Port Question

[billy18bm 10+ year member]

is it true when you use the back of the box to extend your port to your desired length you have to extend an imaginary line (1/2 of the ports width) out like my example below..

also just let me know if this box ends up around 3.10 cuft....@ 36hz....

thanks.

Click to read more...

 

[billy18bm 10+ year member]

anyone?

 

[04_edge 10+ year member]

i dont understand at all.

why would you need to extend an IMAGINARY line?

 

[billy18bm 10+ year member]

like when u calculate the box volume and port length.... iamacomputer told me that when you use the back wall of your box you have to subtract half of your ports width?....

 

[Immacomputer 10+ year member]

Yes, it is true when part of the port is a wall of the enclosure. Part of the air after the port wall acts as part of the port.

No, I'm not making it up and no, I'm not wrong.

http://mobile.jlaudio.com/support_pages.php?page_id=165

You can see it used there as well if you don't believe me.

 

[billy18bm 10+ year member]

lol i didnt say you were wrong i know u know your shit man.. i was just seeing if anyone else knew about this...

 

[Immacomputer 10+ year member]

I'm not offended. You would be surprised though... some people refuse to believe that it exists and not many people take account for it -- including Moe's designs.

 

[Trixter 10+ year member]

it is true and to accurately tune you need to use it. however, for the most part, if you have a 3" wide port and you add your 1.5", not taking the correction factor into consideration, that 1.5" will make how much difference in tuning....1 maybe 2 hz?? the larger the box and the more port it has, the more critical it becomes.