The force with which the anti-skate weight is pulling outward on the tone arm is related not merely to the weight in grams of the AS weight itself. It’s also dependent upon the distance of the connection between the weight and the arm wand from the pivot point. it’s a lever in principle. So if you can get out your old geometry text you can figure out how much AS force is actually pulling on your arm. And you don’t want so much as a 1.5g AS force for a 1.5g VTF. Much less will usually do.
Fidelity Research FR-54 Tonearm. ANTI-SKATE???
FR-54 Tonearm came on dual arm tt I bought. I moved it to the rear board, to use with Grado Mono ME+ cartridge, 1.5g tracking weight recommended.
All is well, but, I do not see any way to adjust the FR-54 amount of anti-skate.
One dangling weight, thru one groove in a wire, that's it. Bottom of weight has threaded hole. Presumably weight can be added, but, how lessened?
On scale, the weight is 2.5g. To a bimp on the bottom of the arm, just in front of the pivot. Does that mean it is transferring it's full weight, 2.5g of anti-skate?
I want cartridge to track at 1.5g, thus want 1.5g anti-skate.
I could grind the weight down to 1.5g I suppose.
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Ideas?
All is well, but, I do not see any way to adjust the FR-54 amount of anti-skate.
One dangling weight, thru one groove in a wire, that's it. Bottom of weight has threaded hole. Presumably weight can be added, but, how lessened?
On scale, the weight is 2.5g. To a bimp on the bottom of the arm, just in front of the pivot. Does that mean it is transferring it's full weight, 2.5g of anti-skate?
I want cartridge to track at 1.5g, thus want 1.5g anti-skate.
I could grind the weight down to 1.5g I suppose.
..................
Ideas?
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- 30 posts total
To get you started, an AS device creates a class 3 lever. Where the tonearm is the lever, the pivot is the fulcrum, and the cantilever is the load. See here: https://en.wikipedia.org/wiki/Lever That's if the AS force is applied to the arm wand. In some cases, the AS force is applied to the short arm that holds the counterweight, to the rear of the pivot, and the AS force pulls the short arm inward. In that case, we have a Class 1 lever. |
thanks. Sometimes I'm glad I ain't too smart. I get the distance from pivot varies the force. I had SME 3009: dangling weight on line, 'inside' toward lp. hung on various notches on rod behind the pivot, progressive distances behind the pivot increase the force gradually. I see arms with the rod on the outside, with the notched rod forward of the pivot. same thing reversed, got it. Fidelity Research FR-54 has an outside weight, the difference is, there is only one location to suspend the line, on a wire outside the arm, and, the line connects to only one place, a bimp on the bottom of the arm, about 1/2" in front of the center of the pivot. No way to lighten, only threads in the bottom of the dangling weight to add sub weights. If it weighs 2.5g, and it is connected 1/2" forward of the pivot, what amount of outward force do you estimate is produces? What makes most sense to me is that it was designed in the days of heavy tracking weights, 2.5g start, method to add more if needed. |
I’ve never seen an FR 54, so I have no comment on its particular AS mechanism. My only point was that because the anti-skate weight itself weighs 2.5 g is not sufficient data to conclude it is putting 2.5 g of anti-skate force on your tone arm. The net anti skating force might will be less than 1.5 g which is your VTF right now. I suggest you examine the tonearm more closely. Maybe there is a way of changing the angle of the string, which also would change the anti-skating force. Also I would check the manual that was once provided with the tonearm. If there indeed were various anti-skating weights for different VTFs (something I’ve never heard of), it should show up in the manual. If it does not show up, I think you are just missing something . I am actually surprised that by now some other owner of an FR 54 hasn’t chimed in to explain what’s going on. Perhaps you can find the manual on vinyl engine, if you don’t already have one. |
- 30 posts total