T-line Box Design Help

[SojiaRaggs9000]

SO... .Since no one in the t-line thred will answer me I decided to make my own thread.. maybe Ill get some responces lol... Im trying to make up a t-line design for a 12" DC lvl4 xl. Port forward sub forward .. that way i can seal it from the trunk and all the pressue will come into the cab.I got the specs from here:

http://www.dcsoundlab.com/specs.html

12"

Mounting Depth

7"

Mounting Hole Diameter

11"

Motor Width

8.75"

Weight

54lbs

VC Diameter

3" Flat 8 layer

Magnet Weight

50lbs

Power Handling RMS/Peak

1500/3000

Impedance

D 1 or 2ohm

Sd

494.00 cm²

Fs

38.90Hz

Qms

6.51

Qes

.31

Qts

.29

Xmax

26mm

Sensitivity

90.73

Suggested Sealed

N/A

Suggested Ported

1.75³-2.75³ ft

Using math on the first page then I should have something like this:

( 1130 / freq ) / ¼ = ¼ wave length and ( Cone Area / 2 ) = ( X )² x 3.14 = X in²

SO....

( 1130 / 38.9 ) / ¼ = 7.26ft and ( 11 / 2 ) = (5.5)² x 3.14 = 90in²

This is were i start getting confused.... I need to keep a constant 109in² ... So... if I want my box to be 16in tall externally. Then height inside would be 14.5in (using ¾ MDF). Which means the width of the port can be 6.21875in wide. 14.5 x 6.21875 = 90.171875in²

The tunnel would be 14 1/2in x 6 7/32ln x 7 1/4ft long??

Im trying to stay within measurable fractions. Figured it wouldn't hurt since we rounded down in the first place. Good enough?? Is my math correct??? Please lmk if it isn't and or what to correct. Also the (freq) is the Fs or does it need to be the desired tuning? Like if i wanted my box tuned @ 32 I need to use 32 in the equation?

If I made a T-line for a single 12" DC lvl4 XL using 3/4 mdf. Th box dimensions of L: 36 3/4in W: 24 3/4in H: 16in and the tunnel measuring 14 1/2in x 6 7/32ln x 7 1/4ft long. Taking that into accoul the guts of the box would loong along the lines of this:

Could someone check my math or w/e and lmk if Im on the right track? Thanks in advance.

-Kurk

Edited April 14, 2009 by SojiaRaggs9000

[BigPimpin91]

Everything looks good.

Unless you are limited on your box size, I would tune closer to 30hz personally.

[brsteinbach]

Everything looks good.

Unless you are limited on your box size, I would tune closer to 30hz personally.

X2 But I also love the lows.

[SojiaRaggs9000]

kk, so the (freg) is for the tuning? ... sweet i need to adjust it cuz I though 38.9 was to high just wasn't sure.

[Neo_frog]

kk, so the (freg) is for the tuning? ... sweet i need to adjust it cuz I though 38.9 was to high just wasn't sure.

You really shouldn't tune below Fs of a sub in a t-line. Tuning at the Fs is the best possible t-line enclosure you can build for the sub. The Qts is .29 so even at that tuning you will be hitting the low lows with ease.

I would stick with the original plan and tune to 38.9. Assuming it's done right, you might be getting a pretty flat response from 20-ish hZ to box tuning. Cabin resonance plays a role in this too, so be aware.

Looking at your measurements, it seems a little small, but the math says it's ok. And tuning lower will yield a much longer port (10+ft). I don't know how much space you have to work with, however.

If it's done right and you maintain the port area (try to round it if possible), you'll have a very loud, very low, very clean sound.

Edited April 14, 2009 by Neo_frog

[SojiaRaggs9000]

ok Neo, I guess u just confused me lol... 38.9 is the subs Fs I built the plans based on it. First you said I should stay with that. Then you suggest tuning it lower... I d like to have it around 32ish... would that perform well? Or would I be better off with something lower or just staying with the fs?

[Neo_frog]

Sorry if that was confusing. I was saying to tune to the sub's Fs.

I was just mentioning that the port would be significantly larger for a 30hZ tune.

[SojiaRaggs9000]

Sorry if that was confusing. I was saying to tune to the sub's Fs.

I was just mentioning that the port would be significantly larger for a 30hZ tune.

ahh ok, just excuse my noob ness.. ive only built one sub box before... but i didnt make the plans for it. Speaking of whick if i figured out all the math etc would someone be willin to auto it up for me??

[Neo_frog]

ahh ok, just excuse my noob ness.. ive only built one sub box before... but i didnt make the plans for it. Speaking of whick if i figured out all the math etc would someone be willin to auto it up for me??

It would be really tricky. We mainly use Sketch-Up for boxes. I haven't seen many use cad.

If you haven't had much experience with boxes (let alone t-lines) this might be a very difficult task. Almost a trial and error going through a LOT of wood.

Where are you located?

EDIT: n/m not near me

Edited April 14, 2009 by Neo_frog

[FYI-Future-Star]

i have an old ED 9kv.2 laying arround i wanna play with a tline

the fs on the 9kv is 23 so it would be

(1130/23)/4 =12.283ft (7/2)= 3.5x3.5x3.14= 38.465sqin

sorry to jump in ur thread bro

just crunchin numbers now