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Need box design for 4 12s...

 

Silver Member
Username: Cwruck

Post Number: 415
Registered: Feb-10
doing a small build for my girls car. 4 12's in a sealed box in the back of her 2004 jetta. can get a good 5.5 cu ft after all displacements, and have plenty of room left in the trunk.
now my question is, should i do 2 separate chambers? 1 chamber for 2 subs?
or should i just let them all play together and really brace the box good?
i mean its not important to have this be crazy loud, more to sound clean and smooth but still be able to crank with clarity.
let me know what you think.. just dont want subs to be out of phase or box becoming weak. i will also do a double baffle to help
 

Silver Member
Username: Cwruck

Post Number: 417
Registered: Feb-10
anyone
 

Gold Member
Username: Jkidder

Worlds gunna end, In 2012

Post Number: 4255
Registered: Nov-05
give max dimensions.... not a lot of cars can fit 4 12s side by side since it requires about 54" of width. you might need to have them firing up with two in back and two in front like...

O O
O O
 

Gold Member
Username: Jkidder

Worlds gunna end, In 2012

Post Number: 4256
Registered: Nov-05
multiply all sides inches and divide by 1728 to find cubic ft btw. keep in mind wood thickness, driver displacement and bracing also while calculating...

12x12x12= 1728
 

Platinum Member
Username: Glasswolf

Post Number: 14044
Registered: Dec-03
considered doing something a little different, and (having 4 12" subs anyway..) build a pair of clamshell isovented 12" subs.

4 12" subs, two pair in a push-pull clamshell config.
 

Silver Member
Username: Cwruck

Post Number: 418
Registered: Feb-10
i have already made the box design.. thats why i was saying after sub, port, and approx bracing displacement i will have 5.5 cu ft total.. or about 1.375 cu ft per sub, which is not too bad for a sealed box.
the subs will be firing up at the trunk.. 2 side by side in the front and in the back.
so i really only need 25 inches of width and 25 inches of depth really to fit them all into a trunk with a sealed box
plenty of room to go bigger if i need to, but i see no need.

just wondering is it a good idea to do 2 separate chambers, and each chamber will have 2 subs in it.
or should i just not worry about it and have them all share the space?
i am also going to paint it as well, and make it look quite nice. i have built quite a few enclosures and have great success in the past.
for spl made a 6 cu ft box tuned to 42 hz for an 18" dc lv 5 and broke 150 with 1800 clamped..

not sure exactly what you mean glasswolf...
im gettin a great deal on some subs, and wanted to do a few projects and this will be one of them
 

Silver Member
Username: Cwruck

Post Number: 419
Registered: Feb-10
oh and if it helps this is all with a stock electrical, so im either going to use a rockford fosgate x1000.1 and run that, which is rated at 1000 watts rms at 2 ohms, or a soundstream rub1.800d which is rated at 800 watts rms at 1 ohm..
not sure on the amp yet, i will wire them all up and see what my resistance is.. if im sitting around 1.5 or so ohms ill just use the rockford figuring impedience rise will easily bring me past 2 ohms and shouldnt stress the amp
 

Platinum Member
Username: Glasswolf

Post Number: 14051
Registered: Dec-03
doesn't matter if you divide the chambers. only benefit to doing so is if one driver fails, it doesn't throw off the volume for the other 3.
 

Platinum Member
Username: Rovin

1 15 = 153 DBs ...Trinidad & T...

Post Number: 16766
Registered: Jul-05
i wud do separation chambers so as to add rigidity to the box ....
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 52
Registered: Oct-10
When using width & depth dimensional bracing,

you add bracing - the box gets smaller - you make the box bigger - the bracing gets bigger - you add bracing - the box gets smaller - you make the box bigger - the bracing gets bigger - you add bracing - the box gets smaller - you make the box bigger - the bracing gets bigger - you add bracing - the box gets smaller - you make the box bigger - the bracing gets bigger - fack that.

I would use 1 chamber with a 3" baffle, subs sitting on 2", with 45's in the corners. You need a constant bracing dimension (height) so you can account for the 45's without the size of the bracing changing.
 

New member
Username: Streetlegal

Post Number: 3
Registered: Nov-10
bigger box thicker wood, it helps, but weight also increases....find the sweet spot...
 

Platinum Member
Username: Nd4spd18

Philadelphia, PA

Post Number: 11528
Registered: Jul-06
4 12"s ain't a "small" system yo. your gf's gonna have a better system than any girl i know
 

New member
Username: Streetlegal

Post Number: 4
Registered: Nov-10
^2 lol..
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 63
Registered: Oct-10
Bracing is stronger than having even thicker wood, besides the baffle.

4 250W 12's sealed will be sweet. What's the model of the driver?
 

Silver Member
Username: Cwruck

Post Number: 420
Registered: Feb-10
i have been thinking and i came up with ill do a double baffle, and 2 chambers and brace each chamber. the box should turn out very solid, and could probably handle a ton of power.
but not sure on the model number of the sub. it is this sub
http://cgi.ebay.com/12-1000-watt-AV123-subwoofer-home-auto-sub_W0QQitemZ28057424 6999QQcategoryZ47095QQcmdZViewItemQQ_trksidZp5197.m7QQ_trkparmsZalgo%3DLVI%26itu %3DUCI%26otn%3D2%26po%3DLVI%26ps%3D63%26clkid%3D4799196609652911826

the guy is local or close to local so it works out to get a bunch and just pick them up and pay no shipping.
they are 27 lbs each so i figure they should be pretty decent subs
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 64
Registered: Oct-10
Unless you know the t/s, you won't know how it'll perform. If it rolls off at 60 HZ, what's the point of having -36dB @ 30 HZ?
 

Silver Member
Username: Cwruck

Post Number: 421
Registered: Feb-10
in the questions he gave a link as to what the model number of the sub was supposed to be used in. it was a big sealed box with a 1000 watt rms amp, and does very well with music. not entirely sure if thats really the sub or not.. but it sure would be nice if it was.
he tried to get the t/s paramters but he doesnt know how to do it and got some wierd numbers. when i visit maybe i can help him since he already has the software.

but do you really think that sub would really start to rolloff at 60 hz? come on now
and he has a few in a sealed box in his car all hooked up and he will let me hear how they perform, which he says is quite wonderful.
i really believe i know a little too much to screw myself in this situation, and im expecting this to turn out very very well
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 65
Registered: Oct-10
I'm just saying - some 12's do roll off high (if they're designed for ported boxes).

I'm sure it will be awesome. 1000W to anything...

Program? Use this calculator

http://www.carstereo.com/help/Articles.cfm?id=30
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