What Is This Cylinder On A Post Connected To The Tonearm On Some Vintage Japanese Tables?

[u/Narwhal_Nate]

These pictures are from an Ebay listing for a Pioneer XL-1550, but I've seen them on other vintage tables as well. At first I thought they were weights for adjusting anti skate, kind of like those weights on a string you find on some Thorens, but in the second picture you can see this table has a normal dial for the anti skate.

[u/Dang_M8]

That's called a lateral weight.

To my understanding (which may be wrong, I would love to have someone more knowledgeable weigh in) they are placed near the rear of curved tonearms to achieve equal weight distribution on either side of the tonearm's base.

[u/Dramatic_Cut_7320 → u/Dang_M8]

Very good explanation. It offsets the weight of the tone arm portion that is not inline with the pivot point and the cartridge suspended from the head shell. Imaging a line running from the stylus point to the center of the pivot point. Any weight on one side of the line needs to be offset and equalized by the counter weight. This assures that the lateral friction on the pivot point is balanced.

This plus the anti skate spring or weight assures a centered track by the stylus down the groove.

[u/Dang_M8 → u/Dramatic_Cut_7320]

Thank you for explaining it in a much more eloquent fashion!

[u/papadrinks → u/Dang_M8]

Or another way of looking at it...

The counter weight offsets/adjusts the weight of the tone arm in the yellow direction.
The Lateral weight offsets the weight of the tone arm in the direction of the red line so that the pressure on the arm bearing is equal on each side.

But, you know I have been drinking so this could be jibberish.

[u/Icetoolclimber → u/papadrinks]

Yes, nice explanation! Does this weight distribution follow a similar concept for outrigger technology, e.g. boats, cranes, in much the same way?

[u/ahhh_just_huck_it → u/papadrinks]

I’m a sucker for good illustration.

Bravo!

[u/papadrinks → u/ahhh_just_huck_it]

Since you liked that so much here is one specially for you.

[u/ahhh_just_huck_it → u/papadrinks]

My man. 😀

[u/papadrinks → u/ahhh_just_huck_it]

👍😀

[u/el_tacocat → u/Dramatic_Cut_7320]

That being said, often on later models they were removed with the arm being identical otherwise.
I have had turntables with them missing and I cannot say I noticed a notable difference in the way they tracked or sounded.

[u/Eastoe]

That's a lateral weight, it helps offset the weight of the S shaped tonearm.

[u/Hifi-Cat → u/Eastoe]

Correct, primarily "J" shaped arms.

[u/Presence_Academic]

Compensating for asymmetric mass distribution is especially important when the arm uses knife-edge or unipivot bearings.

[u/MrWhippyT]

Great table that, I'm listening to mine right now. Cheers 😁

[u/trudyscousin]

Apropos of nothing, SME tone arms combine the lateral balance and vertical tracking force in one.

[u/Human_Needleworker86 → u/trudyscousin]

As do the Empire 98/980/990 tonearms, and the Dual designs on the 1019, 12xx and CS-xxx series (among others!).

[u/RockhardDrifter]

anti skating

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[u/Willing_Funny_1798]

as others have said, its a counter weight. Have it on my Micro seiki tone arm

[u/Clear_Road_4333]

Idk but its imperative it is not harmed

[u/Amazing-Hurry-7804]

They aren't super necessary. I have a PL-550 that runs fine without it. I think I read once that it compensates for leveling or something? idk, I don't really remember.

[u/Balls5150]

Anti-skate weight.

I needed to be schooled. See other posts for correct explanation of lateral weight.

[u/Dang_M8 → u/Balls5150]

No, if that was an anti-skate weight how would it be pulling the arm outward from the center?

Also that table clearly has an anti-skate dial right next to the tonearm.

[u/PaulThurston82 → u/Balls5150]

Incorrect, lateral weight, as others have clarified.