# Need Help with Dual Vent Calculations

#### profoundwill

##### CarAudio.com Elite
10+ year member
I want to build a box with two slotted vents, one on each side of the box. Or a box with one vent in the middle that splits off both ways inside the box. The box is gonna be 50" wide, 18.5" deep, and 17" tall. I have built several single vented boxes but never a dual vent or one with the vent in the middle that goes off in both directions. Any help you guys can provide will be greatly appreciated. Thanks,

#### THATpurpleKUSH

##### Smoke weed everyday
10+ year member
2 ports are less efficient than 1 port , so it's not an ideal design.

If you must use 2 or multiple ports, you calculate the length of each port by dividing the number of ports into the net volume of the enclosure.

For example you have a 4cf box and want to 2 ports divide 2 into 4, so you have 2cf per port then calculate the port length for that.

OP
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#### profoundwill

##### CarAudio.com Elite
10+ year member
One more question. I was thinking about putting the subs on the side, one on each side, with the port facing back of trunk. Will that be okay? Reason being don't want to see the subs when trunk is open and also may want to use trunk space without damaging the subs.

#### THATpurpleKUSH

##### Smoke weed everyday
10+ year member
One more question. I was thinking about putting the subs on the side, one on each side, with the port facing back of trunk. Will that be okay? Reason being don't want to see the subs when trunk is open and also may want to use trunk space without damaging the subs.
Use grills if you are concerned about damaging the subs. You should fire the subs and port to the rear in a trunk......unless you have the ability to test with a meter and don't care about rebuilding the box multiple times.

You can run into cancellation issues if you dont rear fire subs and port.

It's permissible to not fire to the rear if you have the ability to test and rebuild to determine whats best for your vehicle. If you lack the ability, equipment or time to test then its best to fire to the rear and call it a day.

I have seen side firing subs on either side with a rear firing port but without testing to know what works in your vehicle, its possible that you're leaving output on the table.

OP
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10+ year member
Thanks again.

OP
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#### profoundwill

##### CarAudio.com Elite
10+ year member
Just wondering would I be better served going with 3 subs in a sealed box, that would also allow me to give the subs another 500 watts. Thanks just another option I have.

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