Direct Coupling and No bias on JFET guitar preamp's
There is bias on the gate and this bias is as expected negative:

As long as the bias is the voltage from the gate to the source:

$$
U_{gs} = U_g - U_s = 0 - positive &lt; 0
$$







simulate this circuit &ndash; Schematic created using CircuitLab

BTW, JFETs can work with 0 bias when the input signals are in mV range. Such small signals can't open the PN junction of the gate, so the gate current is still close to 0, but the slope of the JFET is maximal.