Alignment Geometry
Alignment geometry is the intended arrangement of cartridge position and angle on a tonearm. Tracking geometry describes how the arm moves instead.
Baerwald (Löfgren A), Löfgren B and Stevenson distribute tracking-angle error differently. In these conventional two-null alignments, the cartridge follows the groove’s direction exactly at two groove positions, called null points. Angular mismatch remains elsewhere. Null positions also depend on the assumed inner and outer recorded groove radii.
Alignment Geometry — Tonearm
Overhang and offset angle set this alignment. Use the arm’s documented geometry and matching setup instructions. A universal protractor offering several alignments does not tell you which one the arm was designed for.
“Japanese / maker-specific” groups other documented geometries; it does not mean one universal alignment. “Not applicable (tangential)” covers linear and pivoted-tangential arms, whose mechanisms maintain close groove alignment as they move. These still need their own setup; the label does not mean adjustment is unnecessary.
Sources
- FAQ — Ortofon
- Protractor NG manual — Dr. Feickert Analogue
- Phono-cartridge alignment protractor — Phædrus Audio
- Reed 5T — Reed
- Thor tonearm setup guide — Bergmann Audio