[Listening test] Audibility of stylus profiles

Vinyl Frontiers:

[metal machine music audio technica burn]

Can we hear stylus profiles?

Do stylus profile shapes have distinct audible signatures?

Manufacturer: Audio Technica, Europe
Prices: VM95 range from £29; VM500 range from £:99 and the VM700 range are typically about £60 more than the VM500 with similar stylie YMMV
Reviewer: Mark Wheeler - TNT UK
Another opportunity to spend money on vinyl visited by TNT-audio, 2018
Reviewed: February 2017 to October 2018

Introduction

It seems that from time immemorial, or at least the living memory of anyone with any high frequency hearing intact, special properties have been invested in the shape of the chip of industrial diamond nestling in the LP groove. The Pickering-Stanton group made much of their elliptical styli being better able to trace the asymmetrical shape of the LP stereo groove than rival conical styli and introduced their proprietary term Traceability.

Stylus profiles used to be extensively discussed when a vinyl replay system was an essential component of every aspirant couple's first home. Your Old Scribe still has a paper copy of a useful article explaining stylus tips in Hi-Fi Snooz back in the day when it still mixed in some technical erudition among its audio consumerism. Fortunately, the article has been scanned and uploaded here.

In the days when moving magnet and moving iron cartridges, with interchangeable styli, dominated the mass market, stylus profile and tracking force were the primary differences between models in any manufacturers range. Such was this a dominant hegemony that your Old Scribe remembers being surprised when Shure introduced the M95 range above the M75 range, with exactly the same range (and alphabetical designations) as the existing M75ED (elliptical 0.75-1.5g), M75G (spherical 0.75-1.5g), M75EJ (elliptical 1.5-3g and the best tracker in the range), M75-6/B/-6S (spherical 1.5-3g) stylus options. Audition proved the M95 models to be superior, adding additional audiophile paranoia, within one range, to questions about whether a better generator body with a cheaper tip was superior to the cheaper generator body with a superior stylus.

Audio Technica have managed, over the years to create a bewildering range of superficially similar moving magnet cartridges, with overlaps in price. Fortunately they have recently streamlined the best features of many of these into three ranges. The three ranges differ from each other by mechanical and generator quality and may host the full range of stylus profiles on largely similar cantilever-suspension systems below the top models. So Clive Atkins, of Audio Technica Europe, was inducted into the secret mountaintop lair of TNT-Audio clutching the whole VM range of styli and a couple of Audio Technica VM500 cartridge bodies.

Gary Hargreaves of Audiofile brought the Audiofile AT LPT5 as a synergistic match for the cartridges, and also brought their own Paratrace stylus for comparison. This is an aftermarket stylus upgrade for the popular AT 95E. Two other experienced listeners were present. Rarely does a range of cartridges offer the opportunity to change only one cluster of variables, so this band of brother audiophiles were keen to conduct comparisons.

The variables to be juggled in any chosen cartridge configuration are from disc surface up:

Stylus profile, mass, attachment method & polish
Cantilever material, length, mass & shape
Suspension compliance, damping, tie & orientation
Generator design & materials
Body design & materials

After this review was written, long after the audition, we find Audio Technica explain the VM500 range of styli thus: "The 500 Series family of cartridges is the entry-level series and consists of four models, all of which feature an aluminum cantilever, centre shield plate between the left and right channels to reduce crosstalk, and a durable low-resonance polymer housing. The VM510CB uses a 0.6 mil conical-shaped stylus bonded to a round shank. Conical-shaped styli are the easiest to make and therefore are typically lower in cost. They are durable and long-wearing, but cannot provide the same level of fidelity compared to a more elaborate-shaped design. For example, the VM520EB, which uses a bonded elliptical-shaped tip, boasts greater channel separation, extended high-frequency response and improved transient response. The VM530EN nude-mounts the same elliptical tip (the tip and shank of nude styli are made from a single piece of diamond), taking the performance up a notch from the 520EB, with even greater high-frequency extension, improved transient response and clarity. At the top of our entry-level VM 500 Series family is the VM540ML. The 540 uses our popular MicroLine stylus, typically found only on more costly models. The stylus is nude-mounted using a square shank for precise alignment to the cantilever. The MicroLine stylus traces the record groove with remarkable accuracy, resulting in nuanced audio reproduction, greater channel separation and low distortion levels that elliptical and conical styli simply cannot match."

Body mount strength

That last factor enjoyed a brief vogue for a period in the 1980s, when there was a trend among certain manufacturers to take an established mass produced design and add a more rigid body. These were particularly popular among the Flat-Earth fraternity (well there are few sororities in the genus audiophilia), the most notable example being the Linn K9 which was named after Dr Who's dog's head, with a similar shape.

There were also variations from other manufacturers on Nagoaka and Grado models among others. The argument was that the mechanical closed loop between turntable platter (and hence LP surface) and stylus cantilever was more cost effective than the same budget allocated to tip quality, which was the dominant narrative until then. This, the then Flat Earth, manufacturers argued, had more effect on Rhythm, bass and pace than other factors. Audio Technica tackle this in-house by offering the VM700 range with its superior mechanical characteristics.

That Linn chose the Audio Technica AT95E as their base generator, cantilever & stylus assembly speaks volumes. Remember Linn K9 was a beefed up body on an AT95E mechanical integrity more important than stylus profile and polish in the context of a Linn front end. They argued that an <>Ittock<> carrying a <>K9<> would sound better than a basic plus carrying a Karma. That Linn and their customers believed the end product Linn k9 was worth double the price of the economy Audio Technica AT95E is equally telling, thus competing against models higher in the Audio Technica range. Thus, the basic generator assemblies chosen for this explorations, the Audio Technica VM500 and the new Audio Technica VM95 are built on excellent foundations with a pedigree that is probably familiar to most audiophiles around the world.

Fortunately, the new Audio Technica VM500 range is available with many of the popular stylus profiles, with mostly similar aluminium cantilevers. Therefore we might be able to develop a series of listening experiences that may correlate to differences in stylus profiles. These might lead us to form hypotheses whether reproduction quality ascends linearly as shapes progress (or regress) from conical to the more extreme derivatives of elliptical or faceted shapes.

The bewildering Audio-Technica nomenclature should soon be now gone. AT91, AT92, AT93, AT95E, AT100E, AT110E (similar to the Nineties, but with PC-OCC internal wiring), AT120 & AT150 (similar body to AT100 with different stylus) ATN150ML (boron cantilever), ATN150MLx (gold-plated boron cantilever), AT440MLa, AT440MLb, etc. The old ranges were considerably less systematic than the new ranges, which is why we can now, on TNT-audio.com, use the new ranges to play with different stylus profiles, confident that the differences can be attributed purely to the stylus and cantilever.

Fortunately for this experiment, the equally bewildering range of tracking forces recommended for the previous ranges are all now merged. All the stylus assemblies have the same suspension block, but different profiles engender different frictional forces with groove walls and because they have different contact patch areas, stylus pressure will be different with different profiles. The different friction will require different bias to keep the stylus centred evenly between on each groove wall and live experience dictated any changes. Audio-Technica are no longer in the race to the lowest tracking forces, loved in the late 1970's, and now recommend forces around 1.8-2.2g. Trial and error reached just under 2.2g for the best compromise between bass quality, tracking and soundstage when mounted in a Rega RB250 on the Audio File upgraded Audio Technica LPT5.

Sound quality

This is not a review, but an exploration of how different stylus profiles affect the sound. The VM500/700 range feature oxygen-free copper para-toroidal coils.
"Para-toroidal? demand Plebs, stage left, "Is that 'para' as in Paramilitary, or Parapsychology or Parallel or Parachute or just Paranoid? It is not explained."

The higher spec coils and more sophisticated generator construction are supposed to endow the VM500 & VM700 ranges with improved transparency and separation, in theory, over the old AT95 and the new VM95 ranges, reviewed here. The coils are separated magnetically by a permalloy centre shield plate. This ensures the effective electrical separation of left and right channels, thus suppressing electrical crosstalk to below 40dB. 40dB is about the the theoretical limit of crosstalk found between left and right channel groove sides of an LP. As Audio Technica point out, the VM500 and VM700 range generator circuits are equal to the information available in the grooves of the record itself. Thus, the interchangeable stylus Audio Technica VM500 range is the perfect mule for our experiment.

The high electrical spec could enable a clearer distinction between the stylus profiles and the data from this test will be triangulated with data from a similar test with the new VM95 range soon. Clive Atkins of Audio Technica Europe tells me that those para-toroidal coils improve generating efficiency and offer greater linearity, since leakage of magnetic flux in this continuous and unitised magnetic circuit is low. Presumably for similar reasons as torroidal inductors and transformers have more focused magentic fields and therefore lower loss. Ditto the high permeability laminated cores of the VM500 and VM700 coils will also preserve more precious energy generated from the turntable motor via the groove wiggles.

We began listening with the entry level conical (C) stylus. There are cult moving coil cartridges that sport conical styli, so its profile simplicity does not imply criticism. A conical stylus is basically a cone of industrial diamond with its apex radiused 0.6 thou. Even as it traces a mono groove, cut laterally by the cutter head adze, the cone's radiused tip will be forced up and down as well as the desired lateral movement in what is known as the pinch effect. A silent spiral groove remains the same width, but as soon as a signal is applied the cutter moves laterally, while the cutter profile remains at 90° to the tangent of the groove. Hence being a chisel shape, the groove width changes. Because spatial information is effectively encoded in the vertical dimension (I.e. the difference between the left & right channels) a conical profile should produce a narrower stereo soundstage and lose a proportion of information related to the tip size.

The low budget conical (C) (spherical in Audio Technical literature, despite the 'C' nomenclature, describing the shape of the tip surface where it contacts the vinyl surface) tip installed in the VM500 body. With so many tips to try and so little time, we decided not to think about absolute sound quality but to make comparisons, but the conical tip proved capable and musically communicative, sufficient to form a basis for comparisons with other profiles.

The elliptical (EB) tip is the tried & tested (0.4 x 0.7) chunk of rock familiar on the AT95E. There has been some confusion, over the years, regarding what tip is designated by what letters. This is not helped by the AT Europe and the AT North America websites differing from the parent company website and the numerous legacy pages still found littering the web. There were various descriptions of the EX stylus, for example. When asked on behalf of TNT-audio, Mr Koizumi of the parent company confirmed that the EX stylus was the same tip as the E with different suspension damping. TNT-Audio presume both will now be obsolete replaced by the VMEB stylus (stylus only is designated with an extra letter 'N').

Inserting the VMEB elliptical stylus in place of the conical there is a BIG jump in sound quality. Moving from conical stylus to elliptical stylus the sound improves in every parameter, especially phase, resolution and soundstage depth. Of course, these are related, soundstage information being dependent on phase performance. Resolution obviously improves at high frequencies. The Audio Technica VM520EB (Elliptical bonded, that is with a shank between diamond tip and cantilever) is such a significant increase in resolution and information retrieval over the conical, or spherical stylus, that the additional spend is as easily justified as the planned outlay for the base model. Your Old Scribe first carried out this sort of comparison in the 1970s using Shure M75 series cartridges, finding the subjective hierarchy did not follow the price or compliance hierarchy, with the medium compliance EJ tip (0.4 x 0.7mil) sitting subjectively between the high compliance top model ED (0.2 x 0.7) and the high compliance conical G (0.6 mil) model. This has been a typical experience when comparing spherical and conical styli, and yet there are several cult moving coil cartridges fitted with a conical stylus for several years of production.

The law of diminishing returns does not begin to come into effect as we replace the elliptical tip glued in a tiny tubular shank, which is in its turn bonded to the cantilever, with one with an elliptical diamond bonded directly to the cantilever. The so called elliptical nude (EN) attached tip (0.3 x 0.7) is a slightly different grind from that bonded to a shank (0.4 x 0.7); how often does a writer get to type a sentence like that. There is an order of magnitude difference between to two. In particular the high frequencies, transient response and phase accuracy (especially noticeable in soundstage scale and accuracy) improve immeasurably...
"Immeasurably?" demand Plebs, stage left, "Surely the tip mass, phase response, frequency response, TID and other distortions may all be measured"

The subjective improvement wrought by the lower mass, smaller minor radius EN stylus is appropriate for the doubling in stylus price, beyond the improvement implied by any numbers. However, for a few dollars more, the Microline (ML) profile is really getting there, beginning to hint at the qualities we expect from a high end cartridge. Resolution is markedly improved, as we would expect from a profile with an even narrower minor radius. Whether it is the deeper contact patch, extending above and below that of a conventional elliptical profile, or some other factor, the sound character is altered too. Most of the big players in the pickup cartridge market, even those now defunct, have offered versions of this extended line contact stylus shape. The sonic difference is not just one of improvement in some parameters, but also a sweeter quality, more clarity at higher frequencies and less fatiguing over an extended period. The generator design and construction of the VM500 body is not only good enough to reveal these differences but also seems particularly suited to exploit the potential of this stylus profile.

The Shibata Stylus and some Esoteric Stylus Profile Theory

In 1976 Ersnt Weinz presentated a paper at the 54th convention of the AES (Audio Engineering Society) considering the roles of different cantilevers and stylus profiles on the capacity to reproduce accurately high frequency information above the human limit of audibility. This paper was prompted by the need to reproduce phase coherent signals over an octave above the human upper frequency limit in order to reproduce CD4 encoded quadraphonic discs. Weinz was considering the Shibata, Paroc and Pramanik cuts of diamond profile.

Weinz was also considering cantilever material (for example boron) for its potential to aid better reproduction of those higher frequencies. However, more useful to us today, Weinz made some key points about the significance of stylus profile as a key link in the reproduction chain. Weinz emphasised that the contact patch between groove wall and stylus tip is primary source of data from which the music signals are constructed. Weinz proposed that a genuine line shaped contact patch is necessary to reproduce the high frequencies as recorded in the undulations on each side of the groove.

The Shibata is an extremely complicated profile, multi-faceted and difficult to manufacture. Originally developed to achieve, from vinyl, sufficient bandwidth to enable FM encoded signals on an ultra-high frequency carrier (dependent on information up to 48kHz accurately recorded and retrieved from a vinyl groove), to contain the rear signals in the quadrophonic system developed by JVC, known as CD4. The JVC X1 cartridge was the first Shibata tip your old scribe heard.

The needs of JVC's CD4 and Denon's rival discrete matrix UD4, progressed vinyl replay significantly. The encoded rear channel carrier was 28kHz on CD4. Therefore cartridges and phono pre-amplifier circuits had to be developed to reproduce above 20kHz to about 48kHz. This demanded new stylus profiles to get that information from the lp groove. Not only that, it had to achieve this without wearing out the delicate ultra high frequency information where rear channel data was encoded. The Shibata stylus, fitted to JVC's flagship cartridge, extended the vertical contacted patch on the record groove wall and thus reduced stylus pressure on the groove wall. Naturally other manufacturers soon introduced similar efforts to reach these higher frequencies, including Bang & Olufsen's Pramanik and the Paroc profile utilised by Denon for UD4 particularly considered by Weinz's paper, being Weinz's own design and famously adopted by the Garrett brothers for their glorious re-tipped Deccas.

Conical - Elliptical - Hyperelliptical - Shibata

A J Van den Hul argued in 1980 that the Shibata tip, being created by grinding flats across conical & elliptical radii, would create its own unique distortion spectra as the stylus traced the curved undulations of the highest frequencies. Van den Hul notes that different parts of the Shibata tip profile would be in contact with the groove, your Old Scribe may be oversimplifying, but it might be thought of as adding a second variable to the differential of an imagined mathematical function describing the shape of one groove.

How a modest magnetic cartridge, carrying a Shibata tip designed for high frequency extension, could sound so differently voiced from the previous Microline ML stylus is difficult to explain. The magnitude of difference between the Shibata and the micro line (hereafter ML) profile, is much as the Linn K9 differs from the AT95E. The new model differs only in stylus profile, while that old Linn differed only in body integrity. Yet both major on being more upfront and dynamic.

The Shibata (Sh) sounded like a newer tip (even though these were all equally fresh out of the box). It had a more forward, flat-earth type presentation. It was as if the frequency response has been tweaked with a slight uplift at the frequency extremes and forward presence region. In the right system the Shibata would be a great improvement over the ML tip. The Shibata is the surprise of the evening, sounding like a cartridge of deliberately different character, even though it is merely a change in tip shape.

The Shibata (Sh) tip was the most engaging version so far, once our ears adjusted to the different balance. Soundstage is much more forward. Heading towards the listener compared with all others in the range. One of the listening group referred to the Shibata presentation as akin to a "Mannered wood block”. Audio Technica;s own tech-advisor guy, Rodrigo Thomaz, says "the Shibata stylus produces mid and bass sound that is strong and rich”.

The SLC Special Line Contact (borrowing a classic Mercedes model designation) looks similar to the Shure Micro Ridge in shape (from the brochure illustrations of each), in which case both may be supplied by Namiki (who supplied Shure). One might therefore infer a profile suited to working in a magnetic cartridge environment. It does. The SLC also features a better, laser-cut, version of the tapered aluminium cantilever, introducing another variable. Overall this profile is tonally darker than the Shibata, while enjoying all the Shibata benefits of resolution. The SLC achieves a quieter background and much better portrayal of acoustic information than the Shibata.

However, the SLC has a unique laser cut cantilever so there are two variables at work. Either or both may be contributing to the audible differences. Even though the Shibata has exaggerated presence region, the SLC profile offers more insight into upper mid-range detail. With that tapered cantilever, the SLC may well have lower moving mass, which will raise the resonant frequency between the tip and the elasticity of the vinyl, improving HF clarity.

Both the Shibata and the SLC were more capable of preservibg PRaT (Pace Rhythm and Timing) than the lesser models and interms of PRaT per Pound the standout Flat Earth best value cartridges would be the basic Eliptical E model and the Shibata SH. Back to back, in this system, the SLC is preferable to the Shibata, but the Shibata is consistently more funky. However, listening to a trumpet trill (Tower of power) your old scribe (who used to play brass) was aware of the valve port transitions during the trill being clearly enunciated via the SLC, whereas the Shibata merely succeeded in warbling the note.

Conclusions

The listening panel, consisting of 4 experienced listeners, could reliably identify differences between the stylus tip profile shapes. As the evening progressed, the styli were changed without announcing which tip was which. Listeners, without a second thought would announce that this [correctly identified] stylus is better or worse at this or that than the previous sample with surprising consistency. Therefore we have to conclude that certain stylus profiles do have, at least in this context, their own unique characters, in addition to differences due to polish quality. One hypothesis may be that the transitional curves described by different profiles tracing the curved groove walls introduce different distortion spectra.

An additional conclusion from this test is that the Audio Technica VM500 moving magnet catridge range are of sufficiently high resolution and transparency to identify a clear progression from simple conical stylus profile, through various gradations of price and quality, up to a stylus costing over 5 times the base model price. Whether, anticipating such future upgrades, buyers should therefore splash out on the Audio Technica VM700 metal mount range, or plump for a superior stylus on the basic (reviewed soon in these pages) Audio Technica VM95 range is a debate for the future.