It would appear that 50 Hz conversions of vintage "made in USA" disk recording lathes are becoming rather fashionable! Last week we examined how we converted a Rek-O-Kut Model V by machining a new capstan and making a special transformer, Type 1760.
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!
Depicted here, are two external rotor, polyphase, electronic commutation motors, fitted to custom mounting plates, ready to be installed in disk recording systems, to control the leadscrew.
These are very high precision motors, with features allowing accurate, closed-loop control of speed over a wide range, as well as positioning applications. A combination of hall sensor arrays and high resolution encoders makes them extremely versatile, compatible with a wide range of lathes.
With powder coated end-bells in Agnew-cream-white and our fancy engraved stainless steel product plates riveted on, with type designation and serial number stamped by hand as a seal of approval following our extensive testing and quality control procedures, our transformers now look as good as they are!
As with the vast majority of disk recording lathes of US manufacture, this 1956 Rek-O-Kut Model V was configured to spin at the correct speeds when powered by 50 Hz mains. One of our customers imported it from the USA and wanted to run it at 230 VAC/50 Hz European mains power. We have encountered this situation countless times by now. We recently also described how we converted a Presto MRC16 to 50 Hz operation by making new rubber rollers to different dimensions, while some years back, we developed the first version of Type 191, a stable electronic frequency converter for professional disk mastering lathes, which are often impractical or costly to convert by other means (Lyrec direct-drive motor on Neumann lathes, belt driven Scully lathes, gear-driven Fairchild systems, etc).
We are very excited to present our new product plates, featuring our new logo, engraved on stainless steel plates!
The new logo was designed by Sabine Agnew and the choice of stainless steel as a material for the plates acts as a further statement of our commitment to exceptional quality, to accompany our products throughout their extremely long service life with no deterioration.
