Repairing an SA-74 suspension unit, from a Neumann VMS-70 disk mastering lathe, which arrived with the head lift/drop lever jammed in the down position, preventing the top lid from being removed! The Neumann SX-74 stereophonic motional feedback cutter head was still attached, as it had been glued to the mount adapter, which can only be removed from the suspension unit by opening the top lid! Several mechanical and electrical repairs, adjustment/calibration procedures and even a bit of machining on the 1961 Moore Special Tools Jig Borer later, it was fully brought back to original specifications!
The Agnew Analog Reference Instrument Type 631 is a high performance direct drive motor, designed for professional disk mastering lathes and turntables. It is usually positioned on the floor under the lathe or turntable, driving the platter directly by means of a long driveshaft, similar to the drive system of the Neumann VMS-70 and several other professional disk mastering systems.
Back in 2015, we started a big lathe project, taking a beat-up Fairchild lathe from the 1930's, fitting it with an RCA cutter head, and eventually going full-on with a stereophonic feedback cutter head, vacuum clamp-down platter and automatically variable pitch.
On January 17, 2016, a very interesting experiment in sound recording technology was conducted at Magnetic Fidelity. Around that time, Naxatras were occupying the studio for a direct-to-master-tape recording, which crystallized beautifully shortly thereafter in their released EP.
Following the publication of my recent article, titled "Absolute Polarity for Disk Records" [1], I received encouraging feedback and requests for further information. Record enthusiasts often wonder about the dark secrets of the record production and manufacturing process, while professional mastering engineers are (or at least should be) striving to keep all their equipment in perfect working order, according to international standards. Their common goal is the best possible transfer of the sound from the performance space to the listening room. Magnetic tape is experiencing an impressive rise in popularity as a consumer medium in audiophile circles, with more albums becoming available in reels of 1/4" tape.
