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In the Forum: Analog Playback
In the Thread: Copper Mat on a Micro Seiki Gun Metal Platter

Post Subject: Skating around the issuePosted by Wellington on: 10/8/2015

Sorry, but I have to tell you that you do have it backwards on the skating forces. Just Google for a force diagram. Another way to know is to look at how the anti-skating force is applied in arms using the weight, pulley and monofilament line approach. In the classic SME arms, for example, the weight is on the record side of the arm, but it pulls on a point which is BEHIND the arm's pivot axis; so that the weight pulls the stylus-end of the arm outward. In my Triplanar, the weight is on the opposite side of the arm, away from the record, and is attached to a point on the arm in FRONT of the pivot axis. So it also pulls the arm outward, away from the spindle. Easy to confirm.
I think the notion of NOT having the LP in intimate contact with a well-damped and heavy platter is misguided, in fact terribly misguided. If the LP is forced into contact with a lively, resonant platter (as many are), that's not good either, of course, but it's the platter's problems that need to be fixed. The answer is not to lift the LP free from the platter. Perhaps starting with the Transcriptors turntable of decades past, to the odd Meitner Platterless table, several have tried a platter-less approach, and none have succeeded. Hold a LP freely in your hand in the usual way, and tap the surface. You will hear that plasticy sound. It's a characteristic sound, not neutral at all, not like tapping a concrete wall. Spectrum analysis shows a number of resonant modes especially at lower frequencies, depending on the LP's weight. Those are the sounds that will be underpinning your music if the LP is not forced onto a neutral platter surface. Look at how records are made: Scully and Neumann lathes used massive turntables with vacuum hold down for the lacquer. Early Neumann lathes had 65-pound platters, later ones went as high as 130 pounds, if I recall correctly. No mats, just hard vacuum pull down. Similar to...Micro Seiki!

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