Unsound et al, Thiel's electronics were all developed and built in-house. Jim was a circuit guy before we took up loudspeakers. His first patent was a sweet phono head amp circuit which we built and shipped for Monster Cable to market. The various equalizers suffered from an identity crisis, being seen as such a valuable and viable solution to us, but being considered a pariah in the marketplace, in no small part via Bose's low-grade application of the idea, and therefore resented by many dealers and consumers as somehow unworthy, therefore limiting the budget to fund exemplary execution.
Regarding the CS5 bass drivers, remember the mid 80s were the Dark Ages. We were designing our drivers and Vifa was making some, such as the CS5 proprietary tweeter. Otherwise, we identified some driver manufacturers to customize appropriate drivers. Those CS5 Kevlar units incorporate Thiel magnet structures and copper shunt rings and long excursions. Those 8" Kevlar cones were extraordinary, much better than their 10" stable-mate, and crossed over superbly to the 5" low midrange. With their extremely long excursions, they moved lots of air. The CS5 bass alignment is different than it looks. The bottom and third subwoofer have mass-loaded cones to lower their natural resonance plus damp the upper breakup mode. The way they straddle the center woofer allows them to create a larger-than-obvious radiation pattern for the 20 to 50 Hz (plus first-order roll out) range. The center woofer is lighter and covers 50 to 400 Hz loaded by its own sub enclosure. Let's just say that drivers are chosen for many interacting reasons. These did the job very well.
As I mentioned, the CS5's Achilles Heel is the low impedance bass load and the delay lines required for proper time-alignment of so many drivers. As I mentioned some time ago, that speaker would do well via incorporating an SS2 powered bass driven through a custom Thiel external passive crossover for the two subwoofers. Above that we might drive the upper woofers via an equalizer and handle the top end with my imaginary driver that mounts a 3.7 coax within a 6.5" wavy cone triax. Let's make all those drivers with carbon fiber diaphragms while we're at it.
Jim's low-impedance choice is indeed a quandary. Even with a 4 to 5 ohm minimum, the voltage sensitivity would not have been too low. If Thiel were starting over today, I think we would settle on higher impedance not only to spare amplifiers, but to reduce cable interactions. Such speculation distinguishes imagination from history.
