Best Box Design For My 18's?

[w87will]

Im having alittle trouble coming up with the port dimensions for this box. Dimensions I have for the box are 41 x 24 x 27 which came out to about 15 Cu Ft. I have no clue how to do the port measurements to get 32Hz (If that would be best) Again Im putting 2 - 18" Dc sound LVL 4's in this box. I would love if someone could help me out.

[andym85]

are those external dimensions?

[andym85]

well..im gonna make a couple of assumptions here:

1. those are internal dimensions that you gave

2. each sub displaces .23cft (i didnt see it on their site so i went off what the displacement was for the FI BL)

with that said...

make your port 7"h x 22"wide x 20"d (that gives you 154sq" of port area...or about 12sq"/cft)

your box will be 12.8 cubes net (6.4/sub)

tuning will be 32.73hz

[w87will]

well..im gonna make a couple of assumptions here:

1. those are internal dimensions that you gave

2. each sub displaces .23cft (i didnt see it on their site so i went off what the displacement was for the FI BL)

with that said...

make your port 7"h x 22"wide x 20"d (that gives you 154sq" of port area...or about 12sq"/cft)

your box will be 12.8 cubes net (6.4/sub)

tuning will be 32.73hz

Measurements I gave were External. and when I put everything into the port lenght calcualor on carstereo.com it was saying I needed minimum of 230 inches of port area...... I dunno, that stuff confusses me

[andym85]

i usually say 12"-16" of port area per cubic foot of box. and those external dimensions (assuming you are using 3/4" mdf all the way around) only give you a gross volume of 13.115cubes...here is what i can come up with

using the external dimensions you gave...and subs up port back...

port: 5.5"h x 23.75"w x 20"d (gives you 130 5/8" of port area...or 12.06"/cube)

after sub and port displacement you have a net volume of 10.83 cubes or 5.4cubes/sub (which is actually a tad small since DC recommends 5.75cubes/sub)

tuning: 33.23hz

[w87will]

wow thanks alot. I appretiate you taking the time to do that. Im going to go with those dimensions. Is the difference between 5.4cubes/ sub and what they recommend 5.75cubes/ sub that big of a loss or difference?

[andym85]

i dont think it will be too much off a difference...i mean, ur only talking .35 cubes/sub

[w87will]

Thats what I figured. Well if it sounds like shit its all your fault J/p. Thanks alot for the help. I tried d/l your calculator for ports I found earlier but it didnt work.....

[andym85]

let me know what you were puttin in it and id be glad to help ya out and walk you through it...its pretty easy really...

[w87will]

2 18" Dc sound LvL 4's going in the box...and 2 Hifonics Bxi1606D's powering them. Everything else I was pretty cool on. Just the carstereo port calculator wasnt making sense to me when I put all my dimensions in it. Im Just going build the port you suggested. Box will be 41 x 24 x 27 Max dimensions and port 5.5"h x 23.75"w x 20"d, Subs will be facing up and Port will be facing back. Most likely Ill be putting alot of bracing, 45's in all corners, and possibly fiberglassing the inside of the box ( That can get pricy so we will see).