Agnew Analog Reference Instruments Blog
Agnew Analog Blog

SA-74 Suspension Unit Repair From Neumann VMS-70 Disk Mastering Lathe

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!

J.l. Agnew will be speaking at Craft Research Network event!

As part of the 5th Craft Studio event, held online via Zoom and organized by the Craft Research Network, J.l. Agnew will be holding a presentation of his work at the Agnew Analog Precision Engineering Laboratory. The event is scheduled for Friday, September 16, 2022, at 17:00 CET. Registration (free of charge) at least a week in advance of the event is required for participation. Registration form: https://craftresearch.org/join The Craft Research Network is an international, multidisciplinary research network for academics and others with an interest in craft. Craft Studio 5 is hosted by Rene Wiedner (Associate Professor, University of Warwick, UK) and Marleen Hofland-Mol (PhD Candidate, Erasmus University, Rotterdam, NL).

Agnew Analog Type 631 Direct Drive Motor and Type 231 Control Module

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.



Repairing a Westrex 2B cutter head

Some time ago we were asked to repair a vintage Westrex 2B feedback cutter head.
As with all Western Electric and Westrex products, their cutter heads were beautifully made and represented the state of the art in their time. Not only did they sound great, they also looked aesthetically pleasing, with curved lines that were not a trivial task to manufacture, in the days before CNC machine tools, CAD software and pocket calculators!

New Series 6500 Driveshafts now available

We have developed a range of precision machined driveshafts that can be supplied in any length required for your applications, with end diameters to your specification. Each end could be made a different diameter, if required, and we can also supply a useful range of accessories, such as constant velocity flexible couplers, vibration dampers, soft-start clutches and mounting flanges, to suit your application.

New line of high precision machine spindles now available

A good machine spindle is one of the factors defining the accuracy attainable from rotating machinery. This applies equally to machine tools used in industrial manufacturing and to disk recording and mastering lathes, used to make phonograph records.

At Agnew Analog Reference Instruments, we use some of the finest and most accurate industrial manufacturing machine tools ever made, to build some of the finest and most accurate disk recording and mastering equipment ever made, so we have had to learn a thing or three about machine spindles along the way.

 New Hydrodynamic Oil-bath Bearing Units Available Now!

For many long years, J. I. Agnew has been examining, adjusting, repairing and replacing bearing systems of all kinds, from disk recording lathes and turntables to tape machines, high precision machine tools, measurement instruments, industrial equipment and all manners of motor vehicles, from passenger cars to heavy trucks. Over the past few years, he has designed and machined countless bearing units to replace worn or damaged units on a diverse range of disk recording lathes and machine tools. Valuable experience was gained, which along with his solid engineering background, was put to good use in improving his designs further and further, up until the current stage of development was reached.

New Series 6100 Vacuum Platters

The ultimate vacuum platter is finally here, and it is very reasonably priced. After three years of exhaustive research and development and several prototypes of different versions, along with field testing, we have finally arrived at what we believe is the most advanced and accurate vacuum platter ever made.



Available in 14" and 12" versions, our Type 6114 and Type 6112 Reference Instruments are now available to order, in any quantity. Do you want 100 of them? We'll make them, and threw in a quantity discount as well!

 Heater Wire Terminals

We now have hundreds of heater wire terminals in stock, as we are in the process of stocking up for the manufacturing of our new stereophonic cutter head. Since these items have been "unobtanium" for a long while now, we are happy to offer these individually or in pairs to anyone needing them for their vintage cutter heads, or those trying their luck at making DIY heads. 
 

The Reliable Stylus Heating System: Type 192

The Agnew Analog Reference Instrument Type 192 is a minimalist, industrial-grade stylus heater supply unit, designed and built to last forever.
It is a current-regulated design, set at the factory for 550 mA, in an ultra-ruggedized configuration, for maximum reliability in constant-duty environments, when downtime is not an option.

The Vacuum Tube Electrochemical Synthesizer: Type 8001

The Agnew Analog Research and Development laboratory makes a major breakthrough in the fight against the SARS-CoV-2 pandemic!



It is not a vaccine and it probably won’t do much against the virus itself (although it has been suggested that it could have an effect not unlike the yodeling of Slim Whitman upon the aliens in Tim Burton’s “Mars Attacks”, either on the virus or on humans, or both), but will at least give you something to do while you wait it out.

The Agnew Analog Reference Instrument Type 8001 is a unique electrochemical synthesizer, generating strange sounds through chemical reactions occurring in the built in reactor cell.

Westrex 2B Stylus Adapter

The Westrex 2B is a motional feedback cutter head, introduced in 1952 by the Western Electric Export Company. It followed hot on the heels of the Westrex 2A, dating from 1947, which was itself a lateral implementation of the principles first described by Wiebusch, Vieth and Yenzer in 1938, with a couple of relevant patents issued by 1939, for a vertical cutter head employing motional feedback.

Direct-Drive Conversion on a Fairchild Lathe

The Fairchild line of disk recording lathes, first appearing in the early 1930’s, featured a General Electric hysteresis synchronous AC motor, running at high speed, with a worm and gear reduction to drive the platter. While this system in its various permutations in their different models was impressively well made and performed well for its time (see here for a more detailed description and pictures), a direct-drive system with a floor mounted motor is clearly the way to go if the highest level of performance is to be attained.


Type 1501 Stylus Shank Adapter gets a Flat!

Our popular Agnew Analog Reference Instrument Type 1501 Stylus shank adapter was intended to make it possible to use the Neumann-style taper shank stylus (Transco 320, Adamant NSH-2, etc) with vintage mono heads such as the Presto 1-C and 1-D, which need a long shank stylus.

Up to now, customers would just install the adapter and leave it there, only occasionally replacing the stylus. One customer, however, wanted to be able to leave the stylii aligned in the adapter, and change them out without needing to realign.

Testing Directly-Heated Triodes

In the darkest corner of the catacombs under the lab, illuminated only by glowing directly-heated triode filaments, top secret experimental research is being conducted…

Presto 1-D Cutter Head Feedback Modification

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.


Rebuilding an Audax R-56 Cutter Head with Feedback

This Audax cutter head arrived with a fried coil and a completely crusted armature. The damping material had not aged well.

A complete disassembly, cleanup and reassembly would be required, with the renewal of the damping material and drive coil. This was yet another perfect candidate for our feedback modification.

Fitting a Neumann Cutter Head to a Presto Lathe

Neumann cutter heads have a rib along the back, for mounting. Presto lathes, on the other hand, together with the vast majority of non-Neumann vintage lathes (Rek-O-Kut, Fairchild, etc.), have a mount with two slots, for cutter heads with two threaded holes on the back (Audax, Presto, Fairchild, RCA, etc).

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.