This detailed manual applies to all 70 or so of the original run of our Type 636 reverbs, both the vintage and new tank versions.
We’re not making any more of these, however we have put the same preamp technology (a distillation of a deep dive into why this particular germanium circuit sounds so good) into our Type 636P Pedal/Desktop Preamp, and also the twin rack transformer balanced version, the Type 636P2.