Box for 18" Xcon Help

[basshead7890]

This is my first box build, & I want to build a box like the one below, and my questions are how do I calculate the ports lengths. dimensions are 14h x 33w x 35d

Do I use a port length calculator and just divide the length(36") in half for both ports & make each port wall 18 inches long & 5 inches wide?

Edited July 26, 2011 by marquez7890

[RAM_Designs]

The port length given is for EACH port, so each port will need to be 36" long. Also, the volume seems to be a bit on the large side, might want to tone it down to 6.5-7ft^3 unless you're running less than rated power and need the efficiency via a larger chamber. The volume that you use in the port length calcs is the final volume after all sub and port displacements. Then you work backwards to find a suitable box size to give you that final volume after displacements.

Edited July 27, 2011 by RAM_Designs

[basshead7890]

The port length given is for EACH port, so each port will need to be 36" long. Also, the volume seems to be a bit on the large side, might want to tone it down to 6.5-7ft^3 unless you're running less than rated power and need the efficiency via a larger chamber. The volume that you use in the port length calcs is the final volume after all sub and port displacements. Then you work backwards to find a suitable box size to give you that final volume after displacements.

Thank you for the help and I have 2 more questions,

How come when I use another port length calculator (the one above, http://www.mobileinf...20lenth%201.htm) the tuning frequency is different from the torres with the same height, widths and lengths & volume? the other one i have square and slot checked, and i have 3 common port walls on the torres & torres gives me a different frequency.

Do I need a double baffle for the box below?

This is what I've came up with

its 6.4 cubes @33hz after port and sub displacement.

Edited July 28, 2011 by marquez7890

[dcofer]

The way torres calculates the port length is a little different, he measures the port length from the midpoint of the port where most calculators probably use the inner wall of the port (essentially making the port longer). From what I have seen and from listening to Torres help me understand his calcs I would trust his calculator over a random online one (though some are really good also if you look hard enough) but honestly if your tuning is only off a couple Hz then I doubt it will make a huge difference for daily. If you really have questions I bet Torres would gladly explain stuff like he did for me.

Box looks sexy though, I really like the sub model too makes it look more legit

Edited July 28, 2011 by dcofer

[Blackedout]

The way torres calculates the port length is a little different, he measures the port length from the midpoint of the port where most calculators probably use the inner wall of the port (essentially making the port longer). From what I have seen and from listening to Torres help me understand his calcs I would trust his calculator over a random online one (though some are really good also if you look hard enough) but honestly if your tuning is only off a couple Hz then I doubt it will make a huge difference for daily. If you really have questions I bet Torres would gladly explain stuff like he did for me.

Box looks sexy though, I really like the sub model too makes it look more legit

http://www.stevemeadedesigns.com/board/topic/38791-torres-box-tuning-calculator/

[ChevyBoy95]

not to get off topic but how did you make that sub in sketchup?

[basshead7890]

not to get off topic but how did you make that sub in sketchup?

It was already made, I just downloaded a enclosure design from SSA and erased the box then imported it into my sketchup

[RAM_Designs]

I just ran the dimensions on the design you just posted because I knew the port area looked too large to be tuned that low with a 21" length. The box you have right now is 6ft^3 tuned to 41hz.

35"x33"x14" = 7.63ft^3 before displacements

4.75"x12.5"x20.75" = .713ft^3, 1.426ft^3 for both

Subtract .25ft^3 for sub displacement, and you're right around 6ft^3

A 6ft^3 box with a pair of 21" long 12.5"x4" ports give you a 41hz tuning.

Edited July 28, 2011 by RAM_Designs

[basshead7890]

I just ran the dimensions on the design you just posted because I knew the port area looked too large to be tuned that low with a 21" length. The box you have right now is 6ft^3 tuned to 41hz.

35"x33"x14" = 7.63ft^3 before displacements

4.75"x12.5"x20.75" = .713ft^3, 1.426ft^3 for both

Subtract .25ft^3 for sub displacement, and you're right around 6ft^3

A 6ft^3 box with a pair of 21" long 12.5"x4" ports give you a 41hz tuning.

I just done it by hand and my length came out to be 27.676

this is where i got the 21.45" for the length,

Edited July 28, 2011 by marquez7890

[RAM_Designs]

You need to use the net volume when finding the needed port length, not the gross volume. Otherwise, you can make a situation where the port would need to take up the entire box and leave you with no chamber volume.

Use the net volume you want to find port length, find the disacement of the ports, then work backwards to find the dimensions needed to give you that net volume after sub and port displacements.

Edited July 28, 2011 by RAM_Designs