I'm curious about the purpose of the circuit that is circled in red. It shows up in a few HiWatts and Harry Joyce models.
It looks somewhat similar to a John Broskie/Akido noise reduction method on a grounded grid circuit. A sampling of the power supply noise is placed on the grid and added into the signal chain out of phase to cancel some of the PS noise...
Not sure if I'm looking at it correctly...maybe it's just there to set a voltage level on the PI grids?
DR504 custom circuit question
Moderators: pompeiisneaks, Colossal
DR504 custom circuit question
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Steve
Re: DR504 custom circuit question
Bingo!maybe it's just there to set a voltage level on the PI grids?
It's just a cathode follower with a dc level (provided by the voltage divider) applied to the grid. The cathode is basically the same dc level.