Alright, I need some help. I followed the OP's pcb layout except for leaving out the D1 diode and for D2 I used a 9.1 Zener diode. I have everything wired up and it has a bad hiss pretty much on any volume. I don't know much about building pedals so any help would be appreciated. Also should I put a 1N4148 diode for D1 or should I leave it out? Thanks in advance.