how to determine port length for 2 pipe ports

[dsw422]

I would use what u said fyrbyrd, but I need a minimum of 7.7 inches diameter port.. is 2 3 Inch ports equal that?? I'm not sure.. I believe I'll have to use 4 tubes.. what length then???

[Triticum Agricolam]

I would use what u said fyrbyrd, but I need a minimum of 7.7 inches diameter port.. is 2 3 Inch ports equal that?? I'm not sure.. I believe I'll have to use 4 tubes.. what length then???

A 7.7" port would have 46.5 sq in of port are. One 3" port has 7 so you would need about seven 3" ports. That being said, you probably don't really need that much port area. Four or five 3" should be sufficient. With that many they are going to have to be longer and you may have issues fitting them in the box.

[dsw422]

so with 4 tubes, what length would I need?? I only have about 8 inches in depth to work with...

here is the box im working with.. the raised sections was where I was going to put the pipes

[Triticum Agricolam]

With four 3" ports they are going to have to be around 30" long to tune your to 40 Hz. They are also going to take up about .15 cubes of box space, each. Obviously thats not going to work out well.

I'm going to pick on you for a bit because you are doing something I see happen here all too often. You start in on a build without figuring out how everything is going to work first. Sometimes you can get away with that, sometime you can't, which is whats happening here. You guys need to remember the seven Ps. Proper prior planning prevents piss poor performance.

Your box looks nicely built and is an interesting design, but you are going to have a tough time making it work. You probably aren't going to be able to fit in enough port area w/o rebuilding it and using too small of ports works about as well as putting a size 8 shoe on your size 10 foot.

[dsw422]

Damn... well it kinda has to stay the shape it is.. it's going into the back of a 95 Camaro.. do you think some sort of slot port Will fit?? I've never done a spot for attendees odd angles obviously lol..

Or what size pipe can I use to achieve the tuning and my depth parameters? ??

1 other thing I should have asked probably a while ago is that the subwoofer manual has a diagram in it for a box tuned to 49 hertz... I can't find much about this speaker and was afraid to tune that high... what input do you have on that??

your help and criticism is much appreciated.

[Skullz]

2 3" ports for a single 10" will be fine, and since your tuning it close to the RF of the car it'll make it seem like a much larger sub.

Technically you could get away with a single 3" port as the enclosure is so large for a single 10" sub.

[dsw422]

well here is the manual for yall. it recommends a box volume of 1.2 and 2 4 inch pipe ports tuned to 49hz..

http://www.manualslib.com/manual/573408/Cerwin-Vega-Stroker-102.html?page=3#manual

i made the box 2 cu ft. b/c i feel like it could use it.. though i could be wrong.. i can add supports on the inside to close off some space if need be.. what do u think?

[Triticum Agricolam]

2 3" ports for a single 10" will be fine, and since your tuning it close to the RF of the car it'll make it seem like a much larger sub.

Technically you could get away with a single 3" port as the enclosure is so large for a single 10" sub.

Please explain how having a larger box allows the use of a smaller port.

Also, what do you estimate his port velocity to be with just two 3" ports?

[Triticum Agricolam]

well here is the manual for yall. it recommends a box volume of 1.2 and 2 4 inch pipe ports tuned to 49hz..

http://www.manualslib.com/manual/573408/Cerwin-Vega-Stroker-102.html?page=3#manual

i made the box 2 cu ft. b/c i feel like it could use it.. though i could be wrong.. i can add supports on the inside to close off some space if need be.. what do u think?

So two 4" ports is just over 25 sq in of port area. Four 3" ports is just over 28", so fairly close, you could go either way. As far as a 49 hz tuning, it depends on what you are trying to do with this sub. Output is going to fall off and cone excursion is going to rise pretty fast once you get below tuning. If you are going to use this sub for music I sure wouldn't tune that high. Depending on what music you listen to would help determine how low you would want to tune to.

[dsw422]

well here is the manual for yall. it recommends a box volume of 1.2 and 2 4 inch pipe ports tuned to 49hz..

http://www.manualslib.com/manual/573408/Cerwin-Vega-Stroker-102.html?page=3#manual

i made the box 2 cu ft. b/c i feel like it could use it.. though i could be wrong.. i can add supports on the inside to close off some space if need be.. what do u think?

So two 4" ports is just over 25 sq in of port area. Four 3" ports is just over 28", so fairly close, you could go either way. As far as a 49 hz tuning, it depends on what you are trying to do with this sub. Output is going to fall off and cone excursion is going to rise pretty fast once you get below tuning. If you are going to use this sub for music I sure wouldn't tune that high. Depending on what music you listen to would help determine how low you would want to tune to.

Ok.. I'll see if my uncle has 4 inch pipe.. what would my length need to be??? My buddy likes the lowe's so I'll stick with 40... would reducing box volume decrease length of port?? What would u recommend? ?