1024 Chapter 27
The skating force compensation consists of applying
a force to the tonearm that is equal to but opposite in
direction to the skating force, Fig. 27-13. For all prac-
tical purposes, the skating force is constant for all radii
of the music groove if the tracking error is small and the
tonearm alignment is correct. There are slight variations
of the skating force due to heavy modulation and
groove wall plastic deformation caused by the sharpness
of the new stylus, but the largest deviation in skating
force is due to the variations in record material. From
the study of various materials, it was established that the
softest materials produce more friction and larger
skating force. Lacquer masters produce up to 25% more
friction (i.e., skating force) than vinyl records. Styrene
records, today’s 45 rpm discs, have approximately 30%
less friction than vinyl, requiring less antiskating
compensation than vinyl LPs.There are many different ways to generate the anti-
skating force. It is incorrect to assume that increasing
the drag on the horizontal motion of the tonearm will
compensate for skating. Skating force is independent of
groove spiraling speed; drag is not. Also, because of theFigure 27-12. Effects of tonearm geometry. Courtesy G.
Alexandrovich.Stylus armRecord grooveForce of
frictionOffset angle
Stylus tipPositioning of the arm
under action of friction
forceVertical
pivotCompliant
pivotStylus
tipOffset
angleForce
of frictionRecord
grooveSkating
forceReaction
forceCenter of
recordVertical
pivot pointA. Position of the arm on the record and the
forces acting on it.B. Effect of friction on tracking error.Figure 27-13. Skating and antiforces in a record groove.
Courtesy G. Alexandrovich.Skating forceRight channelN
Tracking
forceResultant from N & SFLeft channelA. Rear view.
FGrooveVector force
producing torqueSkating forceSTSFRV
B. Top view.RFStylus tipTAntiskating
force appliedOffset angleA