1. ## Rules for port diameter?

Does anyone know the general rule of thumb when determining the port diameter you'll need? I'm making a ported sub with 2 Koda 8s and I don't know if a single 4 inch flared port will cut it.

The 2 kodas can displace about 1444 CCs of air at maximum. (I used Xmech in that calculation)

2. ## Re: Rules for port diameter?

last time i checked it was 8:1

3. ## Re: Rules for port diameter?

Originally Posted by flakko
last time i checked it was 1:8

4. ## Re: Rules for port diameter?

Originally Posted by flakko
last time i checked it was 8:1
Units? you mean 1 unit of length of the port for every 8 units of volume of the box?

6. ## Re: Rules for port diameter?

i use the 1:6 ratio

7. ## Re: Rules for port diameter?

Originally Posted by DBfan187
Remember the dimmensions it supplies are optimal. You can get away with less port surface area in the proper box.

8. ## Re: Rules for port diameter?

Ok, then 6.5 inches it is. Thanks.

9. ## Re: Rules for port diameter?

Originally Posted by JonJT
Ok, then 6.5 inches it is. Thanks.
Good luck finding a 6.5" circle port. Use two 4" ports and you will get 25.12. Plaenty of port surface area for two Kodas.

10. ## Re: Rules for port diameter?

Originally Posted by DBfan187
Whatever this site gives you just cut it in half or so. It is not necessary to have 48 inches or port area for a 12 inch Brahma unless you are tuning around 55hz for spl comps.

11. ## Re: Rules for port diameter?

2 4 inch ports make for about 19 inches or port length, I hope WinISD isn't getting this wrong.

12. ## Re: Rules for port diameter?

a bigger port will increase enclosure efficiency.

2 of these then use this calculator.

13. ## Re: Rules for port diameter?

Originally Posted by tRiGgEr
Good luck finding a 6.5" circle port. Use two 4" ports and you will get 25.12. Plaenty of port surface area for two Kodas.
i know where to get 6" aeros.

14. ## Re: Rules for port diameter?

Originally Posted by DBfan187
a bigger port will increase enclosure efficiency.

2 of these then use this calculator.
Say you have 4 ports. Does each port have to be that long, or does the length of all 4 ports need to equal the total length they give?

15. ## Re: Rules for port diameter?

each.

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