T-Line help and pointers

[hardrock2401 8]

I have been reading on t-line boxes for a good 2-3 hours now and am just not understanding the design part 100%. Only one that I have read and felt like I somewhat understood was the "u-shape" style design. I have always done slot ported boxes and was always happy. I think it is time for me to learn a little more about boxes.

So far, this is what I have grasped

Say I wanted a box tuned to 34hz. I would take 1130 (the speed of sound,) divide that by 34. Which would lead me to 32.25ft (rounded a tad). I would multiply that by .25 because I am looking for the 1/4 wave length. I would need a port 8.0625ft long. And SD equals port area? Also I am aware this is not a full t-line, hence why I am asking about 1/4.

If any one could point me in the right direction or let me know if I am even on the right track would be great.

The box I will be designing is for a single 10 nightshade v1

[95Honda 486]

A T-line doesn't have a port, and is not a port, in fact it is completely non-resonant when executed correctly.

 

A T-line doesn't have tuning.  It has a cut-off frequency.  Tuning refers to resonance, and again, a properly executed T-line is non resonant.

 

A T-line will not have the efficiency of a 4th order vented box under any circumstances, this is do to the non-resonant nature of a T-line.  It's efficiency will be between a 2nd order sealed enclosure and a 4th order vented enclosure, with most of it's efficiency being in the bottom octave.

 

The line is roughly the Sd of the driver.  There are certain ratios that will effect overall performance.

 

A T-line that will reach down to at least 30Hz will be bigger than pretty much any 4th order vented box for the same driver(s).

 

A T-line can be any shape. 

 

If there is any appreciable cabinet volume before the line, it isn't a T-line, and won't behave as one, no matter what anyone says.

 

So, maybe this will clear a few things up for you...

[hardrock2401 8]

I never said anything about it having a port, am only trying to learn how to design one and learn how they work....nor am I comparing them to any other kind of enclosure, simply want to understand them. I know there is no way to have a true t line in a car due to size.

[Quentin Jarrell 671]

http://quarter-wave.com/

[95Honda 486]

Nobody said you can't have a T-line in a car.  I have built several for car audio.  Just don't expect to be putting a pair of 15's or an 18 in one without a huge enclosure. 

 

Your 10" driver may work in one, you just need to understand what you are going to end up with.  Pretty much all "car audio" T-line enclosures aren't really T-lines, or they are severely miss-aligned...  When people realize that the output will be marginally better at best than a sealed alignment, the reality sets in to what they are going to end up with.  Also, I am not sure about the T/S parameters of your 10" driver, but it if has a fairly low Qts, it won't work well in a T-line due to it's self-dampening low end behavior.  But like I said, I have no idea about that 10" driver...

 

It is just important that you understand what goes into them, that is all.

[hardrock2401 8]

Why do so many people use them if they are only marginally better then a standard sealed box? Seams like a lot of hassle for something that can be had with a simple sealed box. I am not questioning your knowledge only trying to learn for myself.

[95Honda 486]

It's not my knowledge, it is facts based on objective design since the 1940's dealing with this type of enclosure.

 

Like I said before, pretty much all "car audio" T-lines aren't T-lines at all...  And most "designers" aren't building T-lines, they are building something else...

 

You need to pick up a copy of the Loudspeaker Design cookbook by Vance Dickson and get ahold of Martin King's T-line white papers before you listen to any car audio "experts" about T-lines as most of them are full of BS... 

[Impious 1,476]

Why do so many people use them if they are only marginally better then a standard sealed box? Seams like a lot of hassle for something that can be had with a simple sealed box. I am not questioning your knowledge only trying to learn for myself.

Monkey-See Monkey-Do

[///M5 2,833]

Why do so many people use them if they are only marginally better then a standard sealed box? Seams like a lot of hassle for something that can be had with a simple sealed box. I am not questioning your knowledge only trying to learn for myself.

If an idiot does something dumb, do you want to copy them?  Not sure how the herd mentality follows suit with tweedle-de, but it seems to happen.  Just look at all the misapplied 4th order BP boxes.  Similar mentality.