Quarter Wave / T-Line tutorial-UPDATED

[TDEaton1021]

edit: sorry i wrote the wrong thing. it was 6.6 cuft. the length was 10.86. so i could reduce the length to 5.43 with polyfil and still get the 26 hz tune. that seems like so much, 50%.  doesnt polyfill in a sealed enclosure only give you maximum of 25%?

this was from the bottom of page 9

[Guest MegaloManiac]

this thread is great.

but i do have a question. how does T-Line compare to a 4th order bp....as far as output & SQ goes?

i have a design of a 4th order if u need to see it let me know i'll pm you(whoever) it.

[LSN2meBoom916]

From my exp-

The T line will have better sound Q and be as loud or louder.

In a BP you still gotta run a decent amount of power to the subs and get them moving pretty good to get loud and you run the risk of over driving them and not hearing them come apart inside the box cuz the distorion is more muffled. In a  T line the sub doesn't need to move as much since (it's optional I know) the box is often tuned to the subs natural Fs/resonance so it'll get loud w/ out moving that much and take some pressure/load off the woofer cone, require less power=less heat, less chance of clipped signal etc.

I'm sure Foreverbmpn will have more along those lines he knows it more in depth but that's my take on the comparison. 

[Forevrbumpn]

damn, I havent looked here in a few days. Well, in a Line, or standard box, there are 2 ways, the 1lb per cubic ft (which still may be a tad much) or just LINE the walls with 1"- 2" of material. You can line the walls of a line with 2" and hear a pretty good change, not huge, but will be noticeable. Basically get a line at 40hz, and if you line it with 2" (depending on line area) and see a drop to 38-35hz or fill it up, and see it drop even more ( doubt 50% I never had to go that much stuffing- that is hear say, and guesstimate-more closer to 25%). Again, I havent done much testing with fill' maybe 5 lines all together- you drop SPL.

As far as measuring the lines, use that first reference on page 1, and measure the length of the marked lines, that works pretty damn accurate.

As far as bandpass Vs Tline/quarter wave

Look at port size baby!  Basically, More port area, more air displaced, more spl. If you are interested in Tline, and/or 4th order, trying doing a simple 40hz tline bandpass. Dont look at the 40hz part, depending on the woofer, and the sealed side, it will play lower, louder

I honestly think a standard bandpass can be murder on a sub. to much restriction, and all that sound expected to shoot out from what, some 4" ports, or a 6" port? how about a 80sq" port?

[LSN2meBoom916]

I think megalo's Q was more along the line of 1st:which will have better SOUND Q? and 2nd: will the spl be close or better one way than the other?

From my understanding he's doing an SQ or SQL setup w/ the emphasis on SQ.

He should correct me if i'm wrong in my assumption.

That said I think what forevrbumpn said reinforces my idea that a T line will have better SQ and still get as loud or louder.

The part in the 1st section (page 1 or 2) about the sub being able to "start and stop on a dime" i.e. better transient response was what got me interested in this setup to begin with.

That to me sounds the the ideal for an SQL setup. Good/quick transients and decent-to-high output.

[Forevrbumpn]

in that case, it would depend on the woofer. a very low Q woofer in a tline would sound better IMO than a standard bandpass. A Low Q woofer in a quarter wave bandpass will be a very tight sound, depending how you design it, and probably see a little higher numbers, and have a wider freq response. I personally  again favor the tline over bandpass. BP will be pretty narrow banded, and peaky

[Forevrbumpn]

Well, my other thread on my box for the show isnt that popular, so I decided to show the new pics of my box here, in the popular thread. If you dont know, this is a dual 15" Iso Band Pass Tline. 2- 15"s one in front of the other. The only advantage of this is, that it peaks at tunning, and cancels out the other freqs below, and above. So basically, it IS a one note wonder, but sounds pretty damn nice. Iam running the 2- 15"s at 3ohms mono on a PA A3000DB Basically, sealed side in front of the line- 2cf, then the line tuned at 34hz- Boost at 35hz, and 1500rms atleast, may wire it down. But anyways, heres the pics.

[Forevrbumpn]

[ChevyBoy]

damn thats a huge box. looks awesome man.

[Forevrbumpn]