Reasons


What are the attempted advantages of a TL speaker cabinet with equal sizes channels all the way to the port, as opposed to each channel being wider than the last?
Also, what is being achieved by a decreasing size horn channel compared to an increasing size channel?
Are there any simple answers to these questions? I probably won’t comprehend a high level answer.
128x128sound22card

@mjking57, wow.  Thank you for sharing this much specific information  and top-level advice.  Wish I still had time for prototyping TL's like I did back in the 70's and 80's. 

Duke

"back in the 70's"

The music was sooooo much better. Big cars, big hair, big LP jackets that I could look for hidden pictures and read without a magnifying glass, big amps and speakers producing huge sound. No earbuds or blue-tooth speakers playing poorly recorded downloaded music. Those were the days.

"The music was sooooo much better. Big cars, big hair, big LP jackets that I could look for hidden pictures and read without a magnifying glass, big amps and speakers producing huge sound."

I miss my big hair.

My daughter decorates the wall of her apartment with some of my old LP’s.

I’m still in love with the first pair of IMF transmission line speakers I heard, which is what sent me on my DIY quest. One thing I learned was, respect for those who had mastered the art of transmission line design. Never could bring myself to outright copy someone else’s design though... always felt like, for better or for worse, part of the calling of DIY speaker builder was to experiment. Alas, almost invariably it was for worse.

"One thing I learned was, respect for those who had mastered the art of transmission line design."

Art is the right word to describe those older designs. By intuitive feel and a lot of trial and error a few people could build very good TLs. But there were more failures than successes.

Now with the computer design tools available, a TL can be designed on the computer and perform as predicted. No more myths or snake oil, an understanding of how a TL works and what trade-offs are available is easily accessible. The accuracy of TL design is on par with the bass reflex and sealed box enclosure designs. Measured results correlate with the predicted response. The calculations are more complicated but the rewards/payback are greater.