Thiel Owners

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. 

Happy Friday! All

thielrules - as I see it, the output of the port is a full cycle behind the output of the upper drivers, with 4th order (24dB/octave) slopes induced by the physical / mechanical interaction of the resonating port (no electronics involved.) Since I think that 4th order slopes maintain phase linearity, the only non-coherence would be in the time domain, where the frequencies covered by the port would emanate one cycle behind (but in phase). My calculation says that lowest tone centered on 38Hz (port peak output) would sound like it comes from 30' behind the speaker.Above 50Hz (the -3dB/half power crosspoint) the output becomes dominated by the woofer which is in-plane and therefore in-time with the upper signal.

The lowest note of a bass is about 40Hz, and most of its information is above that 50Hz crosspoint. So, I'm not surprised if many people can't distinguish between ported and sealed bass. Also, your DSP solution that further minimizes slight phase discrepancies in Jim's original analog filters, does introduce a digital conversion as well as some pre-ringing (which you have minimized.) I am one of those folks who is sensitive to pre-ringing, so I might choose different trade-offs than you do.
Remember that most modern speakers admit these 360° / full rotation phase shifts at every crossover point, where there is lots of musical information. The common call is that "it can't be heard". I suspect most Thiel fans prefer it not be there, even if their ear-brain is deemed to be able to ignore it.

@thielrules  I'm not sure many of us could differentiate a 'coherent source' Thiel from a 'conventional' speaker with standard A/B testing (blind or not) over the course of an evening.  As I related a few months ago, I bought Thiels (2.3 then 2.4) as they checked so many boxes for both design and immediate sonics.  Their coherence was mostly an academic advantage to this engineer.  It was only after a few months of listening only to a good non-coherent speaker in place of 20 years of Thiels in my familiar acoustics and electronics that reinserting the CS2.4 into my system created a profound psycho-acoustic improvement.

@tomthiel  OK, I'll accept that, that the ported bass results in a fixed 1-cycle lag from the radiator, hence phase coherence remains intact throughout the speaker's entire bandwidth.  And time coherence is only impacted in the lowest frequencies where the passive radiator is most active, below 100Hz in my 2.4 instance.  And yes that's a helluva lot better than most other speakers that go through all sorts of phase and timing shifts at each crossover point, as Stereopile plots show, dismissed as 'optimal crossover design' as 'each driver smoothly hands off to the next.'