A couple box design questions

[DigitalFusion 10+ year member]

I am building a box for two eD e12K's (the good ol flat cone models and I have a few quesitions. Here is a pic of the box as it is now for reference:

1.) How much breathing room is the minimum between the magnet and box floor? The subs will nearly touching on one side, and have about 1.5-2" of clearance on the other end. Is that enough space?

2.) I determined the rough volume of each side of the box. My calculations do not take into consideration the volume of the driver, and I am considering the final shape of the fiberglass top to be a wash since one side dips in and the other sticks out. Seperately, it will be 1.09 ft^2 for each sub. I will have 400wrms going to each of them. Any of you box designers have any suggestions for me or does this size seem about right? I have the option to cut a couple holes into the middle chamber to gain another 1/4 of a cube (divided between both subs), but I think I would need to decrease the volume if anything.

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[Trixter 10+ year member]

1.) How much breathing room is the minimum between the magnet and box floor? The subs will nearly touching on one side, and have about 1.5-2" of clearance on the other end. Is that enough space?

the magnet can be as close as needed...unless it has a vented pole piece, hen i give at lease 2".

2.) I determined the rough volume of each side of the box. My calculations do not take into consideration the volume of the driver,

you need to account for this

and I am considering the final shape of the fiberglass top to be a wash since one side dips in and the other sticks out. Seperately, it will be 1.09 ft^2 for each sub. I will have 400wrms going to each of them. Any of you box designers have any suggestions for me or does this size seem about right? I have the option to cut a couple holes into the middle chamber to gain another 1/4 of a cube (divided between both subs), but I think I would need to decrease the volume if anything.

i would use a single piece inbetween the sub to gain a little more room there. also raise the sub up 2-3" to gain a little more volume and vent the pole piece, if needed. when you have your rough design, sub mounting ring and fabric in place, i would use packing peanuts to determine the volume. also, to make things easier, if your sub is .25cu' put something in the enclosuer of equal mass to take up this space and then do the peanut thing. you can minuplate the volume by rasing or lowering the mounting ring at this point. don't stuff in the peanuts, you don't want to distort the fabric, if anything make tha fabric a little larger because the fiberglass can weight it down a little over a large stretch.

 

[DigitalFusion 10+ year member]

interesting... thanks for the response. Did u use any box software to determine that I need to increase the box size? If so, what size did it spit out? The reason I ask is that I tried putting everything in BBPro, and it tells me to use .393 for each driver, which I know cant be right, so I am very confused.

 

[Trixter 10+ year member]

i don't use software to design my boxes...just pencil, paper and a calculator. i estimate about .25cu' for an average 12" sub, .5cu' for average 15" sub. however, i can give you the formula to find the sub's displacement....

4 x 0.33 x 3.14 x (distance from back of the basket to the rear of the magnet^3) x 0.5 x 0.6

answer will be +/- 10%

 

[IamDeMan 5,000+ posts]

i estimate about .25cu' for an average 12" sub,

Are you kiddin me? A 12W7 is only .14 and thats bigger than "average" sized sub. I would say most 12" fall between .1 to .2 at the most.
http://mobile.jlaudio.com/products_subs.php?series_id=9

.5 cu ft for a 15 is way off as well. An 18" MT only eats up .25 Cu Ft

 

[tRiGgEr 5,000+ posts]

Even the old XXX only displaced .19 and it was a large f-er.

 

[DigitalFusion 10+ year member]

i did the calculations on the displacement of the sub at one point in time... I cant remember the exact numbers, but it was very small, like like .08 or something like that.

 

[DigitalFusion 10+ year member]

hmmm.... well now i dont know what to do. I wish I could determine the perfect box size. Thats why I got Bass Box Pro, I wanted to make sure this is right. I really want to do this right the first time. What size should I aim for then? I feel so lost now. Does anyone out there have any box design software that seems to out put correct numbers? I have a scan of the specs sheet that came with the drivers: