Detlof:...I have near your knowledge / maybe less. My amps are the individual socket biasing type. As in CJ Premere5s.--16 el34s--16 trim pots.
I bought a set of 16 of these nos's--The seller told me these were tested 14 way to sundown. However, 4 wouldn't bias at all.-- In these amps you follow the instructions in the book; baisiclly,insert the tubes,turn all the trim pots back to zero,turn on the amps, turn on the pre no volume. after a few minutes bring the trim pots up till the led glows/ then trim pot goes back, to just extinguish the led. On the 4 that wouldn't bias ; means the led wouldn't go out - at all. I tried the 4 in different sockets/ and the other mono--same result.(Blew 2 fuses in the process)
Ok, A novel to ans your query??--Sorry. My point is that no matter how *these* tubes were tested before I bought them;It didn't matter.--They just wouldn't bias in my amps.No I don't know what gremlins were at work here. A tube tester may not tell you all you want to know-(as in my case)
I bought a set of 16 of these nos's--The seller told me these were tested 14 way to sundown. However, 4 wouldn't bias at all.-- In these amps you follow the instructions in the book; baisiclly,insert the tubes,turn all the trim pots back to zero,turn on the amps, turn on the pre no volume. after a few minutes bring the trim pots up till the led glows/ then trim pot goes back, to just extinguish the led. On the 4 that wouldn't bias ; means the led wouldn't go out - at all. I tried the 4 in different sockets/ and the other mono--same result.(Blew 2 fuses in the process)
Ok, A novel to ans your query??--Sorry. My point is that no matter how *these* tubes were tested before I bought them;It didn't matter.--They just wouldn't bias in my amps.No I don't know what gremlins were at work here. A tube tester may not tell you all you want to know-(as in my case)