gofar99 Messages: 1947 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Hi everyone, Over the past few months I have noticed what seemed to be a problem with the anti-skating on my Dual 701 turntable. One cartridge in particular seemed to "want" a huge amount for tracking in the last tracks of some LPs. I discovered the cause today. The Dual platter has circular ridges for the various sizes of records. This is so the outside edges are well supported. If you place a flimsy LP on the platter and use a record clamp or weight it will depress the LP nearly 1/32 to 1/16 inch at the middle. This translates into a highly non-level situation for the cartridge. It will seem to need a lot more AS than it should. With new 180-200 gram LPs this does not happen thus the inconsistency. My fix was to place a large diameter (about 2.5 inches) flat rubber gasket in the center of the platter. This is just thick enough to be sure that it won't interfere with the support on the edge, but still allow the weight to do its thing. Now the AS works just fine.
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I discovered the cause today. The Dual platter has circular ridges for the various sizes of records. This is so the outside edges are well supported. If you place a flimsy LP on the platter and use a record clamp or weight it will depress the LP nearly 1/32 to 1/16 inch at the middle. 
This translates into a highly non-level situation for the cartridge. It will seem to need a lot more AS than it should. With new 180-200 gram LPs this does not happen thus the inconsistency. My fix was to place a large diameter (about 2.5 inches) flat rubber gasket in the center of the platter. This is just thick enough to be sure that it won't interfere with the support on the edge, but still allow the weight to do its thing. Now the AS works just fine. 
