Ported Box question

[Blados]

Let's say I want to make a ported box with a total of 3.2 cu. feet of air space. How would I go about calculating the dimensions?

[squeak9798]

([internal L x W x H]/1728) - port displacement ([external L x W x H of port]/1728) - sub displacement = net internal volume

[Blados]

I see... How does the size of the port effect the overall sound?

[AFLAC]

umm the bigger the better until it gets too big then it is not better... its actually worse.. the SQ will drop btu the SPL will increase

[AFLAC]

also.. waht sub(s) do you have??

[rx7vert]

the way the port is tuned changes with volume and port area.

say if you had a port tuned to 30hz, with 18"^2 of port area, it would be louder than one with the same tuning and only 12"^2 of port area.
and lower tuned ports have better sound quality, while higher tuned ports have more output.

I think from my experiences and listening to other peoples stereos that about 32hz is the best trade off of spl and sq. but that is entirely opinionated.

I listen to more rap and stuff with lots of bass. If you listened to stuff that called for more response (rock, classic, jazz) anything that makes sq shine, you would be better off ported to about 27 or 28 or go sealed.

[Blados]

I think I will be getting a 12" MTX 9500... Just trying to come up with some dimensions for a box to fit in my Mustang (small trunk) ... Box just can't be higher than 12"... So it's getting a little confusing for me.

[rx7vert]

also.. waht sub(s) do you have??

why drop jaw? some 15's work nicely in about 5 or 6 cubes or larger even.

much less the re 18's.

[AFLAC]

lol yeah... i was thinkin bout gettin a 15 alpine type r... but wndd up with 12w7. 15 is big, box is bigger. lets see waht happens...

[rx7vert]

I'm not real fond of the type r 15's. kinda slow responding. I think the cone is just too heavy for the motor.

[AFLAC]

eyah thats y i ende dup gettint he jl.. its all round better neways..

[rx7vert]

I think you try to type too fast...... lol....

yea, w7 is nice, but you can get subs that are just as good for less $$$

[AFLAC]

haha i think i type too fast too.... but listen to this.. i got a 12w7 in a box, with a jbl 1200.1 amp, with wires and jl back 6x9, and the car already had a new altinator with 300 Volts, and dynamat... the system was only 675 and i got the car off him for 400 cause he was gettin rid of it... how u liek them apples??

[rx7vert]

um. alternaotr is still 12v. and is NOT 300amps.

if upgraded maybe 200, but not much more.

either way, not bad on price.

[AFLAC]

na for real its like at 250... he got it from this guy who makes then especially for freggin big SACNUT systems... and DEF good price!!