AT-95ML on a Pro-Ject Debut Carbon

Yogiboy, the given compliance of the cartridge, according to AT, is 20 at 100Hz.  I multiplied by 2 to give a rough approximation of the compliance at 10 Hz, which gives 40 cu. I don't disagree with you at all, but the equation softens the effect of changing M or C, because you are taking the square root of the product.  So, rather large changes in either parameter don't have as much effect on the resonant frequency as one might expect, which, coupled with the fact that we don't really know the compliance of any one sample of any cartridge, is why I take a laissez-faire attitude toward the whole thing. You probably could increase effective mass by 6g and still be within a reasonable lower bound of F for the ensemble.  There is just no reason to do it.

I strongly doubt your data for effective mass of the arm. There have only been a few tonearms in audio history, dating back to the hayday of high compliance cartridges, with such a low effective mass. But I’m guessing you got the number from some reliable source, so I’m puzzled. Perhaps that value doesn’t account for the headshell. I regularly weigh all of my many headshells, and none weigh less than 8-9g. Most weigh 10g or more. So, to begin with, effective mass includes headshell and mounting hardware(add a few grams for that). It also includes the weight of the cartridge (6.1g). Even if your particular tonearm really does have effective mass of 6g without cartridge and even if we discount the weight of hardware, you’re at ~12g minimum. And finally, a high compliance cartridge like yours needs a low effective mass. The two parameters are inversely related. You’re going in the wrong direction if you add mass. Also, in my opinion, this whole issue is way overrated. One reason I say that is you and I don’t really know the compliance of your particular sample. Nor do we know exactly the tonearm effective mass. The equation merely puts you in the right ballpark. And, with apologies, you have somehow made an error in your calculation, if it leads you to believe you need to add 6g of mass.

The AT 95ML is a high compliance cartridge (about 40cu at 10 Hz), so I don’t know why you want to add 6g to the effective mass. With such a compliance you could use a tonearm with 6g effective mass, total, which doesn’t really exist. In any case, don’t add any mass. One wonders what data you used to come up with your conclusions.