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Port Length/tuning-help Wanted


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tuning has to do with net volume, vent area, effective port length. So depending on height and width, your port length can be calculated. Now since you said your ports are 3" in diameter and 16.5 in. High (tall), and you are wanting to figure out the length of the port. Are you using slot ports or circle/aero ports? I am confused. But also, your port does add displacement which needs to be subtracted from your volume as well. And just make your 45's a little bit smaller, they dont necessarily have to be a certain length, width and height, it just seems like 1.61 cu. ft. is a little too much, but it is your box so if you want to go for it.

Maybe a diagram would help a little bit to give an idea of measurements with a side and top view design or something. Paint program is what i use to just get the design.

wow reall good info thanks man :) Im going with sloted ports. but ya you all r right the 45s are going to be smaller.

oh here is wat i thought it would be this is the net measuerments, going to be using 3/4 mdf;

port2.jpg

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Okay, those are a great start, one thing to look at though is the distance b/t the end of the port to the enclosure wall.

On that first diagram (diagram A) when it bends to make the "L" shape, the width must be the same, you probably know that. Measure down the middle and add half the width of the port for end correction because the back wall of the enclosure is used for the port.

On diagram B, depending on the length from the end of the port to the right side enclosure wall can make a difference in port length. If the length between the wall and the end of the port is the same distance as the width of your port, the port carries around, it is minimal distance though but necessary if you want an accurate length for tuning. And then you would add half the width again for end correction. However, if the distance between the end of the port is longer then the distance of the ports width, you would just measure down the middle and add half of the ports width for end correction.

I know, It is hard to understand over a forum where all you can do is read and interpret for things that are not clearly stated. but keep asking questions!

And if you havent found out how to use the tuning formula, i believe it was amatt on this forum, craeted a great excel format where you can just plug in some measurments and it will give you the tuning frequency.

Baylor University

Accounting

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Here are some websites to show you how you measure length properly, i have had to read some of them 5 times in a row to help me grasp it completely.

http://www.caraudiojunkyard.com/forum/showthread.php?t=56

http://www.caraudiojunkyard.com/forum/showthread.php?t=237

and some good reading...

http://www.caraudiojunkyard.com/forum/showthread.php?t=39

Baylor University

Accounting

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Here are some websites to show you how you measure length properly, i have had to read some of them 5 times in a row to help me grasp it completely.

http://www.caraudiojunkyard.com/forum/showthread.php?t=56

http://www.caraudiojunkyard.com/forum/showthread.php?t=237

and some good reading...

http://www.caraudiojunkyard.com/forum/showthread.php?t=39

thanks il take a look :)

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also, here is just a post that is 4 pages long, but it does go through some issues that i was trying to describe.

http://www.caraudio.com/forum/showthread.php?t=218918

Baylor University

Accounting

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