I’ll address a couple of your thoughts.
Yes, performance, sonic signature, and longevity will be closely tied to the circuit design and execution.
Test results are important in predicting performance. But, we need to define performance. If you mean, will the tube last a long time, supply the required voltage, and have no emissions, then the answer is measurements are very important. If performance means that this tube will be sonically to your liking in a particular component and have the signature described by others, the only way to know is try it.
It’s true, not all tubes from a given factory will perform the same, although tolerances were very close and QC was adhered to. Keep in mind, most manufacturing in the 1940’s and into the 50’s was for the military. There was a high level of quality and consistency. Some tubes were "ruggedized" with extra support rods and micas. They were solely for military use.
Other plants made their house brand of tube(s) and had defense department contracts. Tubes were tested and if they met the military’s specs, they were stamped with military codes such as JAN, W, CV, or VT-231. Tubes that were outside milspec parameters were stamped with the proper designation for that tube such as 12AX, AU, 6SN and were distributed for civilian needs.
For our purpose, which is audio, tube factories produced an incredibly consistent product which will have its unique sonic signature when installed in a particular circuit. This is where the conversations and debates about tube rolling come into play.
Yes, performance, sonic signature, and longevity will be closely tied to the circuit design and execution.
Test results are important in predicting performance. But, we need to define performance. If you mean, will the tube last a long time, supply the required voltage, and have no emissions, then the answer is measurements are very important. If performance means that this tube will be sonically to your liking in a particular component and have the signature described by others, the only way to know is try it.
It’s true, not all tubes from a given factory will perform the same, although tolerances were very close and QC was adhered to. Keep in mind, most manufacturing in the 1940’s and into the 50’s was for the military. There was a high level of quality and consistency. Some tubes were "ruggedized" with extra support rods and micas. They were solely for military use.
Other plants made their house brand of tube(s) and had defense department contracts. Tubes were tested and if they met the military’s specs, they were stamped with military codes such as JAN, W, CV, or VT-231. Tubes that were outside milspec parameters were stamped with the proper designation for that tube such as 12AX, AU, 6SN and were distributed for civilian needs.
For our purpose, which is audio, tube factories produced an incredibly consistent product which will have its unique sonic signature when installed in a particular circuit. This is where the conversations and debates about tube rolling come into play.