You bring up a problem about first order crossovers that is technical enough but one that any speaker designer worth their salt should be able to solve with the array of currently available computer based measurement systems (I use MLSSA, LMS, and CLIO) by running simulations.
With regard to the driver configuration of the Starship SE, it is not inspired by “the four-woofer, tweeter-in-the-middle cluster from the bass cab world.” The bass cab world is not a part of my orbit. Instead the Starship SE design is a result of step by step research and development that dates back to the 1990s.
The provenance of the Starship SE has its origin in the NSM Audio Model 5 that was reviewed by Soundstage back in 1999 That review can be found here. Note the drivers used in the Model 5 and their configuration. Having successfully used a SEAS concentric driver in my NSM Audio 20M also reviewed by Soundstage here, I consulted with the SEAS engineers at CES in the 1990s as to whether or not they had a free standing version to the tweeter used in the concentric driver that would allow me to simulate the close coupling of woofer and tweeter approximating the relationship in the coax. They suggested the tweeter used in the Starship series which I imported directly from SEAS because it was not available in the US. Subsequently it was distributed by Madisound.
The first speaker designed in the Role Audio Starship Series—a modular line of speakers-- was the Kayak, which was based on the Model 5 and had the same driver configuration. The Windjammer is the transmission line version of the Kayak. Note something very important: I am using drivers that work well in both acoustic suspension and in my transmission line designs. Next came the Discovery. The Enterprise is the transmission line version of the Discovery. To develop the Enterprise I had to solve the technical issues involved in mating two transmission lines – a configuration I had not seen before or since. So the Enterprise is essentially two Windjammers in one cabinet. Later on came the challenge of designing a speaker with twice the power of the Enterprise – the Starship SE. The first speaker with four transmission lines, to my knowledge. If you draw a vertical line down the center of the Starship SE you can see that it is essentially two Enterprises or four Windjammers. The Starship SE tweeter is different to accommodate the increased sensitivity of the Starship driver configuration. Note in the Starship SE the drivers are spaced even closer together than in the Enterprise. The pedigree of the Starship SE is well established in the series of reviews of the Kayak, Discovery, Windjammer, and Enterprise.
Now onto a different issue. No! I am not using mid-woofers in the Starship that have “the most powerful motors” you “have ever seen in such a small woofer whose other parameters are good for making bass.” Quite the opposite. What I am using is a different transmission line technology. The motor of the woofer is not “more like what you might see on a good 6" or 7" woofer.” And the design is absolutely not “very demanding of the drivers.” Quite the contrary, compared to ported or acoustic suspension designs at a similar SPL these woofers are hardly moving. Reduced cone motion and reduced distortion at similar SPL is one of the hallmarks of transmission line designs.
I think this misunderstanding of my designs is what led to your earlier comments about the NSMT Chorus and your disbelief that the “Chorus has a sensitivity of 96 dB, bass extension to 35 Hz, and an internal volume of about 1/2 cubic feet.” That level of performance inheres from the short transmission line technology and TL-ABC port tuning that I have developed.
There are several reviews of Role Audio speakers with even smaller internal volume: the Sampan FTL (.12 cubic feet), Sampan (.13 cubic feet), and the Windjammer (.36 cubic feet) that have 35 Hz to 20 kHz frequency response. A Google search of the smallest speaker, the Sampan FTL which weighs 4.5 pounds and is 8 X 4 X 9.5 inches, will show an image of a composite MLSSA measurement of the TL-ABC version that is +/- 3.5 dBs from 35 to 20kHz. Hard to believe but true. The Sampan FTL was first shown at AudioKarma Fest ‘07 and there are comments online about its performance from that showing.
The imaging, soundstaging, and bass performance of the Starship SE should not be surprising to anyone who owns or has read the reviews of the Windjammer and Enterprise, considering the Starship is essentially four pairs of Windjammers or alternatively two pairs of Enterprises.