Hello again!
Forgot to thank you for the link to Holmes' article...? Think I skimmed through it a little while back but without paying the closest attention to some of his remarks. And after all, he did state his opinion that the DL-103 is the best buy in audio ever. Opinions are always fine, but there was this questionable accusation leveled at anyone who might have reason to believe in the possible superiority of spherical styli, which is what our DL-103s mostly have, and as it turns out, for specific and well-founded reasons. I will return to the subject shortly.
I can see that I'm among peers who share some of my views on the absurdity of the "high end" market/press/consumer habits/beliefs etc. But enough of that for now, as far as I'm concerned...
Now...
I have to apologise for having refered to, much too simplistically, an article about cutting, cartridges and styli from a magazine that hardly any of you have read. I had to pull it out of my files for a quick reread just now, and, also personally having met the author, Reto Luigi Andreoli in Zürich nine years ago while visiting with Christian Rintelen, I continue to be both impressed, inspired and amused by this man's writings. Reto went to Australia to stay with the Garrotts and learn about cartridge making at their factory a good many years ago.
The particular article I have made reference to was printed in Hi-Fi Scene #17 (November 1998)
"The Final Luigi - Back with a Vengeance" (..."Expect no Mercy")
The whole magazine was based in Zürich and carried articles written in German. German phono-tech-terminology is not very easy to translate smoothly into English, and in addition there are drawings and figures very useful to understanding the technological reasoning. Being a technologically minded "propellerhead" audio nerd myself, I think this would be of interest to some. Perhaps it should have been posted in the cartridges section, but this is just an evening's humble efforts. I will now try to summarize some interesting points...
Different cutter heads with different cutter stylus modulation geometry and with differently shaped/cut cutter styli have always existed, and these all more or less differ from the geometry of playback cartridges' cantilever suspensions and styli. The shape of the cutter stylus gives rise to the modulated grooves having varying wall angles and width, causing the well known "pinch distortion", where the playback stylus is forced up/down due to aforementioned amplitude/frequency-dependent variations in groove width and wall angles.
Curvature overload, which happens if the playback stylus radius is too great as compared to the groove curvature, was studied by the large record companies (like EMI, Nippon Columbia, RCA, Decca)
back when spherical styli were universally used. Special analog compensation circuitry was applied in the recording process to minimize such distortion on playback, ie. many records were produced which would have the lowest distortion in this regard when played back using spherical styli. Some of these processes were known under trade marks such as "Royal Sound", "Dynagroove" etc., but mostly no mention was made of these compensation techniques on album covers.
Modern "flatter" styli playing these records would conversely result in increased distortion, "undoing" the purpose of the tracing simulation/compensation.
When the reproducer stylus follows the groove and has a different shape than the cutter head stylus it makes contact with the two respective groove walls at points which are slightly ahead or behind the points on the groove walls cut by the cutter stylus at a given instant. This gives rise to a form of phase error which is absent in mono recordings (where both groove walls contain complementary signals).
Next, Luigi's headline "Der grosse Denkfehler" (The big Error in Thinking) which is where we get to the main point. To quote:
"That the stereo groove undoubtedly could be traced with less distortion with a narrower stylus than with a spherical stylus is true. But only if the suspension of the cantilever is the same as that of the cutter stylus. And this is never the case!
And here begins the tragedy of the industry, which has been grinding away on the spherical stylus since the first stereo records came about, hoping to improve the reproduction. The actual problem, namely the geometrical design of the cantilever suspension, was wholly ignored - except by Decca, EMI Varilux, Neumann and Ikeda. That this thoughtlessness, or the ignorance of the complexity of the matter has led to design errors, even has increased playback error, is a fact."...
Going into this more closely, it is seen that with a conventional cantilever suspension (we all know how it works), the stylus, on simultaneously moving vertically and horizontally, defines a domed surface (section of a sphere), which mostly defeats the purpose of flatter stylus cuts - which would be fine if they traced the groove as it was cut by the cutterhead stylus. In this situation, a spherical stylus has the same (shape) contact surface with the groove walls independently of the angle of the cantilever (given by groove modulation) vs. the groove, whereas a flatter cut stylus does not behave "as assumed" - at larger vertical deflection angles, for instance" the contact "line" (more or less) is not a vertical line perpendicular to the record surface, but is at an angle and so may fail to correctly trace very small modulations which would still be reproduced by a spherical cut stylus, and additionally could cause groove damage for the same reason.
Further problems/details are discussed, including resonances and intermodulation distortion resulting from this geometrical inconsistency.
Next, the consequences of VTA and (radial) arm adjustments are discussed. Obviously, following the previous reasoning, a spherically cut stylus appears having a constant width as it appears in the groove irrespective of tracking angle, no difference from that observed in the zero points (in the case of a radial arm). Now if a narrow/line cut stylus is substituted, the stylus is relatively narrower at all points on the record than it is at the two zero points, because only here it is tangential to the groove.
"We now observe the path of the stylus which it traverses, seen from the front. The spherical stylus moves from the outside inwards in a plane. With ANY other stylus cut it moves up and down, with the highest points at the two zero points, and the lowest conversely corresponding to the greatest angle errors...It now follows that, except with cartridges having spherical styli, it is completely impossible to adjust the VTA correctly, even if the record is completely warp-free!!! Perplexed?" I personally think that, especially when the matter is treated with all the thoroughness it deserves (and more than my summary can convey), it may be logically deduced, on the basis of geometrical conditions existing in the real world of record engraving and playback, that the departure from spherical styli introduced more problems than it solved, and that neither lower distortion nor better HF response could be expected. I don't carry the kind of phono-technological baggage that RLA does, but I do follow his impeccable reasoning.
Towards the end of the article, the development of the DL-103 by Takeo Shiga is summarized, and it was based on a fascinating discovery by Shiga which was published in Journal of the Acoustical Society of Japan, january 1962. I had long forgotten about this most important point, and I don't know where the JASJ article might be available in English, but will attempt a translation of Luigi's brief description of Shiga's discovery:
"Shiga had established, that by a given design (ie. precisely defined moving mass of the generator system and a spherical stylus in conjunction with the elasticity of vinyl at room temperature) the playback distortion could be compensated for by the plastic deformation of the vinyl and the temporary change of the groove geometry" Some clever trickery there, it appears, specifically requiring a spherical stylus among other things. Some guy named John Walton, a cartridge development engineer at Decca picked up Shigas study in 1966 and confirmed:
"...So it turned out, that equipping even the best cartridges with elliptical styli effected no reduction in distortion whatsoever, rather, an increase..." Walton had studied much the same problems as Shiga and arrived at precisely the same conclusions independently of Shiga, whose Japanese research paper remained unknown in the West between 1962 and until 1966 when it was first presented in English.
Make of all this what you will, folks - but this article is what turned me on to the DL-103 in the first place, and if anything, there is no "odd logic" to be found anywhere in it. It is a 16 page largely very technical article, humorously but knowledgeably written by a guy who builds cartridges and most everything else audio as well, and in fact - in my experience, Reto is one of the most knowledgeable audio people I have ever met, right up there with uh...Hiraga - only not as humble and polite, and vastly more opinionated...
Thomas
