Feedback and mu-followers

[mark_titano]

Hi all.
I’m reading about feedback and stability problems, particularly regarding partial feedback and feedback over two stages, without the transformer in the feedback loop.
I found really nice the Crowhurst’s article regarding feedback amplifiers design (from the series “building your own amplifier”).
There are a lot of interesting math and usable graphics in that description. Above all I found fine the description of how to choose the cut off frequencies when there are more that one reactive element in the feedback loop.
My question is: in the case that I’d like to design a two stage amp using feedback from output plate to driver’s cathode and if the driver stage is a mu-follower, have I to consider the frequency cut off in the mu follower too? I think that yes, I have to do that. C1 is actually in the feedback loop, right?

And if I’d like to use Gary Pimm’s self bias ccs with hybrid mu follower output in place of upper tube?

http://home.pacifier.com/~gpimm/self_bias.htm

Mark

[Sch3mat1c]

Yes, the pole is C1 & R1.

Tim

[mark_titano]

Thankyou Tim
Take a look to the Pimm's ccs, please.
I don't understand which is the pole in that schematic.
Have I to consider the bias as fixed and R14 like “Rg” ?
I’m not sure, at all...

Mark