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Help with enclosure design

2287 Views 5 Replies 3 Participants Last post by  MetropolisLake
Hi i wanna build the subwoofer for my theater. I wanna get the Ultimax from Dayton either 15 Inch or 18 Inch. 2 or 3 if they can be fitted in the space i have. Box have to be 15 Inch Deep at max, so that the main limitation. I have a space in my front wall of 10 Ft long wich i can use to put the subs. So when i cover them with the fabric wall they won't be showing.
Tks in advance
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can i fit a ultimax 18 in an enclosure wich is 15 inch deep?
PE website states that the mounting depth on the UM18-22 is 9". So, even if your O.D. on the box is 15", and you use 3/4" sheet stock (MDF, Ply, etc), and you double up the baffles, you're still at 12.75" of depth I.D. That gives you 3.75" of clearance from the back of the motor assembly to the inside of the rear panel. That's plenty. And if you go one step further towards Worst Case Scenario for mounting depths, and countersink the driver frame into the outer sheet of the baffle, you only lose another 3/8" to 3/4" of clearance, leaving you with a minimum of 3" clearance. You're good.

If you use the UM15-22 instead, you buy another ~1.5" of clearance, as its mounting depth is only 7.55".

Point of Interest: With a driver that moves as much air as these do, and with as much moving mass as these have, a single layer baffle and panels less than 3/4" thick are not advisable. The UM18-22 is throwing a pound and a half of cone around on the surface of that box... you'll want as much mass as you can get to dampen that.
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Hi Thanks for your answer. Sadly the 18-22 is out of stock.. and can't wait so long any other suggestions ( 15 inch is one) but like the looks of the 18 inch haha. Room size is 6.3 Mts.(20.6 ft) by 3.9 Mts (12.8Ft) So im trying to put 3 in the center bellow my screen, and maybe some triad inwall subs on the side walls to balance if needed.
Here is my floor plan, disregard subwoofer location they would have to change to the middle of the front screen.


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four 18's
two boxes with middle divider

external 49 wide X 15 deep X 27 high, side by side = 98 x 15 x 27

internal each chamber
23.375 X 12.75 X 25.5 = 4.4 cubic feet - 0.26 driver = 4.14 - bracing = real close to 4 cubic feet per driver

will work fine. make it taller if you want more air space. At 49" wide you can use entire widths of cabinet grade MDF. Go beyond that and your cut list will start getting inefficient unless you plan well plus it's harder to rip sheets of wood the long way.

Look in the other threads on this subforum for "quad ultimax build", I did this same thing except deeper and shorter. It's the same width and air space.
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