A customer recently imported a vintage Presto 75A disk recording lathe from the USA, with a view to cutting records in Europe.
He quickly discovered, like many people before him, that it was spinning a bit slower than it should, when operated from 50 Hz mains, via a simple step-down transformer. As with most vintage record cutting machines, the platter is powered by a synchronous AC motor, which “locks” to the line frequency.
Mr and Mrs Agnew are now officially husband and wife! What better occasion to preserve forever, on a long lasting format that can be enjoyed by future generations?
The wedding ceremony and the wedding speech of J. I.’s father were recorded direct-to-disk, using a 1930’s Presto 75A disk recording lathe. It was also recorded in parallel on analog tape. A Nikon FT-2 35 mm film SLR camera was used for photography.
Analog media will last a very long time, making them ideal for the documentation of important events. They also contributed beautifully to the romantic aesthetic of our wedding.
We have done 50 Hz conversions (and even some 60 Hz ones!) on many different lathes and turntables, using all of the possible methods of doing so: New rubber rollers, new capstans, new belt pulleys and even electronic frequency conversion (Agnew Analog Type 191 frequency converter) for professional disk mastering systems.
This week, we will have a look at the Presto 75A, a high quality machine, dating from the 1930’s, which was even used by the BBC as a broadcasting turntable!
Inspired by the toolposts used in metalworking lathes and improving upon the cutter head mounting system used by Neumann, the Type 6021 will accurately and rigidly hold any cutter head fitted with a suitable bar, including Neumann, Vinylium and FloKaSon heads, as well as any other head imaginable, through the use of our Series 1400 head mount adapter range.
A rather optimistic gentleman arrived with a Presto MRC-16 disk recording lathe, inquiring about the possibility of repairing the broken suspension and making a cutter head bracket from scratch. He then asked about the possibility of figuring out some way in which lead-in, lead-out, and track mark spirals could be cut on this machine, which was originally intended as a very basic machine, with no provision for spirals, not even a hand crank. Then came the really ambitious part: He would ideally like to be able to adjust the pitch and if possible, control the lathe through his computer!
One glance at the steampunk aesthetic of the manufacturer’s name plate and the overall state of this primitive machine would have been enough to deter the average engineer, in fear that there might be something potentially radioactive hiding within…
Happy new year! Time to reveal what has been secretly developing in the lab throughout the past year: A stereophonic cutter head of an entirely unique design, invented by J. I. Agnew during his work with experimental transducers for measurement and testing purposes.
In the previous episode, we had a look at taper shank stylus adapters and saw a vintage magnetic monophonic cutter head fitted to the AM44 lathe. The two are not normally compatible. Neumann lathe suspensions do not have the same mount as the suspensions of Presto, Fairchild, RCA and other lathes of the monophonic era, which were originally designed to accept such cutter heads.
Stereophonic cutter heads developed by Neumann are designed to accept a cutting stylus with a conical shank, resembling a micro-miniature version of a Morse Taper, a type of fitting frequently encountered in machine tools, especially metalworking lathes. Vinylium and FloKaSon cutter heads also adopted the same fitting for the sake of compatibility. But most other cutter heads, especially all those predating the stereophonic era, used long, thin cylindrical shanks, often with a flat machined on one side, to allow a set-screw to align the stylus and secure it in place.