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dual port box design for l7 15’’?

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=67823
Printed Date: May 04, 2024 at 7:43 PM


Topic: dual port box design for l7 15’’?

Posted By: the fallis
Subject: dual port box design for l7 15’’?
Date Posted: December 06, 2005 at 6:47 PM

alright... as of right now i am thinking of ditching my 12 for a 15" l7 dual 2 ohm.... i'm also ditching my amp for a rf power 1000rms....
anyways with my two tens still inplace i am kind of limited with the box design so since my two 10 are in the corners of my trunk facing forwards angled inwards i was wondering if there is any way to make a square box to fill in the gap between the other two... only prob is that i want the l7 centered and i don't have much hieght room so i want to do a slotted port on each side of the box.... but seeing as how i have no clue when it comes to tuning i am asking for some help...

can it be done or should i just give that up and try a different approach?

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Stop freaking out, its not an earthquake..... its just those 3 little 15's in my trunk....



Replies:

Posted By: stevdart
Date Posted: December 07, 2005 at 12:58 AM

If you use two ports they will occupy a greater amount of your enclosure than using one port.  Each port would be twice as long, using the same opening area, as one slotted port.  These subs need a large enclosure for vented, and you might not have the room to give up so much for the ports.

WinISD Pro has this driver in its database.  I looked at it and found that using just the one recommended slotted port will be okay (as far as port noise is concerned).

Look at the manual for this sub.  In the vented enclosure section you see three designs with different volumes.  I looked at the street design that uses 4.5 cu ft net airspace.  You have to measure your area and see how much room you have to work with.  If you have about 6 cu ft then this is a good one to use (you have to allow for the thickness of the MDF, the bracing, and the entire volume of the port incl. the port walls).  It appears that Kicker has figured for the driver displacement, but you would have to copy their cut sheet exactly as shown.  If your design's box volume differs from one of these examples, you have to figure for all displacements and add those to the cu ft you're targeting.

In that build, the slotted port is listed at 3" X 16.25" and with a length of 14.75".  That box will achieve high SPL levels with a tuning freq at 38 Hz.  Keep in mind this is pure SPL and won't be pleasant to listen to on an everyday level.

If you were to use two of these ports, each port would have to be 35" long.  But you could make each slot narrower by half if you need that symmetrical look.  To keep the same tuning freq you would make each slot 1.5" by the same height of 16.25", and increase each port length to 16.3".  Remember, you have to add total port volume to the enclosure, and two ports have more baffle walls that will count up in the total box size.

https://www.linearteam.dk/default.aspx?pageid=winisdpro

You can make the box shape anyway that fits as long as you attain the air volume you are targeting.  Remember that 12 X 12 X 12 = 1728;  that's the cu inches in a cu ft.



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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.





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