cleeds, I am sure you know that aligning by the cantilever, while a good idea, does not in any way cure zenith error, because a zenith error, besides being created by misalignment of the cantilever per se, is also created by errors in mounting the stylus at the factories that make them such that the contact patches on the stylus tip end up not being perpendicular to the groove walls. I was told by a knowledgeable guru that the companies that make all the stylus/cantilever combinations available allow for a +/-5 degree zenith error. That is their industry standard. This expert also determined that even a 1 or 2 degree zenitherror at the stylus can result in no null points on the LP surface.
Bill, in your post of 5/18 at 12:52 pm, you wrote, "For arms from other manufacturers the answer for Antiskate settings is not universal. For SME arms, I find the factory settings are accurate and should be used. For Technics, Antiskate settings seem to result in lowest distortion set at ~50% of recommended settings. On a Denon DP-3000NE, that I just acquired, the factory settings proved to be accurate. For most TTs from the EU, I am finding it best to start at 50% of recommended setting and increase only if you hear a slight mis-tracking in the upper mids to highs."
Please define factory settings for SME. Do you mean to say that their numerical markings (if such exist; I have never handled a modern SME tonearm) are such that if you are tracking at 2g, you ought to set AS to "2"?
For Technics, how would one determine 50% of recommended settings?
And what about the many well loved vintage and even modern tonearms that still use a string and weight or a rigid lever and weight (e.g., my Kenwood, Dynavector, Triplanar, and Reed tonearms) to set AS? There are no settings, as such.

