BOX CORRECT?

[Ricky A.]

ok yall i made a wierd shaped box to fit my truck for an fi btl 15 and heres how i tuned it. its

32 hertz

6.6 cubes gross volume

port area (area of each side added together) 430 inches squared

port volume is 630 inches squared or .9 cubes. 3.5x10x18 inches deep

port tube ends only 1.5 inches fromt he back wall.

sub displacement is .22 cubes

soo net volume is 6 cubes.

DOES THAT SOUND WRONG OR IS THE PORT TO SMALL?

pic

[zayres29]

port area is the width and the height of the port not the area of each side added together

the port looks too small

[kirill007]

Port IS too small, 35sq inches for 6.6 cu ft is no where near enough.

Optimal would be 85sq inches.(but you would need to make the port longer so you don't mess up the tuning.)

[Ricky A.]

Port IS too small, 35sq inches for 6.6 cu ft is no where near enough.

Optimal would be 85sq inches.(but you would need to make the port longer so you don't mess up the tuning.)

if you increase the opening of the port shouldnt the port depth be shorter not longer to keep the same tuning??

[J-Lane]

if you increase the opening of the port shouldnt the port depth be shorter not longer to keep the same tuning??

No, as the area of the port becomes larger the length will increase as well...

From Fi's web site...

"BTL 15 – Ported box we recommend using 3-5 cubic feet @ 30-35Hz. Again use 12-16 square inches of vent area per cubic foot of volume.
"

So 6.6 cu. ft. x 12 sq. in. = 79.2 sq. in. of port area.

So if your port is say

3.5 in. wide / 79.2 sq in = 22.62 in. tall

and if you have an internal box size of 6.6 cu. ft. and you want to tune it to 35 hz the port length would need to be 20.49 inches in length. I'm not sure if you said 6.6 cu.ft. internal but this is just an example. Remember to also take into account the displacement of the port as well as the speaker when calculating the box volume. The smallest mistakes will greatly affect the tuning of your box. Btw if your internal volume is 6.6 cu.ft. you may want to decrease that to 5 cu. ft. as well because a box that is too large will affect performance as well and that is larger than the manufactures recommended enclosure size.

[Ricky A.]

ohhhh ok thank you very much i also messed up my math a bit ill redo it all tonight and post what i come up with tomorrow. and if the length is to much just 90 degree andgle the port and continue it right?

[Torres]

correct

[Ricky A.]

OKAY haha i re-did all my math and got 4.5 cubes. and im tuning to 32 hertz. so the port area i need is 63 inches squared (14 PER CUBE) and that gives me a size of 4.5 inches tall 14 inches wide and 23.25 inches deep. and after port displacement which is .8 cubes and sub displacemt. .2 cubes ill have 3.5 cubes net volume. which is in the subs reccomended size. so i should be good! right?

port sketch. (rough i know)

[Alex K]

damn lol you like oldstyle dont you? Pen and paper and the trusty mental math..lol. Why not download sketchup, get torres calc, and go nuts?