My guess is that not many of you have heard of a folding transmission line in a loudspeaker, much less ever heard one working. The late Bud Fried, from Fried Audio (pronounced “freed” as opposed to what one might do […]
It’s true. It’s a T-line!
http://www.pstracks.com/pauls-posts/folding/10352/
Attached files 
First we get a woofer in a box - It’s okay but not the best. Then we put a hole in the box… Better AND worse! Then we tweak th size of the hole to get the resonance just right… better. Then we put a tube in the hole, different but not necessarily better. Then we put a big hole in the box but put a compliant plug in the hole. Different and a little better. Now, we are back to a mid sized hole with a LONG tube feeding it. Better yet but… Somehow this is good but perhaps not quite the best?? Time to learn more about all of this.
Come back tomorrow for another episode of ‘As the Woofer Thumps’. 
J.P.