1. ## t-line enclosure help.

Ok guys I am getting a ia flatlyne 15 from spooney. I would like to know anything and everything u guys know about t-line enclosures. The ins outs and all around. What kind of math might be involved. Would this sub do good in a tline. I have built many enclosures so I will be building it my self and would like to have you guys help thru the build.

2. ## Re: t-line enclosure help.

T-lines are rather complex in design, and can be difficult to construct if you're not too familiar with enclosure construction. Are you just trying to learn, or are you planning on creating your own?

3. ## Re: t-line enclosure help.

Both. I want to learn as much as possible and eventually build my own.

4. ## Re: t-line enclosure help.

Quarter wave transmission lines are the easiest boxes on the planet to calculate but the hardest to design, from a space perspective. As for the question "will this sub do well in a t-line"... the answer is always yes. It's the best box for any sub hands down, period, end of discussion.

All you need to know in order to calculate a t-line is the driver's Fs and it's Sd. Fs determines line length and Sd determines line area.Calculations are as follows:

Let's say your flatline has an Fs of 33 Hz and the Sd is 143in².

For line length: Speed of sound / Fs / 4 = Ll or, 1130 / 33 / 4 = 8.56'
For line area (in case you're not aware): Sd is measured from about the center of the surround (or just slightly toward the center of the piston) on one side to the same location on the other side of the driver. That's the usable piston area or, the part of the piston that actually moves air. So, once you have that measurement it's Pi x R², just like you'd measure Sd of a round port.

Once you have those calculations, the fun part is getting that 8-9 foot long tunnel snaked around itself enough to fit in a vehicle. :-)

Another important factor is keeping the line area as consistent as possible in turns. 45° wave guides work plenty good enough but in a perfect world, you'd make rounded wave guides so that line length never changes.

Here are a few lines I've built:

JBL GTO 10 in ¼ Wave T-Line

Audio Anarchy T-Line Demo Truck.... an Impromptu Video

The second thread isn't a build log but I will make one when the project is finished. However, here is a progress pic of that line:

Also, here are some valuable resources on ¼ wave transmission lines:
Quarter Wavelength Loudspeaker Design
Quarter Wave / T-Line tutorial-UPDATED - Subwoofers / Enclosures - SMD Forum

Let me know if you have any other questions. I love to talk about these things. :-)