Don't hold your breath.

Last nite, I tried it on my custom-built special bias testing disc: a plain glass platter. With the specified tracking force (1.5 gram), I adjusted the bias setting until the cartridge/tone-arm is tracking midway across the rotating grooveless glass platter in a 'statioinary' position, i.e. without moving backwards & forwards.
Leave it run for a while to make sure the setting is consistent.

In my situation, the anti-skate setting on the tone-arm to get the absolute dynamically balanced tracking force vs anti-skating is: ZERO !!!!! So, the anti-skate of my 125II on its orignal stock wooden plinth is way way out. I have been tracking it with way way too much anti-skate force since day one !

Of course, before you do this anti-skating setting test, make sure the whole turntable is statically level, dynamically balanced with the platter rotating, & the tone-arm+catridge are dynamically balanced before you start to do this test. Otherwise, it would not be accurate.

Now, I start to track my LPs with zero anti-skate setting.

c-J

 Yes. - olddude55 19:54:49 08/09/06 (0)
 What about this method? - krenzler 14:24:21 08/08/06 (0)
 Jack, why would you expect... - Doug Deacon 14:07:18 08/08/06 (2)

...

Show full thread outline!

 Yes. - olddude55 19:54:49 08/09/06 (0)
 What about this method? - krenzler 14:24:21 08/08/06 (0)
 Jack, why would you expect... - Doug Deacon 14:07:18 08/08/06 (2)
 "Skate Plates" did serve a useful purpose, however. - HenryH 18:53:44 08/08/06 (1)
 Indeed - Doug Deacon 19:43:29 08/08/06 (0)
 Re: Is yr tone-arm anti-skate really accurate ? - Lew 13:59:41 08/08/06 (3)
 I know you're trying to help - Doug Deacon 14:21:12 08/08/06 (2)
 Re: I know you're trying to help - Lew 17:37:47 08/08/06 (1)
 Nailer to nailee - Doug Deacon 18:08:01 08/08/06 (0)
 A groove-less surface doesn't give a true indication... - anumber1 12:09:19 08/08/06 (0)
 "Don't hold your breath" - Fretless 12:07:35 08/08/06 (25)
 Agree .... nt - J.D. 14:53:19 08/08/06 (0)
 Really? - cheap-Jack 12:25:21 08/08/06 (23)
 Wow! It sure doesn't sound like you are willing to listen to reason! - anumber1 12:37:13 08/08/06 (17)
 I am all ears. - cheap-Jack 13:06:46 08/08/06 (16)
 I suppose I can do some heavy lifting. - anumber1 15:55:07 08/08/06 (15)
 What a bunch of nonsense! How can something so simple get so confused? - jsm 11:06:53 08/09/06 (0)
 Is this a joke? If so, it is absolutely hilarious. Relative to skating force, it is totally erroneous.... - John Elison 16:27:53 08/08/06 (13)
 Hey John, Explain the physics better for me then! - anumber1 16:34:43 08/08/06 (12)
 Re: Hey John, Explain the physics better for me then! - John Elison 17:08:38 08/08/06 (11)
 Thanks. - anumber1 17:54:33 08/08/06 (10)
 Hey, you're welcome. I didn't mean to be rude.... - John Elison 18:19:20 08/08/06 (9)
 Yes, you score the bull's eye. (long) - cheap-Jack 13:30:46 08/09/06 (1)
 Re: Yes, you score the bull's eye. (long) - John Elison 16:29:15 08/09/06 (0)
 Sort of a way.... - mosin 19:34:55 08/08/06 (6)
 Re: Sort of a way.... - John Elison 19:49:04 08/08/06 (5)
 Well.... - mosin 20:03:47 08/08/06 (4)
 Sorry! ;-) - John Elison 20:13:12 08/08/06 (3)
 Re: Sorry! ;-) - mosin 20:35:00 08/08/06 (2)
 Look at your Kenwood arm... - tubesforever 10:07:20 08/09/06 (1)
 Re: Look at your Kenwood arm... - mosin 15:25:24 08/09/06 (0)
 Backoff Jack! You sound like the guy with the agenda! (nt) - Garth 12:33:07 08/08/06 (4)
 What agenda? - cheap-Jack 12:43:13 08/08/06 (3)
 Whatta moron!!! c-J, that is. - HenryH 12:45:39 08/08/06 (2)
 So now you tell me? Where were you when we needed you? (-: (nt) - Garth 12:52:17 08/08/06 (1)
 Uh . . . er . . . Sorry 'bout that, G. ;8^) /nt\ - HenryH 12:58:26 08/08/06 (0)

Skating force is dynamic, changing with the modulation of the groove. Measuring the force required to keep you arm stationary on a smooth glass platter doesn't really translate to the force required to provide proper bias in use, playing music from a modulated groove.

Use a modulated test record (Hi-Fi News or simular) to get the adjustment close and fine tune by ear for your final setting.
--
Al G

Travelin' light; It's the only way to fly - J.J. Cale

This grooveless method has been used by many audio boutiques in the past decades to test tracking. I did not invent it.

Please explain to me technically how come "your tonearm with no anti-skating will cause uneven" wear & tears employing the setting determined by this dynamic test.

I auditioned intensively the with this new zero A/S setting vs my usual rule-of-thumb 1.5gm setting, I do find it sounds better on my favourite test tracks.

Don't challege my intelligence, please.

c-J

PS: please don't talk as if you got an undisclosed agenda there.

Past practices by audio boutiques don't impress me, sorry.

Good Luck with your flawed reasoning. At least you don't need to worry about trashing your records since you play them wet, they are "pre-trashed" before you can do any more damage to them with improperly set anti-skate!
--
Al G

Travelin' light; It's the only way to fly - J.J. Cale

Please specify. Or eat your words, dude.

I spent only 12 bucks greenbacks to have this simple disc made by a glass smith in a couple of days. I think it works for me, to say the least.

Or you want every LP consumer here to spend some good money to order a test record from a vendor?

c-J

Henry

A 12-gauge shotgun is the ultimate arbiter of disputes - G. Gordon Liddy

A 12-gauge shotgun is the ultimate arbiter of disputes - G. Gordon Liddy

Please quote me technical papers on grooveless test being a baloney.

I never question of effectiveness of a test record. But you challenged the effectiveness of a grooveless test. So please quote your technical substantiation.

I am listening. Sorry I believe in documentation, not hearsays.

c-J

Situation #1
a) contact surface is glass (low friction)
b) contact is on a single surface only (low friction)
c) contact surface is unmodulated (low friction)
d) stylus contact surfaces are in mid-air, only the point is touching

Situation #2
a) contact surface is vinyl (higher friction)
b) contact is on two surfaces (higher friction)
c) contact surfaces are modulated (higher friction)
d) point is in mid-air, stylus contact surfaces are touching

If papers impress you read the FAQ's. There are good explanations there of skating forces and what causes them. Once you understand this you'll understand why a flat glass plate is a very inaccurate simulation, no matter how many salons used it.

__________
"Do not meddle in the affairs of wizards, for they are subtle and quick to anger." - JRRT

Your conclusion about the inapplicability of a planar surface is correct BTW. A smooth plane cannot emulate a modulated groove.

__________
"Do not meddle in the affairs of wizards, for they are subtle and quick to anger." - JRRT

• Anti-skate thread @ AudiogoN forum.

A well reasoned discussion on the Vinyl Engine explains the physics of anti-skate quite succinctly. The full thread can be found at:

http://www.vinylengine.com/phpBB2/viewtopic.php?t=1025&highlight=anti+skate

This whole discussion is basic physics really, not full rocket science. Here is an excerpt from a post authored by "soundbug":

"As we know, a pivoted tonearm is drawn by inertia or pressure toward the center of the record. If the inertia is strong enough the arm would have a tendency to jump grooves and skate toward the center. Anti-skate devices were incorporated into tonearms to counter this physical force and keep the needle in the center of the groove as it travels. They work by applying a small amount of back-pressure on the arm to pull it slightly toward the edge of the record. Rarely are anti-skate devices accurate. The space between grooves on a record, are not universal. The wider the spacing, the faster the arm travels toward the center of the record(more inertia) and the more anti-skate is needed to counter balance this extra pull. While it is acknowledged that these devices are not accurate, anti-skate devices are completely necessary in order for most arms to work properly?. Knowing that tonearms are full of compromises on perfection, a little error in anti-skate is acceptable and probably seen as a necessary evil.

When a pivoted bearing arm (most arms are of this type, REGA for example) is used with no anti-skate, the needle of the cartridge rides on the inner side of the groove due to inertias pull (or push) . Because the arm is held steady in the vertical plane at two pivot points, its azimuth is not affected. The top of the tonearm is still parallel to the platter or record (at least it should be). What is affected is where the needle rides in the groove. If you could see the needle riding in the groove you would notice that the tip of the stylus is not at the lowest possible point in the groove but is rather riding up on the side of the inner groove of the record. Not only will you get a mismatch in volume left to right but you will also get more distortion from the inner groove and decreased response, because the stylus is no longer seated properly in the groove.

When a uni-pivot tonearm is used without anti skate, the physical reaction of the arm is VERY different. Because the arm is not rigidly held in the vertical plane, it's azimuth is greatly affected by this inertia. (Remember, a pivoted/bearing tonearms azimuth cannot be affected unless manually changed). When the needle on a uni-pivot arm rides the inner groove of the record, the simple mechanics of the arm causes it to pivot to one side thus causing the needle to sit at an angle in the groove. Of course you get all kinds of distortion and balance problems when this happens. Most answers to this problem is to use a little fishing line with weight attached and drape it over the arm. This presents a host of problems involving the arms affect to this extra weight which rarely sits in the same place on the arm , the line used to connect the weight is not frictionless and thus has negative affects as the arm travels toward the center, the line needs to move to specific points on the arm as it travels toward center to work correctly, etc¦etc¦

By using an off axis counter weight, the azimuth of the arm is controlled by what position the weight is in. You can have a gram of weight on the arm and have it pivoted to the left OR to the right depending on what position the counter weight sits. If you position the counter weight so that at no point on the record the arms azimuth changes, then you know that the arm is correctly riding in the center of the groove thus needing no anti-skating? compensation. If it is NOT riding in the center of the groove, then, by the very nature of how a uni-pivot arm works, the azimuth would be incorrect. One edge of the head shell would be tilted up. If we know that the shape of the needle rarely matches the groove exactly, any constant contact of the needle with EITHER side of the groove will reveal itself as an incorrect azimuth! Simply setting the azimuth correctly on a uni pivot arm (and of course making sure VTA and counterbalance weight are correctly set) controls the anti-skate?. When all these are set correctly, the needle rides in the center of the groove at its deepest point possible and no anti-skate mechanism is needed."

While not directly dealing with your smooth glass plate, the point is that you need the modulated grooves of a record to provide the conditions that induce "skating"

Simply put, a smooth glass plate does not present enough friction to the stylus to present a real world situation with which to adjust the proper amount of bias with. Some test records try to approximate a real world situation with test tones, in modulated grooves that distort easily under sub-optimal conditions to give the user an indication of how well the stylus is tracking under various bias settings. You are then to fine tune the settings with music under actual listening conditions.

It is a free world and you can adjust your deck any way you wish but passing out bad information using no basis in fact as truth is wrong.

Good luck with your setup.

--
Al G

Travelin' light; It's the only way to fly - J.J. Cale

Good luck,
John Elison

Help a 'po iliterate soul out and post a nice solid explaination of the forces at work for c-J here please.

Thanks
--
Al G

Travelin' light; It's the only way to fly - J.J. Cale

Skating force is caused by friction (and only friction) of a spinning record against a stationary stylus. The direction of the frictional force is offset to the pivot/stylus line and thereby creates a torque on the tonearm attempting to pull it inward. This torque applies greater stylus pressure on the inner groove wall relative to the outer groove wall and antiskatng is required to equalize the stylus pressure by applying a counteracting torque to the tonearm.

The following is an excerpt from Brian Kearns' A Treatise on Cartridge Alignment - Part II, which can be found in our Vinyl FAQ.

Antiskating force

The skating force, is a torque about the tonearm pivot that arises because a tangent to the record groove at the point of contact of the stylus is offset from the tonearm pivot. The line of action of the frictional force does not pass through the tonearm pivot, so a torque is generated. This torque tends to turn the tonearm inwards towards the centre of the record. If the perpendicular distance from a tangent to the record groove at the point of contact of the stylus and the tonearm pivot is defined as the groove offset, then the skating torque is proportional to the groove offset times the frictional force between the stylus and the record groove. The skating force is not constant across the record surface, it is largest at the inner and outer groove radii, and is minimum somewhere between the two null radii. To counteract the skating force, an antiskating force is applied.

Conveniently, when the stylus is at one of the null radii, the groove offset is the same as the linear offset so the following equation arises.

Skating torque at null radii = Friction * linear offset.--------------(17)

Anyway, I did indicate that I was taking a whack at the question of anti-skate but had some degree of uncertainty. Then whilst walking home from work, I realized I had got it approximately backwards and expected to get nailed for it. No offense meant or taken. My main point was, as you seem to agree, one cannot set anti-skate in the absence of the groove. I should have left it at that.

The basic point I was trying to make to the OP was that without the friction of the groove there is no skating force.

Thanks again for finding and quoting Mr Kearns.
--
Al G

Travelin' light; It's the only way to fly - J.J. Cale

I understand about "centripetal", thanks for the clear definition. It's not that particular force vector which causes "skating", but we both know that so 'nuff said.

Cheers

__________
"Do not meddle in the affairs of wizards, for they are subtle and quick to anger." - JRRT

As far as antiskating is concerned, it really doesn't matter whether grooves are present or not. A spinning flat surface without grooves will also cause skating force. It just might not cause the same amount of skating force as a grooved surface because the stylus contacts a flat surface at its tip while the sides of stylus contact a groove. Depending on the geometry of the stylus, there will normally be a difference in the frictional force. Of course, if you select a completely different material, such as glass instead of vinyl, then you will definitely have a different frictional force in all respects.

There is really no good way to set antiskating that I have found. Since I have a very expensive tonearm, I use its antiskating gauge as a starting point. I figure SME has done their research; however, every cartridge is slightly different due to stylus geometry and cantilever suspension. Therefore, I tweak by ear when I feel I hear tracking problems on highly dynamic LPs. Recently, I felt the need to reduce antiskating slightly on my DL-103R after hearing some anomalies on a couple of records. I'm tracking my DL-103R at 2.5-grams, but my antiskating is set to about 2.2. So far, it seems to be just about right.

Best regards,
John Elison

Henry

A 12-gauge shotgun is the ultimate arbiter of disputes - G. Gordon Liddy

One way to set antiskate that works reasonably well is to make a variety of waves files from vinyl, and then look at the signal in a sound editor, like Sound Forge, on your computer. If the highs are consistently distorted in one channel, it is a reasonably safe bet that the cartridge is mistracking. It is a hassle to do, but it works fairly well. I discovered the method while ripping vinyl to redbook.

My only linear tracker was an HK/Rabco ST-8. Not exactly an air bearing. I doubt if even a 5 degree tilt would have affected it at all! ;-)

__________
"Do not meddle in the affairs of wizards, for they are subtle and quick to anger." - JRRT

LOL! Just normal rude, right? ;-)

Al will live. :)

Thanks,
John Elison

The first one I tried it on was the Magnepan Unitrac. That particular tonearm uses a bucket with number nine lead shot, so it tweaks much closer that a lot of others. For example, Magnepan recommended roughly 150 shot for a tracking force 1.5 grams. A test record with the "by ear" method suggested that this was too much, so I cut accordingly. When I made the wave files, I discovered that the difference was a gross amount. In fact, I was still too heavy by about a third. Subsequent cartridge changes indicate that even the tip style has some effect. You can go nuts doing this crap, so I typically get close, and let it go. Oh, and some line contact cartridges hardly mistrack at all when correctly aligned, so I don't worry too much about them. Mostly, the issue rears its ugly head on vinyl that is in somewhat marginal condition. Still, there is the issue of where a particular cartridge mistracks. As you know, antiskate correction cannot be even across the record, so most manufacturers shoot at the worst points. Although I own no tonearms with progressive antiskate, my method seems to be the best compromise that I have used. I believe it would be helpful even with those tonearms which have a fancy antiskate mechanism.

Pretty nice design and I am confounded by why others do not use a similar variable skate force design.

Did you say 150 lead shot for 1.5 grams of VTF with the Unitrac? I have been using 40-50. Sound like I need to try 100? Please let me know on this.

I paid for the TRX-2 cartridge this morning. Hope to have it by next week. I cannot wait to hear it on the Unitrac.

Damn I love the Pabst motor on this third plinth. The Rondine B12GH is the best sounding platform I have ever owned.

I know you just purchased one, but your guts looks different from my guts. It is a very simple and elegant design and the Pabst motor drives the heavy platter with complete ease.

I know you will love your Rondine. Don't wait a half year like I did to get it mounted and running. I plan to make some mods to mine so I can mount the Unitrac.

Cheers!

There is one point I think that should be stressed in the context of the post that started this thread. As an understanding of the physics makes clear, the skating force is directly proportional to the drag force. The drag force is not a constant for all time. It depends on VTF, stylus geometry (contact area), geometry of the groove tangent and direction to the pivot, groove modulation, rubbing friction of the vinyl-stylus interface, and probably more things I've forgotten to mention. Any anti-skating setting will be not be perfect for all situations, and there are a variety of opinions on how to optimise the setting. But I think using a plain glass disk is terrible. I don't care what any store says. The drag force characteristics of a glass disk are very far from that of a stylus in a groove. The same goes for a unmoduated groove, but probably not quite as strongly; I wouldn't use that approach either.

Joe

This is exactly I wanted to establish: "A spinning flat surface without grooves will also cause skating force.". This is simple physics.

I've proven it with a grooveless platter with the tone-arm/cartridge staying midway across the spinning platter by adjusting the anti-skating force. In my situation of 125II, it just so happend that the A/S force setting is zero. It may be some postiive force reading with other turntables.

No way I will ever suggest that anti-skating is NOT needed for proper LP tracking.

My next experiment will be do it with a PVC grooveless platter, which I can have it made for a few bucks. So the reading should be more realistic than a glass platter though it has been used for decades.

You are right to say there is really no best way to align the A/S force accurately given the scale on the tone-arm is far from being accurate. Oue ears got the final say.

Here is an excerpt from Audiogon on this same subject:

"Read the Thornes white paper on setting anti skating. The correct value is 14-16% of your adjusted tracking force. Therefore if the tracking force is 2 grams, you should set your antiskat to 0.28-0.32 grams.

Make sure your table is ABSOLUTELY level in both horizontal & vertical directions."

With the above guideline, the correct antiskate of my 125II situation would be 14% of 1.5 gram = 0.21 gram. Given the tolerance of the antiskate scale of my 30-year young 125II, it appears that it might be OK to set the A/S force at zero as it is physically impossible to set a decimal gram with the small A/S scale. My audition test cofirms it sounds OK with zero A/S setting.

Strangely enough, my experiement with the grooveless glass plate also went in line with this zero bias setting despite it is against all odds to get the right setting on glass platter.

c-J

Antiskating mechanisms are designed around these sorts of figures. In other words, when you set tracking force to 2.0-grams and you set your antiskating gauge to 2.0, it is applying a lateral force at the headshell of between 14-16% of 2.0-grams.

Anyway, there is a tool you can buy to check antiskating force at the headshell in order to find out the exact percentage of tracking force. It is called the WallySkater and is pictured below. It enables you to accurately measure antiskating as a percentage of track force at all points across a record.

• Wally's Vinyl Corner - Wally Tools for Turntable Setup