Port size ?

Talontsi90

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Why would an 8" sub require a longer port than a 10" or 12"? Im planning my install for when weather is nicer and am trying to design a box to replace my spare for a stealth install. I cant lose trunk space as the rear seat goes flat and i never know when im going to need that space. Is it because the overall box will be smaller than the other larger subs so you need to make up that lack of space with a longer port?

The Kicker S8L5 says .33cu ft for the smallest sealed and 1cu ft for the "SPL/Deep bass" box. The problem is, that designs requires a 21.25" long port, and i dont think i have the space. The sub will be firing up, so i have the entire tire well for use, if needed.
Can you fold a port to get the length needed, or will that turn into a t-line and require a whole other set of calculations?

 
We need more info. Aero or slot port? Diameter or width x height of port.. What tuning frequency you aiming for? What's the max dimensions you are willing to use?

To answer your questions, yes smaller boxes require longer ports so you can play around with the numbers by making the box bigger or choosing a different diameter for the application and/or tuning higher. Yes, you can fold a port but that doesn't make it a T-line. T-line is just straight port all the way thru, no air space. 

 
Why would an 8" sub require a longer port than a 10" or 12"? Im planning my install for when weather is nicer and am trying to design a box to replace my spare for a stealth install. I cant lose trunk space as the rear seat goes flat and i never know when im going to need that space. Is it because the overall box will be smaller than the other larger subs so you need to make up that lack of space with a longer port?

The Kicker S8L5 says .33cu ft for the smallest sealed and 1cu ft for the "SPL/Deep bass" box. The problem is, that designs requires a 21.25" long port, and i dont think i have the space. The sub will be firing up, so i have the entire tire well for use, if needed.
Can you fold a port to get the length needed, or will that turn into a t-line and require a whole other set of calculations?
Port length is determined by tuning desired... in a specific enclosure volume and a specific port area.

Port area needed is for your power in that volume/tuning.

Finding those values and what is gonna meet your goals is best done thru modeling. 

 
We need more info. Aero or slot port? Diameter or width x height of port.. What tuning frequency you aiming for? What's the max dimensions you are willing to use?

To answer your questions, yes smaller boxes require longer ports so you can play around with the numbers by making the box bigger or choosing a different diameter for the application and/or tuning higher. Yes, you can fold a port but that doesn't make it a T-line. T-line is just straight port all the way thru, no air space. 
I pretty much gave that to you, if you had looked at a manual. But they say 2" x 9.5" and 21.25" long.

 
I pretty much gave that to you, if you had looked at a manual. But they say 2" x 9.5" and 21.25" long.
I'm guessing you are completely new to ported boxes.  The port changes depending on your cubic feet airspace, you dont keep whatever bullsh*t they recommend because its beyond stupid recommendations.  box size and port size, length have a direct correlation with box tuning, power handling, and bandwidth.  I'd recommend youtubing up how to use winisd and download torres box calculator and get proper box numbers with projected response graphs, rear air velocity etc... like so.  You just need enough port area to avoid compression and get the tuning you need which will be rear air velocity values on winisd. Too big of a port and too small of a box will literally make it absolutely impossible to get the tuning you desire and you'll still end up in the high 40s port tuning.  

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Last edited by a moderator:
I'm guessing you are completely new to ported boxes.  The port changes depending on your cubic feet airspace, you dont keep whatever bullsh*t they recommend because its beyond stupid recommendations.  box size and port size, length have a direct correlation with box tuning, power handling, and bandwidth.  I'd recommend youtubing up how to use winisd and download torres box calculator and get proper box numbers with projected response graphs, rear air velocity etc... like so.  You just need enough port area to avoid compression and get the tuning you need which will be rear air velocity values on winisd. Too big of a port and too small of a box will literally make it absolutely impossible to get the tuning you desire and you'll still end up in the high 40s port tuning.  

View attachment 4732

View attachment 4733
Yea i was gonna look at WinISD, i assume its gotta stupid price tag on it. However, im dealing with a circular area of yet unknown volume. I was hoping to measure it today, but it decided to act like the amazon rain forest during wet season. And yea, new to ported boxes, but with the space i have i might have to stick to sealed. Im just obsessing over the potential lack of volume potential with a single sub and 500w to it. It may well be more than i need, but ive only had experience with two 10's and around 200-225w and that was about 18 years ago.

 
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