The 3.5 EQ will stay, since it is a vital part of that product. The sealed bass drops off about 100 Hz at 12dB / octave. That would blend very well with a subwoofer, but by itself is pretty bass-shy. The two position EQ extends to 40Hz and 20Hz, which is extraordinary - albeit amplitude must be reduced to avoid bottoming the woofer, which is why the EQ's bass was abandoned as digital sound-tracks came into vogue. In due time I will be addressing the sound quality of the EQ unit. It's a good circuit but could benefit from better signal path components. There is also interest in a fully balanced pair.
I have settled on an order of go. In order to hone my chops, develop hardware and software solutions and walk before running, I have decided to address oldest products first. Their end-of-life is more immenent, and there is generally greater room for improvement than in newer, more advanced Thiel products. So, I am beginning with my prototype 02s. One version will use existing drivers and another will replace the drivers, which are obsolete. There will be cabinet and component upgrades. The 02 pre-dated any knowledge or availability of high purity wire or film capacitors. I will replace all XO components with appropriate best-of-form, keeping the 2nd order XO topology and port, but everything else being fair game. This project should come easier and faster than the more complex models. I hope some folks here will like this - I know I will like doing it. 1976 revisited.
Next will be the CS3/3.5. Since all the drivers need updating, it is likely that we can refit both CS3 (1983) and CS3.5 (1988) with identical drivers and very similar XOs. I'll skip the CS5 and take on the CS2.2 (1991) next. Those products should provide a good foundation for further models.
There has been suggestions to call these updated models -R for Reissue or Resurrection, or -AL for AfterLife, or who knows what.
-cheers
