about transmission line

[MJK]

I have no idea why 11b did not work, I used 11 for a long time without any trouble. If you did not load the patch for 12 that is why things did not work, in general a lot of people had problems with the first release of 12 running all kinds of worksheets.

Does the stuffing placement, driver offset, and/or driver position ratio fix the wavey appearance of the SPL graph (modes is that what you call what causes the waves) in TL Open End.mcd?

Yes, those all help tame the ripple. You will always have some amount of ripple, humps, bumps, and depressions in the plotted SPL responses of TL's and many other enclosures. You need to recognize that most of the box design freeware does not calculate these due the lumped parameter modeling, they are always there. I don't worry too much about 1 or 2 dB wiggles in the SPL curves. When you add baffle step, floor bounce, and other room influences these small wiggles tend to be the least of your problems. Try the "Offset Driver" worksheet to study the impact of moving the driver 0.2 to 0.33 of the way down the TL.

How come folded ML TQWT's, at least all the ones I've seen, have the small ends towards the front of the enclosure? I would like to have the big end towards the front of the enclosure, giving me a slightly more favorable driver position ratio of .56 compared to .4. But they are pretty similar, that's why I ask you if there is a reason folded ML TQWT have the small end towards the front of the cabinet.

Absolutely no reason the bigger section could not be in the front if the desired driver placement fits the geomtry. I have not built a folded ML TQWT, but I see nothing that would be compromised if the layout was as you have described.

[kelticwizard]

After several attempts to use Martin King's worksheets, I finally got to the point where I can use them easily. Well, not as easy as WinISD orSubwoofer Simulator, but neither of those programs do what Martin's worksheets do in calculating resonances.

I have not yet built a Transmission Line-just worked with the worksheets. However, several people on the forum have tested the Transmission Lines built according to Martin J King's software and found good agreement between the calculation and the real result. That's good enough for me.

A couple of hints-remember, I only figured out how to use the software, so if anyone has built one and disagrees with anything I say, please feel free to jump in and correct.

A) Do you have Norton Anti-Virus? If so, you must disable script blocking-just shutting off Norton will not do it. I will include instructions on how to do this.


B) A Transmission Line is a close cousin of the Ported Box, and they have similar bass outputs in most configuration. The stuffing of the Transmission Lines can change things, but Martin J King's software tells you how. So if you want some place to begin, let's plan a Ported Box, see if the response is in the neighborhood, then transfer it over to the Transmission Line. Then we can make changes to the Transmission Line and see the result on Martin J. King's graphs.

C) I'll post various graphs to help you along, and you can make design decisions based on what you see there.

So let's give it a try. We'll plan one together, and the more experienced Transmission Line builders can give us their advice.

So: do you have a specific driver in mind? If so, please tell us what it is and post the Thiele-Small* parameters if possible.

If you do not have a specific driver, can you tell us about how large you want the box to be and what kind of bass output you were hoping for? Remember, the box will be somewhere in the neighborhood of a Ported Box-maybe a little larger to compensate for stuffing.


*Thiele-Small parameters are such things as Qts, Qes, Qms, Vas, Fs, Sd, etc. Don't worry about what they mean right now-we'll get you through it.

[kelticwizard]

Here is a link where instructions are included on downloading free MathCAD demo, (be careful, it can be tricky), and disabling Norton script blocking, if you have Norton. Caution-I made a mistake in this thread on post #18, but I immediately corrected it, so watch for the correction.

The free MathCAD demo plus Martin's free worksheets are all you need to calculate Transmission Line response. Some go ahead and buy the MathCAD program, but the free demo is all you need, and that is what I use. So the whole thing is freeware, if you want it to be.

PS: The free demo does not have a time limit. I downloaded it a couple of years ago and it still works. The only difference between the free demo and the full program are some features that are nice, but not necessary for graphing Transmission Line response.

[bigcatdairy]

Originally posted by Jimmy154


Go to www.quarter-wave.com like Kneadle said. You will find mathcad worksheets. I found them not to work with mathcad 12 and 11 (version 8 or 2000), but maybe my fault in not knowing the MathCAD software. I got MathCAD 2000 and now they work.

Like what? I can tell you that you cannot just pick any driver for a TL, but at the website already mentioned you will find you have severel options for TL enclosures.

"65% of calculation" what does that mean? I would say they are not too reiable. Maybe some companies are reliable or more reiable than others, but I think it's hard information to come by. If you can measure them yourself do it. I'm trying to do it now, but it is not so easy.



Hu? Do you mean taper? It's complex you must go to the websites mentioned and learn things. People will not and/or cannot help you if you do know the basics, that's why Kneadle sent you to those websites. Understand?

can i take a caraudio driver then do it?because i can not find any

good driver for my tl in this city except car audio driver.can u

suppose me any good choice?

65%of calculation means the length of path.i have read that side.

thanks!

Originally posted by RJ
What is you e-mail address?
I'll send you a program for calculating T-Lines.
Here's the formula for a 1/4 wave t-line;

(1128/Fs)/4 = 1/4 wave in feet
Feet x 12 = length in inchs.

An example:
1128/50 fs = 22.56/4 = 5.64 Ft.
5.64 x 12 = 67.68 inches.
That would be the length of your pipe.

T-Line Subs are possible but sound different then closed or sealed subs. Go sealed or horn-loaded. Ported is Ok but it's better if you go Dual-Chambered bass Reflex.

The pic is of my favorite T-Line; A 112" Labyrinth for 5 1/4" drivers.

my e-mail adress is bigcatdairy@hotmail.com what about u?

[viki_v2]

Originally Posted by RJ

What is you e-mail address?
I'll send you a program for calculating T-Lines.
Here's the formula for a 1/4 wave t-line;

(1128/Fs)/4 = 1/4 wave in feet
Feet x 12 = length in inchs.

An example:
1128/50 fs = 22.56/4 = 5.64 Ft.
5.64 x 12 = 67.68 inches.
That would be the length of your pipe.

T-Line Subs are possible but sound different then closed or sealed subs. Go sealed or horn-loaded. Ported is Ok but it's better if you go Dual-Chambered bass Reflex.

The pic is of my favorite T-Line; A 112" Labyrinth for 5 1/4" drivers.

hello, Rj
My email address is viki_v2@yahoo.com Can you mail me program for calculating T-Lines.

Thank You