View Full Version : Comtemplating Doing Something.

05-11-2009, 02:45 AM
I would love to do this but i don't know how practical it is.....

I would like to put 3 10W7's in my truck, np you say right.....i would like them to be in a t-line. I built a t-line based on quarter wave theory for one for a friend of mine and it is f'ing loud...can get vid to prove......lol

I know i need 190 sq inches of port and want it to be 9.5' length.......my problem is i plan on cutting the back wall in the truck anyway but how could i lay it out so that i have enough room to mount all three without having cancellation.

I basically would want to mount the subs inside the truck have the port go into the bed and then come back into the truck if that makes sense.

im working on drawing it up......if it sounded as good as the one i did for my buddy and was 3-4 solid DB louder i would be more then happy.


05-11-2009, 08:12 AM
Just mount the 3 one after another in the start of the line and do whatever folds you need to make the open end come out where you need, even 3 in a line will acoustically appear as one as far as the line is concerned up to at least 80hz or so where you'll be running into the natural TL peaks and dips anyway.

While I haven't personally used 3 drivers in a single line I have done dozens with a pair in quite short TL's for various vehicles with no issues.

Edit, just gave it a quick model with my mathcad script and your proposed dimentions look pretty much spot on, should be most impressive.

05-11-2009, 08:59 AM
You won't need that much line area and you could easily get away with about 100-120in^2 of line area.

05-11-2009, 09:29 AM
volenti....i was thinking that would work, especially if i put in a baffle that dropped even with the bottom of the basket between each one...

Immacomputer....The stuff that i have read(not a lot) seems to say that you need the port area to be the same as the cone area you are using. I would be more then happy to read some other info on this if you could help provide it for me. I haven't had much luck finding info on this kind of design, or horns for that matter.


05-11-2009, 12:48 PM
I've used between 0.5x SD and 2.5x SD (in non-tapered) successfully for car based TL's, with 0.5x SD being the lower limit for a usefull TL.

Once you start modeling and making these things on a regular basis you find you can pretty much ignore the old TL rules of thumb and design the TL's (using line area, driver position, positive and negative tapers) to suit many different applications, indeed I rarely make normal ported enclosures anymore since I can tailor TL's to the same job (only better IMO).

The line area that Immacomputer suggested will also work pretty well, and is slightly smoother around 80hz, though it scarifices a DB or 2 at the very bottom end (25hz-35hz) in the process.

Reading material; http://www.t-linespeakers.org/ and http://www.diyaudio.com/wiki/ should keep you busy for a while :)

05-12-2009, 04:02 AM
thanks for the links......i have actually built several of these things based just off traditional rules be neat to mess with more...

thanks again


05-13-2009, 09:27 AM
For in-depth information on 1/4 wave theory, www.quarter-wave.com is the place to go.

Martin King's mathcad modeling is pretty awesome. I have been able to simulate my t-line in my car and get a very similar response by using the car's interior as part of the line.

05-13-2009, 10:24 AM
I built a t-line based on quarter wave theory for one for a friend of mine and it is f'ing loud...can get vid to prove......lol

I know i need 190 sq inches of port and want it to be 9.5' length

I would LOVE to see vids! :naughty:

What freq did you base this box and your friends t-line off of?