"heavy arm = low compliance cartridge, light arm = high compliance cartridge"
Yes, that is a mantra of the internet that I read very often, too. As I am sure you know, that formula is meant to set the low frequency resonance at a frequency between 8 Hz (so as not to excite resonance via footfalls and other very low frequency sources) and 12 Hz (so as to stay away from the audio bandwidth). The formula for that resonant frequency can be found on Vinyl Asylum and in other places, but tonearm effective mass and cartridge compliance are its principle determinants. So this is why the gurus tell us, "heavy arm = low compliance, etc". However, there are guys on this discussion group, most notably Raul, who point out that there are many other factors that determine the overall "goodness" of a match between tonearm and cartridge and that sometimes one can and should overlook the mantra in search of good sound. One example is that several owners of the Fidelity Research FR66, a 12-inch arm with very very high effective mass, claim it sounds fantastic with MM and MI cartridges that have very high compliance. Conversely, some others who own very light tonearms like the ADC and the Black Widow like to use them with MC cartridges that have low compliance. To all this I say, "go figure". The take home lesson I think is if you have a tonearm you like a lot, don't stop using it just because it might technically be a mismatch with your new cartridge, on the basis of its effective mass vs the cartridge compliance. All bets are off.
Why this is true is worthy of another separate discussion, but I have my ideas.
Yes, that is a mantra of the internet that I read very often, too. As I am sure you know, that formula is meant to set the low frequency resonance at a frequency between 8 Hz (so as not to excite resonance via footfalls and other very low frequency sources) and 12 Hz (so as to stay away from the audio bandwidth). The formula for that resonant frequency can be found on Vinyl Asylum and in other places, but tonearm effective mass and cartridge compliance are its principle determinants. So this is why the gurus tell us, "heavy arm = low compliance, etc". However, there are guys on this discussion group, most notably Raul, who point out that there are many other factors that determine the overall "goodness" of a match between tonearm and cartridge and that sometimes one can and should overlook the mantra in search of good sound. One example is that several owners of the Fidelity Research FR66, a 12-inch arm with very very high effective mass, claim it sounds fantastic with MM and MI cartridges that have very high compliance. Conversely, some others who own very light tonearms like the ADC and the Black Widow like to use them with MC cartridges that have low compliance. To all this I say, "go figure". The take home lesson I think is if you have a tonearm you like a lot, don't stop using it just because it might technically be a mismatch with your new cartridge, on the basis of its effective mass vs the cartridge compliance. All bets are off.
Why this is true is worthy of another separate discussion, but I have my ideas.