Vinyl Asylum: RE: Do you keep changing arm pillar height? by flood2

"Some here undertake arm height changes to a level which I consider near obsessive, changing arm height not only disc to disc but from side to side if thought necessary."

Hi Pete

Arm height calibration for disc thickness becomes important if there is a mismatch between the vertical arm bearing offset with respect to the cantilever offset - the reason can either be due to choice (for example choosing a different overhang/offset from the design value ... as I do) or due to errors in setting offset (perhaps unintentionally due to cantilever skew).
In the event of a mismatch, the (vertical) stylus alignment follows an arc as the arm swings up or down rather than simply moving up and down. In other words, the azimuth is shifting. Since the phase between channels is also influenced by tracking error, for stereo records, the combination of the two factors directly impacts on the stereo imaging (as well as effective VTF and skating force) and this is the reason that small changes in arm height are audible since multiple parameters are changing simultaneously. The magnitude of the change for an audible effect is far less than for a significant angular change in rake angle, but the effect is measurable with channel separation analysis and distortion analysis.
If the cantilever offset matches the bearing perfectly such that the azimuth is constant across a side, then record thickness variations of the order of 1mm would be inaudible given that the angular change for stylus rake is an order of magnitude less than the cutting angle tolerances relative to the "recommended" 2 degree rake.

With a line contact stylus, tip azimuth is by far the most important parameter to optimise as Peter Ledermann also preaches. As my vinyl replay is specifically for transcription purposes, it is worth it to me to shim the record to the reference position, but I don't believe in changing arm height for each side of a record - that is just getting silly! ;)