Combining ports.....

[Demi 10+ year member]

Alright im looking at building a new box for my type x's. I have one in a 2.4 cube @ 32hz box, but it provides to high a SPL peak and to steep a slope for response curve, so i decided to go with alpines specs. The specs are for a single sub but i want a single chamber dual sub box. The recommended vent area for a single sub is 19.5"^2, with a length of 27 inches. To add another sub do i keep the length the same and double the port area?

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[rpfuror 10+ year member]

Yeap, that's about it, make sure to account for driver displacement.

 

[jeepintn 10+ year member]

Alright im looking at building a new box for my type x's. I have one in a 2.4 cube @ 32hz box, but it provides to high a SPL peak and to steep a slope for response curve, so i decided to go with alpines specs. The specs are for a single sub but i want a single chamber dual sub box. The recommended vent area for a single sub is 19.5"^2, with a length of 27 inches. To add another sub do i keep the length the same and double the port area?

no, thats not quite how it works. the larger the port area, the longer the port has to be to maintain the same tuning

 

[jeepintn 10+ year member]

Yeap, that's about it, make sure to account for driver displacement.

please stop

 

[Demi 10+ year member]

no, thats not quite how it works. the larger the port area, the longer the port has to be to maintain the same tuning

Aww crap thats right. Grrr. I guess it would be easier to do a multi chambered box. I will see when i get home, i have the formula for port length at the house.

 

[96civ 10+ year member]

A larger port area directly corresponds to more dB's or is that not true?

 

[jaco 10+ year member]

general rule for port aera is 15 square inches for each cubic foot of air space

 

[rpfuror 10+ year member]

no, thats not quite how it works. the larger the port area, the longer the port has to be to maintain the same tuning

I guess I mis read, but now coming back to the forum there is alot that is needed. If you increase the volume of the port you will decrease the net volume the driver sees so you will have to increase the total size of the box to maintain the correct net volume. This will inturn change the amount of lenght you will need to maintain the desired freq.

please stop

What was I suppost to stop?