Thiel Owners

Yes or nay doesn’t work for me. It depends on the form factor. 
I would think that cross-over updates might be more urgent for older models as their cross-overs are likely to be needed (due to age) as opposed to newer models that have plenty of life in their current caps, etc.

tomthiel

Not that it gives you any more information per se on the Thiel 2.7, but maybe of interest to you is this post in another forum by Philip Bamberg
who worked on the 2.7:

I designed the crossover for the CS2.7 upgrade to their coax mid/tweeter driver. It was not easy. I was present at the voicing sessions in Lexington, after some listening in my own house.

I can vouch for both the CS3.7 and 2.7 speakers having a 2dB/decade downsloping response from 200 to 2kHz, transitioning back to level in the treble. This is a tonal balance curve similar to many high-end speaker brands. However such a speaker still does not sound dark (there are other more technically involved reasons for this).

One shining performance feature that I can vouch for with the CS2.7 -- the bass is spectacular. Their 10" woofer RULES, and the cabinet alignment is excellent. Play acoustic bass or drums on this speaker to believe me.

Also, the coax unit is impressive in its own right. The midrange is actually flat to 20kHz (without crossover). I think the time-coherent acoustic alignment and fast response drivers may lead to the listeners' reaction of bright or forward.

Thiel also spends for PP and polystyrene bypass caps for additional transparency. For these reasons, system matching is a bit more critical with the upper Thiel models. Also, all 3 drive units have aluminum diaphragms. I promise you that I addressed the woofer ring, and achieved excellent time and phase coherency - Thiel was quite demanding of this as you can imagine.

While I performed some reverse engineering of a few of their models (part of a technical familiarization of Jim's work) I am not intimately familiar with the design and history of all their models. I suspect that their models over the past dozen year vary in tonal balance, and that it is a mistake to conclude that the company voices speakers to be bright/lean/forward overall. IOW, I think the time for audiophiles to conclude that Thiel = Bright should come to an end.

I am no longer under contract for Thiel, and I gain no benefit from their sales. These are just my own objective and subjective observations.

Philip Bamberg

more urgent for older models as their cross-overs are likely to be needed (due to age)

Good point! I see that as a secondary benefit. The intention of the upgrades is to notably increase the quality of the passive parts and, thereby, the SQ. As Tom Thiel wrote earlier in this thread:

Thiel was always about finding the optimum point on the cost-performance slope so that real music lovers could afford our products.

Speaking for myself (and not Mr. Thiel), the upgrades seek to maximize SQ beyond what was possible at the price points of the original products. IMO, a cost-no-object approach to the XOs for the CS7.2 or CS3.7 would have likely have placed those speakers on par with the best available. The upgrades intend to seek to squeeze the ultimate SQ from the designs.

I am still burning in my new resistors, so don’t yet have a final verdict but my initial impression is that the Mills MRAs are a worthwhile, yet subtle, improvement over the ERSE resistors originally installed. This change in parts would have added $200-300 retail to the CS2.4 and represents, I think, the kind of decision Jim Thiel would have made when optimizing the “cost-performance slope”.

In my case, I recognize the drivers in my CS2.4s are really frackin’ good. IMO, I would have to move up to something like the Vandersteen carbon or TAD beryllium drivers to find something clearly better. Speakers with these drivers are an order of magnitude more expensive than my Thiels! But I think I can get really close to their level of performance by optimizing the XOs. In other words, it's a solution that gets me close to the very best but at a price I can afford.

Also, keep in mind that the technology has advanced since Jim Thiel designed the original XOs. Even the relatively recent Clarity SA coax feeds in my CS2.4SEs have been notably surpassed by Clarity CSA.

Beetlemania, first let me thank you for your informative updates.
For those of us with older Thiel’s let me say concern over failing caps, etc. is of primary importance.
Keep up the good work.

@unsound Glad you find my updates informative. Your CS3.5s must be close to 30 years old - I understand your concern re: cap life. That should further incentivize you to seek Tom Thiel's upgrades as they become available.