Class A 90% 450v Bias gM Gain
Tube mA      
         
         
         
Sovtek 6550WE 70 43.2 409 7.8
Electro-Harmonix 6550 70 46.7 379 6.8
         
         
Tung-Sol 6L6STR 60 40.6 401 5.8
JJ Tesla 6L6GC 60 39.5 507 7.3
Sino 6L6WGS 60 46 410 5.2
Sovtek 6L6WXT+ 60 38.7 369 5.6
         
         
Fail Point Sovtek 60 30.3 55 2.4
Fail Point JJ tesla 60 42 74 3.3
Fail Point RCA BK. PT 60 37.7 65 3.3
Fail Point GE 60 36.6 70 3.1
         
Sovtek 7027 60 40.2 468 6.9
Tung-Sol 7027 60 44.7 462 6.7
JJ Tesla 7027A 60 40.2 519 7.6
         
Class A 90% 450v Bias gM Gain
         
Gold Lion KT66 60 45.7 485 7.2
Tung-Sol KT66 60 45.7 449 6.2
JJ Tesla KT66 60 36.3 484 7.1
Sino KT66 60 46.4 516 7.2
         
Tung-Sol 7581A 60 38.8 462 6.7
         
Gold Lion KT77 60 28.3 752 10.7
JJ Tesla KT77 60 34.2 766 10.8
JJ Tesla 5881 50 42 596 6.7
Sino 5881 50 40.3 484 5.6
Sovtek 5881WXT 50 40 595 7.5
Sovtek 5881 50 40.6 591 7.4
Tung-Sol 5881 50 45.6 548 6.0
         
Electro-Harmonix 6V6GT 28 37.37 529 4.2
JJ Tesla 6V6S 28 42.5 602 4.7
Tung-Sol 6V6GT 28 40.7 477 3.7
Telefunken 6V6 28 41.6 655 5.2
         
Class A 90% 450v Bias gM Gain
         
Electro-Harmonix 6CA7 50 38.6 399 4.5
JJ Tesla 6CA7 50 34.2 466 5.2
JJ Tesla E34L 50 35 405 4.6
JJ Tesla EL34II 50 35.3 393 4.5
Electro-Harmonix EL34 50 35.3 395 4.6
Mullard EL34 50 36.9 434 4.8
Sino EL34B 50 33.9 912 10.3
Telefunken EL34 50 36.9 467 5.2
Tung-Sol EL34B 50 32.6 330 3.8