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ports

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=115367
Printed Date: December 03, 2022 at 11:06 PM


Topic: ports

Posted By: dp85iroc
Subject: ports
Date Posted: July 30, 2009 at 8:55 AM

so quick question that is probably dumb but i just wanted to know it....

if i have a ported box and the length of the ports is an issue can you basically have 2 ports and ADD there lengths together for tuning the box?

basically heres my issue i wanted a 4" port dia. and needed it to be at 8" long to be tuned to where i want it but i dont have 8" where i need to put it so i was thinking i could get 2 4" long ones and it be the same thing as onr 8" one?



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hmmm...thinking is always good...but question are better



Replies:

Posted By: DYohn
Date Posted: July 30, 2009 at 9:51 AM
No, sorry it doesn't work like that.  Using more than one port means each one would be longer for the same tuning.  You can't make an 8" long port fit?  That is really short.  What are the dimensions of your enclosure plan?

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Posted By: dp85iroc
Date Posted: July 30, 2009 at 10:29 AM

d*** well that puts a damper on my doodie lol i guess i'll just have to go with a higher tuning?posted_image

and ya it was just how i had it set up i mean i could make it fit its just i kinda made my own box and i'm not very good at making the cuts so i just made everything really square lol and it sits in the back of my camaro....third generation i-roc z and i kinda wanted it to look all good and lined up its really tight on space back there...but i managed to get 1.5 ft^3

idk what should i do?



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hmmm...thinking is always good...but question are better




Posted By: DYohn
Date Posted: July 30, 2009 at 1:37 PM
Post a drawing of your enclosure design.

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Posted By: dp85iroc
Date Posted: July 30, 2009 at 2:44 PM
posted_image

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hmmm...thinking is always good...but question are better




Posted By: dp85iroc
Date Posted: July 30, 2009 at 2:45 PM
this is what i made...i couldnt put the sub i had in the center cuz it wasnt a large enough space

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hmmm...thinking is always good...but question are better




Posted By: DYohn
Date Posted: July 30, 2009 at 2:49 PM
OK... well it looks like you have ports in there now?

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Posted By: dp85iroc
Date Posted: July 30, 2009 at 3:22 PM
yes but they are only 4" long and to get to a lower fequency i thought maybe having 2 at 4" would be like having one 8" one....ya kno

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hmmm...thinking is always good...but question are better




Posted By: DYohn
Date Posted: July 30, 2009 at 3:43 PM
If you have 2 X 4" ports @ 4" long in a 1.5cuft enclosure, you are tuned to about 80Hz.  Not good.  If you block one of them you're at about 57 Hz.  Still not good, but better.  What you really want is 1 X 4" port @ 12" long, which will tune you to about 38Hz.  Remove the one closest to the speaker and block it.  Then build a bent port from the last one toward the woofer and you should be able to get close to 12".  Or don't port it at all, and you'll probably end up with better performance.  Just pull them both and seal the enclosure.

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Posted By: dp85iroc
Date Posted: July 30, 2009 at 4:00 PM

oh doodie i had no idea....wow so the best bet would be to not port it at all....i always thought that having a vented enclosure was better for the sub...like less work on it?

but i mean thank you so much for the help



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hmmm...thinking is always good...but question are better




Posted By: stevdart
Date Posted: July 30, 2009 at 7:46 PM

"hmmm...thinking is always good"

"i always thought that having a vented enclosure was better for the sub...like less work on it?"

Thinking is NOT always good, then, is it?   posted_image



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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.




Posted By: dp85iroc
Date Posted: July 30, 2009 at 9:43 PM
ahhhh indeed sir that is why you guys are the experts and we are just the rookies asking the questions

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hmmm...thinking is always good...but question are better




Posted By: xchrisx
Date Posted: December 10, 2009 at 3:30 PM
How would I make the L type port??? and also whats an advantage to it?

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BP




Posted By: DYohn
Date Posted: December 10, 2009 at 5:41 PM

xchrisx wrote:

How would I make the L type port??? and also whats an advantage to it?

An L-shaped port is simply a slot port that follows the inside walls of the enclosure in an "L" shape.  The advantage is it allows a longer port than just running straight into the enclosure (if you need that for your desired tuning.)

Something like this:

posted_image



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Posted By: xchrisx
Date Posted: December 10, 2009 at 7:03 PM
thanks. also, how would i figure out the measurements to make one? like how they have a recommended port size, how would i convert it into the L Port for proper tuning?

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BP




Posted By: DYohn
Date Posted: December 11, 2009 at 1:25 PM
There is nothing different in these from the way any other slot port is calculated.  You simply make it the size and length you need, measuring the length from the center of the opening along the path the port takes to the center of the exit.  It can have 50 bends in it if that's what's required to get the length you need.

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Posted By: xchrisx
Date Posted: December 11, 2009 at 2:43 PM
Thanks. So I heard someone saying the need 28in. of port, and they had a port that was like this. How would I get 28in. of port? Whats the math to figure that out?

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BP




Posted By: DYohn
Date Posted: December 11, 2009 at 3:07 PM
There is no math.  You measure from the front to the back along the center of the port and when it gets to 28in you are done.

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Posted By: j.reed
Date Posted: December 11, 2009 at 11:48 PM
dp85iroc wrote:

yes but they are only 4" long and to get to a lower fequency i thought maybe having 2 at 4" would be like having one 8" one....ya kno


Adding port area will actually raise your tune. Not lower it. If you need to make a port LONGER, which lowers your tune and dont have the depth for full length you need. You can do whats called folding it. put a 90 deg bend and extend the port to make it longer. This can be done both for round and slot ports.

LOL guess i should have looked at the next page posted_image looks like it has already been covered.

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posted_image





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