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Lummerland with 2xel84

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JTM:

--- Zitat von: Dirk am 13.07.2020 16:02 ---Hier schon mal ein Bild vom Bub

--- Ende Zitat ---

Stark, bin gespannt! Mit NFB?

Leadman:
2x6v6 Lummerland is here!

Leadman:
What is the purpose of R14(220k) in the phase inverter of the LummerLand? This resistor donīt exist in the original Blues Express el84 desing.
Itīs the first time I see that resistor in a cathodyne phase inverter and I am curious about it.
Maybe it attenuates the signal before de push pull triodes? because the original desing use pentode tubes and not triode....

iefes:
R14 provides the grid of the cathodyne with a (self-adjusting) bias voltage. Typically the value would be 470k to 1M. Indeed, I would have guessed that the values of R14 and R28 are actually swapped. This would yield a more typical setup but to be honest I'm not very familiar with those small dual-triode push-pull stages and I'm sure Dirk knows his stuff  :topjob:

Leadman:
Ah! the r28 acts like a grid stopper for prevent blocking distortion in that desing, and maybe de r14 has been lowered to 220k for match with the push pull triode power section.

Thanks!

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