What's actually breaking in-stylus tip or suspension?

Discussion in 'Audio Hardware' started by tim185, Apr 16, 2015.

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  1. Sabciu

    Sabciu Member

    Of course it can! Don't people realize we sharpen our knifes after cutting tomatoes and our axes after chopping wood!?
     
  2. Scott Wheeler

    Scott Wheeler Forum Resident

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    It may very well be a definition issue. Yes they do wear. the friction is such that even a diamond gets worn down. But if you look at pictures of worn styli they aren't "polished" However, unless the manufacturer is incompetent, they are polished to begin with.

    http://www.aes.org/aeshc/pdf/how.the.aes.began/marcus_the-diamond-stylus.pdf

    That diamond stylus doesn't look more polished to my eyes.
     
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  3. missan

    missan Forum Resident

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    Stockholm
    The wear is forming flat spots at the needle tip. Consider these spots for most needles to be a polish. For very polished needles these spots might not be more polished than the original needle, maybe.
     
    Last edited: Apr 18, 2015
  4. Scott Wheeler

    Scott Wheeler Forum Resident

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    2 points.
    1. You don't change the shape when you "polish" something. That is deforming it.
    2. Did you look at the pictures? Clearly the stylus is less "polished" (as in less smooth) after the wear.
     
  5. DaleH

    DaleH Forum Resident

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    To be fair the article is from the early days of disk playback. The only diamond tip they show shows no wear after 1000 plays (a few hundred hours) at one and half ounces! VTF.

    a modern LC shape is a whole different thing I think. a narrow minor radius like ML at 1.5 microns will look nothing like the tips shown.

    If you get a real big chip on your diamond tip it will damage your records but I think the tiny chips from normal playback are no bigger than a polish.

    The reason for the flat spots is because the tip spends most of its life in a nearly parallel groove. The highest pressure occurs at the greatest tip acceleration and a small minor radius should wear more evenly cross the minor radius.
     
    Last edited: Apr 18, 2015
  6. missan

    missan Forum Resident

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    Stockholm
    The flat spots that will show up, after some time, starts with polishing at these tiny spots. That means that at the beginning of the needles´ life, these spots will be getting a smoother surface than the rest of the needle. That is polishing, mtrl must be removed to get a lower surface roughness.
    Polishing these spots long enough will mean wear, as the polishing is happening at a very tiny part of the needle tip, continuously, in principle, when playing.

    So what we are talking about is a diamond needle tip, and most needles.
     
    Last edited: Apr 19, 2015
  7. missan

    missan Forum Resident

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    Stockholm
    The highest pressure will occur when the needle is accelerated so much that it will loose contact with one groove wall. That means the VTF is only concentrated at one wall, so that the normal groove force at that wall is: Sqr2 x VTF. The force cannot get higher than this, then the needle will mistrack.
     
  8. Scott Wheeler

    Scott Wheeler Forum Resident

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    Again I suggest you look at the actual photos I posted links to. The spots do get "flatter." They do get deformed. They don't get polished, they don't get "smoother." They get visibly rougher. Just look at the pictures.

    I mean think about it. Do you think that wear on a a high precision polished dry bearing amounts to further polishing and a smoother bearing? A diamond stylus is already polished. It isn't going to get more polished by the wear of playing. It just gets damaged.
     
  9. missan

    missan Forum Resident

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    It´s easy to intuitively think one can transfer what is happening, with other mtrls in similar situations, and also what can happen in other circumstances, also with other mtrls, to also be happening at a diamond needle tip. One cannot. This is a specific real world situation using a diamond tip in a vinyl groove, and using an analogy with other mtrls is not valid, it doesn´t work mainly because the diamond has an extremely different hardness.
     
  10. Scott Wheeler

    Scott Wheeler Forum Resident

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    That wasn't an analogy. It is another example of a hard polished object that is subject to wear from friction. That makes it the same thing. Not an analogy.

    Again the actual photos of an actual *diamond* stylus when new and when worn speaks for itself. Clearly the worn stylus is less smooth.
     
  11. back2vinyl

    back2vinyl Forum Resident

    Location:
    London, UK
    As far as I know, cartridges don't break in. What makes you think they break in? What difference is it that you think you hear?

    The stylus tip will of course be subject to wear but that will only affect tracking and not the frequency response. The other parts aren't subject to wear.
     
  12. missan

    missan Forum Resident

    Location:
    Stockholm
    I have really no idea if some 'break-in' happens, meaning it will sound better after some hours. But if there is one, and knowing how important low friction is, one could speculate that the polishing at the needle´s contact spots might be lowering the friction diamond/vinyl. Just a speculation, but the most reasonable speculation I can think of.
    That would possibly mean that not so expensive styli could more benefit from this polishing.
     
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