Transmission line cross-sectional area question

h@kan · 25th October 2009, 09:26 PM

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

planet10 · 25th October 2009, 09:48 PM

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

h@kan · 25th October 2009, 10:50 PM

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

picowallspeaker · 25th October 2009, 11:02 PM

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!

chris661 · 26th October 2009, 08:34 AM

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

planet10 · 26th October 2009, 10:19 AM

The necessary damping would quickly ruin any see-thruness.

h@kan · 26th October 2009, 10:44 AM

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

planet10 · 26th October 2009, 11:03 AM

Organizing the tubes like this is easier to build small cylindersealed at the top. big one on the bottom. Not to scale.

dave

picowallspeaker · 26th October 2009, 11:18 AM

Those fuzzy legs made you brilliant!
<good one , Dave>

Geek · 26th October 2009, 11:24 AM

Hey Dave,

Wasn't there a dead hot water tank around your place we could get creative with?

Cheers!

25th October 2009, 09:48 PM	#2
planet10 diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	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 ........ commercial site planet10-HiFi p10-hifi forum here at diyA

26th October 2009, 08:34 AM	#5
chris661 diyAudio Member Join Date: Feb 2008 Location: Lancashire Blog Entries: 6	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 __________________ iPod Touch (playing LossLess) > 4th order LR crossover @80Hz > Amp-6b > Fostex FE126eN in folded ML-Voigt Pipes ------------------------------------------------------------> Samson Servo 240 > W6-1139SG Tapped Horns

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25th October 2009, 10:50 PM	#3
h@kan 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 AB 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 "AB" ratio is ~1:12 Regards H@kan

26th October 2009, 11:18 AM	#9
picowallspeaker diyAudio Member Join Date: Apr 2007	Those fuzzy legs made you brilliant! <good one , Dave>

26th October 2009, 11:24 AM	#10
Geek 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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