Adding a reverb in a fender champ circuit

[tubeswell]

Hi guys,
So I have tried to change the nfb on the v3a, that still doesn’t work...

There must be something incorrect in the way you're trying to connect the NFB, because it should work if connected properly. The output of the voltage divider in the NFB loop needs to be connected to the 'other end' of Rk||Ck (i.e. the opposite end from the end which is connected to the cathode). You have to have the 47R resistor between the Rk||Ck and the ground.