Gibson GA50 question

[Leevi]

What is the idea/benefit of the 250p-330K coupling from the PI plate to the power tube plate?That is missing from the GA50T.
https://el34world.com/charts/Schematics/files/Gibson/Gibson_ga_50.pdf
https://el34world.com/charts/Schematics/files/Gibson/Gibson_ga50t.pdf
/Leevi

[sluckey]

What is the idea/benefit of the 250p-330K coupling from the PI plate to the power tube plate?

That is a local negative feedback loop.

[Leevi]

I have built this amp several years ago and I left the loop away.Maybe the reason was that I didn't notice any difference if it was connected or not.Anyway hard to remember./Leevi

[pdf64]

Fender did something similar, but full bandwidth, with the ab165 bassman https://el34world.com/charts/Schematics/files/Fender/Fender_bassman_ab165_schematic.pdf