Port...... SMH!!

[bgowdy 5,000+ posts]

Ok this gets kind of annoys me. Everytime i think i figure something out, i read something that completely throws a wrench into plan lol.

But anyway... To the port. When im trying to figure out amount of port i need(the square inches of port per cube), do i base the amount of port off of the gross internal volume or what?

When you come up with the outer dimensions for the enclosure, Example-L x W x H = gross volume internal. When i look at my dimensions and try and figure out how many "square inches of port per cube" that i want. Do i divide the total square inches of the port(EX- 1-12" aeroport equals 113.04sqin's) by the gross internal volume(EX- 11.07 cubes internal ***berfore displacement***) to figure the amount of square inches of port per cube(EX- 113.04 / 11.07 = 10.21 sqin^3 per cube)? is this the correct way to look at it, or do you divide by the internal net volume(***after displacement***)? (EX- 113.04 / 9.85 = 11.48 sqin^3 per cube)

which way is correct??????

hope this isnt to confusing,

thanks,

Click to read more...

 

[phemps 10+ year member]

anything like that is calculated with net internal volume. the woofer sees net volume as acoustical suspension and tuning to based off of such

 

[Notloud00 10+ year member]

After all displacements.

 

[bgowdy 5,000+ posts]

anything like that is calculated with net internal volume. the woofer sees net volume as acoustical suspension and tuning to based off of such

i know its internal vol. so i go off the volume before any displacement right

 

[Notloud00 10+ year member]

No, its sq inches divided by net volume. Honestly i go by xmax and not volume of the box when doing ports....

 

[phemps 10+ year member]

i know its internal vol. so i go off the volume before any displacement right

no... thats gross volume. i said net internal volume. And yea as noted its not really the best way to calculate how much port area you need

 

[Dub7sonoma Premium Member]

i know its internal vol. so i go off the volume before any displacement right

Here you go

Car Audio - PORT Size Calculations and Formulas for WOOFER and Subwoofer BOXES

 

[bgowdy 5,000+ posts]

After all displacements.

hm.... well if thats the case, i will have more square inches of port per cube then i thought, possibly to much, but idk. Im running 2 18" OA 18s on 3k. Is 11.48 inches of port per cube to much for a daily driver with potential to put up decent term-lab numbers?

 

[Notloud00 10+ year member]

hm.... well if thats the case, i will have more square inches of port per cube then i thought, possibly to much, but idk. Im running 2 18" OA 18s on 3k. Is 11.48 inches of port per cube to much for a daily driver with potential to put up decent term-lab numbers?

i dont know your tuning but you need about 200" of port for those subs and 20mm of xmax.

 

[n8skow 10+ year member]

As stated above - necessary port area is not some arbitrary amount in relation to the size of the enclosure.

It's based on parameters of the woofer - and the tuning of the enclosure (the tuning of which 'does' have a relationship with the size).

hm.... well if thats the case, i will have more square inches of port per cube then i thought, possibly to much, but idk. Im running 2 18" OA 18s on 3k. Is 11.48 inches of port per cube to much for a daily driver with potential to put up decent term-lab numbers?

 

[bgowdy 5,000+ posts]

i dont know your tuning but you need about 200" of port for those subs and 20mm of xmax.

im using an aeroport, not a slot port. Aeros usually need about 1/2 the amount of port vs a slot. theres no way is should need 200 inches of port

 

[Notloud00 10+ year member]

im using an aeroport, not a slot port. Aeros usually need about 1/2 the amount of port vs a slot. theres no way is should need 200 inches of port

Well then you would need 4 6" aeros. Honestly a 220 sq. inch slot port would be louder. Aeros dont quite work as well when u start using a bunch of them.

 

[bgowdy 5,000+ posts]

Well then you would need 4 6" aeros. Honestly a 220 sq. inch slot port would be louder. Aeros dont quite work as well when u start using a bunch of them.

thats why i would be using less ports, i know less ports are more efficient when using aeroports.

4 - 6" = 113.04

2 - 8" = 100.48(close enough)

1 - 12" = 113.04(i more and likely would be using the 1-12")

also i dont have the room for slot port box

 

[n8skow 10+ year member]

0_o

While you can get by with less port area using aerports - it's no where near half... More like 15-20%

im using an aeroport, not a slot port. Aeros usually need about 1/2 the amount of port vs a slot. theres no way is should need 200 inches of port

 

[Notloud00 10+ year member]

0_oWhile you can get by with less port area using aerports - it's no where near half... More like 15-20%

I agree. 113 inches isnt enough unless you have a ton of power to bring the output back up.