Mcintosh 12AX7 - 3 Matched Tubes from a MC275 MK series - Tests 100% or more of New. Although I am a horrible photographer, these guys look,feel.and sound brand new.
These are extra tubes I have. They still have that super smooth, slightly heavier Mcintosh new tube feel and sound. Mac has been sourcing their tubes from China (They have never made tubes). I think they are Mcintosh branded PSVane tubes, although Mcintosh won't say.. If you don't know them, PSVane are fairly expensive, very well respected high end Brand tubes made by the Shugaung Group in china. They ARE NOT of the shelf "Shugaung" .
Mac replacement tubes cost a fair amount.These came from a replacement set of MC275 tubes These are probably the top of the PSVane line which are often bin selected tubes. Thats when they only take the tubes that perform the best on a battery of tests. Semiconductors are speed binned. Thats how some are 2.3GHz and some are 2.9Ghz i7 as an example.They test a wafer on say an Teradyne tester by executing a set of test vectors at increasing speeds. If some pass at 2,3 Ghz but fail at the next higher speed they are 2.3Ghz processors. (I was in that business some years ago). With tubes they test other characteristics. Better characteristics higher value tubes.
I just tested them tonight and immediately packed them,