They are designed in essence of the original BBC monitor, except with modern methods and components. The woofer is the Aurum Cantus 5.25".
Here is the write up for this design.
https://meniscusaudio.com/wp-content/uploads/2015/11/Continuum-Writeup.pdf
Didn't mean to derail your thread. Was just commenting for seeing preferences lean one way or the other with tweeters. I have heard excellent versions of both. With this RS28A-4 being something of a surprise.
This design has been revised since the demise of the RS28A-4. I think now they use a Morel tweeter with an update to the crossover.
This is one of my favorite speakers to date. I would not part with them for all the tea in China. "Laid back?" Hmmmm. . . . I have a hard time with that definition outside of extremes. Very addicting in the near field or small room with the right subwoofer. Half of why I built the RSS315HF subs was to compliment these speakers.