Most tube testers don't test tubes at normal in-use voltages, and that's especially the case with output tubes. Other than noise associated with short circuits or excessive gas, how a tube tests won't really indicate sonic characteristics. That said, I have 4 tube testers because I enjoy the process of testing vintage and/or new production tubes before I deploy them in a vintage amp. Most recently bought a Maxi Matcher which is a little more helpful with matching output tubes, as it will apply 400 volts to the plate. The final test of any tube, whether in a gain stage or output, is the gear in which it's used.
Do vacuum tube test values reflect sound quality?
I recently ordered a pair of output tubes to try in my LTA MicroZOTL preamp. Two Sylvania 6SN7WGT tubes, Gold Brand. I’ve had good luck with Sylvania 12sn7gt bad boy tubes, so I thought I’d give them a try.
After I bought them, I saw a similar pair for more money that had slightly higher test values. Does that mean they might sound better or that they just have more life left? What properties do you look for in tubes?
Below are the values of the tubes that I bought.
Tubes are matched for dynamic gain and structure, testing at 3000-2750 and 3000-2750 where pass/fail is 1625 micromho. They have the same structure inside and out, having matching date codes of "922", the 22nd week of 1959