calculating port length and diameter
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=78288
Printed Date: May 03, 2024 at 7:12 PM
Topic: calculating port length and diameter
Posted By: oxygen65
Subject: calculating port length and diameter
Date Posted: May 25, 2006 at 2:09 PM
ok i am building a box for 2 orion 15 h2's and the dimentions are 38wide x 25high x 30deep for a total of 14.15 cubic feet. and i want to make this box ported but i have no idea how to figure out the port diamiter or the port length, the box will be tuned to 32mhz.
Replies:
Posted By: stevdart
Date Posted: May 25, 2006 at 2:53 PM
https://www.the12volt.com/caraudio/boxcalcs.asp------------- 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: luckydevil
Date Posted: May 25, 2006 at 2:59 PM
Don't forget to subtract the cubic ft of the port from the box also.
Posted By: stevdart
Date Posted: May 25, 2006 at 3:58 PM
...and you should have at least 1 cu ft of bracing incorporated into a box that size.
-------------
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: oxygen65
Date Posted: May 25, 2006 at 11:24 PM
yea i looked at that and tryed to put all the info in and to tune it to 32 mhz it said to have like a 7 inch port like 12 inches long,and that seems a little strange in a box that is 30 inches long
Posted By: luckydevil
Date Posted: May 26, 2006 at 12:42 AM
If I were you I would go with a slot port.
Posted By: killer sonata
Date Posted: May 26, 2006 at 1:37 AM
according to the dimensions you provided 38 x 25 x 30 = 28500 inches when you divide that by 1728 inches to calculate the cubed footage, I get 16.49 ft^3 not 14.51 ft^3. am I doing something wrong?
Posted By: luckydevil
Date Posted: May 26, 2006 at 1:48 AM
killer sonata- you aren't accounting for the 3/4" MDF.
Posted By: killer sonata
Date Posted: May 26, 2006 at 3:06 AM
oh ok. But wouldnt you want to use 1" MDF for a box that large?
Posted By: luckydevil
Date Posted: May 26, 2006 at 3:33 AM
Personally I would, but his original figures were for 3/4" MDF.
Posted By: DYohn
Date Posted: May 26, 2006 at 9:54 AM
oxygen65 wrote:
yea i looked at that and tryed to put all the info in and to tune it to 32 mhz it said to have like a 7 inch port like 12 inches long,and that seems a little strange in a box that is 30 inches long
According to the port calculator on this site, 14.15cuft tuned to 32Hz with a 7" port requires the port to be 2.04" long. 12" length tunes the enclosurre to 20.7Hz. ------------- Support the12volt.com
Posted By: oxygen65
Date Posted: May 26, 2006 at 11:27 AM
alright well i think i am doing somethin wrong when i put the numbers into there. so can anyone help me out and figure out how big the square port should be and how long to tune it to 32 mhz
Posted By: DYohn
Date Posted: May 26, 2006 at 11:38 AM
Do you want to build a square port or a slot port that runs the entire length of one wall? If so, which wall? ------------- Support the12volt.com
Posted By: oxygen65
Date Posted: May 27, 2006 at 8:19 AM
i was thinking a slot port that goes right in the middle for both subs, so it looks like one super huge port.
Posted By: DYohn
Date Posted: May 27, 2006 at 9:51 AM
oxygen65 wrote:
i was thinking a slot port that goes right in the middle for both subs, so it looks like one super huge port.
OK, so how "tall" and "wide" will the slot opening be? I need to know your intended slot dimensions before I can suggest its size. The internal dimensions of the opening is best, and I assume you'll make this out of the same 3/4" MDF as the rest of the enclosure? ------------- Support the12volt.com
Posted By: oxygen65
Date Posted: May 29, 2006 at 5:37 PM
Well i want the port the be as tall as the box is and the width of it could be around 8 to 10 inches
Posted By: killer sonata
Date Posted: May 29, 2006 at 6:13 PM
that is a huge frickin port. 8 to 10 inches is way too wide for a port unless it is like 4-8 ports joining into 1.
Posted By: DYohn
Date Posted: May 29, 2006 at 6:27 PM
OK, assuming you build your port from 3/4" MDF, if the outside dimensions are 25" (the height of your proposed enclosure) X 8" wide, this means the opening would be 23.5" X 6.5". To tune your enclosure to about 32Hz, the slot port needs to be about 16.75" long (your enclosure ends up about 13.3 cuft.) ------------- Support the12volt.com
Posted By: killer sonata
Date Posted: May 29, 2006 at 6:38 PM
DYohn] wrote:
K, assuming you build your port from 3/4" MDF, if the outside dimensions are 25" (the height of your proposed enclosure) X 8" wide, this means the opening would be 23.5" X 6.5". To tune your enclosure to about 32Hz, the slot port needs to be about 16.75" long (your enclosure ends up about 13.3 cuft.)
Oh wow that is huge. I hope that box is going into a van or truck of some sort. I dont even think you need a box that big for the MTX jackhammer.
Posted By: oxygen65
Date Posted: May 29, 2006 at 8:09 PM
so making the 1 port 6.5 inches wide and 16.75 long it will be tuned to 32mhz? could you just tell me how you figured that out becuse i cant.
Posted By: DYohn
Date Posted: May 29, 2006 at 9:08 PM
It's Hz (hertz) not mhz (megahertz) by the way. This page has a fairly accurate slot port calculator. If you want to know the math to figure it out yourself, here ya go. ------------- Support the12volt.com
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