Lew, I asked John Ellison to incorporate .5mm error into his model, since .5mm is about as close as I can get the Trans-Fi to perfect zenith on a clear day(i.e. allowing for the tolerance of measurement tools and small changes in overhang that accompany changes in VTA.) I agree that in common practice the typical owner's set-up may be less accurate. However, with or without perfect zenith as an absolute, IME the point stands that it is possible to hear a 3x difference in tracking distortion between .2% and .7%. The only way to knock a non-believer off his pivot is to try it himself.
BTW, it's not really possible to experience a clear perception of tracking distortion by comparing pivots arm of varying length. Even if acquired from the same manufacturer, the longer arm changes resonance and inertial mass characteristics in addition to tracing arc. Only a linear arm can limit the experiment to one variable.
BTW, it's not really possible to experience a clear perception of tracking distortion by comparing pivots arm of varying length. Even if acquired from the same manufacturer, the longer arm changes resonance and inertial mass characteristics in addition to tracing arc. Only a linear arm can limit the experiment to one variable.