Implementing negative feedback on a JFET amplifier
You are missing some little things .Your first attempt is positive feedback .The second attempt gives a low input impedance which may not be wanted ,This means that the input coupling cap C1 gives far too much low cut .You could make feedback resistor R10 1 meg and place 470K in series with C1 .Expect a gain of about 2 on your sim.If you beat this circuit into shape on the sim and expect consistant performance when built with discrete Jfets you will have to make changes .JFETs have big spreads .