Questions about Bassman70

[H Chandler]

http://schematicheaven.com/fenderamp..._bassman70.pdf


Why are the plate resistors in the preamp bypassed with 500pF caps?
How does the V2 circuit work - what does the 250K resistor from grid to plate do, NFB?
Why no coupling caps on plates of V1b and V3b?
Why is there a PT center tap and why is it connected where it is?
What's the 30K and 2700 power resistor all about?

Thanks
Howard

[H Chandler]

http://schematicheaven.com/fenderamp..._bassman70.pdf

What's the 30K and 2700 power resistor all about?

Figured this one out. It's a voltage divider to drop B+ for the preamp section. Yes?