Continuing on the azimuth and crosstalk issue in this post, but no measurements as yet, only a reasoning about the effects.
Most of us know that azimuth is affecting the crosstalk, but in a left to right crosstalk balance. This is because the angles of coils need to be symmetrical to the groove wall angles. Also the phase can be used to monitor issues. Nothing strange about that. This post is about the absolute values, that both differ between cartridges and between test records.
I say the answer to that issue is the vertical modulation angle (VMA) of the record vs. the vertical tracking angle of the cartridge (VTA). A perfect match will give the lowest possible crosstalk since you will get a 45° modulation angle from the 45° groove ("no" leakage to opposite channel). When VTA is mismatched, the reproducing angle will not be 45° but perhaps 47° or 42° (since tilting a groove triangle change its angles when viewed from the front). In the example of 42°, you will get an out of phase crosstalk signal (in both channels, as long as azimuth is perfect), while a value or 47° will give an in-phase signal of the crosstalk signals. Now, the degrees that VTA has to be changed to adjust it is not the same as those difference, but an out-of phase signal should equal to a too high VTA and vice versa (needs some more thinking though).
The above if true explains why different test records can give different cross-talk, since the VMA is different. We have no idea of the VMA of a particular record but can only make a good guess (see below of standards*) by taking the mean between different test records and leave it at that. One could e.g. use the 50°-40° azimuth test of the Merolemez record to set it perfectly at 45° by adjusting VTA (eidt: this is probably not possible since this is determined by the symmetry of the generator which needs to be correct from start). Or taking a mean between the Ortofon test record and the CA-TRS1007, which seems to be quite different in terms of crosstalk (and thus VMA).
The above also explains why varying VTF also affects azimuth somewhat, since VTF also affects VTA even though it is small. Changing VTA is not easy since cartridges may vary between 20°-30° or even higher. They need to be shimmed at the head shell to get significant results. Theoretically, an incorrectly set VTA could affect the lowest bass and highs since the crosstalk is generally the highest at the frequency extremes. Energy is basically lost in the crosstalk. I did one experiment to test this, but could see no or only very small effect below 50 Hz or so, but really nothing in the high end. This could because crosstalk was sufficiently low not to affect the result (in that case).
It is probably not the whole story since not on the angle of the stylus may matter, but also the angle of the internal coils (for an MM).
*VMA has also been different through history and since 1960s it was 15-20°, revised to 15-25° and from 1981/1987 (DIN45547/IEC98) it was revised further to 20-25°. I think the JVC TRS1007 dates back to 1978, but what the VMA it is cut with is unknown to me. Merolemez was released 1984, and the Flokason/Ortofon is in comparison much more recent (2016).
Thanks to Yosh pages that contains so much information but not always easy to penetrate. The above is with reservation that I've not yet made all required measurements to confirm this. But Yosh do have nice Excel sheets to simulate this and many other things.
