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In Reply to: Anti-skate force : Increase or Decrease posted by Jagdeep on May 12, 2007 at 11:01:49:
Why? Because half the respondents assume you are talking about skating force, and the other half assume you are talking about anti-skating force. Lots of arguments fly back and forth with no resolution. Repeat ad-infinitum...The underlying assumption fueling the argument is that they are one and the same, except they're not.
Skating force is generated by the stylus tracing the groove while riding at the end of a pivoting tonearm.
Anti-skating force is generated by a string and a weight (or a magnet or twisted wires or ...) acting close to the pivot of a pivoting tonearm.
They are two completely different forces, generated by two completely different mechanisms, yet we argue as if they're the same. Hello?!
So let the fun begin!
John Ellison and company will offer diagrams and endless discussion on how skating force is generated and how it varies over the surface of the LP (at 33 and 45!). Groove modulation, stylus profiles and vinyl composition will be mulled over at length.
Others will argue the merits of magnets vs. twisted wires vs. hanging weights. VPI's anti-skate approach will be insulted and defended several times. Everyone will agree it's best set by ear.
Neither side will attempt to analyze the two forces as a system to try and determine which anti-skating approach most closely counters the actual skating forces generated by the stylus tracking the groove, which is the REAL DAMN QUESTION THAT MATTERS!
But WTFDIK?
Wait 5 minutes! I need to get another beer and some popcorn... ;-)
Pete
Follow Ups:
Why are you trying to making something complicated out of something that is so simple? Skating force, the cause of which has been explained clearly many time on the VA (and is explained again in this thread) is the problem, and anti-skating force is the attempted cure. Skating force arises from geometry and friction issues, while anti-skating forces are prurposely-introduced torques about the pivot. The goal is to have them equal and opposite in direction.The original question was whether the skating force increases in the inner grooves. As Bry points out below, the friction that is responsible for the skating force is not very, if at all dependent on the velocity of the stylus in the groove. However, depending on the record, friction could increase or decrease near the center depending on the degree of modulation of the groove. There could also be a small geometry effect. depending on the design of the tone arm. Given all the variables that affect the friction force, the skating force will never be a constant, and hence the ideal, perfect required anti-skating force will be a variable amount. I know of no TT that has a sensor that measures skating force in real time and adjusts anti-skating force accordingly, so one must either make some kind of compromise (others have discussed how to do that here) or use a radial-tracking TT. A separate issue is a TT whose anti-skating force is not constant with position of the tone arm. That is a design issue (problem), and I expect that many tone arms have (undesirable) variable anti-skating forces beacuase of the design approach chosen. I say "undesirable" because, unless one is correcting for some tone-arm geometry-induced variable skating force, variations in skating force will be record-dependent.
Joe
Joe
Except he forgot to note that the HiFi News test record would be discussed and damned at length. And those inmates with linear arms and RS-A1 arms would stand above the fray and scoff at the whole business. :-)
.
> But WTFDIK?It sounds to me like you don't know very much at all or you would have simply answered the question. ;-)
NT
You and others have done a good job at analyzing and describing the way skating forces are generated and how they vary across the surface of an LP. My point was not to criticize those efforts.My humorous jab was intended to point out that these discussions are never taken to the next step - which is to use the understanding of skating force to figure out an optimal anti-skating approach.
Many setups apply AS force highest at the outer grooves and then allow it to taper off toward the inner grooves, which is not optimal. Is there a better approach available? Could one be designed?
I wasn't insulting your intelligence or understanding, just pointing out a huge collective blind-spot with regard to this topic.
Apparently I got your back up and you felt the need to insult my intelligence. Sorry. I am dumb as a post and should have known my place among my betters.
Ignorance is bliss,
Pete
You state: "Many setups apply AS force highest at the outer grooves and then allow it to taper off toward the inner grooves, which is not optimal. Is there a better approach available? Could one be designed?"If I'm not mistaken (and I often am) the string/weight system used by Pro-Ject, Music Hall, and others does apply an increasing anti-skate force as the tonearm pivots towards the inner portion of the groove. The point of nearly perpendicular force angle to the tonearm is when the tonearm is tracking the last portion of the groove.
> My humorous jab was intended to point out that these discussions are never taken to the next step
> - which is to use the understanding of skating force to figure out an optimal anti-skating approach.Personally, I don't think skating force and antiskating are problematic issues for most well designed tonearms. However, there is no practical way to implement a dynamic antiskating mechanism that will perfectly counteract the dynamic skating force caused by the dynamic nature of music. On the other hand, I don't think it really matters too much because the best pivotal tonearms seem to perform quite nicely these days.
For those who place extraordinary emphasis on optimizing antiskating, it might be prudent to use a linear tracking tonearm, which completely eliminates the problem all together.
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