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sealed box , can i port it

Printed From: the12volt.com
Forum Name: Fiberglass, Fabrication, and Interiors
Forum Discription: Fiberglass Kick Panels, Subwoofer Enclosures, Plexiglas, Fabrics, Materials, Finishes, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=112565
Printed Date: May 14, 2025 at 5:35 AM


Topic: sealed box , can i port it

Posted By: spmpdr
Subject: sealed box , can i port it
Date Posted: March 22, 2009 at 10:15 AM

hey everyone, i have a sealed sub box with 2 12s and it hits hard but the bass is quick and clean , i would like the bass to carry more i heard if i port it that it would make the bass carry . the box is 2cft
of airspace and like i said was built to be a sealed box , i dont want to mess up my sound so i figured id ask the pros. also if i can port it how big of a round port can i do

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-A vision without a plan is just a hallucination-



Replies:

Posted By: i am an idiot
Date Posted: March 23, 2009 at 6:49 AM
Your box is 2 Cu/Ft total, or 2 per woofer?   2 total = too small to port.  2 Per = Possibly large enough to port, but we need to know more about your speakers to be sure.




Posted By: spmpdr
Date Posted: March 23, 2009 at 3:10 PM
the box is 2 cubic ft total and has 2 memphis 12s 250watts rms@ 2ohms . my idea was to port each side of the box cuz the speakers are seperated.if i cant port is there any suggestions on how to get my bass to carry more. also is it true if you put pillow stuffing inside the sub box it slows down the air movement tricking the speaker into thinking it is in a larger area?

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-A vision without a plan is just a hallucination-




Posted By: stevdart
Date Posted: March 23, 2009 at 5:05 PM

You have, at the most, 1 cu ft per sub sealed now.  The speakers don't have enough air as it is now, much less to go in and take up some of that space by putting in ports.  Don't do it.  Redesign your enclosure.

Here is the Memphis recommendation chart, depending on model of sub.  And notice that for any sub model that the vented net airspace requirements exceed that for sealed...(even when considering that this particular chart includes port displacement in the total size given).



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: spmpdr
Date Posted: March 23, 2009 at 11:09 PM
thanx for the info and the link. if i drilled a 1.5" hole in each side of the box would it make the bass carry not a true port but just a hole.what about the pillow stuffing thing? does it really make the air slow down to trick the speaker into thinking its in a much larger area.

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-A vision without a plan is just a hallucination-




Posted By: lil evo
Date Posted: March 25, 2009 at 11:04 PM

DO NOT DO THIS!!!!!  There's so much more to a ported box than simply drilling a hole and if you do this it's basically going to sound like absolute dog crap. When you're putting together a subwoofer enclosure for a particular speaker or set of speakers, there's a lot to take into account. You have to look at things like driver Qts. Vas, Fs, Xmax, the shape of the port and all the math that goes along with calculating what frequency you're tuning the port to, the natural resonant frequency of the driver, of the enclosure, so on and so forth.

So please, for the love of all that is good and holy left in the world, don't just drill a hole in your box. It's ideas like this that make my job a living hell



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Posted By: stevdart
Date Posted: March 26, 2009 at 7:49 AM
As for the polyfil question, here is one from the archives and you can further your research by using the google toolbar at the bottom of each page and typing the word polyfill, polyfil, stuffing or others of the like.  I use it in sealed enclosures out of habit and box-building programs such as Unibox allow you to take that data into account.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: spmpdr
Date Posted: March 26, 2009 at 12:44 PM
thanks guys for the info and i wont be drilling a hole in my box.i searched about the polyfill but couldnt find how much per cuft if u know that would be great. thanx again guys

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-A vision without a plan is just a hallucination-




Posted By: spmpdr
Date Posted: March 26, 2009 at 12:49 PM
what about taking out the divider? would that help it out? i really cant go any bigger with the box it goes behind the seat on a reg cab dodge.any suggestions , i know i know build a bigger box but that cant happen

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-A vision without a plan is just a hallucination-




Posted By: lil evo
Date Posted: March 26, 2009 at 6:29 PM
Change the driver,  go with a shallow mount woofer. You can get shallow mount 12's from a number of good manufacturers





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