Zvex BOR, BOM, Catalinbread RAH

[POTL]

Hello everyone, recently I got carried away with projects on JFET, but lately I have been interested in MOSFET
Schemes on the MOSFET are similar in many respects, the main trouble for me was the first cascade, it uses a 9-voltadron, so I can not run the circuit at 18 volts or higher.
The question is whether the zener diode is a necessary part of the circuit or I can replace it with eg 1N4148

[Kipper4]

http://www.diystompboxes.com/smfforum/index.php?topic=69792.0