[orthobiz]

This thread has lasted a really long time without getting thrown into the IGWB!
Antiskate discussions are almost like cable discussions...

Paul

[cheap-Jack]

Hi.

Many use glass discs to check the AS force correct or not. I refer using a vinyl blank though I also get a glass disc. I find a vinyl disc (a DIYed one, modified from a food saucer) resembles the surface friction of our LPs & I find it more accurate.c-J

The idea of using a blank disk for setting AS has been "de-bunked" by many.  Here is Van Den Hul's take on it:
"NEVER use an unmodulated record surface to adjust the anti-skating: This is static replay without the normal friction
between the groove and the stylus, so don’t use this way of setup. The result is always a too low value .

Sorry, I disagree. That's exactly we want to find out if the stylus/tone arm tends to move inward or outward when there is no groove to guide them. Skating force towards the centre of circular track always exist when an object is tracking on it. This is physics.

Any car driver notices such dragging force when driving along a circular road. That's why the road surface must be adequately banks outward to offset the inward dragging force so that the car can track safely along the circular road.

Likewise for a phonocartridge/tone arm tracking a circular groove on a vinly disc, with or without any grooves on it.

I agree most vinyl fans use blank glass disc which is way way to hard & next to zero track friction vs a LP.
That's why the result is not so correct.

Instead I use a blank vinyl disc with surface hardness & tracking friction similar to a LP, the result will be much more accurate.

c-J

[Letitroll98]

I agree Paul.  The most sense I've seen on the page was the mention that anti-bias force is less when using an elliptical vs a conical, and even less with a line contact stylus, about 1/3 of the tracking force. 

The blank disc seems so right intellectually, and seemed right at first to me, but it's just plain wrong.  I liked the idea and tried it numerous times and couldn't get correct results.  You need the groove friction in play to get an accurate reading.  If you visualize what is actually happening you'll see what I mean.  It's well accepted that if you were to adjust anti-bias force on the fly as the stylus tracked the record, you would need more force at the end of the record than the outer grooves.  Although the record speed is slower there, the groove velocity is higher because you're cramming more wiggles in a shorter space.  If groove velocity didn't matter then anti-bias force wouldn't change across the width of the record and using a blank disc would be great.  But the necessary force does change, therefore using a blank disc to set anti-bias force cannot be right.     

[neobop]

I agree Paul.  The most sense I've seen on the page was the mention that anti-bias force is less when using an elliptical vs a conical, and even less with a line contact stylus, about 1/3 of the tracking force. 

The blank disc seems so right intellectually, and seemed right at first to me, but it's just plain wrong.  I liked the idea and tried it numerous times and couldn't get correct results.  You need the groove friction in play to get an accurate reading.  If you visualize what is actually happening you'll see what I mean.  It's well accepted that if you were to adjust anti-bias force on the fly as the stylus tracked the record, you would need more force at the end of the record than the outer grooves.  Although the record speed is slower there, the groove velocity is higher because you're cramming more wiggles in a shorter space.  If groove velocity didn't matter then anti-bias force wouldn't change across the width of the record and using a blank disc would be great.  But the necessary force does change, therefore using a blank disc to set anti-bias force cannot be right.   

Hi Let,
I think part of the problem is looking for an absolute answer when there really isn't one.  Skating force varies with both groove velocity and change in offset angle. This is assuming VTF remains constant.  The main reason for increased inner groove skating is the increase in offset angle as the cart nears the record label, IMO.  Groove velocity reflects amplitude/frequency modulation and speed remains constant (hopefully). The groove concentric circle or spiral narrowing near inner groove tends to cause pinch effect or the stylus being lifted out of the groove. This is the major problem with inexpensive carts/arms exhibiting inner groove distortion.  Having more information crammed into the narrower groove spiral tends to increase this problem, but I don't think it necessarily increases groove velocity per Se.

I don't use a blank disk or groove to set anti-skate so I don't really know, but if it helps ballpark AS it's fine with me.  I look at the cantilever from the front while tracking, to get an idea of what's going on. It's easier for me to ballpark visually like in alignment, where I can see the angle of the cantilever in relation to the cart bottom. Whatever works.
neo

[Ericus Rex]

I agree Paul.  The most sense I've seen on the page was the mention that anti-bias force is less when using an elliptical vs a conical, and even less with a line contact stylus, about 1/3 of the tracking force. 

The blank disc seems so right intellectually, and seemed right at first to me, but it's just plain wrong.  I liked the idea and tried it numerous times and couldn't get correct results.  You need the groove friction in play to get an accurate reading.  If you visualize what is actually happening you'll see what I mean.  It's well accepted that if you were to adjust anti-bias force on the fly as the stylus tracked the record, you would need more force at the end of the record than the outer grooves.  Although the record speed is slower there, the groove velocity is higher because you're cramming more wiggles in a shorter space.  If groove velocity didn't matter then anti-bias force wouldn't change across the width of the record and using a blank disc would be great.  But the necessary force does change, therefore using a blank disc to set anti-bias force cannot be right.   

If the necessary anti-skate changes with the location of the stylus in the grooves (i.e. inner tracks vs. outer tracks) then it would seem to me that all anti-skate settings (and the methods to achieve those settings) are just as 'wrong', as you say, as using a blank disk since no anti-skate mechanism I know of is dynamic enough to give absolute correct anti-skate to both extremes of the disk.  Why argue about which method is 'right' if all methods are compromises?

[BobRex]

If the necessary anti-skate changes with the location of the stylus in the grooves (i.e. inner tracks vs. outer tracks) then it would seem to me that all anti-skate settings (and the methods to achieve those settings) are just as 'wrong', as you say, as using a blank disk since no anti-skate mechanism I know of is dynamic enough to give absolute correct anti-skate to both extremes of the disk.  Why argue about which method is 'right' if all methods are compromises?

Well, just like there is no "truly correct" alignment, (or for that matter arm length, compliance,...) there are possible compromises that may be more correct than others.  Apparently the blank disk approach creates higher compensation than necessary, so by itself, that may be less correct than using it as a starting point and adjusting from there.  I'm willing to accept VDH's "claim" that AS needs to reduce as stylus profiles become more exacting / precise/ agressive (take your pick) - sort of the inverse of alignment when you think about it.  As I posted before, this means that AS compensation can be reduced to nearly zero (okay, below 1/2 of a gram - possibly beyond the accuracy of most mechanisms) depending upon stylus shape and tracking force. 

Both Wally M. and Pete Riggle have jigs to assist in setting AS (Riggle's is based upon Wally's), has anybody tried one of these?

[Wayner]

Without any skating correction, the cantilever and stylus will be out of alignment. Alignments are done with the anti-skate setting to zero, and aligned on a non-moving platter. Now when the record is played, the "rudder" forces exerted on the tonearm, via the offset angle (and VTF) will cause the cantilever assembly and suspension to "take the hit", especially if the arm has resistance to lateral swing. The stylus will also ride on the inside groove and make poor contact with both modulated walls.

Applying a rational amount of anti-skate solves this problem (no, not perfect, but pretty good), helps to maintain a centered stereo image, reduces inner groove stylus chatter (extending the life of the stylus and the record) and takes the stress off of the cantilever suspension.

Almost every arm has this feature, tho some applications of anti-skate work way better then others, and for those that don't (like VPI), this is due to the fact that they can't figure out how to apply outward force on a uni-pivoted arm (IMO).

Wayner

[jimdgoulding]

I have seen what stress can do to a cantilever first hand.  Hence, my interest.  Hope never to repeat it due to my not knowing enough. 

[Ericus Rex]

Since we've now established that anti-skate is a compromise perfectly suited to only one area of the disk (since we can't/shouldn't adjust AS for each track on the record) the question then is; should the AS be set using inside, outside or middle-of-the-road tracks?  Which is the best compromise?

[Wayner]

In my opinion, it should be set in exactly between the null points. That is where the geometry says it should be. I am surprised that question got asked. It's the bottom of the trough, where, at least, it's the middle ground of tracking distortion.

Yikes. Here we go again......

Wayner

[jimdgoulding]

How's about setting it best you know how, then watching the cantilever travel across the record from head on at 45rpm, if you can?  Maybe at different tracking forces?  Not exactly scientific and I can't say that I've even tried it.  Jes thinking outloud.  Maybe with no anti-skate and then with anti-skate . 

[orthobiz]

I tried once to contact Wally regarding the purchase of a WallySkater. At least it gives you a number with some (pseudo?)science behind it. Hard to get a response from him sometimes so I never pursued it...

Paul

[neobop]

Since we've now established that anti-skate is a compromise perfectly suited to only one area of the disk (since we can't/shouldn't adjust AS for each track on the record) the question then is; should the AS be set using inside, outside or middle-of-the-road tracks?  Which is the best compromise?

That's not exactly what was established IMO.  Skating does vary with offset and groove velocity, but variance due to offset seems to be a small amount. Maybe if you have a really short arm skating increase due to offset would be greater, but with arms 9" or longer I don't think it's a major factor.  Groove velocity might be more of a factor.  People setting AS with HiFi News test record seem to consistently set it too high. I've never used this record but I imagine it's modulated in one channel and people use too much level increase for their setting. 

If you're setting by ear I think it's easier to ballpark first by whatever method you find easiest, then use common sense.  Play music similar to your usual fare, not Respighi's Pines of Rome or the Drum Record if you usually listen to chamber music or a vocal with guitar.  I use the middle third of the record, usually, and sometimes you can hear the balance/image lock in the middle and you've got it. You can always adjust it again if find that setting only seemed perfect for that record. Some people say it's better to set it a hair light, than too much.

BTW, VPI arms have anti-skating.  I think it was only the first ones that didn't. Users were told to twist the wires exiting the arm tube to apply torsional AS.
neo     

[Ericus Rex]

In my opinion, it should be set in exactly between the null points. That is where the geometry says it should be. I am surprised that question got asked. It's the bottom of the trough, where, at least, it's the middle ground of tracking distortion.

Yikes. Here we go again......

Wayner

The middle of the record seems obvious but I was thinking it may be better to set AS with the last track of the record.  Since tracking distortion is worst at the last track of a disk maybe optimizing the AS there would give a more 'unified' (that's not quite the right word, I know) sound during all the tracks?  Is this nonsense?

[cheap-Jack]

Hi.

Hi.
 That's exactly we want to find out if the stylus/tone arm tends to move inward or outward when there is no groove to guide them. Skating force towards the centre of circular track always exist when an object is tracking on it. This is physics.

Instead I use a blank vinyl disc with surface hardness & tracking friction similar to a LP, the result will be much more accurate.

c-J

To reconfirm what I said above, I just tried again to track my MM cartridge with a conical stylus (tracking at 1.35gm) on my DIYed blank vinyl disc
with record ballast sat on the TT spindle to minimize any undue vibration.

The tonearm remains stationary across 2/3 of the diameter of the blank disc to the inner possible track position when set at the right anti-skating force at the dial scale. I would also consider the same anti-skating force should work OK to the outermost possible track if I have my blank vinyl disc made thicker & stiffer to eliminate the existing slight but noticeable warping the the disc edge.

I can assume the anti-skating force should be constant across the whole record.

With anti-skating force balanced out across the record, there should NOT be any undue EXTRA pressure applied to the moduated grooves besides the stylys tracking force only.

That's why I do not detect any tracking distortion even when the tonarm is tracking very heavily modulated innermost grooves, e.g. close to subsonic pipe organ bass pedal notes of one of my bass test LP.

c-J

[Letitroll98]

The HFNRR test disc's anti-bias tracks work okay as a starting point if you only use the first one or two tracks.  Further along the ever increasingly over modulated tracks result in too high of a setting because no one on earth has actual musical selections in their library that highly modulated.  Too much of a good thing there IMO.

Yes neo, I like to look at the stylus from the front as a checking tool.  My eyes are too bad now to actually set anti-bias that way.

I don't see anything wrong with Wayner's suggestion of using the middle of the disc to set anti-bias force, I think I recall that being part of the Guru's advice as well.  I would add in try some highly modulated tracks located in the middle as well, but not too much modulation on those blank discs.   

And yes, as I believe setting anti-bias force is an art form, there would be no one right answer.  I believe there are better ways than others to reach an acceptable compromise.  And as silly as it sounds, there is a guy who adjusts anti-bias on the fly as the record plays, and uses different starting points for different records.  He keeps it all in a logbook, perhaps he's moved on to a tablet these days.

[MaxCast]

The middle of the record seems obvious but I was thinking it may be better to set AS with the last track of the record.  Since tracking distortion is worst at the last track of a disk maybe optimizing the AS there would give a more 'unified' (that's not quite the right word, I know) sound during all the tracks?  Is this nonsense?

makes sense to me.  But I do not have a test disc to see what my arm does, or if correcting for the center also corrects for inner.

[BobM]

I'm pretty sure I've posted this before, but here it is again ...

Anti skate can be set by ear. Find a record with some vocals and some decent micro-dynamics. Then set the force to zero. This works best with someone helping you, but you can do it yourself if you're patient.

Listen to the right channel and you should hear it almost lower in dynamic volume than the left (a bit recessed). Slowly turn the tracking force up, I mean very slowly a wee bit at a time. Eventually you should start to hear the right channel coming up and getting closer to what the left channel is producing dynamically. Then as you get higher you should hear both channels sounding more dynamic and just better and better. Move the anti-skate up very slowly now.

At last you will hear a fairly dramatic drop off in the quality of both channels. You have now gone a wee bit too far. Back it off a notch and you have optomized your anti-skate.

Enjoy,
Bob

[THROWBACK]

I agree with everyone:
1. Skating force changes across the disc
2. Any method is a compromise

Frank Schroder, German tonearm maker, recommends the following (if I remember correctly): using a blank disc, set the A/S force such that the stylus tracks very slowly toward the center of the record. How slow is slow? Slow!

[neobop]

    Then as you get higher you should hear both channels sounding more dynamic and just better and better. Move the anti-skate up very slowly now.
Enjoy,
Bob

Seems like a fun way to set AS.  I think it might be better if you get higher on something that heightens your senses, rather than dulls them.  Think I'll give that a try. 
neo