A problem with arc protractors is that you are assuming that the tonearm is accurately mounted at the correct specified distance from the spindle. This is frequently not true, especially with arms that have post held by a single grub screw in an arm collar attached to the turntable plinth,
This is true and it is why I include a pivot to spindle ruler with the WallyTractor. If the user cannot get their stylus to trace the prescribed arc then it means the pivot to spindle distance is no good. With the ruler you can verify and use our online calculator to figure out what is wrong. So, what you call a “problem” becomes a feature to help diagnose the issue.
A problem with arc protractors is that you are assuming that the tonearm is accurately mounted at the correct specified distance from the spindle. This is frequently not true, especially with arms that have post held by a single grub screw in an arm collar attached to the turntable plinth,
This is true and it is why I include a pivot to spindle ruler with the WallyTractor. If the user cannot get their stylus to trace the prescribed arc then it means the pivot to spindle distance is no good. With the ruler you can verify and use our online calculator to figure out what is wrong.
So, what you call a “problem” becomes a feature to help diagnose the issue.