CF in SE?

[Ten Over]

The Champ 12 has NFB around the 6V6 and OT.

[roberto]

This is not strictly local feedback, but it is one of the ways to feedback the secondary of the output transformer to the output tube(s).
Another option is to use the secondary on the cathode of the output transformer in SE, or ground the 4 Ohm tap and connect the two cathodes of the output tubes to 0 and 16 Ohm taps. This way you need more swing to drive the tubes.

[bepone]

what about if we put whole secondary in cathode , to create pentode linearisation.
/ if doesnt exist cathode feedback winding (99.8% that is not there) /
like here
http://livinginthepast-audioweb.co.uk/i ... edback.gif
http://livinginthepast-audioweb.co.uk/i ... ckwindings

[roberto]

As I was writing, it depends on the available swing on the last stage.
To apply local feedback to a stage, you always need to drive it with more voltage swing or more current.
...and then if he likes the new sound. I don't like too much feedback for guitar amps.