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View Full Version : Did I design this Tline correctly?

galacticmonkey
12-19-2007, 07:12 PM
I did a quick read on 1/4 wave Tline design, and was wondering if I got it right. Heres a design I did for one of the cheap Elemental Design 12s. It has an F2 of 25hz I was told. So would this work? Throat length of 11.3' and a Throad width of 8"?

http://i16.photobucket.com/albums/b6/galamonkey/Tline.jpg

Immacomputer
12-19-2007, 08:20 PM
If you just did the 1/4 wave of 25hz and made that the line length and the line area the Sd of the driver then no, you did not design it correctly.

galacticmonkey
12-20-2007, 04:46 AM
Well what is wrong about that? And how would I go about designing it correctly?

Death By Bass
12-20-2007, 04:51 AM
it would work, but that box is huge! :p

Immacomputer
12-20-2007, 02:16 PM
Well what is wrong about that? And how would I go about designing it correctly?

http://www.quarter-wave.com/

goodstuff
12-20-2007, 03:35 PM
http://www.quarter-wave.com/

Wow. I wish I was better at math.

Volenti
12-21-2007, 09:33 AM
It depends on what you want it to do, just eyeballing the enclosure it'll "work" as in it'll make bass, probably more suited to HT use in a room than for in a car (it may sound a little bloated in car and lack upper bass punch) , for car use I'd shorten it up some, look at 7'-8' line length with that same line area or even a little larger, 1.2-1.3x driver SD, that'll give you a little more gain.

TL's are dramatically effected by loading in a car so you can get away with a shorter line length than the calcs/theory would suggest.

Immacomputer
12-21-2007, 10:59 AM
And, the line length is not based on the driver's free air resonance but rather its point of resonance in a sealed enclosure of the same size. That will almost be higher than free-air and will never be lower.

Megalomaniac
12-21-2007, 11:00 AM
If you just did the 1/4 wave of 25hz and made that the line length and the line area the Sd of the driver then no, you did not design it correctly.

I am going to take a wild guess and say he saw the overgeneralized- tutorial on meades site.

twisztdauthorit
12-21-2007, 11:02 AM
I'snt the throat supposed to be taperd down ? Or it this only on some designs to cancel out standing waves?

I created a t-line for one of my 10's (fs 25 or 28) i believe. Anyways it hits a hell lot lower then the prefab it came in... definitely a different sound.

BrianChia
12-21-2007, 01:30 PM
http://www.quarter-wave.com/

Volenti
12-21-2007, 11:07 PM
I'snt the throat supposed to be taperd down ? Or it this only on some designs to cancel out standing waves?

.

You can taper it down, that can help smooth the response and decrease the length of the line you need, but at cost of output, an untapered line will have a higher output, you see all this when you start to use Martin Kings Mathcad software and model different designs.

For the most part standing waves aren't a big issue for bass TL's, especially car ones, most of our output happens below 100hz or so, the standing wave ripples are above that so with a decent low pass filter you won't hear them.

80INCHES
12-21-2007, 11:38 PM
If you just did the 1/4 wave of 25hz and made that the line length and the line area the Sd of the driver then no, you did not design it correctly.

i agree and to add..its not taperd
but it looks like a killer ported box though:D
80

galacticmonkey
12-22-2007, 12:25 PM
Oh, well I designed this to be used as a box for my room, with about 75-100rms. Just as something to test out and mess around with. Anyone know of any good designs that work well for HT? I say HT, but it will only see music if built.

ballstothewall
12-22-2007, 03:49 PM
The cross sectional area needs to be 1.5 to 2 times the Sd

Immacomputer
12-23-2007, 02:16 PM
The cross sectional area needs to be 1.5 to 2 times the Sd

That's not true at all and sometimes, you need a line area lower than the Sd of the driver. I'm about to build a T-line for a 12" sub using only about 50% of Sd for the area of the line. It's also tuned about 6hz above the Fs of the driver.