steveo wrote:Resonant frequency, R = 1000/(2*pi*sqrt((Tm+Cm)*C)), where Tm=tonearm mass, Cm=cartridge mass and C=cart. compliance. In the case of the 3d 10 inch arm and the Kleos, you get R = 1000/(2*pi*sqrt((9+8.8)*12)) is about 10.9, so on paper it looks good (c.f. Teenagediplomat's post). The formula above ignores any mass from the mounting screws, but that shouldn't change the result much.

FWIW, you can just add the hardware mass to the cartridge mass and use their combined mass in the formula. I mounted a 4.1 gram low compliance cartridge on an Ittok LVXX tonight, and I had to add mass (longer screws and extra nuts) to get it to balance and to move the 1st resonance into the desired range.