In the darkest corner of the catacombs under the lab, illuminated only by glowing directly-heated triode filaments, top secret experimental research is being conducted…
J. I. Agnew (52)
Presto 1-D and 1-C cutter heads are frequently encountered on our lab bench for repair and restoration. Some are just regular repairs to original spec, others are rewound to a different impedance, but some undergo more comprehensive and exciting modifications!
We have previously examined modifications where a feedback system was added to a Neumann MS-52H and an Audax R-56 cutter head. This time, we shall discuss adding feedback to a Presto 1-D, which arrived with damaged coils.
This Audax cutter head arrived with a fried coil and a completely crusted armature. The damping material had not aged well.
A complete disassembly, cleanup and reassembly would be required, with the renewal of the damping material and drive coil. This was yet another perfect candidate for our feedback modification.
Neumann cutter heads have a rib along the back, for mounting. Presto lathes, on the other hand, together with the vast majority of non-Neumann vintage lathes (Rek-O-Kut, Fairchild, etc.), have a mount with two slots, for cutter heads with two threaded holes on the back (Audax, Presto, Fairchild, RCA, etc).
The second issue was that the original stylus fitting was broken.