Are linear tracking arms better than pivoted arms?

Derton, regarding your 2/20 post detailing your experience with various arms, one point is not clear to me. As I read it, one of your main concerns relates to ". . . stress on the cantilever/suspension system of the cartridge mounted. And it does so by design." with linear arms.

Well and good, but since groove spacing varies over the side of a record, automated arm movement for playback is out of the question. Thus even a pivoted arm moves as the stylus "leads" the cartridge/arm across the record. Is this not also a stress problem with a pivoted arm? Or is this all a function of the effective mass of the pivoted arm versus that of a linear arm? Therefore not as much of a problem with pivoted arms? Not being an engineer, I'm over my head here.

Pryso,

With a pivoted arm, the cantilever IS stressed, to some extent, in pulling the arm into the new position as the needle moves toward the center of the record. However, the pivot and fulcrum mechanical advantage means much less force is needed to move the arm around the pivot point as compared to dragging a very heavy (in the horizontal plain) linear tracking arm. Again, this is just the THEORY; whether this actually translates into a meaningful issue is another matter.

02-22-10: Larryi

However, the pivot and fulcrum mechanical advantage means much less force is needed to move the arm around the pivot point as compared to dragging a very heavy (in the horizontal plain) linear tracking arm. Again, this is just the THEORY; whether this actually translates into a meaningful issue is another matter.

Exactly, I wonder if this is really significantly so in the real world?

Is there even a way to measure this lateral force/stress on the cantilever/motor assembly?

Anyone know someone who has a Fidelity Research FR 64s for sale?

Is there even a way to measure this lateral force/stress on the cantilever/motor assembly?

it would seem to be simple to place some sort of sensor between the linear arm housing (or the cartridge body) and press against it. the smallest force required to get the arm moving from rest would be the maximum amount of force required. it might be impossible to measure the force required on a pivoted arm since the arm is able to flex in multiple planes. how could you isolate the resistance in one plane?

since i removed the dampening fluid from my arm the lateral resistance of the arm has got to be negligable.

it's the stress of that initial starting force on the canteliver which potentially could cause premature cartridge failure. my experience is that a linear tracker with vaccuum is the least stressful environment for a cartridge since the record is always flat. my favorite Colibri (a fragile cartridge if ever there was one) lasted 5 years on the Rockport before i accidently broke the canteliver while dusting two years ago.

my linear tracking arm only has two issues; and that is to make sure that the lateral shaft that the arm housing slides on is perfectly level, and that the shaft is clean. cleaning is simply a matter of sliding the arm back and forth once prior to using. i check the level by tapping on the arm to unweight it at various places along the shaft to make sure it stays in place. if it drifts to one side i adjust the plinth leveling on the air suspension. it needs adjustment once or twice a year and takes 30 seconds.