The speed of
rotation of the platter should be as exact as possible equal to the nominal. The
DIN standard requires it to be maintained between + 1.5% and -1%. The
technology has largely exceeded these values especially in stereo turntables
that have fine tuning and even better in those controlled by quartz where the
value has reached 0.1%.
Fast speed
variations cause a crying-like hearing sensation. Variations up to a 6 Hz rate
are classified by whine (wow) and the fastest , from 6 Hz onward, are classified
by flutter. Wow is caused by imperfections of the transmission system (
Pulleys, loose or sliding rubber bands) or the turntable itself (eccentricity,
low weight, imbalance). The flutter is caused by elements that rotate faster
(unequal speed of the motor during a revolution, eccentricity of the motor
pulley. A very frequent cause of wow, not attributable to the turntable and
that can have a decisive influence is the eccentricity of the central hole of
the disc with respect to the furrows.
The DIN standard
specifies a maximum wow value of +/- 0.2% in weighted measurement. Currently,
values of 0.1% and very high quality stereo turntable are easily reached at
values of 0.06% always in weighted measure.
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