Thiel Owners

So my dilema is do I upgrade the 2.4's to 2.4SE's as I can get the upgrade kit from Rob and be content with my current system or do I sell the 2.4's and the SS2( hopefully to someone who loves Thiel and appreciates the quality) and get a pair of 3.7's?

The sonic part of the SE "kit" simply replaces the 13 uF polypropylene + 1 uF styrene bypass with a 14 uF Clarity SA and the 27 uF PP + 1 uF bypass with a 28 uF SA. Those are the coax feed caps and SA's were chosen by Jim Thiel and Gary Dayton as the best sounding circa 2008.

But there are better caps available now (eg Clarity CSA) and other passive parts (caps in other positions as well as resistors and coils) can also be upgraded. That is what Tom Thiel is working on. If all goes well, this "super" upgrade kit will be available from Rob Gillum by the end of the year. If you decide to keep the 2.4s I advise waiting for the more robust upgrade kit. "Just" upgrading the resistors made a very nice improvement on my SEs and I suspect the full upgrade will bring the SQ to the next tier.

That said, if you have the coin I recommend the CS3.7 which has better drivers and cabinet than the 2.4. And Tom Thiel might have an upgrade kit for those boards, too, although the time line is further out. I suspect a tricked out CS3.7 would be sonically competitive with some of the very best speakers out there.

Your recollections and future considerations of the CS 5's is most interesting. Perhaps my favorite Thiel model. If it weren't for the associated amplifier demands, I'd probably own a pair.

IMO, the ultimate Thiel would have the 5's sealed bass, the 3.7 coax, and Tom Thiel's optimized passive parts . . . and more amplifier friendly impedance. *That* could be a crazy good speaker!

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. 

I'm wondering if replacing the equalizer of the 3.5 with a mini-dsp or a more professional equalizer such as DBX 1231 STEREO GRAPHIC EQUALIZER (have one sitting unused) could be an improvement, especially if calibrated for the listening space. Any experience with that?

Mr. Thiel
Thank You for the great detail and for giving up so much of your time .

"A factor that contributes to "great bass" is that of articulation which, in a first-order design, includes the low end of the mid-range driver. Jim's 3.7 XO treatment is much more sophisticated and uses better parts than the 2.7 due to budget constraints and designer choices. The 2.7 midrange is fed through a 400uF electrolytic cap, albeit with a PP and styrene bypass in parallel. The 3.7 uses a bank of 75uF polypropylene caps with a styrene bypass. Multiple smaller PP caps provide faster reactions and less distortion than a large electrolytic. "
This explains a lot .

Hopefully when you and Rob  develop an upgrade for the 2.7s
they will based on the 3.7s design with new and higher grade components .
Rob