The major problem mounting cartridges in the RS-A1 is that its headshell has threaded holes. Moreover, there is no room to use conventional screws that would enter the headshell from above, because of that cylindrical housing that houses the headshell pivot point. Ergo, you are limited to cartridges that have no threads in the mounting holes and that permit space for screws that will have to be oriented upward, so that the threads of the screw engage the threads in the headshell. I have not made a survey, but it seems to me that this limits you to using mostly MM cartridges. Most MCs in my experience have threaded mounting holes. That said, I was successful mounting an Ortofon MC7500 in my RS-A1, by mutilating some stock headshell screws and then physically holding the cartridge and headshell together as I screwed in the screws from below. It works OK. You also have the option of drilling out the threads on any cartridge to make it work with the RSA1; I did not care to do this to my Ortofon.
As for mating based on tonearm effective mass and other usual parameters, the RS-A1 is so unorthodox in design that I have no idea how one would estimate its effective mass. Moreover, the designer seems to be claiming that such considerations are rendered moot by his distincitive approach. Despite all of the above, I really do like mine.
As for mating based on tonearm effective mass and other usual parameters, the RS-A1 is so unorthodox in design that I have no idea how one would estimate its effective mass. Moreover, the designer seems to be claiming that such considerations are rendered moot by his distincitive approach. Despite all of the above, I really do like mine.