What have to look for: the same gain?
yup
Yes I know my fault sorry, I guess tubes are OK or gain measurements results not OK, what do you think?
Salas this post is for you.
Yes I know my fault sorry, I guess tubes are OK or gain measurements results not OK, what do you think?
Not exact mu between sections in same bottle is a very common thing. Due to construction process tolerances and/or age. You just swap tubes between positions or change and swap again for best gain and inter-channel match results.
You will not calculate or scope anything. Because I have already measured and posted that using a Zobel as the manufacturer recommends has a true and strong effect.
No need you discover America once again.
After you install with final cabling trim, you start with the Jensen recommendation for Zobel and Itch input load. You just listen to 200pF, 150pF, 100pF in the RC and you decide.
No need you discover America once again.
After you install with final cabling trim, you start with the Jensen recommendation for Zobel and Itch input load. You just listen to 200pF, 150pF, 100pF in the RC and you decide.
So only one resistor 18-20K across seconday?
Obviously, but if you will install directly across the SUT just make the Itch's input load resistor 1Meg. Else you just install 18-20K as Itch's input load and you leave the SUT alone. When in same box without interconnects I see no real reason you damp right at the SUT's secondary.
As the attached pic with SUT load resistor 18-20K across sescondaries?
Only if there is 18-20K directly on the SUT's secondary also. Yes.
One can try the 12SX7 that has a good reputation for very similar triodes within the same bottle. Different heater though and not so common/cheap.Not exact mu between sections in same bottle is a very common thing.
Or a selected pair of 6J5's
The other way is like the attached pic?
I meg parallell with 20 k is 19,6 k. I doesent matter in this case
I meg parallell with 20 k is 19,6 k. I doesent matter in this case
It makes sense when the SUT is a self contained unit in own box, so the grid will not be flapping on the cool breeze when the input is disconnected.
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