[the_dealer]

I'm working on a new box, and the distance to the end of my port and the wall is exactly the port width. Heres a pic to show what I have(sorry for the ****ty drawing)


When calculating does it stop at the end of the port? Do you add half the port width? Do you add half the port with+ half the port width, plus thickness of the wood(like the port has a bend)? If it's calculated like in my drawing, my port length would be 40.25". Wouldnt I add 1.5"+1.5"+.75, which would make the length 44"? I was thinking you treated it like another bend in the port, but want to be sure. I have everything but the port cut, so progress is stopped until i figure it out. Can someone help me out?

 

[GLN305]

Instead of folding it in like that, I would continue it to the right wall of the box.

 

[miniSQ]

For a simple port like that, measure right down the center, so your port there is 40.25 inches. There is a way to measure where you divide it into a sort of pie shaped at the bend using 45 degrees slices. But i bet if you did that you would be within an inch of 40.25 and thats not going to change anything.

 

[the_dealer]

I got my measurements from the centerline of the port. So from my drawing and the measurements I show, my port length is 40.25? Im just stumped because I need to add another 3.75". The 3" line I drew isnt part of the port. The panel where I marked 26.5 is my last port piece, which happens to be the exact with of the port. So if I drew a centerline, it would actually go to the right 1.5" more, down 2.25"(1.5" for 1/2 the port width, and .75" for thickness of the piece. That would make its length 44"(43.25 if I wasn't supposed to add the thickness of the piece. Would that not be correct? I need my port length to be 43.5-44". If my figuring is 3.75" off, that would be noticeable

 

[miniSQ]

ooohhhhh...i thought you needed 40.25 and were second guessing yourself as tyoy iff you had 40.25 of some other number.

So yes, draw your center line 1.5" further to the right and then down 2.25 if that equals your desired port length. If that is what the line is you have drwn thats fine. Just build your last port wall outside the 3" opening and i know it is going to be short. I would round it off, and like wise round off the the two inside bends, and put two little wedges in the 2 outside corners to keep is as smooth as possible thru the turns.

Sorry if i am not quite grasping what you are asking, or more to the point, what are your concerns?

 

[the_dealer]

Ok, I made some better drawings and ill try to make it less complicated. My port width is 3"

If I stop measuring port length at the red arrow, my port length is 40.25. I need it just a little longer.


The end of of port piece B is 3"(port width) from the wall. If I stop at the yellow arrow, my port length would be 43.25". I calculated this by the centerline of the port. For example: If I were to add a panel C that was 3" long my port would be 46.25" long, so I subracted 3" since there is no panel C. Is that correct, since 43.25" would be the end of the port

 

[the_dealer]

Ok, thats what I was thinking. Since port B panel is .75" thick, I didnt know if .75" would also be added (making it 44") since the thickness technically adds length. A double en baffle adds .75", so I assumed it would work the same. I need the port length between 42.5-44, so that would put me right where I should be. This is the first time I've had this happen, so it threw me off a little. I planned on rounding the corners end end (s), but doubt ill do 45's. I bought a 2nd sub, so I wanted to keep it as close as possible to the box I was running with a single sub. The volume and port area per sub and tuning will be the same, so it should work out pretty good

 

[miniSQ]

The total length of the port is the combined length of the 3 boxes in this file.

Red is port....green is 3/4 "mdf and grey is air space based on your measurements on your drawing.



woops...let me edit this pic...i think i finallty see what you are saying . DOH

 

[miniSQ]

This...blue line is your port length...



I can give you the exact cut size of the port walls if you confirm the outsize dimensions of the over all box.

 

[the_dealer]

Ok, the one with the blue line is how I was figuring it up. That puts my volume and tuning right where I was aiming. Including sub displacement, Torres put me at [email protected] net.

32.5"w x 16"d x 12"h, Port 10.5"h x 3"w are the dimensions, .16cuft sub displacement (.08 ea.). I feel pretty good about it now that I saw your drawing, which is what I was thinking was correct. Trying to explain it on the internet is a *****, and my first post was a confusing clusterf**k. I've only done about 8 or 9 slot ported boxes, so I've never ran into this before. Thanks a bunch!

 

[ATOMICTECH62]

When using ports that use a wall for one or more sides its common practice to subtract 1/2 the width from the length.In your case this would be 1.5".
Ether way I doubt there will be a noticeable difference if your off by an inch or two.
It probably wont be more the .5hz.