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What does the size of a port mean?!

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=7952
Printed Date: June 05, 2024 at 7:37 PM


Topic: What does the size of a port mean?!

Posted By: rmjjensen
Subject: What does the size of a port mean?!
Date Posted: January 10, 2003 at 2:03 PM

Ok.  I just finished building my dual bandpass box for my car.  It's ported through my rear deck and allows for no bass to enter the trunk area so I get no rattle.

When I started this I was slightly scared because I do know some basics of subwoofer designs.  I've built a handfull or sealed boxes and this was my first box that used ports.  Well, the sound I'm achieving from my box is a real deep, rumbling bass.  And I hate it.  I was wondering what I can with the port in the box?  Basically:

A large port will create deep bass, while a small one punches?  What's the difference.

Thanks! (And I'm running 2 Audiobahn Alum 12Q each in their own bandpass box, with a JBL BP1200.1 Amp)



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1999 Infiniti G20:
Kenwood DPX-5010
4 JBL GT-1081 Subs



Replies:

Posted By: wvsquirrel
Date Posted: January 10, 2003 at 9:19 PM
Most subs will have a recommended port size associated with them (specs from the factory) for the best sound.  You can "tune" the ports by increasing or decreasing the port length and width until the desired sound/frequency is achieved.  Most ports have a heavy cardboard tube attached to them for tuning the length.

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Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
Donate to the12volt.com




Posted By: rmjjensen
Date Posted: January 11, 2003 at 8:51 AM
yeah I might just have to play with it.  I can't get anything from www.audiobahninc.com.  All they have is subwoofer specifications.  They get pretty advanced though where I can plug them into a program, along with my box, and I should get a requency response graph.  This is what a want to do.  Is there a program out there that I can download and try it out?  Thanks!

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1999 Infiniti G20:
Kenwood DPX-5010
4 JBL GT-1081 Subs




Posted By: CharlzO
Date Posted: January 18, 2003 at 8:58 PM
One thing you might not have seen yet, is that the ALUM's aren't designed to run in a ported box. They recommend about a 1 Cubic foot, sealed box, with I think 20" fill (insulation in the box) for best sound. I ran a pair of them at one point in my Avenger, and tried a pair of 4" ports, one per chamber in the box. To be honest, sounded horrible. I sealed them back up from inside the box with some spare blocks and a heavy epoxy, and it sounded a jillion times better again. Just words of my experience.




Posted By: Derrik
Date Posted: January 19, 2003 at 12:22 AM

here's some help for you. you got to get the tuned frequency right for the box in order for it to sound good.

https://www.jlaudio.com/tutorials/ports/index.html





Posted By: rmjjensen
Date Posted: January 19, 2003 at 8:28 AM

CharlzO ->  Yeah I might just go with a nice sealed box ...it would take up far less room and I think would have an overall better sounding.

Derrik -> That JL site is awesome!  Thanks a lot!!



-------------
1999 Infiniti G20:
Kenwood DPX-5010
4 JBL GT-1081 Subs





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