typical box question (dual 12 t line)

[SanDiegoSlapper]

driving myself crazy in these calculators and design programs but can admit that im fairly inexperienced with this stuff. Looking to hopefully lay down a dual 12 T line box in the rear of my Yukon Denali. thing is i have alpine type r 12's (dual 4 ohm) and im seeing alot of posts about how the type r's dont perform as expected in tline, but im also noticing these are very old threads and possibly dont relate to the new(er) 5th gen type r's. so some suggestions with that would be great.

now as far as design goes, if anyone is willing to help out, it would be MUCHHH appreciated. i can send 15-20$ paypal. now if someone has something OTHER then a t line suggested then im more then willing to go a different route. the reason i want to go t-line was a buddy of mine had a duel 12 t-line box back in highschool like 12 years back with some fosgate p3's i believe, and holly shit i fell in love. havent seen a t-line box since (in person) and just really want to lay one down. i really just want that body rattling low ass bass. so if someone has another suggestion as far as a big as ported box goes, like i said im more then willing to go a different route. the footprint i have to work with in the rear is 45" x 49". 45 front to rear of the car, and 49 from left to right. id really like to have the sub and port facing up as these footprint dimensions are pretty much wall to wall leaving no space for cone excursion ect. as far as height, i dont car if it cuts in to my rear view, i plan on walling the entire rear in the next 6 months or so. id like to take up as much of that footprint as possible tho, but if one dimension needs to be cut, i preffer the 45" cut shorter and i can just make an amp box or something to take the extra few inches up. keep in mind that while i would like to retain sq, i want to feel these bitches as well, and feel them HARD. thanks in advance for any help and suggestions that anyone might have. it REALLY is appreciated

[Triticum Agricolam]

How much power are you going to be running?  A lot of the T-lines you see people using are very oversized (IMHO), which really lowers the mechanical power handling of the subs.  If I know how much power you are running I can give you a better recommendation for t-line specs.  

[SanDiegoSlapper]

a CAB 1600.1 on two 5th gen type r 12's, dual 4ohm coils, wired down to 1ohm

[Triticum Agricolam]

7 hours ago, SanDiegoSlapper said:

a CAB 1600.1 on two 5th gen type r 12's, dual 4ohm coils, wired down to 1ohm

OK, with that amount of power you are going to run excursion issues aren't going to be a huge concern, which makes things easier.  

Here is the deal with T-lines, they do basically the same thing as a ported box, they just do it in a different way.  Just like not all ported boxes sound the same, all t-lines aren't going to perform the same either.  Just because your friend's t-line back in highschool sounded a certain way, doesn't mean if you build one its going sound anything like it.  Doesn't mean it won't either, the point is every box is different and how it sounds depends on the sub being used, the parameters of the box, the vehicle its in, etc.   I'm telling you this just so your expectations are reasonable.  

When it comes to designing a t-line you use a similar mindset to what you would do when designing a ported box.  Making the t-line area larger has the same effect as making a ported box net volume larger, making the t-line longer has the same effect as tuning a ported box lower.  Just like most subs can be used in ported boxes with a range of sizes, you can vary the size of the t-line significantly.  As you make the line area bigger you will get more output around the tuning frequency, but at the expense of power handling, sound quality, and a flat frequency response.  Most t-lines I see for car audio make the line area equal to cone area, which is on the large end of the spectrum.  It will get you a lot of output around tuning but the frequency response usually has a large peak it in, not so good for sound quality.  I can't tell you what will be best for you, you said "while i would like to retain sq, i want to feel these bitches as well" understand that at some point those are competing goals and to improve one you have to sacrifice the other.  

For tuning, low 30's is the generally the place to be, so you are looking of a line length of around 105" for a 32 Hz tuning.  For line area usually 1/2x - 1x of cone area is a reasonable range.  So in your case that 75 - 150 sq inches.  If you wanted to go middle of the road, something like 90 sq in would be a good spot.