The Finish Line for your Phono Cartridge- Stylus Wear by Mike Bodell

Discussion in 'Audio Hardware' started by Bill Hart, May 24, 2019.

  1. Jimi Floyd

    Jimi Floyd Forum Resident

    Location:
    Pisa, Italy
    This question and answer on the Shure website is the only official reference I find on the net about a MM cartridge lifespan. Shure's statement is their V15 type V cartridge body has a lifetime which can exceed 50 years.

    EDIT - It also says 500 to 800 hours play time for the stylus tip.
     
    Last edited: Jul 12, 2019 at 2:02 PM
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  2. Leonthepro

    Leonthepro Skeptically Optimistic Autodidact Debater

    Location:
    Uppsala Sweden
    To resume, as mentioned I think there was a misunderstanding. I assume this is an overhead view. I completely agree that the diamond flattens Horizontally and increases contact area that way, in effect also removing the benefits of the fine stylus cut, increasing distortion. My point was in regards to Vertical contact which is what the numbers I posted talk about, or so Im quite certain. That fine styli are designed like a cutter head to have increased contact area Vertically with the groove walls, nearly maximizing contact usage that way, which is why I said it can not be increased much further.
    But again, you are correct, it will wear Horizontally, increasing contact area that way.
     
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  3. Ray Parkhurst

    Ray Parkhurst Well-Known Member

    Location:
    Santa Clara, CA
    The drawing was intended to represent the major radius, ie the "vertical" profile you would see looking straight-on at the stylus tip, not the minor "horizontal" radius, which governs the contact length in play direction . I drew only one flat representing contact on one side of the groove. It was purely a geometrical representation to make the point that the 75um radius will contact the groove only at a single point in theory, given no vinyl indentation. Sorry for the simplistic representation. I did not expect any confusion.

    The "fine styli" are for sure not designed like a cutter head. Their included angle is <90-deg in order to accommodate azimuth variation.

    I suppose I should update my much earlier (posted in this thread) drawings to show the profile of a Line Contact stylus, and how it wears. I'll work on that.
     
  4. Leonthepro

    Leonthepro Skeptically Optimistic Autodidact Debater

    Location:
    Uppsala Sweden
    So youre saying the drawing was in fact not an above view but from behind or infront of the stylus? And that more exotic shapes of brand new styli dont have more contact with the groove wall than say conical or even basic Elitpticals?
     
  5. Ray Parkhurst

    Ray Parkhurst Well-Known Member

    Location:
    Santa Clara, CA
    Not exactly. Let me explain point by point...

    The drawing was a front/rear view showing the major radius contact on one side of the groove
    If the VTF is set just slightly above zero so that the stylus just contacts the groove surface, the contact is only a point. This is the case for any of the stylus types, and is the situation depicted by the drawing
    With a normal VTF, the point contact spreads into an area due to the stylus indenting into the vinyl
    Brand new Line Contact / MR / SAS styli have a larger major radius than ellipticals or conicals
    The shape of the indented area is a circle for a conical or fake elliptical; an ellipse for a true elliptical; and a narrow line for line contact types
    The indentation is deeper for conical or fake elliptical, slightly less for true elliptical, and much less for line contact
    As the stylus breaks-in, it takes on the shape of the indented area initially, but eventually expands past that area with more extensive wear

    When you say "more contact", to be more precise, I think you mean "longer contact along the major radius", correct?
     
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  6. Ray Parkhurst

    Ray Parkhurst Well-Known Member

    Location:
    Santa Clara, CA
    Interesting read. Seems there is at least one other person on Earth who agrees with Dreams266, though such anecdotes without any logical reasoning or explanations don't help our understanding much. I have an open mind, so did a search on "catridge degradation", and in several pages of results there was not a single thread that had any information in the first 10 pages of search or so. However, I didn't actually put quotes around "cartridge degradation", and when I do this I get the thread you found, and this one as well: Is it foolish to use "vintage" cartridges/stylus?

    So, still keeping an open mind, I suppose I could postulate on why a cartridge could degrade. Here are a few possibilities:
    - oxidation of the coil wires
    - oxidation of the solder joints or welds
    - shrinking or cracking of the potting materials leading to change of shape or misalignment of the coils
    - as above but leading to delamination and material vibration and resonances

    Others may have ideas as well. I don't know if the above can explain the reasons for Dreams266 to have replaced his cartridge, and indeed he could regain some credibility if he would simply tell us why he felt he needed to replace it/them. He could regain even more credibility by posting links from other sites which indicate this is "common knowlege", since there seem to be only a couple of threads (one from 2012, other from 2016) on this forum which address the issue. I guess there have been discussions he was involved in on other forums, but without the links I still am dubious about cartridge degradation being common knowledge.
     
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  7. rebellovw

    rebellovw Forum Resident

    Location:
    Prescott, AZ, USA
    I absolutely do NOT agree that cartridges wear out - sure stylus - but not carts - they will out live you. That is all I will say. Carry on.
     
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  8. TheVinylAddict

    TheVinylAddict ___The Enforcer___

    I agree 100% at face value for practical purposes - with the caveat that it is possible for one to maybe malfunction (anything is possible) and that some day, at some time down the road the eventually will wear out though that could be a long time :) --- but I look at cartridges as a long term ownership item!
     
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  9. rebellovw

    rebellovw Forum Resident

    Location:
    Prescott, AZ, USA
    Yep. I have an old Precept (AT brand) that I bought in 81 - sounds great - and likely will sound great for decades to come.
     
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  10. Anecdotal, but I regularly use two Stanton cartridges from the 80s and they perform perfectly. I’m even using NOS styli, and the suspensions are fine as well, though I
    understand how that could certainly be a point of failure.
     
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  11. Ray Parkhurst

    Ray Parkhurst Well-Known Member

    Location:
    Santa Clara, CA
    I too have old cartridges that are still working great after 35 years or more. In fact most of my cartridges still have their original styli since I have rarely stuck with one cartridge long enough to wear out a stylus, and in that time I've never had a cartridge give me any problems.
     
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  12. Leonthepro

    Leonthepro Skeptically Optimistic Autodidact Debater

    Location:
    Uppsala Sweden
    Ive never heard people mention vinyl forming around that stylus which is what allows better contact. Im sure it happens to a small degree but if the stylus has to squeeze down in the groove with force Id think that would create extreme friction as the groove walls are gripping constantly around it. Especially at such speeds.
    Again, I would really need to see some sort of demonstration of this because it just doesnt make sense from what I understand.

    And yes I think that is what I mean with a bigger vertical contact area.
     
  13. Leonthepro

    Leonthepro Skeptically Optimistic Autodidact Debater

    Location:
    Uppsala Sweden
    It is worth mentioning that I looked too and although nothing special was found I did find it interesting that the Goldring cartridge he mentioned has a removable headshell like many MMs do. Its suggested to switch out when its worn, but why include such a feature if the whole cartridge needs to be replaced before the stylus does?
     
  14. missan

    missan Forum Resident

    Location:
    Stockholm
    If You believe in the contact areas You must also believe in the indentations.
     
  15. Ray Parkhurst

    Ray Parkhurst Well-Known Member

    Location:
    Santa Clara, CA
    Yes, and it does come down to beliefs since the stylus/groove interface is difficult to analyze, and almost impossible to measure in-situ under operation. By calculation, for a static interface, contact forces normal to the stylus surface are very high, and thus indentation must occur due to the modulus of the vinyl. But while the record is spinning, are those indentations the same? Like most materials, vinyl has dynamic properties which are different from the static ones. How quickly can the surface deform, and what role does friction play? I'm not a mechanical engineer so can't give definitive answers, though I've never seen definitive answers on this question from any engineers either. Personally, I don't believe there is as much dynamic deformation as would be calculated by static properties, so this would imply the contacts are closer to a point than an area, but it is only my belief.
     
  16. Slick Willie

    Slick Willie Decisively Indecisive

    Location:
    sweet VA.
    So eight pages into this, with many links/drawings/theories/beliefs...have we 'developed' anything solid besides checking the unit regularly for wear?
    Well possibly new (to me) is having it professionally checked by a tech with experience and correct equipment to do so.
    And if I'm getting this correctly a $50 cart wears as fast as a $5,000 cart under same circumstances.....with a lifespan now thought to be in the neighborhood of 500 hours.
    Am I getting the consensus correct?
     
  17. missan

    missan Forum Resident

    Location:
    Stockholm
    I am a mechanical engineer but it is still difficult to calculate. My opinion is though that most of these sketches don´t make sense for a moving record. There is no time to make an indentation, as I see it. It´s much more likely that the contact is a very small point, that is slightly moving around.
     
  18. BendBound

    BendBound Forum Resident

    Location:
    Bend, OR
    Less expensive cartridges typically use a spherical shaped stylus shape. Those shaped tips wear out in 200 to 300 hours, if not sooner. One of the reasons, besides shape, is the quality of diamond used in some spherical shaped tips. They have more inclusions and impurities in the diamond that give them a dark color, and those lower the hardness of diamond. Therefore, they wear out sooner. See in the article, the images of the N99E for an example.

    The 500 hour threshold is for advanced tip shapes, such as hyperelliptical, line contact or Micro Ridge. If I may, refer to the table in the article that shows the JICO determined hours to 3% distortion levels. Those hours are a reference point for each tip shape on when to have the tip examined.
     
  19. Ray Parkhurst

    Ray Parkhurst Well-Known Member

    Location:
    Santa Clara, CA
    I'd add that the MR / SAS type "seems like it should" last longer since the contact length in play direction is set by the distance between the laser-cut grooves. As folks have stated, this type "should" have fairly stable sonics as it wears. However, as the tip wears, it goes deeper into the groove, so I would still expect gradual and subtle changes to occur over time, until the tip starts to encroach into the radius at the bottom of the groove. From my experience this causes a high surface noise, sort of like what you hear in some end grooves. This is not the "catastrophic failure" some folks describe. Indeed for this type, I'd expect the sonics to improve right up to the point of groove-bottoming "soft failure".

    I tend to agree, though it does seem to be the common wisdom that some indentation does occur and that this broadens the contact area. I like to think of it in terms of static and dynamic friction. In the static state, the tip will sink fairly far into the vinyl, and this would create a large static friction that would need to be overcome before the tip could move along the groove surface. If the tip indented that much when moving, then that high friction level would continue, but it does not, yet there is still some amount of dynamic friction during play. That dynamic friction is likely due to shallow indentation, since if the contact were only a point, there would be no dynamic friction. I'd bet an indirect method of determining the amount of indentation would be to measure the static friction vs VTF, and then the dynamic friction during play, and then somehow calculating static VTF-equivalence. There are engineers around who specialize in friction, and I'd bet they could work up a simple model for this.
     
  20. BendBound

    BendBound Forum Resident

    Location:
    Bend, OR
    I wonder if that is what occurs initially when the tip is new, then as the tip encounters debris in the groove and the sheer interface frictional wear on the tip progresses, flats develop on that tip. The flats indeed do develop. That increases the surface contract to the record as the tip moves back and forth, up and down in a groove that is constantly changing its shape. That decreases the unit area loading force on the tip. I wonder also if diamond wears because interface temperatures rise even if for only milliseconds, and diamond is more prone to increased wear at elevated temperatures. But to your point and that of Ray Parkhurst, we don't know the physics of wear at that interface. But we do know tips wear and record grooves lose signal.

    A guy I know was an inventor for Analogic Corporation dealing specifically in digitization from analog sources. The guy holds a ton of patents for A-D converters, most from the 1990s. He told me once that it only took one play of a test lp record to remove the highest frequency information on it. From that information I assume the vinyl record begins wear too. All I know here is what he told me, and I have written here all I know.

    My take is that if records are repeatedly played on a critically worn stylus, accelerated groove damage occurs. That groove damage is progressive. The research in the Finish Line article bears that out. And I have too many records that look VG++ to even M that were played on a worn stylus tip. Most end up in the trash bin.
     
  21. Slick Willie

    Slick Willie Decisively Indecisive

    Location:
    sweet VA.

    Then let's change the price point to $100 and $5,000. And dismiss spherical.
    So for more money one can hope to gain another 200-300 hours?
     
  22. Ray Parkhurst

    Ray Parkhurst Well-Known Member

    Location:
    Santa Clara, CA
    I think this is correct, and is consistent with my "Long Break In" hypothesis. As I stated earlier, the indentation area is where the flats will wear. I see this in the before/after stylus photographs I have taken using the 45-deg ringlight method, which gives a good view of those areas which are not flat, but are "close to flat" and become flat after some wear occurs. My hypothesis is that sonics are not stable until those initial flats wear, and thus the curved stylus contacts are no longer indenting the groove surfaces, but are now riding smoothly over the surfaces on the flats. I don't have a lot of data on this, but experimentally this happens between 50 and 200 hours of play. Once the flats develop, I'd postulate that the sonics are quite stable, gradually degrading as the stylus wears (except MR/SAS types) and the contact length in play direction increases.
     
  23. Ray Parkhurst

    Ray Parkhurst Well-Known Member

    Location:
    Santa Clara, CA
    I've seen some VDH and other LC type styli that even when new have a fairly short distance between the lowest contacts at bottom of groove. There seems to be a tendency for folks to think that getting "deeper into the groove" is a good thing, and indeed sonically that may be true, but from a stylus wear perspective it simply shortens the stylus life. As the stylus wears, it goes deeper into the groove quite naturally, and at some point starts hitting the bottom radius and generating noise. So it's hard to generalize stylus life based on cost. There is certainly not an obvious relationship between these factors.
     
  24. Slick Willie

    Slick Willie Decisively Indecisive

    Location:
    sweet VA.
    So short of sending a unit off for periodic inspection (something that is far from practical), what can one take away from this thread?
    Personally I just want to play vinyl, not invest time and money into cart inspection.
    And somehow my 40/50 year old vinyl has survived what has probably been played with rocks far beyond the 500 hour mark.
    So then, how does one factor cart wear into permanent sonic degradation of the LP?
    Is the safest bet to use carts/records for display purposes and play digital?
     
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  25. BendBound

    BendBound Forum Resident

    Location:
    Bend, OR
    Diamond stylus tips don't last forever. If you care about the condition of your records, consider getting an advanced stylus tipped cartridge retipped or replaced at about 600 hours.

    I rotate my tires. Have them checked periodically for wear. Change my oil. Do all the stuff necessary to keep my vehicle in top running shape. I care about it. Its called maintenance. Does not detract from my enjoyment of driving. I do annual maintenance on my mountain bike, does not detract from my riding and I ride a few hours a week.

    The same for my stereo gear. And I also like playing records yet I care about them too. Everyone has to figure out for themselves what is worth it to them. After all, they are your records. But as you say, decisively indecisive. ;)
     

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