Port size/area recommendations

[Revdoc]

I have started my build in my 07 Escape, 2 PSi Platform 2 18s are in my living room next to the Soundqubed Q1-3500D.1 amp, and I need some recommendations on port area please.

The box is a C pillar wall that's about 11.65 cubes net after woofer displacement and estimated port displacement. http://imgur.com/a/FNEhV has a couple of pics of my Sketchup progress so far.

Currently I am planning on a port 10" x 15" x 30", aiming for about 31 hz. This is mainly estimated from the PSi Redneck Ported Box calculator on their site. I have heard the "X sq in of port per Y cu ft of box" is not really the right way to do it, but will get you close. What do you experts recommend?

Also the only way I could figure to get such a long port in my short depth box was to put a divider in the middle of the port and run it back to the rear wall, then split it like a T. Essentially it will be 2 L shaped 10" x 7.5" x 30" ports with a shared center wall. Is that "OK"? I would guess put 45's at the corners of the L in the port?

[alaskanzx5]

So if I'm reading correctly

2 chambers with 2 separate port measuring 10" x 7.5" giving 75" of port per 18?

[Revdoc]

The subs share airspace, the port will run along the bottom of the box from the front to the back, then when it hits the back wall it splits and runs opposite directions. The port would be 10 x 15 but since it splits it is technically 10 x 7.5 and there are 2 of them. Yes, 75" of port area per 18" sub. About 5.825 cubic foot net per sub.

I was aiming for 30-35 hz, preferably the lower end of that. I listen to mainly rap and hip hop, not looking for a competition SPL number but would be nice to break 150.

[alaskanzx5]

Ok, one chamber one port opening on the outside 2 on the inside. I understand.

I'm not seeing an issue here so far but I'm unsure of needed port area.

Have you taking into consideration of bracing? With out it you will get some no flex which can hurt performance and output.

With the tuning I would aim for around 33hz personally. With a good design and taking your time putting the box together even at 33hz you coil play into the low 20s.

[Triticum Agricolam]

I have a done a "T" shaped port like you are talking about before. While not an ideal situation, it has seemed to work just fine and I wouldn't hesitate to do it that way again if the need arises. I would recommend putting 45 pieces inside the port for better airflow though.

[Revdoc]

Cool, thanks. After crunching numbers and redesigning the box a bit, it is now looking like about 12.3 cubic foot, net, after sub displacement, port displacement, etc. I might make the port a bit bigger since it seems on the small end and I now have a bit more room to work with. Maybe 180 sq. in. instead of 150.