Torres' Box Tuning Calculator design HELP!!! (15''Sp4)

[Altima1]

So Im building a box for my 15'' Sp4. i have built many boxes but i have always stayed away from angled ports but this time i cant avoid it so i need help in the calculation for the angle/curve in the port. I know that the port should be the same width the entire length of the port but at the corner it will actually be a little larger unless you put a 45 angle in it. so by doing this will it mess up the calculations in torres' program? and im still trying to understand the physical port length and the port length you put in and the port length used in the calculations in the green box at the bottom (Lv). I have something drawn up with the program so i wanted to know if i am going in the right direction on building the port.

[john253a]

If you just 45deg in the cnr. then it's down the middle of the port like norma L-port

If the 45's are large enough it's still down the centre but follow the cnr. So as the the port has 2x 45 deg bends and not 1x 90

If you kerfing the port on both sides then you follow the it round as if it a straight port but again down the middle

[Joe X]

These would be the dimensions of the port parts for that box:

L Port Internal Assembly Parts:

Front to Back = 18 1/2 x 15 1/2

Extension = 13 x 15 1/2

But then 0.4 cubic feet of bracing?

[Altima1]

If you just 45deg in the cnr. then it's down the middle of the port like norma L-port

If the 45's are large enough it's still down the centre but follow the cnr. So as the the port has 2x 45 deg bends and not 1x 90

If you kerfing the port on both sides then you follow the it round as if it a straight port but again down the middle

i kinda get what your saying but what i really wanna know is if by putting the 45's in the bend to keep it at a consistant 5" width will effect the tuning freq compared to just doing a 90 deg turn with no 45's at all. Noting that the 90 degree turn will not be a consistant 5'' in width at the turn from the corner of the box wall to the corner of the port wall. From my understanding of what i saw Torres say is that the port length you put in is what the sub will actually see (Center of port measurement??) and the physical port length is what you would get if you measured the inner port wall entirly. and im guessing the Lv in the green box is the outter wall??

These would be the dimensions of the port parts for that box:

L Port Internal Assembly Parts:

Front to Back = 18 1/2 x 15 1/2

Extension = 13 x 15 1/2

But then 0.4 cubic feet of bracing?

thats 31.5" and then add 1.5" for the thickness of the front baffle of the box and the front to back port wall comes out to 33''. so why that number? and also im trying to put 45's in the ports turn like in the picture above. explaining the 0.4 bracing, I will be putting resin and matting on the inside of the box with some dowel rods for bracing and putting 45's in all the corners.

[Joe X]

Ok so for a box that assembles like in the picture below here is a cut sheet list (port length is 38"):

Enclosure Specifications:

External Height = 17 in

External Width = 35.5 in

External Depth = 25 in

Port Width = 5 in

Cut Sheet List:

* All Dimensions in Inches.

* Wood Thickness is 3/4 for all Parts.

External Enclosure Parts:

Front = 29 3/4 x 15 1/2

Front Internal = 28 1/4 x 15 1/2

Back = 35 1/2 x 15 1/2

Left & Right Sides:

Side 1 = 23 1/2 x 15 1/2

Side 2 = 24 1/4 x 15 1/2

Top & Bottom = 35 1/2 x 25

L Port Internal Assembly Parts:

Front to Back = 18 1/2 x 15 1/2

Extension = 13 x 15 1/2

[Altima1]

Ok, so your saying you get the 38" from adding

front to back- 18.5''

Extension - 13"

baffle thicknesses- 1.5"

port width- 5"

= 38" ........Correct? and if so then the physical port length is 18.5" + 13" = 31.5". but the unknown is the Lv/Port Length in the green box, how was that calculated? and when i 45 both corners in the port it shouldnt effect the tuning freq or the port area right??

Edited May 9, 2012 by Altima1

[Joe X]

That question came up (once again) very recently, I left an explanation there, take a look;

http://www.stevemeadedesigns.com/board/topic/141928-how-to-measure-a-port-when-it-turns/page__view__findpost__p__2005951

[Altima1]

That question came up (once again) very recently, I left an explanation there, take a look;

http://www.stevemead...ost__p__2005951

Ok i see this explains it well, another question is since i will be fiberglassing the inside of the box a double baffle wouldnt be needed like the box you put up???

[Altima1]

since i will be fiberglassing the inside of the box, would i still need to double baffling the face of the box?

Anyone????

[john253a]

only if you allowed for it,

joe's drawing is a generic one, for visualisation only,

if you allowed for it then yes, if you didn't then no,

should it have one? then comes down to power and box design