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Inmates, should the antiskate force increase or decrease as the stylus moves towards the record spindle.In my mind, it should decrease as the velocity is less when the scribed diameter is smaller.
Follow Ups:
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
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.
My Hi-Fi News test record tells me that the outer grooves needs the highest amount of anti-skating - all else being equal of course (comparing track 1, 4 & 8 on side 2). I believe you're right on the money.
If you look at the instructions for the WallySkater you will see that Wally recommends lighter anti-skating force on the outer grooves and more anti-skate force on the inner
grooves.
*skating* force increases (tendency for stylus to move toward the spindle) as the stylus tracks grooves closer to the spindle.therefore, anti-skating devices are generally designed to increase force as the stylus approaches the center, to counterbalance the greater skating force.
As far as I know, the stylus arc hits a zero skating point somewhere in the middle.I am not a mathematician, but the skating force is the resultant of the groove drag (one vector, tangential to the grooves) and the deviation from the true tangential point (IOW tracking error) as the other vector. The resultant of those two vectors is the skating vector, which is perpendicular (or centripetal) to the grooves.
However, that easy calculation assumes that you have either unmodulated grooves, or grooves that have a modulation in such a way that the stylus drag is constant (again, that would take some thinking for me, how a signal would need to evolve over a record to cause constant drag.)
You are aware that the skating force will increase on louder passages, and decrease on silent passages.
What was your original question again? : )
I think what you're thinking is that skating force comes from tracking error, which would be incorrect. Skating force is present all the way across the record and is due to the overhang/offset angle employed on pivoting arms.The motion of the vinyl at the point of contact is always perpendicular to a radius line from the center of the LP to that point. This is the direction of pull on the arm from friction. If you draw a line representing the direction of drag on the stylus, then draw a line from the stylus to the arm suspension, you'll see that they're not parallel. The arm will always want to swing in a direction to make the lines parallel, and thus we have skating force.
Right, I did not think that through. It's a function of the overhang, unless you have a tone arm with an underhang (some straight tone arms do that), then you have a centrifugal skate.Still my point is: the overhang is not static over the course of the record, nor is the drag of the record on the needle. Hence the skate force is chaning from moment to moment.
The biggest factor on skating force is the music itself, however. Vibrating the cantilever and producing electricity requires energy from somewhere and the only source of energy in a phonograph is the spinning platter, so the energy comes at the expense of more drag.This makes it hard to set anti-skate because there's no setting that removes the effect, but rather only one that provides the best average of cancellation. Loud test bands for setting anti-skate cause you to compensate for the worst case scenario, while setting a stylus on a grooveless area only compensates for an unrealistic 1-point contact scenario.
Bry
Yes, i believe the skating is a function of the head offset and the velocity. So, in my head, the velocity is reduced as the stylus approaches the centre, so, my confusion.In my head, one needs to have higher antiskating at the outside but, many advise it should be on the inside.
Read this topic John E pointed to above. The friction between 2 materials doesn't really change with speed, allowing for the same anti-skate setting for 33's and 45's, and theoretically for the inner and outer grooves.However, I believe there are some side-effects of the closely-spaced modulations in the inner grooves that can increase drag, by causing the stylus to climb steeper slopes to achieve the same frequencies. Someone else could probably answer this better.
-Bry
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