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 Neumann cutter head arrived as a particularly clean example, but in need of repair. The first obvious issue was that the coil was fried. The second issue was that the original stylus fitting was broken.
This item is the latest addition to our collection of experimental transducer prototypes. What you see is a multi-layer miniature winding on a custom machined former, entirely made in-house at the Agnew Analog Research & Development Laboratory.