Raul: Yes, I think that to insist on 9.52 would be a severe limitation on cartridge designers. I can easily envision configurations which would tend to be shorter than 9.52, and I can envision configurations which would tend to be longer, too. Of course, if cartridge designers all avoided architectural diversity and only used configurations which fit into the 9~10mm range, 9.52mm would be OK (grin).
One other major variable is the rubber damper systems used in most cartridges. In the small sizes used in cartridges, rubber is not a very consistent material. The characteristic that you are looking for primarily from a damper is consistent damping behavior, but due to the variable nature of the material, consistent damping behavior is not the same thing as consistent thickness, or even consistent pressure. When I was just starting out in cartridge design and still inexperienced, I thought that a consistent pressure system would be perfect for adjusting the dampers and suspension, and would make a major step towards consistent dimensions. So I designed a calibrated adjustable weight system to apply consistent pressure to the dampers and suspension during the building process, and instructed a batch of cartridges to be built like this. The dimensions were fairly consistent (albeit not absolutely so). However, the performance measurements were all over the place, really bad, and that batch of cartridges needed to be built again.
I learned the hard way that each damper is unique, it is better to let a trained and experienced cartridge craftsman adjust the dampers individually, and accept whatever dimensions that arise from this.
You can, of course, prioritize consistent dimensions (like I did decades ago), but most likely you will find that the cure leads to worse diseases in other areas.
One thing that I haven't seen yet in these threads is an effort to _quantify_ the change in distortion that will occur if a cartridge is not precisely 9.52mm, what happens to the distortion if the base is shifted backwards (assuming an SME), how much the headshell offset angle needs to be changed to compensate, and how much slack you need between the headshell screwholes and mounting screws to accomplish the requisite change in offset angle. Cartridge alignment is never going to be perfect - for example a Baerwald alignment only results in zero tracking distortion at two tiny places over a span of 100mm or so. If we are going to talk about distortion, at least let us try to first quantify it, and then we can decide for ourselves if the level of distortion is acceptable or not.
FWIW, also note that some other tonearms with fixed screwhole headshells, like the Naim Aro, appear to have been designed with a much shorter cartridge in mind, From what I can tell, these were designed for cartridges of 7.5mm or 7mm pitch. The same applies to the Linn arms, if you use the third hole.
cheers!
