Completed builds: Alembic-like state-variable and sallen-key filter preamps Lovepedal Eternity Phase 100 Brown source Fuzz Face Flipster Alembic F2B (tube preamp) Opamp and FET buffers Loads of speakercabinets and ampracks Busy building a modular synth (ssm2044 vcfs, preamps, ADSR's, VCO's, VCA's) Tables Bookshelves Basses So many things! :D
The schematic for the other bass preamp by Alembic, the F2b, can be found quite easily on the net, but I hadn't earlier seen the schematic for the F1x.
The product blurb mentioned something that to me pointed to integrated filter IC's like the UAF42 (although that is reported to sound "not great"), but apparently not