In the few minutes I have . . . Andy, good observations - the 2.4 upper coax is crossed over as a single driver - the electrical signal drives the tweeter only, and the midrange piggy-backs through a mechanical elastic surround. Indeed the CC-SAs in the 2.4SE are less than state of the art, but at the time were CC's best offering. Regarding the "glow", Thiel always avoided artifacts even if they sound beautiful. In my present upgrade work with beetlemania, we have chosen ClarityCap CSA's which are 2 generations beyond the SA and are extremely good as being extremely neutral, without artifacts. We're testing efficacy of various bypasses in parallel to the CSAs.
You are correct about the 2.7 XO midrange feed cap. It is a 400uF electrolytic, which is audio grade, but nonetheless degrades the mid signal a little, even though it is bypassed by a 15uF polypropylene and a 1uF styrene & tin foil. My upgrade strategy is to eliminate all electrolytics (somehow!) to make the speakers virtually perpetual (electrolytics drift and fail over time). As you say, great caps are very expensive. I am assembling cap bundles based on a custom Japanese best in world film, bypassed by CC CSAs, rebypassed by the custom Thiel Styrene/tin and possibly a CC-CMR - all depending on which circuits. Much comparative evaluation will continue toward finding the best performance/ cost plateaus. It is easy to spend $thousands on caps. We are likely to have at least 2 upgrade levels for each of the products we address. The 2.4 is on the list and progress is being made slowly but slowly.
You are correct about the 2.7 XO midrange feed cap. It is a 400uF electrolytic, which is audio grade, but nonetheless degrades the mid signal a little, even though it is bypassed by a 15uF polypropylene and a 1uF styrene & tin foil. My upgrade strategy is to eliminate all electrolytics (somehow!) to make the speakers virtually perpetual (electrolytics drift and fail over time). As you say, great caps are very expensive. I am assembling cap bundles based on a custom Japanese best in world film, bypassed by CC CSAs, rebypassed by the custom Thiel Styrene/tin and possibly a CC-CMR - all depending on which circuits. Much comparative evaluation will continue toward finding the best performance/ cost plateaus. It is easy to spend $thousands on caps. We are likely to have at least 2 upgrade levels for each of the products we address. The 2.4 is on the list and progress is being made slowly but slowly.