[Wayner]

I don't think we've had a thread on this for awhile, so why not. The one thing about a stylus that I have thought about for quite awhile concerns stylus wear and alignment.

I do think it's funny that the stylus wears out, being one of the hardest substances known to man, and the LP doesn't ever seem to be the worse for the wear. At least that's my take on it.

Now for the alignment thought. Here is a theory: If we align our stylus incorrectly (at least in angular terms (offset)), certainly the stylus must, after some hours, wear itself into alignment?

And if we concede to that theory, would it then be a bad idea to change the alignment after the stylus is "broke-in" to the natural wear of the record?

And, when is it time to replace/re-tip.

Any other discussions on the topic are also welcome (like types, shapes, materials, etc.).

Wayner

[Sonny]

Wayner, you're always like Michael Jackson says "Wanna be startin' somethin'" huh?

You know, I've owned and listened to a few cartridge and can't tell you that after looking at the styli with a 30x magnifying glass that I've noticed any "wear" on the styli other than color, which can be from debris.

I tend to like "nude elliptical" though I know it's not the best shape to pull out the all the music, but it's easier to align (more room for error) than say a line contact styli, right?

Regarding your statements about wear and wearing itself to the groove "self correcting/aligning" as you will, I have no ideal...that's why I like uni-pivot tonearms as it allows for the styli to be flexible when tracking...which can also be a bad thing too, I guess.

T

[Delta Wave]

Nice. I'd like to know these things too. As our styluses wear down I'm sure we become acclimatized to the sound getting more dull. Maybe one day it just hits you after not playing anything for a few days and then you put on one of your favorites that you know every little sound by heart. Then whammo!... Time for a re-tip. I have yet to wear down a stylus, I think? I do have a few worn out records though.

[Wayner]

Do you think that poor alignments cause early stylus or record wear? At some point does a bad alignment start acting like a cutting tool on groove walls, or is this stylus type dependent, like maybe better with a conical stylus? And what was the "downfall" of the conical stylus? Poor tracking?

Wayner

[Delta Wave]

I've never had much luck with a conical stylus, I'm not the best person for scientific jargon but it seems to me it doesn't reach into the groove deep enough and has a "glancing-blow" effect on the signal area.

I'm pretty much sold on the line contact types or a nude elliptical. My Ortofon uses a nude fritz gyger type and it seems to reach every little bit of information a record has to offer. However, it also picks up every teensy bit of dust or gunk. My records have to be squeaky clean to enjoy.

[neobop]

Yes, styli wear and no, they don't wear themselves into alignment. The contact area is too small/thin to realign the stylus. I used to examine styli for wear with an AT prof microscope. This was a more sophisticated instrument than the Shure scope. Under 300 to 500X the worn area is like a point of light on the side of a new tip (nonexistent). As the tip wears this point of light spreads out and starts to cover the side. The rounded contact area becomes flat. The edges of that flat are what can damage a groove wall.

Micro stylus shapes have a thinner side, more knife like and tend to be much smaller. While they can extract more detail, if one of these chips or fractures it can damage records. So, if you have a minor accident and it bounces on a metal platter or something similar, try to check it out before playing a treasured record.

[Wayner]

Yes, styli wear and no, they don't wear themselves into alignment. The contact area is too small/thin to realign the stylus. I used to examine styli for wear with an AT prof microscope. This was a more sophisticated instrument than the Shure scope. Under 300 to 500X the worn area is like a point of light on the side of a new tip (nonexistent). As the tip wears this point of light spreads out and starts to cover the side. The rounded contact area becomes flat. The edges of that flat are what can damage a groove wall.

Micro stylus shapes have a thinner side, more knife like and tend to be much smaller. While they can extract more detail, if one of these chips or fractures it can damage records. So, if you have a minor accident and it bounces on a metal platter or something similar, try to check it out before playing a treasured record.

Hate to disagree with you Neobop, but I think the stylus will wear into the groove configuration of the the alignment. The shape of the stylii will conform to the shape of the groove and roughly thru the arc of travel. Physics forces it to. Now, if the overhang is not right, and the angle is too great, I agree, but the other part of my theory is if it's a smart idea to change alignment after lots of hours on a stylus. It has changed shape to conform.

W

[neobop]

That makes no sense to me. The diamond is much harder than the vinyl. The reason it wears is because it travels so many miles of groove. With a pivoting arm, the angles of misalignment keep changing so there is no set groove configuration. How about a linear tracker? Those tips also wear. High quality linear arms have virtually no misalignment.

Tips do tend to wear unevenly. This is usually attributed to anti-skate maladjustment where one side wears more than the other. If a cart is severely misaligned the front or back of a side profile might get more wear, but for most alignments the error is both + and - at different parts of the record.

Think what you will, it doesn't change anything.

[*Scotty*]

The obvious point here is that if the diamond tip has worn to the point that the flat spot is more or less in alignment with the groove walls it is probably time to replace the stylus anyway.
 Significant misalignment of 2x7 elliptical or a line contact stylus is going to result in a substantially higher amount of distortion that should be audible in a system capable of high resolution.
 It should be especially obvious if a test record is used to setup the cartridge.
Scotty

[*Scotty*]

As far as when the stylus should be replaced, the crudest indicator of stylus wear is a rise in surface noise which is caused by the stylus wearing down and the tip of the stylus getting down into the bottom of the groove where all of the dirt and debris is lurking.
 I used to have an hour meter that kept track of the playing time on my stylus but after four moves the little thing has gotten misplaced or lost. The alternative to an hour meter is keeping a log of album sides. It would be a pain the a** but I don't see an alternative.
Scotty

[Wayner]

That makes no sense to me. The diamond is much harder than the vinyl. The reason it wears is because it travels so many miles of groove. With a pivoting arm, the angles of misalignment keep changing so there is no set groove configuration. How about a linear tracker? Those tips also wear. High quality linear arms have virtually no misalignment.

Tips do tend to wear unevenly. This is usually attributed to anti-skate maladjustment where one side wears more than the other. If a cart is severely misaligned the front or back of a side profile might get more wear, but for most alignments the error is both + and - at different parts of the record.

Think what you will, it doesn't change anything.

It makes lots of sense. Yes, it does travel miles and miles during its lifetime, and you are also right that on pivoting tonearm, it's travel is going from a + to a -  side of tracking error, but like a cam, it has a wear pattern.

Like putting a pencil into a pencil sharpener, it's tip will sooner or later conform to the vinyl groove's 90° shape and like the pencil,, become shorter and shorter.

You have to also understand that there is no perfect cartridge. The relationship between stylus, cantilever, poles, etc. is all subject to tolerances. Then, there is no such thing as "perfect" cartridge alignment, everything will be slightly off, from offset angle to VTA. The stylii profile, footpring and azimuth will "globally" always be in error, just because we don't have the tools or the methods for a "perfect" alignment. As the stylus wears down threw friction, the contact area with the grooves will increase, the tip will become a third contact surface, bottoming out with shallower groove modulations.

Wayner

[dlaloum]

Wayner your idea would only apply with a linear tracker.... with pivoted arms the tracking error implies a stylus wearing in different ways at different parts of the record, and antiskating/bias implies uneven left/right wear as well.

Also with elipticals or LC's, the quality is driven by the small minor radius (which allows it to track smaller modulations more closely) - with wear this radius increases/ the contact patch widens....

If you were to rotate the stylus, the shape of the needle implies you would move to a wider radius in any case... (for shibata, standard eliptical, HE) - only with the conical would the unworn area provide an improved contact patch.

There ain't no gain to be found here!
And of course the extreme shapes (MicroRidge, VdH, FG etc...) are much much worse.

If the stylus wears to conform more closely to the shape of the groove, it will in fact be conforming to the shape of the cutter used to create the groove.

The nearest SAFE shapes to that cutter are the MR/VdH/FG types - otherwise you are turning the needle into a cutter..... which effectively is what happens when you hear wear on the record!

 

bye for now

David

[Wayner]

Wayner your idea would only apply with a linear tracker.... with pivoted arms the tracking error implies a stylus wearing in different ways at different parts of the record, and antiskating/bias. If the stylus wears to conform more closely to the shape of the groove, it will in fact be conforming to the shape of the cutter used to create the groove.
 (yes!)

The arc of the tonearm is repeated thru each record play, so I believe there is an influence to wear with this repeated pattern. I do agree that the wear is more conforming to a linear tracker, cause the wear pressures are at constant angles.

Some of the older tables that I have bought thru the years, like ARs, have had really worn Shure cartridges in them, like the M91ED, that were worn to a point and they certainly looked like the 90° modulated wall of a record groove.

Anyway, the stylii wear theory was a thinking out load moment, that I will still ponder upon.

Wayner

[Ericus Rex]

I appreciate you bringing up this topic, Wayner.  You always present lots to think about.

[cheap-Jack]

HI.

(1) ... the stylus wears out, being one of the hardest substances known to man, and the LP doesn't ever seem to be the worse for the wear. At least that's my take on it.
(2) for the alignment thought. Here is a theory: If we align our stylus incorrectly (at least in angular terms (offset)), certainly the stylus must, after some hours, wear itself into alignment?
(3)other discussions on the topic are also welcome (like types, shapes, materials, etc.).
Wayner

(1) Diamond is the 2nd hardest material on earth (next to lonsdaleite, also a carbon material like diamond, 58% harder than diamond). It can damage any   vinyl discs but cannot be damaged by any vinyl tracking. This is physics.

(2) Any mistracking due to stylus, cartridge, tonearm "misalightment" only generate audio distortion due to mistracking. No physical will be done to the stylus itself.

(3) Ellipical (bi-radial) stylus is basically a re-shaping of a conical/spherical to make its profile closer to the triangular shape of the cutting head stylus.
All the texts I've read seem to favour using ellipical styli due to following advantages vs conical stylus:-

(1) the elongated tip of an ellipical stylus requires LIGHTER tracking force will cause LESSER damage to the vinyl grooves.

(2) finer tip can dig deeper into the groove, having tighter contact with the groove side surface, & therefore tracks high-frequency modulations better.

Ellipical shaped stylus cost more to cut & therefore asks for more money.

Sales pitch or what?????

A paper published by Acoustical Society of America 1942 told us another story:-
"A large radius stylus for the reproduction of lateral cut disc records".

The paper shows unexpected benefits for using a stylus of sufficiently
large tip radius to contact only the upper portions of the side walls of a laterally cut record groove:-

(1) increase in high frequency output;
(2) decrease in acoustic radiation from the surface of the record;
(3) increase in stylus life;
(4) increase in record life;
(5) decrease in scratch noises from both old & new records.
(6) decrease in stylus point pressure for proper tracking.

Mind you, in 1940 era, commercial records has a radius of 2.3mil & to get such "unexpected benefits", the conical stylus should double the wide of the groove.

Today, a conical stylus gets a tip size of 0.5-0.7mil.

This paper is just to give our readers some idea of the stylus size & shape.

FYI, for years I am still using my MM cartridge of conical stylus which tracks ALL my new & recyled LPs perfectly with minimum tracking noises.

c-J

[*Scotty*]

The Acoustical Society of America paper is dated 1942.
The modern microgroove record was introduced by Columbia Records in 1948.
The benefits of a large radius stylus are probably not applicable to microgroove LP records.
 Modern records contain signals with large amplitudes and hard-to-track modulation. The cutting stylus cuts a narrower groove when the stylus moves sideways. This narrowing of the groove produces the pinch effect, which is responsible for lifting the playback stylus out of the groove and producing second harmonic distortion in the vertical direction.
 The pinch effect is much more noticeable with spherical styli and less troublesome with fine-line shapes because the fine-line playback stylus is slimmer and fits into the curvature of the groove better.
 Lower second harmonic distortion, increased frequency response, lower record wear and longer stylus life are a few of the reasons that the modern line-contact or micro-ridge stylus shapes were
invented over thirty years ago.
Scotty

[Delta Wave]

The Acoustical Society of America paper is dated 1942.
The modern microgroove record was introduced by Columbia Records in 1948.
The benefits of a large radius stylus are probably not applicable to microgroove LP records.
 Modern records contain signals with large amplitudes and hard-to-track modulation. The cutting stylus cuts a narrower groove when the stylus moves sideways. This narrowing of the groove produces the pinch effect, which is responsible for lifting the playback stylus out of the groove and producing second harmonic distortion in the vertical direction.
 The pinch effect is much more noticeable with spherical styli and less troublesome with fine-line shapes because the fine-line playback stylus is slimmer and fits into the curvature of the groove better.
 Lower second harmonic distortion, increased frequency response, lower record wear and longer stylus life are a few of the reasons that the modern line-contact or micro-ridge stylus shapes were
invented over thirty years ago.
Scotty

 

[Æ]

To understand the dimensions involved in the record system we shall construct an enlarged model in which one micron (one thousandth of a millimeter) is represented by one inch. A midband modulation in the groove at a “typical” level (1kHz, 5cm/sec) gives a 16 inch peak-to-peak excursion for the stylus, while a 50Hz organ pedal at 10dB higher will require 10’6" and the low level harmonic of a violin (10kHz, -40dB) only 0.068"! A typical stylus with a “line contact” profile on a high quality cartridge would produce vertical oval “foot-prints” on the groove walls 10" by 4” and would deform the vinyl by about one inch (twenty times the size of the violin harmonic). The stylus itself is about 30' high, and is attached to a bent pipe that represents the cantilever of 50' diameter and 275' length, extending from a 2000’ long cartridge body that is some 80’ from the record surface! The arm has a diameter of 450’ and crosses 1300’ above the record surface from its pivot point nearly four miles away! This approach deals only with dimension, not mass or velocity, yet it certainly illustrates the problems of relative magnitude that the turntable system has to deal with. In fact it is quite amazing that record decks work as well as they do, and it is hardly surprising that there are differences among them.

[cheap-Jack]

Hi.

Some of the older tables that I have bought thru the years, like ARs, have had really worn Shure cartridges in them, like the M91ED, that were worn to a point and they certainly looked like the 90° modulated wall of a record groove.

Anyway, the stylii wear theory was a thinking out load moment, that I will still ponder upon.

Wayner
[/quote

Yes, a misaligned tonearm can deform the cantilever system of the stylus for long run, but the stylus shaft itself will not be worn out, being a much much ahrder material.

Of cousrse, when the cantilever is deformed, the whole stylus assembly must be tossed out.

c-J

[dlaloum]

Ay Ay Ay we are mixing things up here 

Yes a wider stylus helps ensure better contact with the groove wall - this is wider across the groove (wall to wall) and not along the groove

A narrower stylus helps ensure that the stylus tracks the corrugations of the groove better at higher frequencies - being narrower along the groove wall rather than across between the walls.

Elliptical styli were the first shape that allowed the width across to differ from the width along the groove... so you could get both the advantages of a wider and narrower stylus at the same time!
So eliptical styli have a MAJOR radius (across the groove between the two walls) and a MINOR or small radius (along the groove wall). this is why they are quoted as 0.3mil x 0.7mil - as an example.
(actually the major radius is parallel to the 45 degree groove walls rather than horizontal... but that is geometric nitpicking...)


The very best ellipticals in terms of sound are 0.2 x 0.7mil.

Now for the down side... - so far we have talked about radii looking at a cross section horizontally through the stylus.... so what happens vertically along the groove wall?

With the conical styli the contact patch with the groove wall is a little circle - the wider the radius, the wider the circle (roughly).

This has an interesting corollary: as the contact patch grows, wear decreases, the load of the Vertical Tracking Force is now distributed across a larger surface area, and therefore friction per area is reduced, reducing wear.
Older records specified maximum VTF's for differing stylus radii... with maximum VTF being lower for the finer/narrower styli.

With elipticals, the contact patch is slightly pear shaped, but substantially smaller, and continues to shrink as the eliptical's minor radius continues to shrink.

This in turn begins to cause a problem when looking at very fine (0.2mil minor radius) elipticals... the tiny contact patch improves tracking ability, reduces distortion and therefore improves audio capability noticeably - but wear is increased markedly. (this is why elipticals were never produced with finer minor radii than 0.2)

Historically speaking, this is where high compliance, low VTF design started to come into play, as the VTF needed to be reduced to ensure vinyl longevity.

Designers also started working on other stylus profiles... specifically, they started working on stylus shapes that extend the contact patch vertically along the stylus wall, permitting the reduced minor radius to be kept while reducing the wear/friction on both the stylus and the vinyl - through increase surface area while still maintaining large major radius and small minor radius. (later this development would allow more advanced Line Contact designs to then use narrower minor radii... as low as 0.1mil)

The first such design appears to have been the "pyramid" stylus, in the 1950's.... (which appears to have sunk in the mists of time without leaving much trace... )

The Hyperbolic and  HyperEliptical styli appear to have been the next developments - and were at risk of disappearing just like the "pyramid" when Quad CD4 came along.... which required an ability to trace the record at 50kHz - withouth wearing out the very fine groove corrugations.
0.2 mil elipticals could do it a couple of times, and then the record wore out, and the high frequencies were lost.
JVC led the efforts on CD4 and their designer Shibata produced the first commercially successful LC (line contact) stylus shape which was named after him.... the "Shibata".

Through the two cuts on the back of the stylus, a wide cone was turned into a semi faceted point, the properties of which are:
1) a narrow minor radius
2) a wide or very wide major radius (original design was for either 1.6mil or 2.8mil major radius)
3) A long contact patch -a bit less than double the contact patch length of a 0.3mil eliptical and around triple the contact patch length of a 0.2mil eliptical
4) substantially increased total surface area...
  conical 0.7mil = 30.5 sq um
  conical 0.5mil = 23.4 sq um
  elliptical 0.3mil = 20.6 sq um
  shibata (large) 0.3mil = 46.7 sq um
  Namiki MR  0.12mil= 62.1 sq um 

The other interesting thing about the geometry of a stylus, is that as the major radius increases, the contact patch length also increases ... - so the more extreme designs like the Ortofon Replicant have a major radius of as high as 100um (5mil !!).

It is also interesting to note that some of these highly regarded "extreme" designs do not necessarily have a very narrow side radius - the original Shibata was 0.3mil minor radius, and the TOTL Ortofon Replicant is 5um x 100 um or 0.28mil x 5.6mil.

The Namiki designed microline / microridge shape has a minor radius that can go as low as 0.14mil - I believe that few designers go below that, as it starts to become a bit of a cutter!

So your "ideal" needle has a side radius narrow enough to easily negotiate the narrowest audible groove corrugations (I think I recall Shure saying that 3.5um was the required minor radius for 20kHz in one of their research papers), and a major radius as wide as possible so as to maximise the vertical contact patch, thereby reducing wear on both stylus and vinyl, and allowing the stylus to ride at a higher VTF safely.

All of the above of course does not consider other aspects, like the quality/level of the polishing applied to a needle, or the quality of the vinyl compound used.... these also have a substantial influence.
As an example Denon DL103 styli are justly famed for the very high quality of the polish used on the needles- this reduces friction, thereby reducing wear and improving performance for what is a relatively basic conical design.
But given equal levels of polish, a Line contact stylus is much more capable than a conical.

bye for now

David