You need a mirrored surface with lines finely etched and magnification.
and certainty that the diamond tracing faces (assuming advanced profile) are aligned precisely 90° to the cantilever.
dave
Why do tonearm specifications list null points?
I happened to be going through the manual that came with my Clearaudio Universal 12" tonearm and noticed they list inner and outer null points, 66.04 and 120.9 respectively, along with all the other specs.
I was under the impression that tonearm geometry can be set to anything you want to use (Lofgren, Baerwald, Stevenson, custom) by setting it up with the specified spindle to pivot, overhang, and angle settings using a tonearm protractor, e.g., Dr Feickert, etc.
So, is the tonearm manufacturer trying to say that this particular tonearm is somehow optimized or was designed to utilize those null points they list in the spec?