Current JJ ECC83S test results is also posted in the Z Lounge
These are still the highest true gain 12AX7 tubes on average of current 12AX7 production types. A number of these had a gain of over 100 in a batch of 100 tubes tested.
The typical preamp tube today has a measured gain of less than 85 and ranges of 70-80 are the average that are typically seen.
This is just test data that is done on every run received from vendors. I am not saying this is good, bad, black, white, loud, quiet, right, wrong, etc. It is just data that I am putting up here for folks that can understand what this is showing and can use this information. I do not intend to explain what these columns mean. Either you know what these figures mean or you do not. If you do not then there are many good books out there that will give you a great foundation. One book that should be in every library of amp folks is a copy of the RCA Receiving Tube Manual. You can find these at www.tubesandmore.com and other sources.
1/24/08 As a side note .... the second batch of ECC83S tubes from JJ in a group of 100 had an average gain of 94.6. This is about 10 points higher in average than any other current 12AX7 at the moment. There were over 15 tubes in the 100 with gain of between 99.9 and 107.6