Considering T-Line bandpass, need input!

[white4d96]

I am considering buying a pair of Alpine R-12's and am trying to think of enclosure ideas. I have plenty of room to play around with I think...enclosure will go in trunk of 1996 Pontiac Grand Prix, dimensions tomorrow hopefully. I was playing with the idea of a 4th-order or a T-line bandpass just to try it, with the port firing up through some slots stamped into the package tray. I saw a enclosure build somewhere on here with a T-line BP for a dd1508, which is where I got the idea.

Questions are:

-What information do I need about the drivers/vehicle/etc. to design a bandpass?

-What formulas or calculations will I need to do?

-Should I use a different port arrangement? I don't have the carpet cover for the package tray due to some stupid install work on my part before (hacked it up for some by-nine boxes) so that isn't an issue. However, the package tray flexing kinda is. Leading into my next question...

-Regardless of what enclosure I use, can I brace the package tray to the top of it?

-Finally, what would YOU do with this trunk and these drivers?

I forgot to mention the subs I am looking at are dual 2's and will be seeing power from a Power Acoustik OV1-2000d *gag* amp.

Thanks in advance for your time and input,

-Austin

[white4d96]

Bump diddly bump bump

[white4d96]

Additional questions:

-What do I use to calculate the port length and sealed volume I need?

-Is there another enclosure I could build to get a flat(ter) frequency response? My ported box tuned to 33Hz was like the worst of both worlds, nothing below 32Hz or above 55Hz. I would like to at least get up to 80-100Hz semi-flat, and if I could get a little higher that would be great (I have low-pass set at 120 on both HU and amp now).

Thanks in advance

-Austin

[will77530]

i just come up with an idea i like for the design of the box sketch it in auto cad and then use win isd for the port length and tuning

[zfrerichs]

you should try to contact foreverbumpin about a bandpass tline desgin

[Forevrbumpn]

2-12s ain't gonna happen in any conventional quarter wave box

1-12" in a high Q tline design, something a little better for higher tuned SPL, or a ISO design for a lower Q, more of a SQ design, flatter sound, lower tuning

The best thing is to design the subs to be in a sealed box, use a program like WINISD or Bass box to find the box Q- peak freq, and work on a quarter wave from there

a single 12" will peak somewhere around 45-60hz, when a ISO design sealed box will peak around 35-45hz more than likely

Now these boxes will play a lot lower in a tline bandpass, mainly due to the transfer function of the car

Sometimes you can just get a box and practice with with some simple built tunnel, start long, say 8ft long, and cut to length until you get the best results

sounds complicated, but these boxes you can get excellent sound, and output

[white4d96]

I'm definitely looking more for lower and cleaner than I am for louder. By an ISO design do you mean an isobaric setup?

I don't know if this is readable at all but I will elaborate as best I can. The top plan was like the one I saw for a single eight. I basically just drew up two side by side and ran with that. The bottom sketch ditches the amp racks on the sides of the enclosure for more port length. There's some random blurbs on there as well as far as materials needed and such that can be disregarded.

The only TS parameter I could recall while in class was an Fs of 28hz which is scribbled on there.

The <20hz-~100hz is desired frequency response.

Any more questions let me know.

[white4d96]

Did some quick scribbling and following along on the 1/4-wave tutorial and got a length of 10ft and area of about 226 sq in for the port. Probably not gonna work. Shoulda listened to ya guys =/

Maybe I could try building a 4th-order bandpass? What do I need to know to design one of those?