Max - I use Delignit / panzerholtz in piano restoration work - and love it.The earliest Thiels from 1975 to 1985, up to the CS3.5 used various products. The 01 and 02 were medium density particle board. The 03 and 03a were Baltic Birch (actually the higher quality FinPly). The CS2, 3 and 3.5 were high density particle board walls with high density particle board baffles. The model 2 and 3 had internal spruce struts inside the cabinets. I consider all these models to be of superior materials and outcome than the later MDF cabinets.
MDF was chosen for its consistency, universality of sourcing, flatness for laminating and gluing, and machinibility. With well engineered internal shelf braces, it was adequate for the job. Note that Thiel was producing extremely complex cabinets in a production environment with no room for anything to go wrong, and needing a universal material for feasible stock management. 1" MDF filled that bill. We were never a boutique, cost no object shop. Our finished products sold for sometimes a small fraction of what some manufactures lavished on their cabinets alone.
There are no CAD / manufacturing drawings available; but that may change in the future. I believe a more cost-effective retrospective approach might be to experiment with Panzerholtz, etc. as bracing material to quiet any cabinet wall resonances that can be identified. I am adding strategic long-grain spruce cross-braces to settle the enclosures, and have chosen torrified bamboo for bracing as a very high performance / cost effective candidate.
In the mid to late 80s, I experimented with various Corian-type products as well as honeycomb substrates with technical skins, curved panels and so forth. So much cost was added that we stayed away from them. We went to cast baffles machined with abrasive diamond tooling as an effective solution to affordable extreme rigidity It would have been very easy to double our manufacturing costs with multipliers applied for retail prices, and stray from our intended niche of phenomenal high value. Cost effectiveness was one of Thiel's evaluation lenses.
By the way, the CS3.7 / 2.7 returned to one of those 1980 experiments. The curved side panels are 17 ply birch laminates, using the material and its geometry for added rigidity and waveform propagation.
