ported clamshell help/build

[irpirate]

This is why I generally design first then buy the woofers, saves you headaches.....

lol probably a good idea. i got a bit too eager with wanting to do a clam with bunches of subs

ok so i now i know i can fit the subs on the face, only thing i hafta figure out before i start building is the port length. how long do i need to make each of the split ports? im guessing from my design the tuning is gonna drop quite a bit. so if i go with the port lengths i have in the pic above. 5 inches in middle, 6 inches split off on each side. calculating a port length of 11 (probably not right cuz im guessing the splitting the port into two sides will change the tuning) it will give me a tuning of 35-36. im thinking this should be low enough with the long ass clam.

[irpirate]

if you cut holes that close together all the way across the damn thing its gonna have practically no support and be hard to brace.

crappy :/ ill try and space it out a bit then. also the subs arent level 5 800 pound subs or anything like that, think theyre around 16-17 pounds each. regardless though, if i do spread them out a bit i think i should be able to fit four thread rods around the middle.

[AMI CUSTOMS]

I would use 1 1/4 diameter dowel wood like in my wall build log. Treaded rod is not necessary unless you already have it.

[irpirate]

I would use 1 1/4 diameter dowel wood like in my wall build log. Treaded rod is not necessary unless you already have it.

alrite, ill do that then. already read through your log and know what youre talking about

[fritosaregood]

added some port. changed the calculation to three common walls.

the beginning of the port goes for five inches. the split goes around 6.5 for each side. 6 inches away from the wall for both. im not sure how splitting the port changes the tuning. any ideas?

*edit - with this box ill only get around 1 cube per sub maybe ill switch the amp from a 3500 to a 4500 and juice them a bit more if this is what i do and i dont feel like its performing like it should. also, the widest part of the clam/opening is 14 inches tall.

If you are splitting the port like that to add length, and your port width is 5 inches, you need to only be 2.5 inches way from the back wall with it or it wont act as a port.

[AMI CUSTOMS]

If you are splitting the port like that to add length, and your port width is 5 inches, you need to only be 2.5 inches way from the back wall with it or it wont act as a port.

Explain.

[irpirate]

If you are splitting the port like that to add length, and your port width is 5 inches, you need to only be 2.5 inches way from the back wall with it or it wont act as a port.

thats what i thought at first as well, no experience just the logic of it. cuz if the port width is 6 inches for both chambers when i split it and leave it at 6 for each that means the port area will be changing halfway through the port, which seems like it would change the tuning. thing is colin specifically said that 3.5 inches would be way too close. his was 4.5 or 5 away with less subs and a smaller box. should i leave it at 6 inches throughout or change it to maybe 5 when the port splits?

[irpirate]

another question, will i need to put something in the middle of the port against the back wall to angle and separate where the ports for the two chamber come together?

[Colin - STAPUFT]

3.5" would be too close for the Entire port (what with your number of subs and total volume). With it like that, it shouldn't matter. Like has been said by someone on here already- whatever the closest distance the two baffles are together, that should be the distance from the back of the box. I get what you are saying about going Half of that for each (top only needs half, bottom needs half- together they make the distance between the baffles).

I dunno- tough call. The closer you make it, the more it chokes it up and the lower the tune. What with the constraints that the angles are going to put on the design anyway- I don't think you will be able to make the "port" too big.

Remember, the subs play off of each other, lowering the tune. In the back where the "port" is and where the air comes from the top part and bottom part of the enclosure- as the air meets there, it will naturally slow as it fights for a way out. I don't think you will have an issue with the box being "tuned" too high.

Just me thinking- you don't need the port extensions (parts that go up and down following the back of the box). But you are deeper into the calculations than I am- I am just wet finger in the air. Just KNOW that it will tune lower than any box building or box tune program will tell you. Just how much...

[Colin - STAPUFT]

another question, will i need to put something in the middle of the port against the back wall to angle and separate where the ports for the two chamber come together?

You could... I saw a write up once on someone who tested this with this type of "loaded" enclosure. They did it with nothing between, a small "v", and a larger "v" (presumably to help air flow). It was the loudest with nothing in there. Bigger the "v", the lower the SPL. I know that was his box and not yours- just saying. I would do it if it makes you happy- I intended to make one for mine and did not. I haven't noticed it as not being there.