@vair68robert - what a mess. It sounds like Nashville Thiel may not have had final product testing, because your value drifts would have failed your finished speakers.
We took quality assurance very seriously. There are many approaches - our methods were always changing - with lots of thought and care. The 1980s saw the advent of ISO-9000 where manufacturers processes were certified rather than their final testing. We bought from suppliers with essentially the approaches that became codified in ISO9001. In that environment, incoming testing is not necessary. Every part can be assumed to be correct. The flip side is that if any single part flunks at any point in process, then the entire batch is quarantined, the problem is investigated, solved and re-documented. We co-developed our implementation with Vifa (and their group of co-producers) to good success.
Please permit me a story, an important, meaningful story that helped form Thiel Audio's identity. Consider the CS3 woofer. It was our first real foray into partnered product development. That woofer was a big leap ahead, especially with the copper shorting rings and field-focusing top plate geometry. It also pushed the envelope of what a woofer was expected to do: perform well and consistently to 10kHz. That long, even high-end roll-off depended on tight control of many factors including viscosity of the bobbin / cone glueline. We spent more than two years working on that woofer with Vifa. Perhaps because there had been so many iterations (?10+?), and perhaps because we had developed so much mutual respect, perhaps a dash of time / annual cycle pressure . . . the first production run of woofers had an anomaly that missed all of us. Its upper range, perhaps 4-8kHz had too much energy. 'Normally' a woofer's response in that range is irrelevant; but with Thiel's first order rollout, it mattered. Good lessons were learned that paid strong dividends over the following decades.
The root cause turned out to be a change of adhesive caused by the Danish government outlawing epoxies for health concerns. The replacement 'equivalent' glue acted differently at operating temperature than the prior well-understood epoxy. The new glue eventually also failed in the field for our first (possibly only) recall. That 'problem' clarified our MO for customer service. We replaced every one of the woofers at no charge and our dealers magnanimously swapped them out at no charge to us! To make lemonade from the lemons, we provided a record (yes, vinyl) to each customer as consolation for their trouble. The record was Michael Hedges 'Aerial Boundaries', which was both musically and technically masterful. That situation became legendary and performative - defining our image both internally and in the marketplace. Kathy Gornik gets much of that credit.
When I first heard of your wildly out of spec components, I was dumbfounded. As the particulars came to light it made some sense. New Thiel was not the same company with the same values of product integrity and customer satisfaction. I wonder how many more 2.7s are out there from New Thiel.
