here is where i become a car audio noob

[ampresearch 10+ year member]

hey ya'll.

in the car audio world i know just about all i need to know in order to build a system. EXCEPT one thing

PORTS. i have always done sealed boxes so this is one area that I know nothing about so i'm turning to you.

here is the question.

my box has two chambers. each one is 5 cubes. i want to tune the box to 38HZ

each will have its own slot port. if i make the port 16"wide x 4 inches tall and 16 " long. the port speed will be .02. and the tuning should be 38

does this seem right to everyone. if so does this seem like a good idea? what is my goal for port speed? 00? is .02 good? any info would be very helpful

thanks

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[helotaxi 5,000+ posts]

0 is impossible. Lower is better. WinISD uses .10 mach as the threshod for port noise but that isn't a hard and fast rule.

Have you figured out the amount of air displaced by the port and subtracted that from the 5cf to get the actual net volume from which your tuning is derived? Failing to do that will raise the tuning freq because the box volume i lower than whatyou planned for.

 

[ampresearch 10+ year member]

0 is impossible. Lower is better. WinISD uses .10 mach as the threshod for port noise but that isn't a hard and fast rule.
Have you figured out the amount of air displaced by the port and subtracted that from the 5cf to get the actual net volume from which your tuning is derived? Failing to do that will raise the tuning freq because the box volume i lower than whatyou planned for.

yes 5 cubes is AFTER the port i listed.

so your saying that anythign under .10 in prt speed will be fine? is so then i guess my only need now is if that port size is correct

 

[helotaxi 5,000+ posts]

If it's giving you .02 then it is plenty of port area, in fact you could probably go smaller (and shorter) giving a smaller gross box volume.