This is a pedal conversion of the preamp of the Lab Series® L5, a Moog-designed solid-state amplifier from the late 1970s that is widely considered the best and most tube-like solid-state amplifier ever made. It has two channels which are both fed into a shared distortion/master volume circuit as well as a compressor/limiter.
The original amps had the preamp integrated with the power amp. By splitting out the preamp, we can use this either as a normal pedal in a chain (e.g. tuner → overdrive → L5 Preamp → modulation / delay → amp input) or as a true preamp by plugging its output straight into a power amp (either a dedicated power amp or the “return” jack of an amp with an effects loop). The main difference will be the volume you run it at. This thing is capable of enormous volume, far more than any stompbox, so if you are using it like a pedal, don’t feel like you are doing something wrong by keeping the master volume down really low!
We’ve made a spreadsheet of the parts so you can very easily order most of what you need from Mouser. The remaining items can be obtained from Small Bear or Tayda Electronics in the United States or any of the major European part stores. There are no “unobtainium” or mojo NOS parts to hunt down.