No, I am not an Electronic Engineer. I am a "Hydraulic" Engineer... (I dont know the exactly designation).
The holes for the rotary pots and the slots for the sliders were milled with a cnc milling machine.
I really like JohnK's pedals! As I saw his MonoBlock I got the Idea to use sliders instead of rotary pots.
I used this schematic: Klick
I had the PCBs made locally. But you can made pcbs also online: Klick
I am a big "fan" of Gallien-Krueger amps. That are my favourite amps. But I am also a big fan of tube amps. I've been testing various overdrives for twenty years. But I haven't found the perfect OD for myself yet. Recently I've been testing pedals with transformers. They could be the right way.
The 800RAIL sound good. A lot of OD-variations are possible. But it doesn't sound 100% like an 800RB.
My first one: sonnßeta
It is a Sunn Beat Bass Preamp in pedal format.
I used an existing schematic from dirtbox layouts and create a pcd that fits in a 1590B enclosure