multiple ports

[Jspawn80]

Im trying to redesign the port for my box for 4 sa8's i previously had a 4 inch port, but got too much port noise. I input all my data into winisd and i can run (2) 3 inch port or even (3) 2 inch ports. Is there any downsides to running multiple smaller ports instead of one big port? also this box is going in a nissan titan that had a transmission hump and the ports would be on one side of the box behind one set of subwoofers, if there anything wrong with the ports being closer to 2 subs and the others being farther away? I attached a picture of the box, the ports would be on the right side where the hole for the 4 inch port currently is and the box is all one chamber

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[Jeffdachef 5,000+ posts]

Im trying to redesign the port for my box for 4 sa8's i previously had a 4 inch port, but got too much port noise. I input all my data into winisd and i can run (2) 3 inch port or even (3) 2 inch ports. Is there any downsides to running multiple smaller ports instead of one big port? also this box is going in a nissan titan that had a transmission hump and the ports would be on one side of the box behind one set of subwoofers, if there anything wrong with the ports being closer to 2 subs and the others being farther away? I attached a picture of the box, the ports would be on the right side where the hole for the 4 inch port currently is and the box is all one chamber

two 3 inch ports isnt much better than a single 4 inch port. Your ports are simply too small you need to divide the center up and do a 4 inch port on each side dual side fire.

 

[Jspawn80]

two 3 inch ports isnt much better than a single 4 inch port. Your ports are simply too small you need to divide the center up and do a 4 inch port on each side dual side fire.

I have tried running that though winisd and every time i do it gives me a port thats too long, it says that with a 4 inch port is had to be 31" long which i cannot possibly fit, and if i split the box each chamber becomes about .85ft^3

 

[Jeffdachef 5,000+ posts]

I have tried running that though winisd and every time i do it gives me a port thats too long, it says that with a 4 inch port is had to be 31" long which i cannot possibly fit, and if i split the box each chamber becomes about .85ft^3

are you calculating your box purely on winsid? Did you account for sub and port displacement? Winisd does not account for those factors. The box may be too small to begin with if your port lengths have to be that long.

 

[Jspawn80]

are you calculating your box purely on winsid? Did you account for sub and port displacement? Winisd does not account for those factors. The box may be too small to begin with if your port lengths have to be that long.

yes i am accounting for port and subwoofer displacement, my box is on the small side but a tech from sundown said is enough air space for the subs since im giving them more power than the recommended rms. I was just trying out different port sizes and i input (2) 2" ports which it calculated have to be 15.5 long and would leave me with a vent mach of 0.12, would that be enough port area? also thats with the box split and those ports would only be for 2 subs i would also put the same thing on the other side of the box

 

[Jeffdachef 5,000+ posts]

yes i am accounting for port and subwoofer displacement, my box is on the small side but a tech from sundown said is enough air space for the subs since im giving them more power than the recommended rms. I was just trying out different port sizes and i input (2) 2" ports which it calculated have to be 15.5 long and would leave me with a vent mach of 0.12, would that be enough port area? also thats with the box split and those ports would only be for 2 subs i would also put the same thing on the other side of the box

they might work if you do some flares. Flares will help a lot.

 

[Jspawn80]

they might work if you do some flares. Flares will help a lot.

so would it be better to divide the box and do the (2) 2" ports on both side?? or can i leave it one chamber and do (2) 3" ports to ones side??

 

[Jeffdachef 5,000+ posts]

so would it be better to divide the box and do the (2) 2" ports on both side?? or can i leave it one chamber and do (2) 3" ports to ones side??

I've been in a 02 silverado with two 10s that have an under the seat box with a middle divider and a 4 inch port on each side that did a 146 db and sounded great on music. That middle hump blocks a lot of airflow.

 

[adulbrich 5,000+ posts]

Yeah, more ports is not going to solve it, and will probably make it worse. If you're getting bad port noise, you need more port area. It would be better to get one pipe that's larger, like say 6" if you can get enough port length and still maintain desired tuning. Don't do two 2" ports on each side. BAD IDEA.

You want more area in the middle of the circle that is the port. Air moving in and out past the rough edges will cause a "chuffing" sound once it starts moving fast enough.

Like Jeff said, flares would be a good place to start. Might be able to keep a single 4" port

 

[Jspawn80]

Yeah, more ports is not going to solve it, and will probably make it worse. If you're getting bad port noise, you need more port area. It would be better to get one pipe that's larger, like say 6" if you can get enough port length and still maintain desired tuning. Don't do two 2" ports on each side. BAD IDEA.
You want more area in the middle of the circle that is the port. Air moving in and out past the rough edges will cause a "chuffing" sound once it starts moving fast enough.

Like Jeff said, flares would be a good place to start. Might be able to keep a single 4" port

Well i tried splitting the box and seeing what would happen if i put a 4 inch port but is says i need a port thats 30" long and i dont have enough space to fit that, thats why i was wanting to try the 2" port but i just calculated and it reduces my port area by alot

 

[adulbrich 5,000+ posts]

You're trying to fit too much in the space you have. Seal the hole where the port was and call it a day. After internal port displacement, you're not going to get something that is tuned low enough and has enough port area. A sealed box is more "correct" for your space if you're running that many 8's

 

[Jspawn80]

You're trying to fit too much in the space you have. Seal the hole where the port was and call it a day. After internal port displacement, you're not going to get something that is tuned low enough and has enough port area. A sealed box is more "correct" for your space if you're running that many 8's

Well i closed the hole already but i dont think i can run the sundown sa8's sealed.

The only things i think i can do to save this box would be either a single 6" port thats 17" long but it would be close to where the transmission hump is. It would only be 2 inches away from a wall which is where the transmission hump starts but only half of the port would be that close the the wall and it would leave me with 1.7 ft^3 tuned to 43hz

or

Do 2 3" ports that are both 15" long and that would leave me with 1.8 ft^3 tuned to 36hz

 

[Jspawn80]

You're trying to fit too much in the space you have. Seal the hole where the port was and call it a day. After internal port displacement, you're not going to get something that is tuned low enough and has enough port area. A sealed box is more "correct" for your space if you're running that many 8's

Also is tuning with a flared port different then just tuning for a regular pvc port? if i could just use one 4" port then that would be great

 

[adulbrich 5,000+ posts]

Well i closed the hole already but i dont think i can run the sundown sa8's sealed.
The only things i think i can do to save this box would be either a single 6" port thats 17" long but it would be close to where the transmission hump is. It would only be 2 inches away from a wall which is where the transmission hump starts but only half of the port would be that close the the wall and it would leave me with 1.7 ft^3 tuned to 43hz

or

Do 2 3" ports that are both 15" long and that would leave me with 1.8 ft^3 tuned to 36hz

Explain why you "can't run them sealed"

We've advised you to not use multiple ports several times now.

Also is tuning with a flared port different then just tuning for a regular pvc port? if i could just use one 4" port then that would be great

If you want to get really technical with it, yes. You only add half the distance of the flare as port length iirc. If you added flares to the existing 4" port though, I see that as a way for you to possibly still run ported.

 

[Jspawn80]

Explain why you "can't run them sealed"
We've advised you to not use multiple ports several times now.

If you want to get really technical with it, yes. You only add half the distance of the flare as port length iirc. If you added flares to the existing 4" port though, I see that as a way for you to possibly still run ported.

I've looked on alot a places online that say its not a good idea to run the sa8's ported and sundown doesn't even have a recommended box for the subwoofer sealed.

Also i dont really understand the way flared ports work. When i put my box info into winisd with a 4" port thats 10 inches long, my tuning is at 38hz and my vent mach (which from what i understand has to do with the speed of the air traveling through the port) is a 0.21. And from what i've read it has to be below 0.16.

Now if i put in a flared port thats the same length will it reduce the vent mach or will it just keep the port from making noise?

Also while messing around in winisd and using the same 4"diameter port, the only way for me to reduce the vent mach is to raise the tuning. Which reduces my vent length and brings it down to a port thats 4" long but my tuning is ridiculously high a 52hz