Dr. Feickert's revised Universal Protractor covers all three major alignment geometries — Baerwald, Lofgren and Stevenson — with improved handling and accuracy. This is the revised version of Dr. Feickert's well-known Universal Protractor. Handling is easier than the original and both functionality and accuracy have been improved, and Stevenson has joined Baerwald and Lofgren so that all three of the major geometries are on one tool. A unified overhang point makes the three-step alignment faster and more repeatable than the version it replaces. The geometric relationships governing a pivoted tonearm have been understood since Baerwald and Lofgren published in the first half of the twentieth century. Both concluded that such a tracking device needs an angular offset, or zenith, together with a defined overhang, and that the two vary with the arm's effective length. As the stylus crosses the record it reaches true tangential alignment at two points, the inner and outer null points. In the early 1960s Stevenson recalculated the parameters on the reasoning that classical records often place their crescendos in the innermost grooves. Construction is aluminium: a 3 mm alloy base disc with an adjustable rule mounted above it at pivot height, and a metal jig for measuring pivot-to-spindle distance. The disc is white rather than mirrored, which makes reading the cantilever against the printed line considerably easier. It covers 200 to 345 mm pivot-to-spindle, so 9 through 14 inch arms, and doubles as a drilling jig when you are making a new armboard. It will not work with linear-tracking tonearms. Features All three major geometries on one tool — Baerwald, Lofgren and Stevenson Unified overhang point makes the three-step setup faster and more repeatable than the original Covers 200 to 345 mm pivot-to-spindle, suiting 9 through 14 inch tonearms Aluminium construction with a 3 mm alloy base and an adjustable rule set at pivot height White disc rather than a mirror, so the cantilever reads clearly against the printed line Doubles as a drilling jig when making a new armboard Supplied with gauge tower, instruction booklet and strobe pattern Specifications Type: Universal cartridge alignment protractor Geometries: Baerwald, Lofgren and Stevenson Adjustment Range: 200 to 345 mm pivot-to-spindle Tonearm Lengths: 9 through 14 inch effective length Materials: Aluminium — 3 mm alloy base disc, adjustable rule at pivot height, metal pivot-to-spindle jig Disc Finish: White, for contrast against the cantilever Included: Protractor disc with adjustable rule, gauge tower, instruction booklet and strobe pattern Not Suitable For: Linear-tracking tonearms Note: Dr. Feickert publishes no null point radii, dimensions or weight for this tool How to Use It Choose your geometry. Baerwald (B), Lofgren (L) or Stevenson (S). Set the overhang. Screw the gauge tower onto the disc and place the protractor on the platter. Aim the pin in the gauge exactly over the tonearm's pivot point, then move the cartridge in the headshell until the stylus lands on the crosslines of your chosen geometry at step 1. If you cannot reach either point, check your pivot-to-spindle distance. Tighten one screw lightly, leaving the cartridge still turnable, and set anti-skate to zero. Set the zenith. Turn the protractor to the outer null point at step 2 and adjust the angular offset until the printed line and your cantilever fall in line when viewed from the front. Tighten both screws alternately, taking care the cartridge does not move. Do not overdo it — really tight is followed by infinitely loose, forever. Check your work. At step 3, the inner null point, the cantilever must fall in line with the printed line; alternatively re-check the overhang at step 1. The two are mathematically equivalent, so if two points are correct the third follows. If the cartridge is still off, start again from the overhang.
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