Background information

Sound reproduction Over more than 25 years I am building loudspeakers and can conclude it will always be a compromise te reproduce sound. No loudspeaker in the world will reproduce music that will satisfy all people and can be used in every livingroom. You may prefer large bass drivers (10" or bigger), diamond tweeters (very expensive) but they will never reproduce all sounds as recorded. Bigger is not always better!

My preference is to have two bass drivers of about 7" and a coaxial driver for mid and high. Two 7" bass drivers will have the same "Sd" (surface area of the cone) as one 10" bass driver. In a livingroom I prefer the two 7" bass drivers in one box. Not only for the sound quality, also to be able to built "small" (WAF - Wife Acceptance Factor ).

Why a coaxial driver? In the higher frequency area it's tricky and sometimes very complicated to time align a tweeter and a mid driver. Often you see baffle steps or other "design" solutions. Always a compromise between sound and looks. More important, Mid and high from one center position is contributing to a wider and deeper sound stage.

Finally, a transmission line? Why the most challenging contruction? Because it sounds the best, nothing comes near. Bass from a transmission line is always "open" and not "boxed". It also makes it possible to tweak the damping material in the line to give the bass more "air" or make it more "solid".