[Andre Jute]

Ian Iveson quotes Pompass Plodnick on whether NFB is built into
triodes:
..."Yes, if you want it to, no if you don't."...

and then concludes:
You can't say that about real feedback. If it's optional, it's in your
head. If you must take it into account in design, then it is in the
circuit.

Or of course the NFB could be sealed into the component itself, eh
Iveson.

See my reply to Chris Hornbeck in this thread about the beneficial
effect of black box thinking.

Andre Jute
Put your mind in gear, sonny