I was asked a question on another forum and grabbed some of my reply to post it here.
If you want to push the output section as hard as possible the JJ 803S long plates are currently the highest gain 12AX7 tubes made at the moment today. Typically their gain is over 90 and most other 12AX7s today are 80-85. Five points of gain might not sound like much but it is quite a difference.
Here are the actual gain numbers in circuit that the last batch two weeks ago showed in testing which was even stronger than the previous run from JJ:
98.2
99.6
94.4
98.5
96.1
101.7
95.8
100.6
100.0
101.9
98.9
99.5
98.5
102.5
97.8
102.2
94.0
93.1
98.5
100.4
92.8
95.6
96.1
99.4
98.1
100.6
97.6
94.8
100.5
94.8
95.2
92.3
96.5
95.9
96.8
97.8
92.9
98.2
96.2
101.9
100.6
99.5
97.4
100.0
98.5
102.5
94.3
97.0
Pretty spectacular.
If you want to push the output section as hard as possible the JJ 803S long plates are currently the highest gain 12AX7 tubes made at the moment today. Typically their gain is over 90 and most other 12AX7s today are 80-85. Five points of gain might not sound like much but it is quite a difference.
Here are the actual gain numbers in circuit that the last batch two weeks ago showed in testing which was even stronger than the previous run from JJ:
98.2
99.6
94.4
98.5
96.1
101.7
95.8
100.6
100.0
101.9
98.9
99.5
98.5
102.5
97.8
102.2
94.0
93.1
98.5
100.4
92.8
95.6
96.1
99.4
98.1
100.6
97.6
94.8
100.5
94.8
95.2
92.3
96.5
95.9
96.8
97.8
92.9
98.2
96.2
101.9
100.6
99.5
97.4
100.0
98.5
102.5
94.3
97.0
Pretty spectacular.