• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Gold mine of DI¥ audio tubes schematics from Japan

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:magnet: Decembre and January DIY articles are on line now : DHT RIAA EQ, headamplifier, line pre and tube amp's etc
 

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And what do you expect the DC difference to be between 50K and 100 Ohms?

(hint: they are both at 0V DC)

Of course I know (understand) that both control grids are at 0V level. But first I do not understand the use of a grid stopper resistance of only 100 Ohm value. I expect at least about 10 times higher, 1kOhm to be effective if that was the purpose of that resistor. Otherwise you could simply shortcut the grid to earth saving a resistor. It is the way I am looking at this diagram but I may me wrong.
And second, if the resistor is around 50k and for some reason one drives the input signal close to or exceeding 0V causing some control grid current, both control grids shift about the same amount in DC working point.
 
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