Antiskate help Technics SL1200g?...

I don’t believe that. I believe there are several variables, including tip radius and surface material. For example, vinyl would drag differently than acetate.

 

Have you tried increasing playing weight and readjusting? Also repeat on an old scratched up record. Wildly incorrect anti skate and arm should move across the grooves.

 

The tip radius is pretty much the same for most styli according to Ledermann. Thats what I mean when I say its the same surface area. The overall profile is of course different however.

 

Nah, we don´t really know the needle tip radius, and actually the friction isn´t the same in a groove. As one has two contact points the friction force will be considerably higher. So friction force on a flat surface could be anything.

 

Watch the video I posted. Never suggested its the same in a groove, but it doesnt need to be.

 

'Logic' suggests to me that as we are trying to equalise contact with the two groove walls as best as possible, then setting anti skate with the stylus in the groove makes most sense. As with much in hifi, there are opinions either way so whatever works best for each of us is OK.

 

My method tends to be a bit of trial and error. I have seen way too many canted cantilevers that I suspect have had too much anti skate applied to them.

My starting point is 2/3 of tracking force. I then listen to records that have higher energy information on the inner groove tracks, and listen for tracking distortion in either channel. I also listen to records with a centered vocalist, or a mono record to make sure there are no imbalances. If I accomplish all three of these at a particular setting, then I go with it. For a parity check I will take all the anti skate off and see what happens. I remember hearing tracking distortion in the songs I use for this test, so I go back to the anti skate setting I determined to be the best

I have yet to hear a damaged album due to this, and I have never skewed a cantilever. Not very scientific, but it does seem to work. Since anti skate needs vary across the surface of the disc, it seems to me to be impossible to have a best setting, but rather a target window of settings that will accomplish the intended goal.Couple this with the fact that there are current production arms that use the weight on a string method, the application of anti skate cannot be an uber precise application. Then there is the question about some arm designers who believe anti skate is not required on their designs...and that is a completely different point of contention.

 

Which groove wall? Each one is completely different and gives different skating forces. The video I posted should explain how it works and what we try to achieve with anti skating pretty well.
You are sort of right though, the method doesnt work best for all types of listeners. If you only listen to 7" singles or heavy metal then you would need more anti skating than the average listener. But this is the mathmatically best way to set it if you like many genres and types of music.

 

As I wrote previously, we don´t know the needle tip. We don´t know if the needle tip works in the elastic zone, or if actually works in the plastic zone, of the vinyl. So the friction force can really be anything. But if we theorize that the tip is spherical and it´s working in the elastic zone, the friction force in a groove is 1,414 times the friction force on a blank surface.

 

You must understand that a skating force doesn´t happen instantly, it´s a slow process. We can for this forget about the forces that aren´t parallel to groove, they are insignificant.

 

That's a very unconvincing video. I understand and accept Peter Ledermann's expertise in building a cartridge, but his talk did not explain this topic accurately. I knew about his recommended technique for setting skating force and was satisfied he could be right, but I'm disappointed with his reasoning. Yes - I realize I'm disagreeing with a recognized authority in this forum, but I still think he's got some significant inaccuracies in that video.

The reason for the angled friction force is not the offset installation of the cartridge. The offset cartridge is a design response to the offset angle of the groove caused by overhang. He blows right past the key difference between Baerwald and Stevenson - different overhang. With no overhang (as in a tangential tracker), there would be no skating force. With less overhang, there would be less skating force. A 12-inch arm skates less than a 9-inch arm, due to less overhang. Technics overhang skates less than Baerwald. The diagram below (drawn by me) shows a fictitious tonearm design with an offset cartridge installation. But it has no overhang, so this layout would have no skating force at this point. And it would actually skate in the opposite direction of the cartridge offset after this point.

We are all free to choose which expert to believe, if any. After all, many people don't seem to believe the manufacturer's instructions on how to set the antiskating on their Technics SL-1200. If Panasonic aren't the experts, I don't know who is.

 

Well, to be fair to the OP, he is just asking for our advice as to whether we think the anti-skate is working correctly on his new table, but as you and missan and others have pointed out, the results of the blank disc test can be inconclusive. Myself and others offered variations on that test to help the OP determine that the anti-skate function is working, not as a device for setting it to the proper value (at least in my case), but ultimately they should find a method that gives them confidence that the tonearm is functioning correctly, if they have a concern (though I would imagine most people dropping that much cash on a turntable probably have enough past experience to make the point moot).

OP: The normal method of observing and comparing the cantilever deflection when the stylus is in the groove versus not in the groove when playing a "normal" record is one easy method you could use to gain confidence in your settings. The skating compensation could be varied in both directions while observing the deflection, with no deflection being the usual goal, but the results depend somewhat on the cartridge compliance.

 

I didn’t intend even the slightest criticism of the OP.

 

In my experience, using the HFN lp to set anti skate will result in the cantilever not deflecting as described in the second part of your post.

 

In my experience, setting anti-skate using a blank disc requires you to overcompensate significantly for the amount of anti-skate needed. I tried it once and had to crank the anti-skate almost all the way up to get the tonearm to stop moving to the center. Then I read in countless places how you're not supposed to set anti-skate that way, and it makes perfect senes because because it doesn't factor in the force of the stylus against the groove walls. A blank-sided disc doesn't reflect the normal conditions of a stylus riding in the grooves, because there are no grooves!

For all of my turntables, I had the anti-skate set to the same as VTF before using the HiFi News LP, and found I didn't have to change the anti-skate after doing the test, because it performed perfectly on all tests except that last, impossible to pass one.

 

What are you saying? The skating force is applied as soon as the stylus is introduced to pressure and friction.

 

I dont see why it wouldnt have skating, the contact point of the record is not tangential to the arm line.

 

The arm has an effective mass. I think You need to read up quite a bit on mechanics.

 

I suggest you watch the video, or I could explain it in text if you prefer.

What creates skating? Mainly its modulation of grooves. Whats the modulation of all grooves? There is no value, it changes depending on the music thats being reproduced. The important question is whats the average value for most of the modulation. Well according to Ledermann the math has been done and it turns out that about 90% of the time music spends its time at 30 - 40% modulation, across many sampled genres. Great, so we want to set an anti skate force to counter that force for best overall performance. And it turns out that what you read is right, the arm is not supposed to sit still but rather move in slowly towards the spindle.
That gives us a an approperiate force to counter act the general skating forces. And you dont need any grooves to set it.

 

The force vector goes right through the pivot, as he showed in the drawing, though I think this thread is kind of getting off topic now

 

I think I see, but no arm is designed like that Im pretty sure.

 

I have been giving this issue of anti-skate a great deal of thought over the last two and half decades, and I admit that I am absolutely BAFLED by it. But I have come to a number of personal conclusions, one of those concerns that which has been set forth above. The method for setting anti-skate that you recommend is commonly employed, and it also happens to be one of the methods endorsed by Michael Fremer. But it strikes me as quite wrong. Let me explain my reasoning by looking at the situation when no anti-skating force is being applied in the usual ways (and then somebody can help me figure out why I'm wrong):

We can (and have) debated the degree of skating force applied to the cartridge resulting from either (1) the bottom tip of the stylus riding along a flat surface (ie., in a run-out section or a non-grooved section), or (2) from the interaction of the sides of the stylus running along the inclined groove walls. In EITHER case, I think we can all agree that whatever force is applied to the cartridge (and, through it's rigid attachment to the headshell, to the arm itself) it MUST do so through the interface of the stylus with the record surface. THAT is the point of contact; and the skating "force" vector is exerted on the stylus in the direction towards the spindle (hence, it acts to push or pull the stylus towards the spindle). Now, the stylus is rigidly attached to the cantilever. I think we can all agree that if the Cantilever were not itself attached to anything else at it's other end (but could magically remain upright), it would move freely towards the center of the record just as the stylus does . . . again, because it is rigidly attached to the stylus - where the stylus goes, the cantilever must follow. But, of course, it IS attached to something else - notably the generator assembly, which is attached to the cartridge body, which is attached to the headshell, and so on and so forth. And so when the stylus gets pulled towards the spindle, it brings the entire assembly along with it. I hope I have not written anything controversial so far.

Now, let us make two assumptions (both of which we will blow up in a moment or two). First, let's presume there is absolutely no rotational friction of any kind at the arm bearing. Which is to say two things: a) that fully 100% of the force applied to the stylus by the "skating" phenomenon will be applied to accelerate the cartridge towards the spindle; and b), that there is absolutely no opposing force acting on the cantilever in a direction opposite to that applied by the skating force on the stylus (to which the cantilever is rigidly attached, as we have established). HENCE, IF there is an inward directed force applied to the stylus, which is rigidly attached to bottom of the cantilever, and there is NO opposite force acting on the top of the cantilever WHY should the cantilever deflect at all? I submit to you that it would NOT. In fact, what I mean to suggest is that in a world where there is no anti-skating force and no rotational friction acting at the arm bearing, as the stylus slides happily across the record towards the spindle due to the skating force acting upon it, the whole cartridge, headshell and arm wand will follow right along with it, offering no resistance, and therefore no reason for the cantilever to be anything but straight up and down throughout its fateful trip.

Which brings me to the second assumption: that the cantilever is rigidly attached to the cartridge body through the generator assembly. Of course, we know this assumption is not true. In fact, the cantilever is attached to the cartridge body through a more or less compliant interface. And, in fact, it is precisely this compliance which permits the cantilever to deflect at all (if it is going to deflect) due to the application of oppositely directed forces at opposite ends of its length. However, IF you will permit me to continue to insist that my first assumption remains in effect (ie., that there is no friction force, nor any "anti-skating force" be applied), you would agree that even where the compliance between the cantilever and the cartridge body is extremely high, there will STILL be no deflection of the cantilever as the skating force pulls the stylus towards the spindle. Again, this is because there can be no deflection of the cantilever as long as there is no oppositely directed force acting on the end of the cantilever opposite that of the stylus.

But, of course, there ARE ALWAYS forces acting on the opposite end of the cantilever. Rotational friction at the arm bearing is one. Inertia (rotational or otherwise - both of which I have so far ignored) of the cartridge, headshell and armwand are a few others. And, therefore, as the skating force acting on the stylus pulls the bottom of the cantilever towards the spindle, rotational friction of the arm bearing and inertia (represented by the "effective mass") of the arm and cartridge combination act through the compliant attachment of the cantilever to the cartridge, and resist letting the top of the cantilever move towards the spindle. THIS causes deflection of the cantilever with the bottom of the cantilever canted slightly towards the spindle, and the top canted slightly away.

And again, this is, in theory, without the application of ANY anti-skating force. So then, the next logical question I asked myself is what happens when we ADD anti-skating force. This is additional force acting to resist the skating force pulling the bottom of the cantilever towards the spindle. And, just as friction and inertia does, this force acts through the compliant attachment of the cantilever to the cartridge body, and pulls the top of the cantilever towards the outside of the record. Ie., ANY amount of antiskating force (no matter how small) will tend to INCREASE the degree of deflection of the cantilever, NOT decrease it! The cantilever will never be more straight up and down than it is when there is no anti-skating force applied to it. Hence, I cannot see or understand why applying any degree of anti-skating force would tend to decrease deflection. And, in fact, I take the position that the proper amount of anti-skate must necessarily result in some degree of deflection. Which means, the method suggested by Michael Fremer (and many others) wherein one sets anti-skating force such that deflection of the cantilever is minimizes will necessarily result in too little anti-skate (and, in theory, actually none at all).

This issue has been driving me crazy. Where have I gone wrong?

Judd

 

Yes, good thought experiment, except for the fact that a stylus etching a blank record (have a look at the vinyl after "playing" it) and a stylus riding above the bottom of the groove, hanging between two tangential points of support are not even close to comparable.

 

It's the arm that wants to skate towards the spindle, the needle will prevent this if in a groove. So this force, between the needle and groove wall, will slightly deflect the cantilever outwards.

So if the needle friction force isn't pointing straight to the arm pivot, there will always be a side force on the arm.

 

Sorry, but we're going to have to agree to disagree here. On my turntables, even just getting the arm to move slowly inward across a blank-sided disc, I had to crank the anti-skate up well above the VTF.

And this post below makes a great point:

Again, I reiterate - anyone concerned about anti-skate should get a test record and they'll be able to know definitively if they've got it set correctly. No messing about etching lines into a blank-sided LP.