Raul, your point is well taken. That is what makes vinyl playback so interesting. Perfection gets boring after a while. Something so special or romantic about the glow of the preamp tubes, the spinning platter and those golden tones- with a little background crackle :)
Zero Antiskate vs Stylus Wear
This article, based on a long term study, was “plagiarised” from another Forum. It’s quite an old article so apologies to “older heads” for whom this may be old news.
It comes from an era when light VTF = good, but was not necessarily true, however the basic principle of long term wear looks sound.
Styli were tested to destruction over their full lifecycle.
http://www.audiomods.co.uk/papers/kogen_skatingforce.PDF
Viewers may have to cut & paste but in the event of difficulty with the link I will give a brief summary :
Of 14 cartridge samples tested without bias, 9 of them suffered excessive wear on the inner groove. One was neutral and the remaining 4 were “outer wall”.
When bias compensation was applied to a group of 6 samples, the wear pattern that resulted was symmetrical.
Given the strong and logical argument that skating damages styli asymmetrically – and gives a skewed reading of the LP over time, the “deviations” are a concern i.e. why 4 of them behaved oppositely.
Poor bearings? Arm cable too stiff? Wrong geometry?
IMO most turntable enthusiasts considered it self evident that unilateral force would cause this type of wear pattern so we didn’t need to be told but documented study, even one as old as this, is always interesting.
The photograph of the spherical stylus is poorly resolved on this copy but it makes the point quite graphically.
Based on long term experience that the simplest things can affect the sound of a turntable, I cannot deny that the idea of “de-stressing” the cantilever by removing a poorly directed/located AS force IS attractive and may produce a degree of audible benefit…at first...(?!?!?!!!)
The doubter in me always asks the question : can a mechanical assembly successfully zero out all mechanical influence and give a pure result? (If true zero AS is the goal even arm damping might be prohibited?)
The principle of using excessive VTF (up to 50% more) to achieve the same “trackability”, without bias, it was suggested, merely accelerates the unilateral wear & tear with (presumably) commensurate damage to the LP(?)
The proposed compensation of up to ”50% extra VTF” sounded a bit excessive to me.
(I’d balk at applying more than 0.1g over maximum.)
Old as it is, I found this study mildly unsettling.
Comments and opinions are invited from both Zero-antiskate adherents and those who always use AS.
It comes from an era when light VTF = good, but was not necessarily true, however the basic principle of long term wear looks sound.
Styli were tested to destruction over their full lifecycle.
http://www.audiomods.co.uk/papers/kogen_skatingforce.PDF
Viewers may have to cut & paste but in the event of difficulty with the link I will give a brief summary :
Of 14 cartridge samples tested without bias, 9 of them suffered excessive wear on the inner groove. One was neutral and the remaining 4 were “outer wall”.
When bias compensation was applied to a group of 6 samples, the wear pattern that resulted was symmetrical.
Given the strong and logical argument that skating damages styli asymmetrically – and gives a skewed reading of the LP over time, the “deviations” are a concern i.e. why 4 of them behaved oppositely.
Poor bearings? Arm cable too stiff? Wrong geometry?
IMO most turntable enthusiasts considered it self evident that unilateral force would cause this type of wear pattern so we didn’t need to be told but documented study, even one as old as this, is always interesting.
The photograph of the spherical stylus is poorly resolved on this copy but it makes the point quite graphically.
Based on long term experience that the simplest things can affect the sound of a turntable, I cannot deny that the idea of “de-stressing” the cantilever by removing a poorly directed/located AS force IS attractive and may produce a degree of audible benefit…at first...(?!?!?!!!)
The doubter in me always asks the question : can a mechanical assembly successfully zero out all mechanical influence and give a pure result? (If true zero AS is the goal even arm damping might be prohibited?)
The principle of using excessive VTF (up to 50% more) to achieve the same “trackability”, without bias, it was suggested, merely accelerates the unilateral wear & tear with (presumably) commensurate damage to the LP(?)
The proposed compensation of up to ”50% extra VTF” sounded a bit excessive to me.
(I’d balk at applying more than 0.1g over maximum.)
Old as it is, I found this study mildly unsettling.
Comments and opinions are invited from both Zero-antiskate adherents and those who always use AS.
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- 24 posts total
Dear Raul, I cannot agree more. Like you say, perfection can only ever be a theoretical one. Adjusting factors e.g. on a per record basis would be soul destroying because one factor offsets others – which in turn would require correction. Such levels of technicality would quench the spirit and defeat the very purpose of listening to music. It’s eminently more sensible to spend many days and many records advancing the setup to a happy medium then simply enjoying it. Perfectionism is only useful insofar as achieving the working ideal for one’s own turntable/s whilst in full realisation that temperature, humidity, record warps, manufacturing errors, stylus cleanliness, record cleanliness, etc are the Devil’s way of making sure it doesn’t always run smoothly. It’s true, we can change our ambient temp or VTA or VTF seasonally to compensate for Summer-Winter changes, depending on which is easier, and we may clean our styli at different intervals, and if we have easy VTA adjustable arms we can alter the level of the arm from 120g -180g as easily as throwing a switch - thereby keeping that idealised relationship unaltered but when it comes right down to it, it’s all about maintaining a reasonable equilibrium. Regarding your comments about record warps, I do find it interesting that if we introduce a 120g to 180g VTA offset we can clearly hear it and quantify it, yet our ears can be extraordinarily forgiving when it comes to warped LPs (which affects all LPs to at least some degree). Perhaps the ear/brain interface actually compares average rather than instantaneous values? :^) Speaking of mis-drilling : one of the most obvious examples of wrongly produced vinyl is the HFN/RR test disc. I’ve owned a couple of samples of this and the centre was always drilled 1 or 2mm off centre. This would result in a wavering effect when using it to adjust bias, with associated intermittent cyclic mistracking on the more severe tracks. (Personally, I only use music to adjust bias but if one must use an HFN/RR I would advise only to focus on the fadeout of the 12db tone. With some carts of varied trackability and in various states of wear, I’ve heard the tone pulling to one side as the signal level falls to zero instead of remaining centred…although don’t be surprised if your cart shows no difference at your ”ideal” setting.) Best regards… |
Thanks for bringing that old study to our attention. I don't recall whether I ever read it the first time around. I could summarize my response with three statements: (1) I don't know who ever promulgated the idea of increasing VTF to compensate for skating force without applying AS, but it's ridiculous on the face of it, since skating force will go up as VTF goes up (because friction of the stylus in the groove will also go up). (2) We all know, and you guys have accurately restated, the pitfalls and inadequacies of the AS mechanisms on a typical tonearm, but the study would suggest that imperfect application of AS is better than no AS at all, unless one applies far too much AS, in which case one has created a new problem. (3) So best compromise is to use AS but use it conservatively. By the way, Raul, in passing you wrote something that suggested that headshell offset angle is a culprit in causing skating force, but even a straight tonearm with no headshell offset will generate skating force, so long as the cartridge is aligned with the stylus tip overhanging the spindle, because in that case the cartridge/cantilever is never tangent to the groove. (Not Newton in this case; Pythagorus is responsible.) The RS-A1 tonearm attempts to mitigate the problem by using UNDER-hang; the stylus tip is recommended to be about 20mm short of the spindle. (I am really testing this idea out, about the effect of overhang, but it seems correct to me.) |
First let me thank moonglum for posting the link, the paper was very interesting as were some of the others listed on the Audomods site. I would have to agree with Raul, skating force is a direct result of offset angle, the greater the angle, the greater the vector force created. That is the angle the stylus is offset from line drawn between the stylus and the pivot point of the tonearm, regardless of the shape of the arm. Here is a video by Wally Malewicz that explains the theory and demonstrates the ill effects of poorly set AS. http://m.youtube.com/#/watch?v=iEVuP6-zYLE&feature=plcp Don't get me wrong, the Points raised by Kogen are valid they are just secondary. As i see it, if you could line up the stylus in the same plane as the tonearm then there would be no skating forces. Of course this would cause enormous tracking error, so it remains a hypothetical scenario. |
Nick, But consider this: if a straight tonearm (no headshell offset) is set up such that there is any amount of overhang (meaning stylus tip overhangs the spindle, as is typical for all conventional tonearms), then the stylus can never be tangent to the groove walls, because, by the Pythagorean theorem, where the P2S distance is the hypotenuse of a right angle triangle, the condition a-squared (where a is the pivot to stylus tip distance) + b-squared (where b is the radial distance between the stylus tip and the spindle) can never = c-squared, the P2S distance, because a>c. So now I posit that lack of tangency of the stylus to the groove walls will per se produce a skating force. This is NOT to say that offset angle cannot also cause skating force. Picture a little red wagon where the front wheels are fixed in line with the rear wheels, but the long handle is free to pivot left to right. Now if you pull the wagon using its handle forward following any straight path that is parallel to but not directly in line with the direction determined by the four fixed wheels, you will generate a side force on the wagon. I think this is true. |
- 24 posts total