I am beginning to see. I checked out some webs. It would appear that the reason the rb-250 would end up being better after mods is because it is coupled to the base on both ends of the vertical bearings, where the arms built with the springs are coupled on on side only; the are not coupled where the spring is attached(except by the spring itself).
Furthermore, it seems the reason rb-300's and above are better "out of the box" is they use better materiels on the end stubs, where the rb-250 uses plastic.
What I can see is the importance of the end stub & counterweight, as this is a place where resonences can reflect and the mass is significant as to compete or interfere with the mechanical grounding of the arm.
What I don't see is how couplng the counterweight rigidly with a set screw would make a improvement, or coupling the end stub solidly, for that matter. I understand that the origin mod is supposed to be solid with "less" coupling. The expressimo end stub appears to be the same as a stock one, with the exception of having a allen screw to torque it down, I can't see how the origin is attatched.
Question; is there something about a rigid mount to the end stub/counterweight assembly that makes a tonearm perform better? (as opposed, for instance, to coupled with some sort of damping?)
Question 2; is there something to the "torque" involved that makes the end stub behave differently, as to perhaps be better than further or appropriate "decoupling" of the whole assembly?
Has anyone done any exploring with the attatchment of the counterweight, either before or after the mods? Or with other tonearms?
I am sure there is something to this that can help us build a better tonearm. I am especailly curious as it appears that there is knowledge in this area that I may have been previously unaware existed.
