TL - cross section

[00940]

I'm attempting to build a pair of colums based on the vifa D25TG-05-06 and P17WJ-00-08. I found a few designs using this woofer in transmission lines :

- Timc's here : Vifa PW17J in a TL enclosure
- These : http://www.geocities.com/bunkie21/index.html
- The PMC FB1.

Looking around the web I found a lot of info. I've been playing a bit with Martin King alignement tables and now I'm a bit puzzled.

The size of the boxes above are all around 200/300mm for the external width/length. But, from the results from the alignement tables (for a tapered TL, SL/SO=0.5), I need a cross section of 4*136mm² for SO. This is way more than the cross section found on the designs above. A tapered line with a ratio of 0.5 for Sl/So won't fit in such columns.

Question one thus is : should I build a bigger box to follow the alignement tables or go with known speakers ?

Question two (unrelated) : a single fold line with the vent on top (such as this one : http://www.humblehomemadehifi.com/Optimo.html ) seems the easiest way to design and build a TL. Any reasons not to use it ?


Thanks

[00940]

here's the rough idea of what I've in mind :

[Notax]

Originally posted by 00940
here's the rough idea of what I've in mind :

Something like that, but its to big cross section. I recommend 80 mm instead 130 mm, 120 mm instead 200 mm and 180 mm instead 270 mm. Width 180 mm.

So=8x18=144 cm2 (little more than cone - Sd)
Sl=17x18=306 cm2

[00940]

Thanks Notax. If I may ask (I'm trying to learn), what are you basing yourself on for deciding on the cross-section ? Experience, other equations ?

[Notax]

Originally posted by 00940
Thanks Notax. If I may ask (I'm trying to learn), what are you basing yourself on for deciding on the cross-section ? Experience, other equations ?

Other projects. Mostly open area is something between 0,65-1,15*Sd.
And Sl/So is from 1:1 till 10:1 (but more till 3:1). Smaller Sl is mostly for 2-way. Its more complicated. Look at


www.quarter-wave.com

and

t-line