滑冰与反滑冰——基础知识
在音响发烧友乃至音响媒体中，关于滑移力和防滑补偿的概念存在诸多误解。一些备受尊敬的唱臂制造商声称滑移力无关紧要，甚至认为任何防滑补偿都会对唱臂性能产生负面影响。在一些音响发烧友和唱臂制造商的网站上，也存在着对滑移力和防滑补偿的错误解释，而且这种情况至今仍然存在。
即使解释准确无误，它们也常常使用一些对物理学基础薄弱的人来说晦涩难懂的术语。WAM 工程公司提出了一个简单的类比，可以帮助大家轻松理解滑冰的受力原理。我们不会深入探讨滑冰受力的原因和成因，因为这部分内容往往容易让人感到困惑。相反，我们提供一个许多人都经历过的场景，希望它能帮助大家理解其中的原理。
示例
你玩过滑水或尾波滑水吗？如果玩过，你可能还记得，被快艇拖曳时，最容易滑行、最省力的滑行位置就在快艇行驶方向所形成的直线上——也就是快艇的正后方。当你向尾流的一侧或另一侧摆动，试图保持在尾流之外时，你就必须消耗能量来抵抗将你拉回快艇行驶方向正后方直线上的力。
把你拉回船后方的力是滑行力。你试图摆脱这种力，用力向一侧倾斜身体，以便保持在船尾流的外侧，这种力是反滑行力。
唱针的滑动力并非如常人所误认为的那样是由偏移角产生的，而是主要取决于唱针在唱片沟槽中产生的摩擦力以及唱臂枢轴点的位置——而唱臂枢轴点并不在唱针所循唱片沟槽的切线上。（圆的切线是指与圆相切于一点，且从该点到圆心的直线垂直于该切线的直线。 ）
Imagine that the tonearm pivot point is the boat, the stylus is the skier and a line defined by the tonearm pivot point and the spindle is the center line of the wake of the boat. As the distance between the stylus (skier) and the straight line defined by the pivot point and the spindle (center of the boat wake) increases, skating forces also increase. As the skier moves back toward the center of the wake, skating forces decrease until they reach zero in the center of the wake.
While the above description of skating force in vinyl playback is incomplete, it is certainly sufficient for purposes of making the general principles more accessible to the average audiophile. Videos to help you understand it in its entirety coming very soon!
WATCH SKATING FORCE IN ACTION - *EXTREME CAUTION REQUIRED*
If you have a record with no grooves or run out grooves pressed on it you can see this force in action for yourself. (Classic Records did a few 45rpm pressings in this manner in the late 90s to early 00s). *BE FOREWARNED THAT THIS PROCEDURE COULD RESULT IN SEVERE DAMAGE TO YOUR CARTRIDGE AND WALLET IF YOU ARE NOT CAREFUL*
Turn your amplifier OFF. Re-confirm that your platter is level using a small bubble level. Initially, set your anti-skating at least mid-range in order to keep the stylus from flying too fast toward the center in this process. With the record turning no more than 33rpm, lower the stylus at the outer edge and watch it skate toward the label. Be ready to catch the arm before it gets too close to the label. Notice that the velocity slows as the stylus gets closer to the center of the record. Decrease your anti-skating a bit more and notice the difference in velocity and the change in velocity as it approaches the label.
Now disengage the anti-skating entirely and lower the stylus onto the record at a point about 1.5 inches from the label. Notice the velocity with which it approaches the label. Compare this velocity with what you see when you lower the stylus at the very outer edge of the record and watch how fast it travels the same distance of about 1.5 inches. You should notice the stylus picks up inward velocity much faster if you lower it at the outer area versus the inner area of the "playing" surface. This is happening because the skating forces are more powerful further away from the center of the record. If you don't see this in action and your anti-skating is disengaged there may be something wrong with your tonearm's horizontal bearing. Check this on a WallySkater.
Now look at your blank record in bright light and notice the micro groove you have just etched in the record surface. CLEAN YOUR STYLUS!
WHY DO WE NEED TO APPLY AN ANTI-SKATING FORCE?
Since skating forces generated on the stylus as it travels through the record groove cause it to lean hard toward the center of the recrod, without an opposing anti-skating force you will cause uneven stylus wear and premature stylus aging. Further, the increased likelihood of mis-tracking on the right groove (right channel) can result in damage to that groove during mis-tracking and the higher forces the left groove sees can cause its own wear problems.
The bottom line: We apply anti-skating to preserve the stylus and our precious record collection. Do we need a better reason than that to do it and to do it with accuracy?
HOW TO APPLY THE RIGHT AMOUNT OF ANTI-SKATING FORCE?
The perfect amount of anti-skating force varies depending upon the distance of the stylus to the center of the record, vertical tracking force, the amplitude of the music being played, the playing speed, stylus profile, the type of anti-skating mechanism being used, the alignment of the cantilever with the groove, etc. In other words, there is no PERFECT amount of anti-skating. A compromise must be struck.
By applying anti-skating as a percentage of vertical tracking force you can get to an excellent compromised "average" in your anti-skating across most of the record surface for most music at normal playing speeds.
And so, was born, the WallySkater.
The WallySkater is not only useful for measuring anti-skating - and is the only product of its type known to us - but is also very useful for learning about your tonearm's horizontal bearing quality and whether you have any unwanted horizontal forces on your tonearm applied by your tonearm wiring.
IMPORTANT: Using a blank record or the groove-less area of the inner run-out on a record to adjust anti-skating so that the tonearm remains stationary is not a recommended method to adjust anti-skating as it results in about 50% too much anti-skating force applied. A FAR WORSE method is the use of "anti-skating bias tracks" found on some test records. The high amplitude such tracks are made at will result in applying far too much anti-skating force and the premature death of your stylus and precious records. At the end of the day, the final litmus test of proper anti-skating application is to have even stylus wear over time. This is one of the reasons we inspect our stylii regularly under our modified optical microscope. The wear patterns we find confirm the science behind the WallySkater!