Grilles - The issue is multi-faceted and full of trade-offs. Early 3s had wooden 3-D frames stretched with fabric. Fabric absorbs some high frequencies; Jim voiced assuming fabric. 1983’s CS3 used the baffle-level of the frame to complete the baffle's rounded edge profile, and the aerial parts to support fabric away from the baffle. 1989’s CS5 had a 3-D steel frame with aerial fabric (away from the baffle.) The low (1/4") profile of the frame reduced its diffractive contribution to low enough to ignore. But we knew it was there. 1990 CS2.2 and 1992 CS3.6 used the baffle perimeter edge profile of the CS3-3.5, but eliminated the aerial structure. The all-MDF 3.6 frame proved too fragile and a side-bar reinforcement was added. We considered aluminum and steel and steel won for cost. We knew side-effects (more on that later.) 1995’s CS7 (my last industrial engineering contribution) again addressed the same issues and again landed on steel. Note, that baffle was cast concrete which required re-bar in the narrow areas beside the woofers. Those eddy currents could be heard and inferred from measurements. Note that 1999’s CS7.2 upgrade changed the frame to aluminum and eliminated the rebar via fiber reinforced mineral casting medium replacing concrete.
Directly to your question: 2002’s CS1.6 seems to be the first product with the thin steel plate supporting stretched fabric. The shallow baffle indentation was probably deemed not too problematic. An aluminum plate could not have been fastened with magnets. (BTW magnets near a driver are detrimental.) This ’fabric on plate with magnets’ solution persisted. The SCS4 has a formed steel cage in a shallow perimeter groove, adhered with magnets. Nice solution, with downsides. I’m replacing every element of it.
Regarding ’more on that later’. Jim was a disciplined pragmatist. Any and all design elements had to carry their cost burden. Incorporating ’better ways’ could increase costs which were doubled by the retailers’ 50 point margin. We were constantly juggling those equations. Although not sexy or particularly marketable, value engineering was a major aspect of Thiel’s approach, both in product outcome and in manufacturing technology.
So, concerning audibility, Thiel (which included Kathy as marketing director) played tug of war quite a bit. How much can be heard by whom (% of target market), etc. Every brand has a niche. As an aside, in the early 90s it was clear that something had to be done about home theater to stay viable. Thiel dove in and the rest is history. But there were other options considered. Among them was my idea of creating a brand offshoot (much like Lexus is to Toyota.) The name was to be ’Perigee - the closest approach’. It would follow a different paradigm that allowed and developed its own layers of sophistication to stretch the cost/performance paradigm. Jim’s principle objection was that it would cheapen the image of standard Thiel branded products. Fair enough. That route would have concentrated our resources in high resolution stereo playback. And it would have required product development collaboration beyond Jim's comfort zone and vision.
More complete solutions for the subtleties of ultra-fidelity music reproduction exist and can be developed. Many were beyond our knowledge or scope, and remain so today. Some have come into focus or feasibility as time goes by. New materials science is a robust field. And there are old ideas that fell away and may be re-imagined today.
