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Discussion Starter #1
New to the forum with a couple questions.

Just purchased a Maelstrom-X and EP2500. This will go in my 13'9"W, 19'L, 10'H theater. I'm space constrained in that it needs to fit behind the false wall of a 10'W SMX screen. I have two positions in mind. One is 19"L,68"H,48"W below my center channel:



The other is on the right of the false wall. When I move my current sub to this location, it sounds pretty good. I have 19"W,19"L,8'H to work with in this location.


No room behind as it's all occupied by seats.


I'd like to go ported due to familarity with building my previous sub but I'm open to whatever you think would sound the best given my space constraints.

Thanks,
Tommy
 

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I'd use the one in the corner, I'd aim for 10 cubic feet internal and use a 8" port which you can find at home depot. You are going to have to port it out the top, or leave a space for it on the bottom. Plan on using shelf braces all the way up, spaced about 14". Flare the ports on both ends and the overall port length should be 34" long. Stuff the enclosure with 80oz. of polyfill.

For amplification make sure to use something with a subsonic filter. The PE1000W rack-mount I have on my site will work and I also sell the Velodyne SC-1250 which has room measurement & equalization tools. The Velodyne will give you about 2dB more headroom and the room measurement & equalization are very nice but cost is twice as much.

You will get a terrifying amount of deep bass with this set-up.

Kevin Haskins
Exodus Audio
www.diycable.com
 

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Discussion Starter #4
Thanks Kevin!

How should I orientate the Mal-X? Down firing, or does it matter? Also, since I have an EP2500, how should it be connected? Any other suggestions in regards to a subsonic filter?

Thanks!

Tommy
 

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Down firing is fine but you are going to have a of a time mounting it in that space. I'd probably aim it forward just for ease of service.

The EP2500 should be bridged but it doesn't have any sort of subsonic filter. You will quickly toast the driver running it without one. Elemental Designs sells a stand-alone box for about $100 that has one and a couple bands of PEQ. I sell the Velodyne SMS-1 which is another good solution, but much more money (around $500 with a sub).

The other option is to just run it sealed. You get plenty of output from a single Maelstrom so it may do the trick for you.

Kevin Haskins
Exodus Audio
www.diycable.com
 

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Discussion Starter #8
Here's my feable attempt at a design.


I'd have 11.5L ~ pre displacement, 20"X19"X63" OD with a 34" port using 3/4" MDF.

Thoughts?
 

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Discussion Starter #9
Update: Just downloaded WinISD, though I'm not exactly sure what I'm looking for.

How about 20"X19"X84" for 15.4ft^3 before displacement ~14.5ft^3 or 410L. 8" port 53" long. If the tune's not 12.5, I'm definitely using WinISD incorrectly (which is a very good possibility!)
 

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Looks good... I'm a little confused about the displacement. By my math you have just around 11 cubic feet internal and the port will occupy about 1 cubic foot. Net volume should be just around 10 cubic feet.

This is what you would get with a 17Hz subsonic filter in place and just around 1000W.



Kevin Haskins
Exodus Audio
www.diycable.com
 

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Discussion Starter #14
Well I think this should work and I'll plan on starting tomorrow unless I hear of a major design flaw.


19"X20"X72". 12.5cuft after displacement. Two 4" ports, 28" long. Tuned to 13.1hz.

I'll be adding a subsonic filter, most likely the Reckhorn B1 or the Elemental Designs eQ.2. Hopefully I can find one for less than $100.

So, any critical issues I should be aware of or am I good to go?

Thanks,
Tommy
 

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2 4" ports is not enough for this 18 It will easily overload them. 3 would be better and a single 8" or dual 6"ers better still.
 

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Discussion Starter #16
Then I guess I'm in trouble!


WinISD and Boxnotes showed acceptable port resonances with two 4" ports.
 

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Yes... two 4" ports are way undersized. They will chuff fairly easily with a driver like the Maelstrom. Theoretically, you can overload the 8" port also but an 8" port has a LOT of output potential so it gives you a lot of headroom before port noise will become a problem. I still advocate doing a roundover on both ends of the port so that you have a smooth transition at both port terminations.

Kevin Haskins
Exodus Audio
www.diycable.com
 

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Discussion Starter #19
I've rounded over both ends of the ports.

If I add another 4" port, my tuning will be about 16.7hz. What do you look at to determine if a port is undersized? I can't seem to find anything in WinISD or Boxnotes.

I was planning on closing it all up today so any advice/help is appreciated.

Thanks,
Tommy
 

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There's nothing wrong with a 16 hz tuning, it'll definitely be better than the "undersized" 13 hz tuning.

What do you look at to determine if a port is undersized?
The port air speed. In WinISD you select the "Rear Port - Air Velocity" graph and try to keep the air speed at 26 m/s or below.
 
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