Anti-skating vs. "lateral balance" on Sansui SR-2050
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gusten
Addicted Member
The only thing that can happen, if the mass center is too far from a center line between stylus and pivot, is that one bearing theoretically has so small downforce, so there will be an upforce when the arm is accelerating upwards.
Skating force of course is another matter all together.
gusten
marcmorin
RIP 1953-2020
Hi Nat, I think we're having a different view of what lateral imbalance is, and is not. I believe you are refering to a twisting of the arm due to more mass one side than another. One bearing has a load on the lower half of the bearing, and the other has a load on the upper half of the bearing? The maximum of that twist is set by the maximum clearance of the bearing(s). Except in such cases like the SME knife edge where one knife would be loaded much more than the other.
Forget the twisting part for a moment.
Lateral weight most certainly will cause a lateral force. When an arm is skating that is a lateral force towards the spindle. That is corrected by adding an opposite, but equal (we hope) lateral force to "pull" the arm outward.....in a lateral manner. Email me, and we'll go over some things before this thread turns into something it shouldn't.
I think the confusion comes from the use to the term 'lateral' in various different ways. The origin of the thread was about a problem with setting the location of the outrigger that provides lateral balance for arms that would not otherwise be putting equal force on both sides of the horizontal bearing. At least theoretically this seems to be desireable, though plenty of arms seem to do fine without, and the little arm and outrigger can introduce resonances, which may be more of a problem than the problem they are trying to solve. So some dispense with them.
What I was disagreeing with was the idea that seemed to be being put forth that the lateral balance outrigger actually creates an antiskating force (which is a lateral force, a torque on the arm) -- I don't see how this is possible since any imbalance or balance created by the outrigger would be vertical, whereas the torque is horizontal.
Marc -- I assume that what you mean by an antiskating counterweight is a weight on a string or pivot that creates an outward force. No disagreement there -- of course it creates a lateral force since its weight is set up to pull laterally. But a weight on a fixed rod outward from the arm doesn't do that, as far as I can tell.
What I was disagreeing with was the idea that seemed to be being put forth that the lateral balance outrigger actually creates an antiskating force (which is a lateral force, a torque on the arm) -- I don't see how this is possible since any imbalance or balance created by the outrigger would be vertical, whereas the torque is horizontal.
Marc -- I assume that what you mean by an antiskating counterweight is a weight on a string or pivot that creates an outward force. No disagreement there -- of course it creates a lateral force since its weight is set up to pull laterally. But a weight on a fixed rod outward from the arm doesn't do that, as far as I can tell.
Neyson
New Member
When I add the lateral balance weight onto my Sansui 2050C tonearm, the tonearm gets pulled outward (away from the center) no matter where I have the lateral balance OR the fishing line anti-skate set. I can't even put the tonearm over the record. Should I just put this lateral balance weight away?
I think that is some sort of inertia device rather than a lateral weight. But that is a hunch, not a fact. The point of the lateral weight is to equalize the down force on the vertical bearings and to ensure the arm is balanced in all three dimensions. The thing in the picture would do nothing for the first issue, obviously. So what is it for? Hmmm.
Neyson
New Member
It just seems like there would be too much weight on that side of the tonearm if I add the second lateral weight on the outside.
As soon as I put that second weight on, I can't even cue the tonearm. It just pulls it all the way out.
Yet I see that lateral weight in all the old pics of the 2050C
Wait - I suddenly realized that maybe that maybe what you mean by lateral weight is actually the antiskating weight. The lateral weight is the thing attached to the rod sticking out of the side of the arm. The antiskating weight is the little weight on filament. Its purpose is to make the arm want to move outward, so the behavior of your arm when you put it on makes sense.
MartinG
Active Member
Take a look at post #25 in this thread then follow along for the next few posts.
PC46F3
New Member
I know many people seem to not use the lateral weight. I also see the specs for the anti-skate bias weight but not for the lateral weight. Another poster once mentioned that it is somewhere around 2.4g but that seems unlikely given the dimensions of the lateral weight compared to the anti-skate bias weight - the lateral weight seems like it would be a little heavier.
Given that they are positioned on an outrigger, often at an arbitrarily position, but when they are used correctly, they get moved in or out on the shaft til the arm balances when the table is tilted somewhat on it's side, the weight could probably vary a fair amount as long as it was moved in or out correctly.
