Owners of standard CS2.4 speakers may be interested to know that the only internal difference that makes a 2.4SE is the use of ClarityCap SA film capacitors. DIYers can make this upgrade or better by substituting the more recently introduced ESA range.
. I don't have a schematic, but during that time Thiel was purchasing 14uf and 28uf values. They may have been bypassing these with 1uf polystyrene caps. You should be able to confirm this by inspecting the crossover.
Since then we have surpassed SA by two generations-- ESA and now CSA. For that application I suggest CSA/250V or, space permitting, our top CMR/400V model.
Looking at Partsconnexion and Madisound, I don't see these values from Clarity (or Mundorf), especially as a close-up of the CS2.3SE crossover indicates 630 V. Are Thiel's values a special order?You should inspect the board to be sure. The configuration is likely 14uf in parallel with 1uf(=15uf) and 28uf in parallel with 1uf(=29uf). If this is the case, then you could (1) replace the 14uf and 28uf values and leave the stock 1uf polystryrene caps in place, or (2) replace both the high values and the paralleled 1uf caps with 15uf and 29uf.
It is advisable to look carefully at the circuit before ordering anything.