ported box design need advice

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=77126
Printed Date: May 29, 2024 at 12:31 AM

Topic: ported box design need advice

Posted By: ghettob
Subject: ported box design need advice
Date Posted: May 01, 2006 at 6:15 PM

i have 4 pioneer 3002spl 12"s and am trying to build a box in the trunk of my 300c with the speakers facing up and the port facing in the cabin from where the seats fold down it would be 2 seperate chambers 2 speakers each chamber and dimensions are 30.75" wide by 31.5" length and 15" tall after subtracting wood

box volume is 8.40 ft^3 net

speaker displacement is .084 each total .336 ft^3

after subtracting speaker displacement i should have 4.03 ft^3 for each chamber

now i need to know using square ports what dimensions the ports on each side should be length,port area etc.

please help someone

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Replies:

Posted By: DYohn
Date Posted: May 01, 2006 at 6:19 PM

I suggest your design is not good. Directing standard vented design ports into a different compartment than the speakers will result in some cancellations, and all you will end up listening to is the low frequency resonance of the port. If you want to do something like you propose, the best enclosure to do it would be a bandpass where 100% of the output is through the port.

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Posted By: ghettob
Date Posted: May 01, 2006 at 6:20 PM

how do i build one

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Posted By: DYohn
Date Posted: May 01, 2006 at 8:09 PM

Start HERE. A bandpass is not easy to build and get it to sound right, so if you really want to do what you propose you may be better off paying someone to do it.

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Posted By: stevdart
Date Posted: May 01, 2006 at 10:04 PM

ghettob, if you open a space from the trunk to the cabin the sub sound will get in there. Believe it. The sound pressure will fill the space, and with an opening it all becomes one space.

You've got a good handle so far on calculating air space. You seem to have ability, so I suggest you take the step to using a box-building program like WinISD to help you calculate ports. Read my sticky above and download the free program. Take a couple of days making sure you get your sub parameters inputted correctly and start understanding what the program is telling you. Slot ports are easily chosen over round in that program. You can probably do it faster and have better results than asking around on the forums and using whatever Mr. Anybody tells you.

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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.