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The modulation of tracking force by a warp
permits the operator to see a particular pick-
up's distortion both tracking and mistracking,
thus eliminating the confusion due to non-
linearities other than mistracking. It also sug-
gests the means to separate the contribution
to distortion of mistracking from the other
possible causes, without benefit of a warp.
By checking the pickup at two different track-
ing forces on the same band, a large change
in distortion at the lower force would indicate
mistracking at the lower force. A small change
in distortion may be expected at the two forces
as a result of indentation, irrespective of mis-
tracking.
Test Procedure
The C-PEK-3 displays the total 270 Hz com-
ponent signal on theosci~loscope by depress-
ing the "High" button on the test panel. Begin
the test by playing Band 1, Side 1, of the
TTR-103. The test must begin with the pickup
tracking this band, with appropriate consid-
eration of record warp. The display should
resemble Figure 20. The tracking should be
verified by checking the pickup at two track-
ing forces. Changing the force is easily ac-
complished by placing a weight on the head
shell and then removing it. The weight should
be about
' / 2
gram for pickups in the
3/4
to
11/2
gram range, about 1 gram for pickups in the
11/2
to 3 gram range, and
11/2
grams for pick-
ups in the 3 to 5 gram range. In some cases,
the additional weight will increase the tracking
force beyond the recommended range, but,
for all Shure pickups, no damage will result
during the short observation period.
Note: Under no circumstances should the
tracking force be set above the rec-
ommended range
for
long term use.
Fig. 20
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