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Are ellipitical styli destroying our records? (Merged Topic)

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Are ellipitical styli destroying our records? (Merged Topic)

Postby e-skeptic » 01 Dec 2010 02:57

Cleaning my stylus the other day, I noticed what must be slivers of vinyl. I am using a .3x.7 mil elliptical stylus tracking at 1.5 grams. Tracking force and grove tangency was carefully set with external stylus weight and alignment gauges. So I did some investigating and came up with a potential answer which I have not found anyone else to have ever suggested.

In all the sales literature and analysis of stylus tip shapes, an elliptical stylus tip is depicted as having a shape like an true ellipse, with rounded edges (See Fig.1 on page 2) -- but this is not actually the case. An elliptical stylus starts off as a conical, with a flat surface cut on the front and back sides. As we all remember from high school geometry, the intersection of a plane and a cone produces an ellipse, hence “elliptical“. But there is a sharp edge where the plane and cone intersect. This is verified by looking at on-line microphotographs of elliptical stylus tips. The horizontal cross section through an elliptical cartridge will then look like two convex arcs connected by parallel lines. I have also seen cross-sections drawn as two hemispheres connected by parallel lines, but this shape neither corresponds to the photos nor manufacturing process.

Although these stylus tips are finely polished, an edge line is formed at the intersection of the plane surface and the curved surface, which radius of curvature must be an order of magnitude less than the advertised minor radius of 0.2-0.4 mils. This advertised radius probably refers to the distance between the front and back planes.

Concerning this edge line at the intersection, either one of two conditions must be true:
1) The edge does not contact the grove wall. In this case , the stylus must trace the grove just like a conical, because the surface that touches the grove has the same radius of curvature as the conical it was machined from. There is no improvement in tracing distortion. Then we should bring back Dynagroove.
2) The edge does contact the grove wall. In this case, there will be the improvement in tracing distortion claimed for the elliptical type. But the edge contacting the vinyl is not the smooth rounded edge of an ideal ellipse as depicted in the drawings in cartridge literature and engineering calculations, but this chisel-like edge, shaving off vinyl on each pass.

So I tried to examine the condition where the stylus meets the grove myself, using no math or equipment, but by creating a large scale model of groove and stylus. In a spreadsheet program, I printed graphs of parallel sine waves of various frequencies (see Fig.2 on page 2); then I drew circles with flat ends inside the parallel grooves using a draftsman’s template. This process shows that the edge line does bit into the groove, as Shibata claims. As the “elliptical” stylus travels along the groove, “pinch effect” still causes vertical modulation of the stylus. The narrower the distance between the two flat ends, the less the pinch effect.

Therefore, I would recommend using an elliptical tip only when archiving a record, when fidelity is paramount and the record will not be replayed. For repeated enjoyment of a record, use the conical tip. Moreover, the higher tracking force taken by conical tips will improve trackability, given the same cantilever design and tip mass, since we know from Newton’s laws of motion that the ability to accelerate to a high recorded velocity is proportional to tracking force. The elimination of harsh mistracking may be more pleasing to the ear than the harmonic distortion due to tracking error

Of course, the best option, for those who can afford it, is some kind of elongated contact stylus.

Have cartridge manufacturers been believing there own advertising art departments and “misunderestimating” the record damage potential of ellipticals these past 45 years, or is this analysis wrong?
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Postby Whitneyville » 01 Dec 2010 07:11

Well the Shibata shape with it's spade shape viewed from the front and near razor edges still plays my CD-4 LP's just fine, with the limitations being mid-late '70's recording techniques and mass-produced LP's. The nude Shibata and the Micro-Line stylii should be the hardest on LP's, but they aren't, infact, quite the opposite. A-T calls many of their "ellipticals", "bi-radial", so I suppose they are shaped like a football or rugby ball. I have seen about the same analysis before, and I totally agree than a misalinged conical is less wearing to LP's than a misaligned elliptical. Actually, I think the shaped of the cuttinghead stylus should be modified to produce a groove shape that is easier to track. I also understand the "master" has little in common with the grooves in the "mother" and stampers. We have to accept the fact that an LP has "X" number of plays in it before the wear becomes "unacceptable", just like some of my Century-old Victrola and Edison discs that are so worn, I need something like a 7 mil stylus to touch the groove edges. My 4 channel R-T-R tapes have a finite number of plays in them. All audio media except optical (read: photographic film) are finite in the number of plays, and old vinyl, especially mass-marketed, is nowhere near what "audiophile" vinyl is today. Acetate R-T-R tape was nowhere near the quality of mylar or even polyester recording tape. Evaporated metal tapes are even better IF your tape heads will hold-up to them. I understand your concern, but I'm not sure it's justified. The only way to really know would be to set-up a conical TT and an ellipitical TT and destructively test two identical LP's, and count noses. But since there are very few high-quality conicals made today, and they require greater VTF than most ellipticals, wouldn't we be comparing apples to oranges? :?:
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Re: Are ellipitical styli destroying our records?

Postby flavio81 » 01 Dec 2010 16:32

e-skeptic wrote:Cleaning my stylus the other day, I noticed what must be slivers of vinyl.

It can also be dust. Dust comes in all colors.
e-skeptic wrote:So I did some investigating and came up with a potential answer which I have not found anyone else to have ever suggested.


Perhaps you would like to review all the threads we already have that had discussed all this topics in depth.

e-skeptic wrote:As we all remember from high school geometry, the intersection of a plane and a cone produces an ellipse, hence “elliptical“. But there is a sharp edge where the plane and cone intersect.

You are assuming that said edge touches the record, which is not the case.
e-skeptic wrote:The horizontal cross section through an elliptical cartridge will then look like two convex arcs connected by parallel lines.


Yes, and only the arcs touch the record.

e-skeptic wrote:Concerning this edge line at the intersection, either one of two conditions must be true:
1) The edge does not contact the grove wall. In this case , the stylus must trace the grove just like a conical, because the surface that touches the grove has the same radius of curvature as the conical it was machined from. There is no improvement in tracing distortion. Then we should bring back Dynagroove.


The stylus traces the groove like a conical, but only on the plane that is parallel to the groove contact surface. On the plane parallel to the record surface, things are different. There is an improvement in tracing distortion and we have discussed this plenty of times, just google "minor radius" and "distortion".

Bring back Dynagroove? No thanks. How about using better styli?

e-skeptic wrote:2) The edge does contact the grove wall. In this case, there will be the improvement in tracing distortion claimed for the elliptical type.


No, this is not correct. I suggest you to review the literature on tracing distortion and the pinch effect. Google the "around the bend" page by "jim lesurf".

e-skeptic wrote:Therefore, I would recommend using an elliptical tip only when archiving a record, when fidelity is paramount and the record will not be replayed. For repeated enjoyment of a record, use the conical tip.


This does not agree fully with the AES studies on record wear. Plus you are not taking into account the far longer contact surfaces of better styli.

e-skeptic wrote:Moreover, the higher tracking force taken by conical tips will improve trackability, given the same cantilever design and tip mass, since we know from Newton’s laws of motion that the ability to accelerate to a high recorded velocity is proportional to tracking force. The elimination of harsh mistracking may be more pleasing to the ear than the harmonic distortion due to tracking error


You are oversimplifying. Your paragraph mixes low frequency tracking ability with high frequency tracking ability with tracking distortion. The first is dependent on VTF and compliance, the second is more dependent on effective tip mass, and the third is dependent on the tip's minor radius.

e-skeptic wrote:Have cartridge manufacturers been believing there own advertising art departments and “misunderestimating” the record damage potential of ellipticals these past 45 years, or is this analysis wrong?


My dear friend, i think you're seeing dangers where they aren't.

Welcome to the forum, i like the fact that you are very technically minded. Please check out this thread:

https://www.vinylengine.com/turntable_forum/viewtopic.php?t=22894

And then search for threads on distortion, pinch effect, tracking ability and tip mass by user "ld".
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Postby missan » 01 Dec 2010 16:54

Hi
I think I´m getting more and more inclined to believe there is no record wear at all, when playing at normal conditions. If, the record is reasonably free from harder particles and the vinyl compound at the surface have the right composition.
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Postby lini » 01 Dec 2010 17:33

e-s: On a sidenote, not all ellipticals are equal - if you look at a high quality elliptical like for example on an ATN13 or ATN130E/132EP, those edges don't exist.

Greetings from Munich!

Manfred / lini
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Postby Guest » 02 Dec 2010 17:19

Hi,

I think he has a valid point, the edges must come into play for
the elliptical tip to have lower tracing distortion than spherical.

However I understand tips can be polished by simply tumbling
them together (like the old stone polishing tumblers), and that
this process is not expensive, so a quick tumble would remove
those sharp edges but still leave the basic coutour untouched.

rgds, sreten.

Nice picture of the Ortofon nude LC tip type I have :
Image

A not so nice used Ortofon bonded elliptical :
Image
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Postby Guest » 02 Dec 2010 18:26

sreten wrote:I think he has a valid point, the edges must come into play for
the elliptical tip to have lower tracing distortion than spherical]
No, the edges aren't ever part of the contact area. That would be bad !

Also groove curvature in an eliptical is always lower (higher radius of curvature) than the minor radius, for real recordings. Nevertheless, harmonic distortion still arises from the pinch effect.

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Postby nat » 03 Dec 2010 00:46

If ellipticals, even worn ellipticals, were destroying our records, there ought not be many used records that are playable. But that's not the case at all -- most of the used records I come across (and that is a large number from all sorts of sources) are just fine once cleaned.
I recognize that different size and shape stylii trace different heights in the groove, but if ellipticals were dangerous, you'd expect at least a healthy minority of used records to sound bad. And they don't.
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Postby Alec124c41 » 03 Dec 2010 04:01

I've been using elliptical stylii for 40 years. Only one ever got to the point of being dangerous to my records. It was quickly changed, and I am still playing records I had 40 years ago and more.

Cheers,
Alec
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Revisiting "Are elliptical styli destroying our records

Postby e-skeptic » 04 Dec 2010 00:00

Let me revise and extend my previous remarks regarding elliptical styli. The point I am trying to make is that the elliptical stylus one buys may not give the performance improvement claimed in advertising and engineering analysis, and may in fact wear records even more than admitted.

In what I read on ellipticals, it’s cross-section shape is depicted as an ellipse, or alternatively as two opposed hemispheres joined by parallel lines. In the patent application for the elliptical tip, Grado describes that at the bottom edge of the tip there are to be two opposed hemispheres. The footprint of the tip on the grove wall is often drawn as an ellipse, longer and narrower than a spherical. But in fact elliptical cartridges do not seem to be manufactured that way. Looking at all the microphotographs of ellipticals on the web, they all seem to be conical styli with flat edges cut through the front and back surfaces of the cone. A cross section is like two opposed arcs; the minor “radius” must actually be the chord of the arc. Two other factoids to support the suggestion that ellipticals are not cut as claimed: 1) the fine line drawings by Audio-Technica of tip shapes show them as cones with flat front and back ends; 2) Grado claims to mount a true ellipsoid tip on only their top-of-the-line cartridge, so lesser cartridges must not have a true ellipsoid shape. Why do production elliptical styli deviate from the patent description? 1) so other manufacturers did not have to pay a royalty to Grado when the patent was still in effect, and 2) it is so much easier to fabricate cutting two planes into a cone than doing that step plus fabricating two opposed hemispheres at the bottom edge as well, and you can honestly advertise the product as “elliptical”, since a plane cut into a cone produces an ellipse.

So it appears that what is sold as an elliptical is a conical with just an ellipse cut onto the front and back edges. No less an authority than Van den Hul calls this a “pseudo-elliptical” @ https://www.vinylengine.com/ve_downloads ... l_1980.pdf, in the topic on advanced stylus shapes. The radius of curvature at the groove side is the same as the conical it was machined from. Moreover, there is an edge line where the conical surface meets the flat surface.

Since the “pseudo-elliptical” has the same radius, footprint and tangency points where the stylus rests in the groove as the original conical, there will be no improvement in tracing distortion. (Van den Hul too shows the footprint is the same as the conical.) Not only is there no benefit, the potential for record damage will be much greater. Where the radius of curvature of the groove is less than the major radius of the stylus, then these sharp edge lines will bite into the grove, possibly chiseling off vinyl on each pass. In less highly modulated grooves, the conical side will trace most of the groove, but the edge line may still cut into the grove at the 180 degree point of the sine wave, where the groove is narrowest front-to-back. The “pseudo-elliptical” does at least reduce pinch effect, but only where the edge line cuts into the groove. Maybe entire albums will have no sections where groove curvature is less than the major radius, but where they do, I think grove destruction is occurring. For all the other less tightly curved portions of the groove, a conical would perform the same as an elliptical, assuming equal tracking force and tip mass; and on the tightly curved portions, the smooth conical surface would do less damage the groove.

One can verify this behavior of the “pseudo-elliptical” with simple modeling. Print parallel sine waves of various amplitudes and frequencies from a spreadsheet program, and draw circles with flat front and backs within them. Results should be like claimed in the above paragraph.

This site should call upon volume cartridge manufacturers to label their “pseudo-ellipticals” as such. Until then, choose ellipticals carefully, because one can‘t know for sure what they are getting. If they are like the micro photos, then there is no improvement over otherwise equivalent conicals along most of the groove, and at the points where there is a benefit, the edge lines may be doing damage to the groove. Carefully weigh the pros and cons of cartridges labeled as “ellipticals”, because the benefits are based on unverified assumptions about it’s actual shape, and the possible effects on the vinyl at the edge line resulting from its actual shape is never mentioned.

Or maybe the microphotographs are just not resolving the hemispheres at the tip edge, then never mind. But I don’t think so.
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Re: Revisiting "Are elliptical styli destroying our rec

Postby flavio81 » 04 Dec 2010 00:51

e-skeptic wrote:Let me revise and extend my previous remarks regarding elliptical styli.


You already have a thread on this topic:
https://www.vinylengine.com/phpBB2/viewtopic.php?t=32763

Post your message in that topic and let's continue the discussion there. There is no need to open a new thread when the topic is exactly the same than another topic started by you.
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Postby flavio81 » 04 Dec 2010 01:10

E-skeptic opened a new thread for posting on this topic, so i'm replying him in this thread instead of needlessly creating another thread.

e-skeptic wrote:Let me revise and extend my previous remarks regarding elliptical styli. The point I am trying to make is that the elliptical stylus one buys may not give the performance improvement claimed in advertising and engineering analysis, and may in fact wear records even more than admitted.


Tracing distortion has been measured to be lower with the common elliptical stylus, depending on the minor radius. I don't know why do you persist with denial. Record wear has tested to be of no consequence with the 1-3g tracking forces used today, assuming the cartridge will not mistrack due to too high effective mass or too low compliance.

e-skeptic wrote:In what I read on ellipticals, it’s cross-section shape is depicted as an ellipse, or alternatively as two opposed hemispheres joined by parallel lines. In the patent application for the elliptical tip, Grado (...) But in fact elliptical cartridges do not seem to be manufactured that way. Looking at all the microphotographs of ellipticals on the web, they all seem to be conical styli with flat edges cut through the front and back surfaces of the cone. (...) Grado claims to mount a true ellipsoid tip on only their top-of-the-line cartridge, so lesser cartridges must not have a true ellipsoid shape. Why do production elliptical styli deviate from the patent description? (...) so other manufacturers did not have to pay a royalty to Grado when the patent was still in effect


This is the common elliptical stylus. Carefully check how far those lateral cuts go.

https://img.photobucket.com/albums/v716/flavio81/vinyl/gradoelliptical.gif

The elliptical isn't an exclusive invention by Grado, that every other manufacturer is desperate to copy but they cannot copy correctly. It wasn't invented by Grado; it appeared in the 50s in a patent by Pathè Marconi (france), and previously Edison had a similar design, for his gramophones.

Grado's "special elliptical" (or whatever fancy name they wish to christen it) is another stylus design.

e-skeptic wrote:Since the “pseudo-elliptical” has the same radius, footprint and tangency points where the stylus rests in the groove as the original conical, there will be no improvement in tracing distortion.


Starting from a certain groove modulation angle, the groove will touch the edges of the conical while it will not touch the edges of the pseudo-elliptical (because said edges were trimmed.)

The way how the tracing distortion is reduced, is evident. Have you checked the "around the bend" article i suggested you to read days ago?

e-skeptic wrote:Where the radius of curvature of the groove is less than the major radius of the stylus, then these sharp edge lines will bite into the groove


For starters, you are incorrectly assuming that the edge is sharp. Then, where the radius of curvature of the groove is less than the MINOR radius of the stylus, the stylus will ride up, just like the conical. This is the famous "pinch effect".
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Postby Guest » 04 Dec 2010 07:39

e-skeptic wrote:Since the “pseudo-elliptical” has the same radius, footprint and tangency points where the stylus rests in the groove as the original conical, there will be no improvement in tracing distortion. (Van den Hul too shows the footprint is the same as the conical.) Not only is there no benefit, the potential for record damage will be much greater. Where the radius of curvature of the groove is less than the major radius of the stylus, then these sharp edge lines will bite into the grove, possibly chiseling off vinyl on each pass. In less highly modulated grooves, the conical side will trace most of the groove, but the edge line may still cut into the grove at the 180 degree point of the sine wave, where the groove is narrowest front-to-back. The “pseudo-elliptical” does at least reduce pinch effect, but only where the edge line cuts into the groove. Maybe entire albums will have no sections where groove curvature is less than the major radius, but where they do, I think grove destruction is occurring. For all the other less tightly curved portions of the groove, a conical would perform the same as an elliptical, assuming equal tracking force and tip mass; and on the tightly curved portions, the smooth conical surface would do less damage the groove.


The original conical has a descending radius of curvature. It also has an included angle (typically 60 deg ?), rather than the groove angle 45 deg.

The pseudo-eliptical always has a minor radius less than any realistic groove curvature radius. It's impossible for the cut edge to contact the groove ! That's the construction, even in a pseudo eliptical. The reduced minor radius reduces pinch effect and tracing distortion.

I think perhaps you have the major axis in the wrong plane when thinking about this ?

I like your approach to this, BTW !

Groove curvature/ stylus acceleration (measured) and stylus minor radius curvature :

15390
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Postby Doug G. » 05 Dec 2010 00:48

Speculative discussions like this may be interesting but there is more than enough history to demonstrate that elliptical styli do NOT destroy records.

It is even a bit nonsensical to entertain such speculation. Is it not highly probable that the designers of this invention and the grantors of the patents took all of this into consideration?

Doug
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Postby flavio81 » 06 Dec 2010 07:47

The OP is gone... He only put these two posts.
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