Cartridge Loading and Compliance Laws

One more twist to the plot is that the cartridge specs may not be accurate to real world application. eg. the compliance of the cartridge may be given at a high frequency point and could be much different at low frequency. My SME tonearm conveniently lists the mass and compliance in the manual. So I can use the website calculators to determine my total system resonance frequency. I had a Denon cartridge at one time. It made my system Fn equal about 16Hz because my SME arm has low effective mass. It sounded good, but even the slightest warp in the record would cause the needle to skip. The stylus and tonearm were very animated when observing it closely while playing a record. I solved the issue by adding a 4 gram mass from England made for the Denon/SME combo. (It had threaded holes to fit the SME headshell and was designed to be glued to the cartridge. It also raised the tonearm making it easier to get the right VTA.) The 4 gram mass made Fn about 10Hz as I recall. The tracking was much more stable. A low system Fn such as 5-6Hz can make your turntable more susceptible to footfalls or other low frequency vibrations, including warps in the record. In the end, the calculation is only as good as the data supplied by the tonearm and cartridge manufacturers, but test records are available that can be used to determine actual system Fn.

So then in your case, you were able to fix things with a low compliance cart and lightish med mass arm by adding mass to the arm...hmmmm good thinking!

But how about this - what if the tables were turned and someone was dealing with a highish compliance cart and an arm that was a little too heavy for that cart? You can't take away mass from the arm and you wouldn't want to add mass to the headshell either like in your case....maybe a person could find lighter headshell screws for the cart or something....geesh what a ordeal this whole turntable business can be.

Correct, if the tables are turned, then you are out of luck. The only choice is a new tonearm or cartridge. Some might say dampening the tonearm would help, and it might. Only thing is, dampening is masking the underlying problem. There still might be consequences or undesireable attributes with dampening. That is different from isolation. Isolating the turntable and tonearm from airborne and mechanical vibrations is always beneficial.