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Inner groove distortion

Discussion in 'audio' started by unit, Nov 20, 2013.

  1. paskinn

    paskinn pfm Member

    Of course; the weird thing about vinyl is that aspects of its technical performance are poor...such as inner groove issues, noise, warps, tracking and so on. Quite high distortion too. And yet it can still sound the best recorded medium we have. A true mystery.
    And for those who can't accept the compromises, there is digital. Something for everyone. I don't concern myself with the basic vinyl flaws...it's a bit like humans, we ignore the bad bits if we really like the rest.
     
  2. TheDecameron

    TheDecameron Unicorns fart glitter.

    Yeahbut you can't role on one a streamer.
     
  3. kneecap

    kneecap pfm Member

    Fafftacular !! a much better word than "selfie"
     
  4. Covkxw

    Covkxw pfm Member

    I believe the designer of the Eminent Technology ET2 linear tracking arm incorporated an isolation (lateral-compliance decoupling) feature in its counterweight system to bring the arm's horizontal effective mass, at the point of (arm/cartridge) system resonance, to the same/similar value as vertical effective mass. I've also read of ET2 users fine tuning the counterweight decoupling when using cartridges with particularly low or high compliance to optimise tracking performance as well as improve coherence over the frequency range.

    An ET2.5 version of this arm is currently available (albeit limited production) from the designer, but is quite costly at $4500
     
  5. pure sound

    pure sound Trade: manufacturer/distributor

    I had an ET2 for a while. It did have that lateral sprung arrangement for the counterweight. But it still had the LF shortcomings I've heard with every arm of that type (and the good bits). The best air bearing arm I've heard would be the Kuzma.
     
  6. F1eng

    F1eng pfm Member

    Decoupling the counterweight in that way will somewhat reduce the lateral effective mass a little, but still nowhere near enough to have much effect at ~10Hz.
     
  7. Covkxw

    Covkxw pfm Member

    Hi ps, I've read that the ET2's LF shortcoming originate primarily from sub optimum air supply pressure due to inadequacies of the supply system, eg. too long air tubing (undue flow resistance) or air leaks sufficiently problematic for the standard, supplied air pump. Most informed users today use higher ouput pumps and I've heard (some time ago) a WISA Model 1000 air pump together with an Airtech surge tank/air reservoir used to great effect on a friend's ET2 system.
     
  8. pure sound

    pure sound Trade: manufacturer/distributor

    I used a larger pump & 5L surge tank.
     
  9. Covkxw

    Covkxw pfm Member

    ps, that's interesting. Did you ever check what sort of running pressure was being provided to the arm bearing? I ask this as not all the usual air pump makes/types can give adequate pressure (say 8+ PSI) even though their specs may indicate relatively high flow (500-1000 L/hr) capacity.
     
  10. Hepokatti

    Hepokatti pfm Member

    I simply had to return to this topic. I couldn't live with such misinformation being passed on in a forum I have respect for.

    Now, without making any further comments about 440Mla, AT95E or Denon DL-100, I'm simply going to post some specs.

    MOST RECORDS?

    Ortofon 2M Red
    Stylus tip radius r/R 8/18 µm

    Ortofon 2M Blue
    Stylus tip radius r/R 8/18 µm

    Ortofon 2M Bronze
    Stylus tip radius r/R 8/40 µm

    Ortofon 2M Black
    Stylus tip radius r/R 6/50 µm

    So, according to you, 2M Black and 2M Bronze has audible IGD on MOST RECORDS, while 2M red tracks those equally well with 2M blue and 2M bronze.
     
  11. Robert

    Robert Tapehead

    No not according to me at all - you should try reading what I actually say, not what you think I say.

    A scanning minor radius of 6um is superior to one at 8um, so it will have lower IGD, other things being equal. Yes a 6um stylus will have some IGD on most records, but its very slight compared to most other cartridges and only occurs on the innermost track where wavelengths are shortest. If you want to remove the effect completely you need <3um.

    Tip mass also features in the equation, so if you have two styli at 8um and one has lower tip mass, it will perform a little better on high amplitude high frequencies sitting on the innermost grooves. But whatever happens with tip mass, the diamond scanning edge still needs to fit whatever it's attempting to trace so we come back to profile. The difference between the 2M Red and Blue is tip mass, with the latter lower due to having a nude mounted stone. Both have IGD, but you can push levels on the Blue a little higher before the distortion becomes as audible as with the Red. The Bronze has a lower mass still and some line extension but won't perform as well as the Black. There is a reason Ortofon reduce the minor radius from 8um to 6um, and it's better tracing.
     
  12. antonio1

    antonio1 pfm Member

    hi Robert , how to interpret this? i.e Elliptical .0007"x.0003 (goldring 2200)…
    should read 7/30 µm?

    thanks
     
  13. Robert

    Robert Tapehead

    Hi Antonio,

    Thats a bi-radial or elliptical @ 8/18um.

    A normal spec elliptical. One set of figures are imperial and the other metric, so they don't perfectly translate.

    Better elliptical or whats often refereed to as 'special' or hyper elliptical are 5/18um. (.0002)
    MicroLine, MicroRidge, Pathfinder, and VDH will be typically 2-3.5um (often specified as .00012)
     
  14. antonio1

    antonio1 pfm Member

    OK,

    thanks for the accurate description , cold comfort as mine is a nude mounted .
     
  15. Hepokatti

    Hepokatti pfm Member

    http://www.audiomisc.co.uk/HFN/LP3/aroundthebend.html

    "Overall, the above tells us that if we wish to be able to play real-world LPs without mistracking we really need a tip mass of around half a milligram or less, and a minor radius of curvature (or equivalent) of around 3-4 microns or less."

    But;

    "So although theory tells us we’d need to cope with 6000g and very tight curves to obtain a 0dB 20kHz test tone, the reality seems to be that practical LPs of music don’t normally have modulations which reach such extreme levels. This agrees with the results in the previous article and explains the difference between the theoretical requirements and reality!"

    .. and even this article is somewhat biased and old. Not to mention the fact that you did mention tip mass as well. Thus, it is clearly not down to the shape only, as I've been saying all the time.

    Nobody is claiming that advanced styli profile don't bring advantages in tracking - they do. Just how much, is another question. The recommendation of AT440MLa to avoid distortion is only half good. Yes, the diamond is small enough for most modulations at the end of the side, but then again the cantilever material is such that it resonates 13-16khz range and creates distortion. The same is true for the stylus guard and whole plastic construction of the cartridge. The cart can be dampened or loaded differently to some extent, and while it might tame some shrillness, it doesn't solve the actual problems.

    Much much better option is the AT 150MLX which has gold plate boron cantilever. Boron's resonance is much higher (outside audible frequency range), and the manufacturer even claims the gold plating dampens the cantilever further.

    I'm sorry but it just makes me see red people writing about vinyl playback distortion and claiming the whole culprit being about stylus shape only. It is simply not true. The only true thing in that is the fact that better stylus shapes trace high frequencies better. But it is only a small part (albeit important!) of the equation when attempting to remove distortion in vinyl playback.

    On a side note:
    I don't see many people complaining serious IGD issues with 2M Bronze - not to mention 2M Black. But, like I said earlier, mistracking is never truly banished. However, what can be considered "obvious" or "in most LPs" is another matter.

    One more thing. Those figures like .03x.07 etc. often represent the size of the stylus SHANK , not the tip itself. Goldring vaguely states "stylus radius".
     
  16. Robert

    Robert Tapehead

    You really do need to read what's actually written, not what you think is written.

    I can see nobody claiming that stylus shape is the sole arbiter of good tracing.
    Clearly the finest cut stylus on the planet isn't much use if the tip mass is 10x optimal. But you can go on reducing tip mass to your heart's content - if the shapes don't fit you'll get nowhere fast.

    That's incorrect.
    Again you need to read what's written.
    All stylus profile specifications refer to minor and major radii - giving the user the shank dimensions is about as useful as the proverbial chocolate teapot.


    That's becasue they don't have serious IGD - its simply higher than with a MicroLine or VDH profile. More with Bronze than the Black which has very little becasue it has a better stylus. These cartridges are otherwise identical.

    Most people don't complain about IGD becasue, like you it seems, they can't separate it from the other potential forms of distortion. If you think a 8/18um elliptical is fine for low IGD then you obviously aren't hearing it, even though it's there.
    You seem to be mixing tracking ability, which is usually specified at around 300hz, with HF tracing. When you grasp the difference we can explore further.

    Specifically on the AT150 v 440, the former does not have better HF tracing, for while it's boron cantilever is stiffer than the tapered aluminium, its also going to have higher mass. Comments about ultrasonic resonance differences are meaningless unless you can produce the figures to compare rather than just mouthing the manufacturer sales blurb. The resonance simply needs to be well removed from the audible range, which is obviously the case with even standard aluminium cantilevers since wide bandwidth MC cartridges show no cantilever ringing anywhere near the top of the audio band.
     
  17. kristoffer

    kristoffer Danish Hi Fi NERD

    Ever since I changed my DL 103 to a Denon DL160 IGD has disappeared.
     
  18. Hepokatti

    Hepokatti pfm Member

    Ah.. personal arguments/ad hominem. Not interested in discussing anymore :)

    I don't understand where you get these assumptions. You ask me to read what is written, yet you interpret heavily between the lines yourself. Not to mention you put words into my mouth; "If you think 8/18um elliptical is fine for low IGD.." etc. I've never said such thing, nor am I under any illusions that low frequency tracking ability has much to do with the high frequency tracking ability.

    But why should anyone care what you or me think? Why should people care is some random bloke "right" or "wrong" about vinyl playback? The only interesting thing here is the matter itself, not you or me as people or what kind of knowledge we hold.

    It is extremely frustrating to try to explain what I mean in my 3rd language, when people make dumb personal remarks, which have nothing to do with matter itself. Rather serving only as weapon to "win" an argument on an internet forum. If I'd like to jump on the same ship I could say something like 'I guess to some people their ego/identity are hanging by a thread, and they're not as interested in the facts as they're interested in being 'right'.'
     
  19. Hepokatti

    Hepokatti pfm Member

    Finally found what I was looking for earlier, but couldn't come across the topic. I have to bookmark this for future reference;

    http://www.vinylengine.com/turntable_forum/viewtopic.php?f=19&t=31549

    Anyone interested the Inner Groove Distortion, tracking, "stylus not fitting the groove" and whatnot, please take a look. It's a bit mathy and hard to grasp (as it is just a discussion - not an article), but worth a read nevertheless. Read the whole thread as the conclusions are at the end.

    EDIT: Further read might be this, which better (in addition to the fore mentioned topic) explains the benefits of fine styli on inner grooves; http://www.vinylengine.com/turntable_forum/viewtopic.php?t=31865, but there are many good discussions about the subject @ ve
     
  20. Robert

    Robert Tapehead

    Or have a chat with Jonathan Carr of Lyra or the good Prof Van Den Hul. Go straight to those who've done a mountain of research and built the products to demonstrate their findings.
    They'll give you chapter and verse quite freely and are keen to share knowledge.

    Alternatively, after Scalford is over I'll arrange to place two tracks side by side, same cartridge but one with an 8x18um elliptical tip and the other with 3x75um Line.
    Something nice and hot, and of side with plenty of HF and sibilance. That's the only way to settle this nonsense. I'll host the files given the needledrop policy.
     

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