help with port calculations
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=50091
Printed Date: May 21, 2024 at 3:03 PM
Topic: help with port calculations
Posted By: 97Avalonxls
Subject: help with port calculations
Date Posted: February 14, 2005 at 3:03 PM
so the manufacturer's recommend a 4 x 14.25 round port for my enclosure. I would like to have a slot port that is 13.5 inches tall. how wide and deep would it need to be to not effect the tuning of the box. In short, what is the equivallent slot port
Replies:
Posted By: DYohn
Date Posted: February 14, 2005 at 3:15 PM
What's the enclosure volume? ------------- Support the12volt.com
Posted By: 97Avalonxls
Date Posted: February 14, 2005 at 3:59 PM
the enclosure is 35x15x14, 14 inches deep. it is constructed out of .75 inch MDF so without driver or port diplacement it comes to 3.27148 ft^3. the driver (mtx 8000 12" ,4 ohm DVC) is about .1 displacement
Posted By: DYohn
Date Posted: February 14, 2005 at 4:23 PM
OK, your enclosure is tuned to about 25.2Hz. To have a slot port at 13.5" width, you need your slot to be 1.75" height and a depth of 21.58". Those are inside dimensions. Looks like it'll have to bend along the walls inside your enclosure. Cheers. ------------- Support the12volt.com
Posted By: 97Avalonxls
Date Posted: February 14, 2005 at 4:47 PM
awesome, thanks a lot. now should I use 1/2 inch mdf for the port construction, to minimize the effetive loss of volume, or will the box suffer a loss of integrity rom the thinner walled port? also, what should the end look like, inside end of port, as far as the shape of the wood. I'd like o use the sides and top/bottom for the outside edge and then only add one wall on the interior, so should it have square edges, tapered into the port, tapered away from the port.. just to clairfy, i am asking about the actual end of the wooden wall that is the side of the port, not the actual port, I know that must be parallel and even. thanks a lot for taking the time to help.
Posted By: DYohn
Date Posted: February 14, 2005 at 4:57 PM
1/2" should be fine as long as the actual outer wall of the enclosure is 3/4". You can leave the edges square, but running a router along the inner edge at the visible opening to create a "quarter round" gives it a more professional appearance. I also suggest you paint the inner walls black before you assemble it... it can be a pain afterwards! ------------- Support the12volt.com
Posted By: 97Avalonxls
Date Posted: February 15, 2005 at 10:34 AM
nice, thanks again, I am experimenting here, as this is not only my first ported enclosure, but I'm also covering the inside with second skin v.2 to see how it works within an enclosure, could end up in some bookshelf monitors I'm working on. thanks
Posted By: DYohn
Date Posted: February 15, 2005 at 11:54 AM
In my experience it is much easier to calculate round ports and simply purchase them pre-made or to use good old PVC pipe from a hardware store than it is to build slot ports. Of course, I am not a very good carpenter and usually bribe or pay my associates to build enclosures for me, so anything usable that is pre-made is good in my book! ------------- Support the12volt.com
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