall, but each axis should be damped.

So if you have thick foam (50mm to 70mm):

A layer attached to the back of the cabinet.
A layer attached to one of the side walls.
A layer attached to the top or bottom.

Will thoroughly do the job and avoid having to cut it.

If you want to add more stuffing you need something much
more acoustically porous, BAF or something similar.

/sreten.
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Old 1st December 2003, 01:01 PM   #10
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the felt underpad glued to the walls combined with loosely stuffed poly fill works great


DIRT®
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