2nd stage grid stoppers

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Smokebreak
Posts: 1391
Joined: Tue Dec 18, 2012 5:53 pm
Location: Texas

2nd stage grid stoppers

Post by Smokebreak »

Looking at Marshall type preamps, sometimes I see the 470K resistor for 2nd stage between preceding vol pot wiper and grid, ala 1987, and sometimes it's before the pot, ala JCM800 2204 amongst others . What does this accomplish?

Also, when used as voltage divider, usually the junction of 470K pair feeds the grid, but I've seen it (ala chupacabra) reversed(?) where the leg to ground precedes the grid stopper. What effect does this have?

At first glance it would seem each scenario is specific to either 2stage+CF or 3+CF but I'm a bit unsure..
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