Cartridge Loading and Compliance Laws

I wonder would using lighter cartridge screws help if your arm were a little heavy and cart a little light compliance wise? Or would that make things even worse or with cart screws does it even matter really?

I have seen these really light aluminum and plastic cartrdge screws before and of course steel or stainless steel ones. Someone told me before that these little screws can affect the sound, how though I am not really sure.

Lighter screws are definitely better because that mass is at the farthest point from the pivot. So that affects the inertia of the tonearm. Aluminum screws are preferred for both less weight and the non-magnetic properties. Don't use plastic screws. Plastic creeps, ie. stretches, and you won't be able to maintain the torque with plastic screws.

Lewn,
To use your truck/sports car analogy however, a truck would be less likely to be knocked off its straight path than a sports car hitting the same bump. I dont know that the analogy works because the tonearm is not moving, and therefore has no momentum inertia of its own, only its fixed inertia as an impediment to motion. But since I dont want the tonearm to move relative to the stylus, why wouldnt that be better. Dont we want to keep the headshell/cartridge/stylus relationship fixed except for those movement in the stylus that correspond to the vinyl groove. Why would we want the tonearm to move? And if it did at the same rate as the stylus, which of course it can't, wouldnt that result in no sound at all. Isnt it the movement of the stylus and coil assembly relative to a fixed magnet what produces the sound. And if that fixed magnet moved the same as the stylus/coil, no sound would be reproduced.

Picture the stylus like a wheel on a car. The stylus has micromotion as it tracks the groove on a record and that motion is absorbed by the suspension. Just like the wheel on a car moves over small bumps in the road but the car remains fixed. In both cases in regards to the micromotion and inertia of the stylus and the wheel, they are very small compared to the mass of the tonearm or mass of the vehicle. So that micromotion causes little or no motion in their relatively massive counterparts. But when the stylus moves over a warp in the record, for example, now the entire tonearm must move in response to that warp. Consider that a macro-motion. In this case, if the tonearm has too much interia, the tonearm raises up to ride over the warp but takes too long to come back down resulting in a skip. Similar sitation in a car- a dip in the road or bump in the road causes the car to move up/down, but if the car has too much inertia, then it leaves the road surface. In both cases, a car or a tonearm, the spring rate and the effective mass affect how they respond to those macro-motions.

Manitunc, You wrote, "To use your truck/sports car analogy however, a truck would be less likely to be knocked off its straight path than a sports car hitting the same bump. I dont know that the analogy works because the tonearm is not moving, and therefore has no momentum inertia of its own, only its fixed inertia as an impediment to motion."

I don't really see what you are getting at. The tonearm most certainly does move, in the lateral plane it has to move in order for the stylus to trace the groove, in the vertical plane we don't want it to move (up and down), but it will to a degree that is directly dependent upon the compliance of the cartridge (the springiness of the cantilever) and the mass of the whole ensemble of the tonearm/cartridge. Obviously, the less vertical motion of the tonearm wand, the better.

As an aside, "momentum" and "moment of inertia" are two different things. Don't know what "momentum inertia" is. Finally, for both a truck and a sports car, the correct shock absorber damping will result in the least reaction to a "bump". (I don't really like my own sports car/truck analogy so much, either.)