Thiel Owners

@hifi28, fitter468’s point about drivers are spot on. But, whether the 3.5’s or the 3.6’s are better comes down to individual preferences. I think if you read through this thread, you’ll find preferences pretty evenly divided for either one.

From a historical perspective the 3.5 > 3.6 transition is a watershed. The 3.5 has the more "correct" sealed box bass response. The model 2 was invented to implement the less expensive reflex bass. That introduces phase / time lag at the bottom of the spectrum, but the model 2’s reduced budget admitted that trade-off. Our pipe-dream vision of the model 3 was to develop a subwoofer that matched the second order sealed roll-off model three bass and which, by careful placement, can be made time correct and phase benign.

Around 1990 we had entered a subwoofer development project with Vifa creating a very early class D implementation. That should have become the bass foundation for a breakthrough 3.6. Another intriguing option was a transmission line bass, but at that time adequate modeling was not extant, and TL bass included tons of guess-work, trial and error and mixed results. An improved equalizer option was also floated as an intermediate step between acoustic and subwoofered bass. Through a few years of significant grief - that subwoofer didn’t materialize - it took years too long to develop. The market demanded a new model 3 offering, especially in Kathy’s opinion. Without putting too sharp a point on it, the 3.6 with its reflex bass became the result. Its bass is quite well executed, some say about as good as the form gets. But, it’s still a reflex bass system with its limitations and trade-offs.

I’m somewhat surprised that Jim continued with the reflex bass in his subsequent higher-end products rather than building on the seminal work of the sealed CS5, as well as developing transmission line and/or including subwoofer augmentation. A one-man development team can only take on so many challenges.

I second what's been said above. The 3.6 is the more mature and accurate product, plus it can be maintained with available rebuilt drivers.

@tomthiel, Your entitled your opinion and yours will deservedly carry more weight than mine. I’m not so sure that the 3.6’s are more accurate, perhaps not even more mature. But, while the 3.6’s are more dynamic, play louder and are more suave from the midrange up, the 3.5’s go deeper, have better time and phase coherence, and get more from less costly amplification. You’ve confirmed what I always suspected: that the 3.6’s were rushed to meet cyclical market demands. I was and remain disappointed. I would have guessed the 3.5’s would have been followed with a 4 way sealed box with time compensated bi-wiring keeping the eq out of the upper range. I can understand why some might prefer the 3.6’s, but I’ll go with 3.5’s every time. I think all things considered the 3.5’s were Thiel’s best product. The port made sense for the CS2’s down, but I think it was a mistake that kept being made (except for CS5’s whose amp requirements keep it from being the best Thiel) with the 3.6’s on.
YYMMV. To each his own.

Unsound, I mostly agree with your preference for the 3.5 but can't say that it is better then the 3.7. 

^That’s a different comparison. A sealed box 3.7 would be a triumph!