JA - concerning the workspace. No room for multiple speakers, so no longer a 'hotrod garage' - more like a lab/studio. I've spent half-days working here since April with real progress.
One surprise is that capacitor (and all components to a lesser degree) directionality is far more important than I thought. Thiel didn't consider this factor in production. I find directionality more efficacious than higher-cost parts. My present method of determination and optimization is very cumbersome. I'm working toward an easier method. Considerable upgrade potential with your same parts!
I wholeheartedly endorse replacing your stock Thiel resistors with Mills MRA12s. Short money, real improvement.
Wire is a rabbit-warren way deeper than expected. Serious work in that department for two years. I (right now) have a solution that is very satisfying. It's another matter to get it manufactured . . . another story still being written. My present sample development method may amuse you. Imagine a bracket near the ceiling to which stuff can be clamped. Imagine a miniature 'diving board' clamped to it with some array of holes in a circle to accept wires / fiber cords, at various spacings and radii. Imagine a similar set of holes in a hand-held puck. Imagine a center non-conductive cord fastened to the ceiling bracket and stretched tightly to a turnbuckle on the floor - a vertical tight-rope. That core and/or other separating cords are fixed to the diving board and through the puck which is hand-twisted to determine the cable lay and packing density. The various wire and cord components are typically cut 44" long which wind up to a meter long. Those 1 meter setups are installed between a pair of RCA plugs with screw terminations. Placed between my Benchmark DAC3 and HPA4, their attributes can be readily heard and their FuzzMeasure sweeps show differences that correlate with listening. The test method is time-consuming and tedious - making a meter of cable takes an hour or two. But in a half-day session I can make and document an idea. Rinse and repeat. Winners are long enough to cut down to woofer and tweeter runs (two different cables) in a pair of SCS4s.
A significant part of my work is less-technical. Suitable wire comes from many approaches. Partners here who have upgraded their speakers have (I believe) always chosen to upgrade from the stock Thiel 18-2 solid in teflon. I have tested many/most of the wires they used. My determination is that their differences from stock gain something and lose something and change the fundamental characteristic sound signature - which I am unwilling to do. I must say that the cables out there are works of art, intellectual - technical - musical. If anyone tells you 'wire doesn't matter', be suspicious of whatever else they may say.
My work has surveyed a broad range of approaches and I owe a debt of gratitude to the manufacturers who have provided samples, knowledge, and special insight. My approach has been from the perspective of Applied Physics rather than engineering and I thank my friend, neighbor and MIT operative for references and insights from beyond the usual perspectives. This has been a very long, deep journey - the deepest dive of my lifetime. It wouldn't have happened without the Thiel community, which I have accessed here on this forum.
There is more work to do, but this pair of SCS4s, in the works for around a year, is about ready to head to California for Fluid Dynamics wavelaunch technologies. That rabbit-hole is another world of its own.
Off to the lab/studio -
