Dear @sampsa55 : """ I align the cartridges based on the alignment the tonearm was designed for. Since most of my tonearms use removable head shells and were designed for a 52mm distance from the head shell connection to the stylus... """
that’s true only if those tonearms has the same effective length.
Ah, no. The effective length of the tonearm has nothing to do with this. You can have tonearms of very different length that are still designed to have the same 52mm distance from stylus to tonearm connection or tonearms with the exact same length that are designed for a different distance (e.g., 50mm) from stylus to tonearm connection.
Again, think about the SPU: it can be used in short and long tonearms.

