Dual SA12 box

[ALL4SPL 4]

Ok, I am on my way to selling things I have to get another SA12 and then change my amp to a SAZ1500D. I am working on a design for the 2 12s now, however I have never done this kind of design so I need someone to check it, and if I am wrong just let me know. Anyway the box is net of 4cuft after displacement, with a 18.5"x2"x24" port tuned at 29Hz. As I said I have never done this kind of design so I do need input, what I figured was the port needed to be with the sharing of 2 walls 24" long, so I designed a T shaped port, now the way I thought it through was because the port had two sections extending out that they should each be half the remaining length of port after the straight section was done. I also kept the port the same distance from the back wall as the width of the port 2". The design you will see is only basic, no 45s yet, but they will be added. Also the top plate of the enclosure is left off, that is why you see 19 3/4" as the height.

So if anyone can check this, and by all means let me know if I am wrong, I want to learn so just keep it constructive please.

[ALL4SPL 4]

Here is Phase 2, granted this assumes I did the math correctly.

[ALL4SPL 4]

And phase three cleaned up a few things, and colored it solid colors to show port and what not a little better.

[NB50 206]

Your numbers are all off. Your total height is going to be 20.5" but you have your port height at 18.5" when its going to end up 19" (assuming .75" mdf). And your port width should be cut in half when it splits to the separate chambers. Basically think of each chamber as a separate box.

[ALL4SPL 4]

I had the port height at 18.5 because of .75 top and .75 bottom plates, so 20-1.5=18.5. And I was pretty sure the width needed to stay the same even when split, but I don't know if that is the case I can redo the port portion to 1" width, does the length look like I did it correctly?

[NB50 206]

Your drawing says it is 19.75 plus the top .75 = 20.5" and yes the port width needs to be made smaller when split. Length is to short. Think of each side as its own box.

[ALL4SPL 4]

Your drawing says it is 19.75 plus the top .75 = 20.5" and yes the port width needs to be made smaller when split. Length is to short. Think of each side as its own box.

Ok I just got off on the number for the height then, total height is 20" minus the top and bottom plate it makes the port 18.5" in height. As for the width I can make those adjustments, however the part where you are saying think of each side as it's own box, how does that accommodate for the port length that is shared, so where I have 12.25" shared length do I then need to make each port per side 11.75" long?

[ALL4SPL 4]

Here is the detail on the box how I started with numbers.

[NB50 206]

All you need to worry about is doubling the port width when the two ports combine. From my calculations you are going to be tuned about 1hz higher then what that calculator says, and when you start putting in the 45*s like you are, you are going to have to figure out how much your port length and volume changed then recalculate.. Your also really low on port area.

[ALL4SPL 4]

Ok how about this instead then, since I am screwing this up royally it seems. 20"x37"x16", 18.5"x3"x28" port, after displacement should be 3.91cuft with tuning at 32.75Hz, port area is 55.5sqin. 3 common port walls, so basically it's a L port box.

[ALL4SPL 4]

This is the L port box I described in the above post.

[ALL4SPL 4]

Ok, got someone to basically tell me in stupid terms where I messed up. So I will post another sketch design in a little bit which should be correct.

[ALL4SPL 4]

Alright this "should" be correct, I hope LOL! Overall port length is 28", port area is 58.5sqin tuning is (because calc's are diff between the12volt.com and torres calc) 32.8Hz(torres) and 33.5(the12volt.com).

Edited July 10, 2011 by All4Spl

[ALL4SPL 4]

And I changed my mind again, LOL it's ok my second 12 isn't here yet. Here is what I am going to be doing for sure as the first box and yes the cut out is left so you can see the ports nothing more.

[matj1990 11]

And I changed my mind again, LOL it's ok my second 12 isn't here yet. Here is what I am going to be doing for sure as the first box and yes the cut out is left so you can see the ports nothing more.

that would look cool with inverted subs dont no how it would perform though as im a noob

[ALL4SPL 4]

Well got it done, didn't take as long as the other would have that is for sure. Here are the pics.

Just awaiting the arrival of my second SA12 now, to put it to use!

[matj1990 11]

looks good man whats that tuned to ?

[ALL4SPL 4]

Thanks, its tuned at 42Hz.

Edited July 13, 2011 by All4Spl