TLine for 15" lvl 2.

[95Honda 486]

Normal ported enclosures are less than 5% efficient. t/l and horn loaded enclosures can be upwards of 75% efficient. The free air response is 8-12 db louder than a ported enclosure.

This is the most ridiculous thing I have ever heard. If this was actually measured this way, whomever measured it had no idea what they were doing, did not understand average efficiency, or they had one (or more) driver(s) that were severly miss-aligned.

[Quentin Jarrell 671]

That is fantastic that you have all that knowledge on t/l enclosures. Instead of just saying my facts and figures are wrong use your extensive knowlege to add some helpful information Duke can use to build his enclosure.

[Tyan 1]

so....95Honda ... do u have a simple short recipe for a T-line in a car ...? ... or is it ...just dont do it

[95Honda 486]

so....95Honda ... do u have a simple short recipe for a T-line in a car ...? ... or is it ...just dont do it

You don't need anything special for the car. A 1/4 wave t-line is the same for either home or car. The only difference is you may not need such a long line (low cut-off) in the car due to cabin gain. A 6' line will do fine in a car, reach well into the low 30Hz range. I have built a few for car audio, none over 6' long.

There are a few things you need to understand about 1/4 wave t-lines:

They won't be any more (average) efficient than a 4th order vented alignment, the only efficiency gain will be way on the bottom end... They are usually less efficient than a 4th order vented above the F3 of the vented alignment.

T-lines are large. If you build a 6' line for a single 15" woofer, the line itself will displace around 6.5 ft3. This doesn't account for any wood, unused cabinet space, etc. This no matter what shape you make the line.....

T-lines are not peaky if built correctly and are one of the last alignments that would be practical (especially given the size) for SPL. T-lines are intended to be non-resonant, as opposed to a vented alignment. They are supposed to have a flat response. They will have a flat response if built correctly.

They should be stuffed. With something other than Dacron. Dacron works, but I don't find it works as good as acousta stuff. If you don't stuff the line, it will not be well dampened and will need to be much longer. Like a few feet longer for the same cut-off. A majority of the line is stuffed. It is not stuffed for the same reason a sealed or vented box is. It is stuffed primarily to increace the effective length of the line by slowing down the speed of sound inside the line.

T-lines should be tuned. This is done by generating an impedance plot and adjusting stuffing to get a flat impedance curve. This is easy in a sonotube. It isn't in a box. On all my t-lines I would leave one side of the cabinet only attached with biscuits, no glue. So I could take it off, adjust stuffing, and put it back (smacking it with a rubber mallet to get it to fit snug) and measure impedance. When I got what I figured was a decent curve, I put it on one last time with glue and clamped it in place. This worked well for me.

So, for a short answer.... Build a 5-6' line that starts out around or a little more than the Sd of the driver, taper the line to terminate at Sd, stuff it with acousta stuff and measure it for impedance if you can. If you can't measure, just use some of the stuffing density reccomondations from Martin King, even Mahogany sound (makers of acousta stuff) have guidlines, but I haven't seen them for years.

If you want something that is peaky and loud and not so big, don't build a 1/4 wave T-line, build somehing else. If you are looking for high efficiency, complicated designs, check out Decware or something like that....

[SPLChris 0]

Damn, alls tgus searhing for TL's and I learned more from this post than anything. This needs a sticky. Thanks to Chimay grand reserve(s0) I's soo drunk rigt now too.,

[///M5 2,833]

I do have one question since I came to this party a bit late to get in on the letting the OP know he built a ported box. Where did the rumor that TL enclosures are great for SPL come from? There seem to be a hell of a lot of people completely misinformed about their whole behavior all over the car audio websites.

Just wait a few months, the same crap will pop up again as another misconstrued reality gets plopped into the world of car audio.

Oh, and ROFL for arguing with 95 on this.

[aznboi3644 2]

75% efficient...lol.