Kuzma STOGI REF 313 110513 - Manual (Page 9)

points are used when aligning the cartridge. In practice these points lie at 66mm and 121mm
from the record centre (see protractor).
Other protractors make use of different zero points due to the use of different parameters in
calculation. In this case 60mm has been chosen as the inner groove and 146 mm as the outer
groove which still has optimum tracking distortion.
For a distance of 212mm from the record centre to the centre of the tonearms horizontal
rotation, the optimum overhang is 18mm and the effective length, ie. the distance from the
centre of the tonearm horizontal bearing to the tip of the cartridge is 230mm. This is gained
with offset angle of 24°, and gives a maximum tracking error of less than 2° and the distortion
of less than 1 %. These are harmonics of the second order which are not as irritating as the
third, which are very common in
amplifiers.
Ensure that bias is on minimum and place the protractor over the spindle on the platter.
Using the protractor, adjust geometry at two null points. Rough guidance is by the edges of the
cartridge body, but accurate adjustment is by observing whether the cantilever and lines are
parallel at the two null (zero) points.
4.2.3. Fixing cartridge:
The screws holding the cartridge must now be tightened and it is very important
to avoid moving the position of the cartridge, so tighten in the following way:
slowly, one screw at a time in extremely small stages. Before screws are
completely tight check that the cartridge is still in alignment. Then tighten screws firmly
bearing in mind whether the cartridge
body is made of metal or plastic!
Note: If you find it impossible to align the cartridge, ie. the cartridge cannot move far enough
forward in the slots of the headshell, then the tonearm is incorrectly positioned on the armboard,
being too far from the record centre. If the cartridge cannot be moved far enough back in the
headshell, then the arm is too near the centre of the record.
In either case the tonearm will have to be repositioned on the armboard. It should be noted
however, that different cartridges allow for more or less movement than others.
4.3. Adjustment of VTA:
VTA describes the angle between the record surface and the stylus. This angle changes as the
height of the tonearm is altered. The standard angle is 15° but cartridge manufacturers work
with degrees of anything between 10°- 30° so only by listening tests can one ascertain the
correct angle for your particular cartridge. The VTA also varies according to the tracking force
and thickness of records. An increase in tracking force is equivalent to lowering the tonearm
and vice-versa.
For your information to change the angle by 1° means a change in height of approximately 3mm
on the pillar. Some styluses need more precise adjustment of VTA than others.
The starting position is that the central axis of the tube is parallel to record surface.
With a felt pen mark the position where the pillar meets the base, as a point of
reference.
Use a good recording, preferably acoustic instruments and listen.
If the tonearm is too low the sound has a tendency to have an overblown base and
the stereo picture is imprecise.
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