Questions About Distortion on Last Track of LPs

Discussion in 'Audio Hardware' started by jtw, Dec 31, 2015.

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  1. jtw

    jtw Forum Resident Thread Starter

    Hi All! As bad as my ears are, I always hear lots of distortion on the last track of LPs. Is this due to tracking error? If I've been using a turntable that produces this distortion, are the albums trashed?
     
  2. BayouTiger

    BayouTiger Forum Resident

    Generally an alignment issue, but some cartridges are notoriously bad on the inner part. Worst for me was the Rega ElysII.
     
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  3. John R Leddy

    John R Leddy Active Member

    Location:
    England
    LPs are just made that way. At a constant RPM the distance travelled per revolution reduces as the stylus proceeds towards the centre of the LP. That's why you'll usually find a nice quiet track ending each side of an album, as anything remotely dynamic or loud simply sounds awful. You should be able to hear the sound quality getting progressively worse from the start of the LP, and all the way through, not just the last track, though of course at that point the distortion is easier to hear.
     
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  4. Captain Wiggette

    Captain Wiggette Forum Resident

    Location:
    Seattle
    Yes its due to tracking error. Many things can contribute to this. Moving to a microline type stylus will help tremendously. But alignment, the mastering of the album itself, tonearm, etc etc can all contribute as well.

    You should be able to largely eliminate it with better cartridges and more advanced styli.
     
  5. Hubert jan

    Hubert jan Forum Resident

    That's right. Large modulations at the end to heavy for the needle tip (pinch effect), but that is bad mastering and also cutting to close to the label.
    To many platters are cut to loud, pinch effect everywhere.
     
  6. FJosh

    FJosh Forum Resident

    Doesn't a linear tracking table help combat this?
     
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  7. Hubert jan

    Hubert jan Forum Resident

    No. Needle radius bigger than groove width when cutted to loud. Pinch effect because modulation near zero crossing narrower than at the top of the wave, that's because cutting head has a sharp shape.

    Perhaps a needle with sharp sides will track oke, but that damages the vinyl instantly.
     
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  8. Captain Wiggette

    Captain Wiggette Forum Resident

    Location:
    Seattle
    No, not really.
     
  9. Drewan77

    Drewan77 Forum Resident

    Location:
    UK/USA
    Not necessarily... if the cartridge has been very precisely set up with something like an arc protractor there should be two null points where the stylus is exactly aligned and no distortion exists. Likewise, depending on the quality of the turntable, arm, cartridge & stylus (!), overall distortion will be so minimal that it is undetectable on all but the worst produced or damaged LPs - even at the inner groove.
     
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  10. Morbius

    Morbius Forum Resident

    Location:
    Brookline, MA
    I second Drewan's comment and IGD or mistracking doesn't ever have to be a reality!
     
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  11. The FRiNgE

    The FRiNgE Forum Resident

    The condition of your albums depends on what turntable you're playing them on, more specifically, what cartridge you have. Ceramic cartridges are known to quickly damage records, the worst ones in just one play. A better cartridge is a magnetic, lower cost models come with a conical stylus, or a mild elliptical, ie: 0.4 x 0.7 mil.

    Inner groove distortion will be produced by a lower cost magnetic cartridge. If the stylus is not worn, and distortion not severe, chances are your records have survived it. Cartridges tracking at about 2.5 grams and lighter are generally gentle on the records. In a previous comment, Hubert Jan, mentions "pinch effect". The Pinch effect occurs only at the inner groove area. Simply, the stylus encounters widening and narrowing of the groove, as this is how the cutting stylus cuts the groove. So, a conical stylus is forced upward as it tracks the narrower parts of the groove. (it has nowhere else to go) This upward motion is not not part of the signal, so we hear this as distortion.

    The best remedy is a higher quality cartridge equipped with a hyper-elliptical stylus, a line contact stylus, or Shibata stylus. If $500.00 + is too pricey, I can recommend at about $80.00, the Shure M97-XE with a 0.2 x 0.7 mil elliptical, which is an excellent tracker. The AT-440 MLA is also en excellent tracker and better sounding at a price point of about $200.00

    The new cartridge will need to be aligned. The stylus needs to be shaped more like the cutting head to track the inner groove. The cheaper cartridges/ styli usually sound clean all the way to just past the mid-point of a 12 inch LP, but are not capable of clean reproduction at the inner groove.
     
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  12. The Pinhead

    The Pinhead KING OF BOOM AND SIZZLE IN HELL

    All I hear differently on lp's last tracks is a slight reduction in upper treble, and just on some lps.
     
  13. BayouTiger

    BayouTiger Forum Resident

    You would know it if you had IGD!
     
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  14. Dentdog

    Dentdog Forum Resident

    Location:
    Atlanta
    To say linear trackers don't help with inner grove distortion is to ignore physics. A perfect tangent is always helpful. Granted, with the speed of the groove reduced significantly the dynamics may be reduced, but the tracking error, or lack thereof, does make a significant difference. I can't hear any difference in the inner grooves and have had comments from other listeners to this effect as well.
     
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  15. missan

    missan Forum Resident

    Location:
    Stockholm
    Of course. A linear tracker will have a great advantage in that the resultant force will pass through the pivot. This is big help at avoiding mistracking, which is partly what IGD is. If there is no offset angle the needle can track the inner groove wall much easier.
     
  16. missan

    missan Forum Resident

    Location:
    Stockholm
    That is not correct. An arm with an offset angle cannot track the inner groove wall when groove angles become to steep.
    A linear tracker has a great advantage in tracking.
     
  17. KT88

    KT88 Senior Member

    In theory, yes; in practice, rarely. Most turntables are equipped with tonearms at the factory and most tables with linear tracking arms are cheap units that have mediocre performance. As others have pointed out, much of the tracking capability of a record player is due the stylus and cartridge quality, and cheaper turntables are almost always fitted with very cheap cartridges. In fact, most linear tracking tables / arms only accept one or two cartridge types / models. Of course there are exceptions to every case. Look-up "air bearing tonearm" and you will find some extremely expensive and capable linear tracking arms that are designed to be fitted to very high end turntables. They are very impractical but when made to that level of quality and accepting the best cartridges, thy can finally offer the improved performance suggested by the makers of the cheap linear designs. In almost all other cases, a high quality radial (standard arm pivot design) tonearm will outperform a linear arm due to the quality advantages. The only linear tracker that I had, which I thought was a nice design (not the only one ever, just the only one that I have used that I liked at all) was a ReVox unit that I restored. The trouble even with it was that it had such a low mass tonearm that it would only track properly with a Shure V15 cartridge, which it was designed for. Even then, It wasn't really better than other tables that i owned which were more cost effective and which allowed many more options for cartridges.
    -Bill
     
  18. KT88

    KT88 Senior Member

    He does have a point though. Pardon the pun.
    -Bill
     
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  19. missan

    missan Forum Resident

    Location:
    Stockholm
    Maybe. There are in principle two causes of IGD, one is 'pinch effect', the other is the offset angle.
    If we can eliminate one cause the distortion will be lower, if we can elimenate both causes well distortion can be considerably lower. If implimented correctly, most linear trackers haven´t done that. Having said that personally I think I prefer a pivoted design, but I think it´s essential to understand the physics behind the problems.
     
    Last edited: Jan 1, 2016
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  20. Fedot L

    Fedot L Forum Resident

    The distortion that increases as the stylus passes from the “outer” to the “inner” grooves, is not an “inner groove distortion”, the so-called "inner groove distortion" is the "tracing distortion", non-linear distortion proper fundamentally to the mechanical reproduction of any groove (and not only "inner") of a gramophone record, and by any stylus or laser beam, due to the difference between the shapes of the cutter chisel and a stylus or a laser beam. But to a variable degree, depending, at equal signal frequency and amplitude, on the radius of the groove. And in the same groove, on the shape of the stylus' surface or laser beam dot in contact with the groove.

    The so-called "inner groove distortion" has nothing to do with neither tone-arm type (pivoting or linear tracking) nor cartridge alignment adjustment. Even with the best cartridge alignment adjustment, the "tracing distortion" will be present, as not depending on it.

    The only way to reduce it very considerably with "mechanical" cartridges: the use of styli types designed and manufactured for CD-4 discrete quadraphonic reproduction, or their modern analogues (“MicroRidge”, “Fine-line”, “Line contact” etc.) having the finest possible radius of contact with the groove sides.

    An explanation of the nature of the "tracing distortion" on the Net:

    “One of the several problems with analog recording is the fact that a rounded playback stylus cannot perfectly trace the exact motion in a groove created by a sharp-edged cutting stylus. This is a purely geometrical problem related to the difference between the stylus shapes and is now known by the name "tracing distortion"…
    Tracing distortion produces primarily harmonic distortion which is rich in the even order harmonics (2nd, 4th, etc. harmonics), and it increases with increased loudness and with increasing frequency of the signal.
    Tracing distortion also generates a type of intermodulation distortion of the high frequencies by the low which is particularly unmusical and objectionable…”
    http://www.intellitechcomputing.com/pipermail/phono-l/2008-November/009989.html
    ===

    For those who stay interested in this definition so far:

    http://www.gearslutz.com/board/mastering-forum/359343-combating-distortion-vinyl.html

    “Almost all of the distortion comes from a thing called Tracing Distortion which is caused by trying to play back a groove made with a triangular cutting stylus by using a round (or rounded) playback stylus. As the groove get shaper (because of level or diminishing wavelength) you get more tracing error and more distortion.”
    ===

    http://www.tronola.com/html/dynagroove.html
    “a significant amount of distortion as the ball-shaped tip attempted to trace the path cut by the chisel-shaped cutter stylus. This is called tracing distortion.”
    ===

    http://www.neumann.com/?lang=en&id=about_us_history_part_4
    “One interesting phenomenon in this connection is the tracing distortion that results from the difference in geometric shape between the tool used to cut the grooves and the playback stylus. The cutting stylus is shaped like a spade, while the playback stylus is spherical. During playback, this results in tracing distortion…”
     
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  21. missan

    missan Forum Resident

    Location:
    Stockholm

    The problem is that IGD cannot be only tracing distortion, if so it would be very difficult to perceive, very hard. When IGD becomes audible there is always an element of mistracking present. This mistracking is depending on groove angle and therefor the offset angle has an impact on the mistracking. It´s rather easy to see that an arm with an offset angle has to track the inner groove wall with a much, much larger groove angle than at the outer groove wall. That is the problem at inner grooves. Mistracking combined with tracing distortion is a needle acceleration problem, it will be audible at the frequencies where acceleration of the needle becomes difficult at these very steep groove angles at inner groove wall, mostly at high output S or Shh sounds.
     
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  22. The FRiNgE

    The FRiNgE Forum Resident

    A linear arm has two advantages
    1) no offset angle and no pivot (almost none) so tracking error (should be) held to a minimum
    2) no skating forces applied on the stylus, no anti-skate needed.

    The linear arm has many disadvantages "the imperfect 6" :tsk:
    1) no benefit from a conical stylus, as this type of stylus is not affected by even moderate tracking error, inner groove dist will be the same.
    2) no benefit from a mild elliptical stylus, as it too will produce inner groove distortion, and is not fusy with the alignment, tracking error makes no difference.
    3) the ultra low mass of a linear tracker requires an ULM type of cartridge, very limited choices
    4) most linear tracking turntables are not well made, flimsy platters, high rumble, lower fidelity reproduced overall
    5) Most linear trackers are "convenience" turntables for people who prefer a "close n play" type of turntable.
    6) Most linear tracking arms do introduce 1 to 2 degrees error (or more) the arm DOES pivot until the servo reads the error, and the arm motor moves the arm to the next sector.
     
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  23. The FRiNgE

    The FRiNgE Forum Resident

    Yes, some mastering engineers applied level reduction and limited frequency range on the last track, mostly a progressive reduction to avoid any abrupt changes. I notice this on some LP's and do not like! RCA Dynagroove was one of the first to apply compensation for the mass produced (cheap) record player, even apply some pre-distortion "pinch effect" out of phase to help cancel the actual mistracking of the cheap record player.

    The dynagroove and others that followed sound cleaner on the mass produced record player, but sound inferior on a high quality system
     
  24. daglesj

    daglesj Forum Resident

    Location:
    Norfolk, UK
    Heard this distortion on every turntable I've listened to. By track three I'm hearing nails down a blackboard rather than music. Its why I abandoned it long ago.

    Turntables, lovely to look at and fiddle with. Horrible to listen to.
     
  25. reb

    reb Money Beats Soul

    Location:
    Long Island
    Your math is off. Its a challenge, but possible. Keep trying until you get it perfect.
     
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