Port area for a single SSD 15

[scameron 0]

is a single 4"ID x 5.5"L port enough for an SSD 15 in 3.5cu ft. the box will be tuned to 33. trying to finish up the details on my enclosure and i keep questioning this.

[Duran 387]

Anywhere between 42 and 56 square inches will do you right. Rust remember it will change tuning, you you'll need to adjust the length accordingly.

[KU40 173]

I would say you'd want a minimum of 35 sq. inches in a slot style port. If you're using aero ports, you could probably get away with two 4 inchers.

[scameron 0]

I would say you'd want a minimum of 35 sq. inches in a slot style port. If you're using aero ports, you could probably get away with two 4 inchers.

don't have enough space to allow for the slot style port. i was looking at an aero port. the calculators i have been using say a single 4 incher would work.

[KU40 173]

What do the calculators that you use calculate? Port air velocity?

[scameron 0]

What do the calculators that you use calculate? Port air velocity?

nothing fancy. i have bass box pro and another excel sheet i play around with. looks like a 4"ID x 5.5" aero port will give me 65 sq.in.

[KU40 173]

I think you are using the wrong calculations. That 65 sq. inches is actually cubic inches, as in the volume of the port, correct? That's not what you want to look at. You want the area of the actual port opening. So in your case you have a 4" round port, and the area of a circle is pi*r^2. With a 4" port that gives you around 12.56 sq. inches.

[scameron 0]

I think you are using the wrong calculations. That 65 sq. inches is actually cubic inches, as in the volume of the port, correct? That's not what you want to look at. You want the area of the actual port opening. So in your case you have a 4" round port, and the area of a circle is pi*r^2. With a 4" port that gives you around 12.56 sq. inches.

i knew something didn't look right or sound right. this is why i keep questioning myself. so, what would you suggest. my box measures 33.5"W x 17"H x 15.5"D. i have an 1.5" baffle.

[KU40 173]

ok, so your box is 3.92 cubes gross. minus about .12 for sub to make it easy, 3.8. If you use two 4" aero ports and make them 14.5" long each, you'll end up with a 3.6 cubic foot box tuned to 33 hz. You could also use a single 6" aeroport that's 15.25" long and have basically the same box. That would save you on cost of an extra port and cutting another hole out of your baffle.

[scameron 0]

how much room is needed from the back of the port to the back of the enclosure. using a 14.5" length puts the back of the port 1/4" off the back of the enclosure. is it a big deal if the ports are not in the baffle?

[KU40 173]

Oh I forgot to compare the depth of port to the depth of the box. You can do a couple of things to fix it, and I'll put them in order of most desirable to least, based on a generic trunked car. You can put a 90 degree angle in the port inside the box so that it runs parallel with the back wall, you can stick the port out of the front of the box by a couple inches, or you can put the port on a different baffle, such as the side, so that it fits completely within the enclosure.

What kind of car do you have? If you have a hatchback or an SUV, many people have actually had luck with the sub facing up with the port facing backwards. That would solve the problem fairly well in that case.

As for the port distance question, you generally want to be at least the diameter of the port away from the back wall or wherever the port opens to.

[scameron 0]

Oh I forgot to compare the depth of port to the depth of the box. You can do a couple of things to fix it, and I'll put them in order of most desirable to least, based on a generic trunked car. You can put a 90 degree angle in the port inside the box so that it runs parallel with the back wall, you can stick the port out of the front of the box by a couple inches, or you can put the port on a different baffle, such as the side, so that it fits completely within the enclosure.

What kind of car do you have? If you have a hatchback or an SUV, many people have actually had luck with the sub facing up with the port facing backwards. That would solve the problem fairly well in that case.

As for the port distance question, you generally want to be at least the diameter of the port away from the back wall or wherever the port opens to.

i'm doing this in an 02 cavalier. i thought about the 90. would there be a crazy sound issue porting the cabinet out the bottom then 90 into the spare tire well. would be the same as porting it on another baffle. something like this.

horizontal section

vertical section

[scameron 0]

couple quick Iso drawings. these iso don't have my amp rack concept.

Front view. sorry my plot got cut off.

Back view

[scameron 0]

well, scrape that idea. not enough room in the well for the elbow. it wasn't correct, but was a cool idea....lol. i will port the front and use a 90 pointing up. i'll just make custom flares in the baffle and on the 90.