Thought I might add the Wampler Plexi-Drive to the list after I did another Benson layout, as they are similar in many ways.  Just look at the two schematics side by side, and you’ll see what I mean.

Like anything involving JFETS, choose the resistors going to the drains to suit your JEFTS; they can and often do vary.   Usually, aiming for half voltage on the drain is an excellent place to start; this is where a breadboard and some clips come in handy.

WAMPLER PLEXI-DRIVE – VERO LAYOUT

WAMPLER PLEXI-DRIVE – VIDEO

WAMPLER PLEXI-DRIVE – SCHEMATIC & LTSPICE RESULTS

note: LTspice doesn’t have a regular switch in the library, so I’ve used a 100meg resistor in place of the “open” switch setting, and a 1ohm resistor for “closed”.