Agnew Analog Reference Instruments Blog
Agnew Analog Blog

A Fashionable Rek-O-Kut Lathe Cabinet

Have you ever noticed the total absence of audio equipment from the luxury houses presented in glossy architecture and interior design magazines? It makes the inhabitants of such property come across as rather uncultured.

In fact, not only is an audiophile grade sound system a minimum requirement for the home of anyone affluent enough to hire an interior designer, but it is important to choose a designer who can appreciate the aura of sophistication and intellect projected by a beautifully restored vintage disk recording lathe, set in a handcrafted custom cabinet, in a conspicuous corner of the living room!

RCA reaches 100 Years of Age!

One hundred years ago, on October 19, 1919, RCA was founded. Among countless other things, they made some amazing ribbon microphones, several disk recording lathes, a few different cutter heads and some of the best sounding vacuum tubes, many of which are still in regular use to this day. 

School of Cut - Learning how to cut records at Agnew Analog

We recently had the pleasure of having Symatic over, from Bristol, UK, for a week of training on how to cut (and how not to cut) records.

Symatic runs Cut & Paste Records, a record label attracting some serious attention among skratchers, with high quality releases of skipless skratch samples, lock-groove tones, beats, and relevant music.

Hardinge HLV Super-Precision Lathe Restoration: Variable-Speed Drive

All Hardinge HLV and HLV-H variants feature a continuously variable speed drive to the spindle. It starts with a 3-phase, two speed squirrel cage induction motor, rated at 500 rpm and 1500 rpm nominal (less in practice, due to slip) at 50 Hz. This would be 600 rpm and 1800 rpm at 60 Hz.

Restoring a 1954 Hardinge HLV Super Precision Toolroom Lathe: The Carriage

Finding a Hardinge HLV can be challenging enough, especially if, like us, you happen to be located in Europe. At 1400 lbs, shipping and handling gets complicated. In a previous post, we described the joys of forklifting the beast onto a platform trolley (with suitable structural support added to the building), to get it to the workshop, though narrow corridors and doorways. Once there, it had to be lifted off the trolley and placed directly on the floor. With no chance of being able to drive the period-correct forklift truck into the shop, we had to get creative. A hydraulic engine hoist along with slings and tacks got the job done neatly. With the lathe on the floor and properly leveled, it was time to check it over, replacing, adjusting, lubricating and cleaning parts along the way!

Rek-O-Kut Master Pro System with modified Presto 1D Cutter Head

Tasos of Epos Laboratory (a Grado retipping specialist) from the beautiful south of Greece is the lucky owner of this 1950's Rek-O-Kut disk recording system.

It consists of a Rek-O-Kut Model V 16" turntable, which he found in the USA (where else?) as a non-runner. The motor was in bad shape and refused to run at all. Even if it would run, it was expecting to be fed on a regular diet of 110 VAC/60 Hz!

A new vintage lathe in the shop: The Hardinge HLV!

The best finds always pop up in the summer, when everyone else is on holidays! Still, they are not always nearby or easy to deal with. When this 1954 Hardinge HLV precision toolroom lathe appeared on the horizon, it took all of 5 minutes to decide to go for it and one week of frantic international phone calls to organize everything. An engineer was sent to check it over, local transportation to an industrial machinery crating facility, international transportation, more local transportation and another week later it was finally in our yard!

Presto 75A Restoration Project

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.

Presto 75A: 50 Hz 33 1/3 and 45 rpm Conversion

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!

Precision Motors and Control Systems for Leadscrew Automation

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.

Rek-O-Kut Model V: Repair and 50 Hz Conversion

  

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).

New Agnew Analog Product Plates

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.

Precision Transducer Development

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.

 

Restoring Vintage SME Tonearms

Over the past few years, we have restored a number of SME 3009 and 3012 tonearms, covering most of their variants made over the impressively long production life span of this model range.

This outstanding tonearm was first introduced in 1959, setting a standard for high performance tonearm design which is still hard to beat, 60 years later.

We have used our restored SME tonearms on a large number of reference reproduction systems, for our own use and for our customers, such as the Thorens TD160 project which was presented here last February. These systems are excellent for Quality Control in vinyl record manufacturing, to ensure that any defects are caught early.

They are of course also capable of offering an intensely enjoyable, accurate listening experience, coupled with an accurate cartridge.

Lab Report: An improved cutter head mounting system with integrated dashpot

The need for a new suspension for our recently presented Presto MRC-16 modification project brought about yet another innovation from our R&D laboratory: The Agnew Analog Reference Instrument Type 6021 Lathe Suspension Toolpost!

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.

Presto MRC-16 Variable Pitch Modification

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...

Repairing a Dial Indicator

A simple yet effective movement which has seen many decades of regular use, appears under the lid of this dial indicator.

It was once able to indicate accurately in 0.01 mm graduations, through a gear train driven by a rack on one side of the spindle.

Presto MRC-16 Lathe Motor

Presto disk recording lathes are often still in active use nowadays, nearly 80 years after they originally left the factory in New York. Let us have a closer look at what keeps them spinning!

Accurate Record Reproduction: Thorens TD160, SME 3009 and Van den Hul MC Two

For some reason, the people involved with the manufacturing of vinyl records are rather stoic types. The rare occasion when they are in a talkative mood, they mostly talk about the manufacturing process and equipment. They are not often talking about what happens after the records have been manufactured, the actual reproduction of these records, for pleasure or for the most critical step of manufacturing: Quality control.

Modified Thorens TD160 with SME 3009 and Van den Hul MC Two cartridge, with a test record
Modified Thorens TD160 with SME 3009 and Van den Hul MC Two cartridge, with a test record

What follows is the story of the restoration, modification, assembly, calibration and testing, of some components, which, if used properly, can result in a highly accurate phonograph disk reproduction system.

Motional Feedback Disk Recording System Design

 

In 2015, J. I. Agnew started developing a high-end cutting amplifier for disk mastering systems, to be used with motional feedback stereophonic cutter heads. During this process, he investigated the design and implementation problems of such transducers in great detail. As usual, he documented his progress, which evolved into an engineering report, titled "An Investigation of Motional Feedback Disk Recording System Design", which was accepted for publication in the November 2018 issue of the Journal of the Audio Engineering Society, following the customary peer review process.

Lab Report: The Agnew Analog Stereophonic Cutter Head

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.

Scully Lathe Restoration and Modification

This beauty is a fully restored and extensively modified, vintage Scully lathe, operated by Eric Conn at Independent Mastering, in Nashville, TN.

It started life in the 1940's as a completely manual machine. A sturdy design, capable of very decent results, these lathes were extensively used across the USA and other parts of the world for several decades. Many are still in operation today. In the original condition, they were quite limited in what they could do. But, as with most good lathes, they can take a lot of modification and improvement.

Precious Stones for Cutting Precious Records

There is a long history of use of precious stones as industrial materials, from precision bearings to cutting tools, lapping compounds to grinding tools and several other specialised applications.

The recording of phonograph records is essentially a machining operation, performed by means of a machine tool called a disk recording lathe. A special cutting tool is used to cut a continuous spiral groove on the surface of a blank disk. This tool is called a disk recording stylus, or simply cutting stylus.
The big difference to other forms of machining is that there is sonic information stored as modulation of the cut groove, which can be reproduced on another special machine, often called turntable or record player, or disk reproduction system.

Lab Report: Cutter Head Mounting Adapters

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.

But, in fact, almost any cutter head can be fitted to any lathe, as long as there is enough space for it to physically fit, by means of a suitable adapter. The eagle-eyed reader will probably have noticed that the cutter head mount on our prototype AM44 suspension is similar to, but not the same as, the mount used in Neumann suspension boxes. So, the adapter shown here was made specifically for our AM44 suspension unit.

Lab Report: Making cutting stylus shank adapters

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.

Critical listening at home: Audiophile High Fidelity Sound Reproducing Systems and the Recording Industry

audiophile analog audio setup

Meet George Vardis, a retired biologist with a Master's Degree in Food Technology, residing in Athens, Greece. George is a sophisticated man with many interests, including sailing, photography, motorbikes, and music. He plays the piano and the guitar, but his career always steered well clear of the music industry. He was never a recording artist, nor was he a recording engineer. In fact, he has probably never seen a recording studio in real life.

Schaublin 102 and Simonet two speed drive unit

Swiss Precision Engineering: The legendary Schaublin 102 precision lathe with parts of a Simonet lathe in the Agnew Analog laboratory! These pictures are from a 2016 restoration project, documented on the Agnew Analog website. Read the full report here: Schaublin 102 Swiss Precision Lathe Restoration

The AM44 Disk Mastering Lathe Project

The AM44 is a Neumann-based lathe, built on original Neumann castings, manufactured around 1944, during the second world war.

The project was founded by Flo Kaufmann, in Switzerland, when he managed to find a pile of these rare beds in the unexplored depth of a warehouse. The plan is to build them up into fully functional disk mastering systems, using newly designed and manufactured parts.

In 2016, Sabine and J. I. Agnew acquired one of these beds, built up and further developed it, into an exceptional quality disk mastering system, which was put to professional service at Magnetic Fidelity.

Absolute Polarity for Magnetic Tape

https://www.agnewanalog.com
https://www.magneticfidelity.com
PDF version

The Tape story

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.