Transmission line cross-sectional area question - diyAudio
 Transmission line cross-sectional area question
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diyAudio Member

Join Date: Apr 2008
Location: North of Sweden
Transmission line cross-sectional area question

I'm planning to build a Classic TL out of standard sewer pipes.

The sketch shows how I intend to construct it.
My question is if this is possible considering the physics of a TL, I mean the cross-sectional area of, especially, section 2 is quite funny. Will MJK's mathcad sheets give me a relevant simulation?

Something tells me that a cross-sectional area like this will be problematic but
thats just a feeling...

Regards H@kan
Attached Images
 classic-tl-pipes-dim.jpg (221.6 KB, 139 views)

 25th October 2009, 08:48 PM #2 frugal-phile(tm) diyAudio Moderator     Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5 There should be no reason that can't be modeled. With a driver suitable sized for that pipe, it is going to be too long i'd guess. dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA
 25th October 2009, 09:50 PM #3 diyAudio Member     Join Date: Apr 2008 Location: North of Sweden The sketch is just for illustrating purpose. I think I will use a ~3" FR driver, perhaps Alpair 6, and tune the line to ~65-70 Hz so the total hight of the cabinet will end up around half a meter. Yes I can model it with MJK's sheets but I was uncertain if the geometry of the cross-sectional area is restricted to certain conventional geometries. Suppose that you have a A*B cross-sectional area. Wouldn't there be a break-point, when one of the sides become significant greater than the other, when the model no longer gives you a relevant output? In my case (in section 2) the "A*B" ratio is ~1:12 Regards H@kan
diyAudio Member

Join Date: Apr 2007
Quote:
 when the model no longer gives you a relevant output?
Give it a relevant input! I would start with a speaker of 100 cm2.
Also , an oven might be useful when playing with PVC...I mean if you don't want to add the extra baffle!

 26th October 2009, 07:34 AM #5 diyAudio Member     Join Date: Feb 2008 Location: Sheffield Brilliant idea. It would be pretty neat to build it out of clear plastic, so everyone can see the "magic" that goes on inside. Chris __________________ My work: www.grimshawaudio.com
frugal-phile(tm)
diyAudio Moderator

Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
The necessary damping would quickly ruin any see-thruness.
Attached Images
 CylindricalTL_inside.gif (21.1 KB, 84 views)
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA

diyAudio Member

Join Date: Apr 2008
Location: North of Sweden
Quote:
 Originally Posted by chris661 Brilliant idea. It would be pretty neat to build it out of clear plastic, so everyone can see the "magic" that goes on inside. Chris
Yea that would have been nice but besides that you probably would just see damping material, as Dave pointed out, the main idea was to use standard sewer pipes and I have never seen any transparent ones. I can see why considering the conventional usage of sewer pipes

One can of course, if using clear plastic, use some "fancy" damping material

Regards H@kan

frugal-phile(tm)
diyAudio Moderator

Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Organizing the tubes like this is easier to build small cylindersealed at the top. big one on the bottom. Not to scale.

dave
Attached Images
 CylindricalTL.gif (62.9 KB, 75 views)
Attached Files
 AssymetricalCylindricalTL.zip (36.4 KB, 9 views)
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA

 26th October 2009, 10:18 AM #9 diyAudio Member     Join Date: Apr 2007 Those fuzzy legs made you brilliant!
 26th October 2009, 10:24 AM #10 diyAudio Member     Join Date: Sep 2004 Hey Dave, Wasn't there a dead hot water tank around your place we could get creative with? Cheers!

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