Dual box sealed 18" Mal X build begins. - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 99 Old 01-28-09, 12:49 PM Thread Starter
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Dual box sealed 18" Mal X build begins.

After alot of reading around and getting great advice from this site in particular I started building one of the two cabinets for my sealed dual sub build.

It will be based on the Maelstrom X 18" and cabinets 61,5cm on all sides, thats 24.21".

I've started building and I am basing my design on other peoples good experiences.

Tomorrow I will cut out the baffels and assemble the rest.

So far so good:





Here's the subwoofer ready to be sent to the painter, won't send until both are completed though. 2 pictures, one with grille frame.



Here's without the grille.



Here's another DIY project that I just finished, I'm planning to give both subwoofers similar finish in white.


Last edited by clausdk; 02-08-09 at 07:56 AM.
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post #2 of 99 Old 02-08-09, 03:06 AM Thread Starter
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Re: Dual box sealed 18" Mal X build begins.

Box is completed. Need it painted now. Also need some fabric for the grilles, they are completed as well, both of them. I've just build the one sub at first, second to follow in a week or so.

I'm gonna post a few more pictures, but my camera isn't really cooperating with my new laptop!

A quick question:


With these enclosure dimensions: ~180 liters = ~ 6.35 cubic feet minus internal bracing which i calculated to be around 6 liters (0.21 cubic feet).

So net internal volume before the driver is ~ 174 liters = ~ 6.15 cubic feet

EDIT: found a post on AVS forum, the driver takes up ~ 0.2 cubic feetså net volume is then 5.95^feet

How much does the driver displace inside the enclosure?

And so here is the real question:

With the net volume given, how much polyfill do I need?

And: is this the right polyfill stuff? http://www.hoejttalerbutikken.dk/pro...sp?product=566 (sorry danish site, but you can see the picture and click to enlarge)

My own thoughts on polyfill: I need to raise the perceived volume to around 200 liters to get a QTC of desired 0.7, so I need enough polyfill to gain around 26 liters + whatever the driver displaces. Far off??
Reading off the net I found this rule of thumb: no more than 1 pound of filling / cubic feet enclosure if the enclosure is larger than 3^feet.

Regards

claus linde

Last edited by clausdk; 02-08-09 at 08:42 AM.
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post #3 of 99 Old 02-08-09, 10:41 AM
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Re: Dual box sealed 18" Mal X build begins.

I am not sure about the polyfill, but I wanted to say the work looks very nice thus far.
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post #4 of 99 Old 02-08-09, 10:58 AM
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Re: Dual box sealed 18" Mal X build begins.

Quote:
no more than 1 pound of filling / cubic feet enclosure if the enclosure is larger than 3^feet.
That is my understanding of it as well. The 1 pound per cubic foot is equal to a 10% increase in cabinet volume.




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post #5 of 99 Old 02-08-09, 11:03 AM
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Re: Dual box sealed 18" Mal X build begins.

Looks good Claus. I think you'll be happy with the results.
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post #6 of 99 Old 02-09-09, 09:33 PM
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Re: Dual box sealed 18" Mal X build begins.

Looks great....

I haven't stuffed any of my 3 Mal-X's, but I probably should, so far I do like how they sound.

I look forward to your grill results.... looks like you went 3/4" thick....

Mine flush mounted seem to have a bit more excursion then 3/4", you may want to test before you finalize your design...
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post #7 of 99 Old 02-09-09, 11:40 PM Thread Starter
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Re: Dual box sealed 18" Mal X build begins.

Quote:
Warpdrv wrote: View Post
Looks great....

I haven't stuffed any of my 3 Mal-X's, but I probably should, so far I do like how they sound.

I look forward to your grill results.... looks like you went 3/4" thick....

Mine flush mounted seem to have a bit more excursion then 3/4", you may want to test before you finalize your design...
That's a pretty good point, haven't even thought about that. At the moment the grille isn't drilled flush it actually rests with a good 1/2 inch gab from the front baffle.

Maybe that will look ok, having it hover with a small gab from the cube itself.

Never had the excursion of the driver in mind when making that grille!

About polyfill, I'll stuff some in there, according to the theories I've read and the comments I've seen around here. If lucky I can get closer to modelled 200 liter cabinet which should give me a little more buttom end and lower the Qtc to 0.7 or so.
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post #8 of 99 Old 02-12-09, 01:52 PM
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Re: Dual box sealed 18" Mal X build begins.

the driver is .2 cu ft if i recall
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post #9 of 99 Old 02-12-09, 06:56 PM
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Re: Dual box sealed 18" Mal X build begins.

Looks great so far. I am also thinking of finishing my Mal project in white (saw some piano white Totems with black drivers, awesome). When ready, please post some pics of the finished paint job with driver exposed!!
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post #10 of 99 Old 04-01-09, 03:51 PM
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Re: Dual box sealed 18" Mal X build begins.

I love these Mael-Xs in small (well, if you can call it small) cubes! Keep the pics coming, claus, great work!

- OJ -

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