Guys - thanks for the grace for my rant. The marble baffle was a work of art as it stood. The concrete of the 6 and 7 has its own story. My last project in the mid 90s was developing a lower cost baffle for the 6 and 7, which was a Hydrostone product combining gypsum with portland cements , is highly machinable, accepts damping agents and paints quite well, and has zero shrinkage. It also requires forced hot air kiln drying, could not be outsourced and all-in, cost more than the CS5 baffle in its final painted form. That never made it to production.
Back story: introduction of mystery character. Walter Kling was one of the 5 partners who started Thiel Audio as our communal venture. Walter was genius at tooling, jigs, fixtures, and so forth. He complemented my skill set very well, and we wouldn’t have created a company without him. He left after a few years for personal reasons and had a career in architecture. For my exit plan after 20 years, I hired 3 people to carry on the rigors of growing production. Walter was central to that transition, and he shone till he left at Jim’s death. Unsung hero, and Jim’s right-hand man.
Walter brought his architectural mind-set, and Jim had always asserted that "Concrete would be the ultimate cabinet material". I disagreed due to its high Q, low impact strength, continual shrinking over time and its quirkiness as a paint substrate.
You probably saw this coming: they chose concrete for the next baffles. And it shrank and cracked and required replacement with the "polymer mineral compound", which is shorthand for aggregated polyester, similar to the CS5 baffle but strictly paint-grade with no marble / pretensions of high-gloss, see-into glamor. I understand that it worked fine. But then what to do with that Hydrostone research and development? After Thiel, I did some consulting including Hales. Remember the mid 90s upper end Hales’ with cast baffles? That’s the stuff.