about transmission line

[bigcatdairy]

hey everybody!

i have some questions about design and making transmission

line loudspeaker,i hope that i can get help here.

1 how to determine the length of the pipe(better explain with a

figure,because i am stupid

2 how to choose the loudspeaker?can i use a full range car

audio loudspeaker to do?

3 what's Q number?what's Qms,Qts n' Qes n' what's the

difference between them?what do they characterize?

4 i used some software to calculate the length of pipe,just

need to input Fo value n' Q value ,Q value here should be which

one?and the result of calculation was without volume of the box.

does it mean the volume doesn't effect to the final effect?

5 can i design a transmission line as a subwoofer?

[kneadle]

Hi welcome to TL design.

Here are some resources for ya:

www.t-linespeakers.org
www.quarter-wave.com

Start your journey there. Much happiness is down that path.

Dave

[Jimmy154]

Originally posted by kneadle
Start your journey there. Much happiness is down that path.

Or much frustration, followed by the realization that designing a good TL speaker is much more complicated than you ever imagined.

Originally posted by bigcatdairy
hey everybody!

i have some questions about design and making transmission

line loudspeaker,i hope that i can get help here.

1 how to determine the length of the pipe(better explain with a

figure,because i am stupid

2 how to choose the loudspeaker?can i use a full range car

audio loudspeaker to do?

3 what's Q number?what's Qms,Qts n' Qes n' what's the

difference between them?what do they characterize?

4 i used some software to calculate the length of pipe,just

need to input Fo value n' Q value ,Q value here should be which

one?and the result of calculation was without volume of the box.

does it mean the volume doesn't effect to the final effect?

5 can i design a transmission line as a subwoofer?

1. Line length is usually 1/4th wavelength of fs in free air, but is shorter usually because of stuffing.

2. You have to model speakers and/or use general rules for choosing good TL woofer.

3. Qms is mechanical losses, Qes is electrical losses, Qts is total losses 1/(1/Qms+1/Qts).

4. Don't know.

5. Yes, if I understand you question correctly.

[bigcatdairy]

THANKS GUYS!

I'LL TRY ANYWAY~BECAUSE I LOVE BASS!

AH~CAN U SUPPOSE SOME SOFTWARE FOR ME.

AND CAN ANYONE TELL ME SOMETHING ABOUT TL LOUDSPEAKER?

IN GENERAL ARE THE FACTORS OFFERED BY THE MANUFACTURER

RELIABLE?SOME BODIES TOLD ME THAT WE JUST NEED 2 USE

65% OF CALCULATION IS IT CORRECT?

HOW 2 CALCULATE THE AREA OF OPENING?

THANKS AGAIN~

[Jimmy154]

Originally posted by bigcatdairy
AH~CAN U SUPPOSE SOME SOFTWARE FOR ME.

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.

Originally posted by bigcatdairy
AND CAN ANYONE TELL ME SOMETHING ABOUT TL LOUDSPEAKER?

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.

Originally posted by bigcatdairy
IN GENERAL ARE THE FACTORS OFFERED BY THE MANUFACTURER

RELIABLE?SOME BODIES TOLD ME THAT WE JUST NEED 2 USE

65% OF CALCULATION IS IT CORRECT?

"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.

Originally posted by bigcatdairy
HOW 2 CALCULATE THE AREA OF OPENING?

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?

[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.

[planet10]

Originally posted by Jimmy154
1. Line length is usually 1/4th wavelength of fs in free air, but is shorter usually because of stuffing.

It is a 1/4 wl (less end correction in a straight pipe, shorter in a taper pipe (closed end bigger than terminus end), longer in a flared pipe (losed end smaller than terminus end). The stuffing has little or no effect on length.

2. You have to model speakers and/or use general rules for choosing good TL woofer.

The gerneral rules (classic line) don't work all that well.

dave

[Jimmy154]

Originally posted by planet10
It is a 1/4 wl (less end correction in a straight pipe, shorter in a taper pipe (closed end bigger than terminus end), longer in a flared pipe (losed end smaller than terminus end). The stuffing has little or no effect on length.

I remember reading a few days ago that you had to adjust line length after you add sfuffing in one of these PDF's http://www.quarter-wave.com/Project01/Project01.html

Maybe it's not a lot though?

Originally posted by planet10
The gerneral rules (classic line) don't work all that well.

I guess you have to model a woofer then.

[MJK]

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.

I have used all of the recent MathCad releases to develop and run my worksheets. I am now using release 12. What specifically were the symptoms when you tried to run the worksheets using MathCad 11 or 12?

MathCad 2000 is without question the most stable release I have worked with and I go back as far as version 4. I am surprised you had problems with MathCad 11 since it was almost as stable as 2000. MathCad 12 would not run the worksheets right out of the box because of MathSoft screw ups, they released a patch very quickly to correct programming problems so now it runs the worksheets OK (just barely OK in my opinion). MathCad 12 is very S L O O O O W.

But MathCad 12 is still prone to crashing and I have been very unhappy with this release. MathSoft got a very blunt e-mail from me questioning if they even did any beta testing before pushing version 12 out to the users. I am not sure what I am going to do about version 13 (lucky or unlucky?). Many other engineers have also expressed their dissatisfaction with version 12, my former employer would not buy the upgrade.

If you tell me what happens with 11 and 12 (aftre loading the 12.1 patch) I might have a few suggestions for fixing the problem.

[Jimmy154]

Originally posted by MJK
If you tell me what happens with 11 and 12 (aftre loading the 12.1 patch) I might have a few suggestions for fixing the problem.

The graphs did not show up in 11b and 12. So I got 2000 and they show up. I no longer have 11b and 12 on my pc.

Your Focal 8V 4412 mid-bass driver does not seem to model very well as a TL. 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?

I'm asking cause I have an Eton 8-800 with similar specs that models the same as the focal in TL Open End. Maybe I'm bad with that worksheet. Seems to model much better as a ML TQWT. 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.