Transmission line cross-sectional area question - diyAudio
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Old 25th October 2009, 09:26 PM   #1
h@kan is offline h@kan  Sweden
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Default 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
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Old 25th October 2009, 09:48 PM   #2
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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
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Old 25th October 2009, 10:50 PM   #3
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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
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Old 25th October 2009, 11:02 PM   #4
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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!
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Old 26th October 2009, 08:34 AM   #5
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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
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Old 26th October 2009, 10:19 AM   #6
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The necessary damping would quickly ruin any see-thruness.
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Old 26th October 2009, 10:44 AM   #7
h@kan is offline h@kan  Sweden
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Originally Posted by chris661 View Post
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

Click the image to open in full size.

Regards H@kan
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Old 26th October 2009, 11:03 AM   #8
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Organizing the tubes like this is easier to build small cylindersealed at the top. big one on the bottom. Not to scale.

dave
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Old 26th October 2009, 11:18 AM   #9
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Those fuzzy legs made you brilliant!
<good one , Dave>
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Old 26th October 2009, 11:24 AM   #10
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Hey Dave,

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

Cheers!
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