Thiel Owners

Tweak - in a first order alignment, neither driver rotates more than 90° phase shift, and the overlapping drivers are in opposite directions - they sum to zero. But that's only if each driver, in its enclosure rolls off at 6dB / octave. All that 'extra stuff' in Jim's crossovers is to counteract any anomalies in the entire system such that they do just that. Then they cancel each other and sum to zero phase shift. Since the world is never perfect, plus/minus 10% is achieved, except for the CS5 @ 5%. Convention allows these claims for 100Hz and up. We'll talk about bass later.

sdecker - I am not fluent enough in the art to answer much about the nuances of Thiel's phase coherence. I will point out that your "completely time and phase coherent" is not something that Thiel claimed. The applicable term of art is "minimum phase transducer", which has a complex set of definitions revolving around the least phase error possible given the particulars of the design parameters. To a prior question of whether this is marketing-speak, I say it is not. Jim was extremely careful to not claim anything beyond the real, hard facts. I must demure to more knowledgeable folks regarding bass reflex phase error. Please let  us know what you learn from your studies, The Asylum, etc.
Here is something I do know. If the bass extends below the program limit, much of the phase shift problem evaporates. All Thiel models push that lower limit quite deep. Note also that Thiel's bass tunings typically produce low and controlled impedance peaks with phase plot following closely and well, indicating significant attention paid to coherence at all frequencies.

As you know, I am a fan of sealed bass, and I have shared here how disappointed Jim was that his equalized bass solution did not meet better market acceptance. I speculate that a more purist EQ execution, along with true balanced design, and today's better interconnects - that an equalized sealed-box bass might be viable.
Just for fun, you all might enjoy reading about Thiel's first product the 01. It is an equalized 10" 2-way with bass to 30Hz with third order slopes which are phase correct in many ways, excluding polar dispersion, in a 1.2 cubic foot enclosure at 94dB efficiency. That product got us to Germany by 1978 and via Europe got the attention of advante-garde American dealers. I have seen no evidence of audiophile interest in the 01, but it most clearly represents Jim's initial design impulses and orientation. 

@tomtheil Not to put too fine a point on it [although it seems I did!], but I have most of the hardcopy 'glossy' marketing brochures for 2.3, 2.4 and the 2000s entire Thiel line.

The 2.4SE brochure's lead headline under "Features and Benefits" is "Completely Time and Phase Coherent" and repeats that in the text.

A text printout of the CS2.3 web page states "As with other THIEL speakers, the CS2.3 achieves complete time and phase accuracy for very realistic ...".

The CS2.4 brochure in the center section of bulleted features "Completely time and phase coherent for greater realism" and repeats the same sentence in the headline of the text that repeats it again and its benefits.

A four page glossy full-line brochure from 1/2011 makes the same statement at the top of their bulleted features, as does the CS2.4 "New Product Press Release."

So perhaps the marketing folks took liberties that Jim would not have approved of personally and technically?

I'm uncertain what you mean by the "phase shift problem evaporates" when the "bass extends below the program limit." What is the 'program limit'? There's essentially no 'real' bass below my 2.4 passband of 33Hz. It's the range between 33 and 100Hz that the radiator is fully active that it seems there is the phase shift.

Please don't anyone take this as a critique, only critical thinking. Just in the last few days I've reconfirmed how the relaxed and lifelike presentation of my 2.4 exceed all the lesser benefits of my recent KEF LS50 Meta purchase, and put them back into the big rig indefinitely.

sdecker - I appreciate your feedback. Remember that I did not keep up with Thiel for its last 15 years. I agree "completely time and phase coherent" is a marketing, rather than an engineering term, so it would have come through Kathy's channel. Fair point.
On the other hand, excepting that stuff in the bass, those speakers are phase coherent.
What I mean by the "phase shift problem evaporating" is not clear to me either. My measurements show group delay remaining constant through that 33 to 100Hz range, and I don't have a handle on what frequency the full rotation occurs to cause the lower fundamental to be be behind the upper range. I'm not being coy, I'm admitting my limited knowledge of the particulars. I do believe the effect is audible, if we compared your 2.4 to a CS5. So much to learn, so little time. Please educate us if you learn more from the Asylum or other study.

It is my understanding that a 360 degree phase rotation has no audible impact. The audible impact of a phase shift is more likely if the drivers interact and deviate from the baseline phase. My measurements of individual thiel drivers show remarkable near zero phase of the main frequency range of each driver but the xo range usually needs work. As the xo range is wide, this is a challenge. I was not able to validate that the cross over filters cause the cancelling out of the opposite phase effects. I don't know if this is a result of variation in the speakers and/or the limited sample size. What I do know is using digital linear filters is able to come close to the ideal and maintain near zero phase in the xo range and if carefully designed can keep any pre-ringing to a minimum. Comparing the near zero phase speaker with the variable phase speaker seems a subtle audible difference at best.