I'm getting back to this discussion after a day or so. Ack, What do you mean by "adjust your own records"? I have been discussing adjusting tonearm height to better match SRA/VTA for different cutting angles and/or record thicknesses. I happen to listen for timing errors, or I suppose distortion, and the relationship between the fundamental of a note and its harmonics. I adjust the tonearm height accordingly to what sounds best for each LP and record the setting so that I can refer to it for later playings.
It is self evident that if you do not adjust the arm height for different LPs, then the overhang and VTF will change if the LP being played is of a different thickness (height) than the one used when originally aligning the cartridge. In other words, a thin LP will give a particular arm a different effective length and overhang as well as a different VTF than will a thicker LP, if the arm is at a fixed height. So just playing different thickness LPs will change the set up parameters of the arm/cartridge. One is simply finding the best compromise of the various parameter settings when he uses his alignment jig and sets up the cartridge.
The overhang, VTF, and SRA/VTA are set for a particular alignment jig at a particular height above the platter surface. How high is the platform on the scale when measuring VTF? Is it the same height as all of the records in one's collection? Surely not. I set my VTF by setting up the measuring platform of my scale at the same height as the average LP in my collection. That is a compromise, simply because some LPs are thicker or thinner than the average. When I play ones different from the average, VTF will be different unless I move the arm up or down to compensate. If one does adjust the height of the arm for different LP thicknesses, or more properly, for different original cutting angles, then at least the parameters of VTF and and SRA/VTA will remain the same. That is because as LP thickness goes up and one raises the arm by the same amount, the angle of the arm remains constant, so SRA/VTA remains constant, and VTF remains constant. Overhang should remain the same also if the angle of the arm remains constant.
I would argue that by not changing arm height, you are actually creating more intermodulation distortion every time you play an LP which is of a different thickness than your test LP which you used to set up your arm/cartridge by listening for intermodulation distortion. Of course, that is your choice, as it is inconvenient to constantly change the arm height for different LPs. But if one's goal is to reproduce accurately the information on the recording with as little distortion as possible, one would be well served by adjusting the height of his tonearm for different cutting angles and/or LP thicknesses. The proof is in the listening, as Al M. has experienced. One does not need to own a vinyl source to hear this and appreciate what it does for a more accurate rendition of the recording.
Tomorrow when Al visits you to hear your system, you should play for him a thin LP like Beethoven's Appassionata, D2D 45 rpm on RCA and a thicker reissue like Heifetz' "Kreutzer" Sonata or the Janaki Trio. Let us know if you hear the same lack of intermodulation distortion on each LP without changing the arm height. VTF, VTA, SRA, and overhang will all change when you play these two LPs and don't change the arm height, simply because they are different thicknesses, and the tonearm angle, relative to the surface of the LP, will necessarily be different for each one.
Happy Easter Peter,
There is plenty of good useful info in your above quote, thank you for dedicating your time and passion.
A simple remark; in the paragraph preceding the last, the last sentence:
"One does not need to own a vinyl source to hear this and appreciate what it does for a more accurate rendition of the recording."