Thsee are the extremely rare,and sought after,Bill Putnam era Preamps. Transformer in and out,cascode input stage. 2 tube. one 12AX7 and one 12AY7. They have a tap for the negative feedback loop,for inserting passive EQ or light dependent gain elements. These are the “B” types,which are even rarer; the last modification Bill made before switching to solid state. Multipin connectors,and mounting bracket included. They will need a cap job,like all gear from this era. One dual 10MF electrolytic,and 3 other standard value caps. Copy of original schematic..None of the on line drawings are of this model. The changes are subtle.A few cathode resistors and caps to accommodate different output tubes. If interested,message me,and I will take more photos,if you want.