AT VM540ML Unusable

Yes I am a member
The graphs are from the paper

I found 2 graphs from Dual which further confuse the issue. They show AS force vs TF vs their setting scale. For the smallest (largest area) elliptical:
TF 2
Setting 2.7, AS 0.26
The other
2, 0.32

It looks like 2 things:
need to know the AS force for the stylus
need to know the TT setting vs AS force

It may not always be a fixed number, ie 1.2 or 0.75,, etc., since the setting/AS relationship varies.

The bottom line:
It varies widely
There is no sweet spot
It varies with music
You must listen, achieve balance & forget it

 

Never had this problem with my VM540ML

 

Problem?
Just messing around.

 

1) Skating force is a sideways force.
2) "Frictional drag" and "sliding friction" have almost nothing, or actually nothing, to do with skating force and anti-skating force. "Frictional drag" may be useful in evaluating stylus wear and record wear.
3) On different brands of turntables, the actual "anti-skate" force could be different at what could appear to be the same setting. A zero setting should always mean no anti-skate force, but a "3" could mean one thing on a Technics and something totally different on a different brand turntable, and so on between 0 and 3.
4) In that chart, using a bunch of carts that mostly were never available in US and little available elsewhere, and using "special stylus without damping", was/is virtually worthless for any purpose in the real world. Even so, the tests, for the time, should have at least included a Shure and a Pickering/Stanton, standards of the time, and used the best-selling models from each company (and maybe ADC and Ortofon and AT), because that would have been what counts. The carts used in the table are different than the carts used in the chart.
5) Pshaw.

 

The arbitrary 'units' used on most anti-skate dials don't help matters much, at least in this situation. It's true that many tables do give some indication of what type of stylus the dial is calibrated for. My old Dual 1218 had two scales, one for conical and one for 'elliptical' (good luck guessing which elliptical, though), and the 1200 has a circular dot at the zero mark (indicating conical). However, basically saying 'match the VTF and the AS for conical, and set the AS to 1.5 (or 1.25 or some other coefficient) VTF for elliptical' doesn't give much guidance, particularly with the advanced shapes. As the paper seems to indicate, generalizations appear dodgy at best.

Also worth noting that of the discs listed in the letter @Ingenieur posted, all the catalog numbers I could quickly pull up using Discogs are classical - this may skew the results a bit compared to a broader selection of genres, though the level the discs are cut at would also be a major factor.

[Also also worth noting that the ranges on the DG's are pretty squashed compared several of the other labels.]

 

The force on the stylus can be resolved into 2 vectors. Both involve the coef of friction u.

Inward
Fas = u sin(offset) Ft

towards pivot
F = u cos(offset) Ft

offset = offset angle
Ft = tracking force
These are constants

u is all over the place: signal, vinyl, stylus, etc.

The chart was not meant to be used for setting the force, only to illustrate the variation of u with velocity and different shapes.

It may be useful. The avg of avg ~0.4
With an offset of 22 and 2 gm, AS ~ 0.3
As a starting point, IF you knew the correlation of TT setting vs actual Fas

That is why people say guess and listen

 

I was not replying to you, but to the problem of VM540ML being "virtually unusable" because it would be "a dirt and dust magnet".

 

Well the graphics posted up thread I think are all from Kogen. I'd like to find an actual copy of the paper I referenced but I don't want to pay $33 for it.

Nonetheless my own experiments with music and test records seem to confirm the rather higher #s I often see quoted for Shibata styli are also appropriate for MR/ML, maybe actually a little low.

It doesn't matter for mainstream vinyl, though.

 

Conrad Hoffman has a short write up on anti-skate that does away with most of the math but (I think) does a good job of lining out the underlying principles: Anti-Skate for Poets and Musicians .

 

This is interesting
Graph on page 10 M vs radius
For any point on the curve Fas = M/r
At 100 mm ~0.33

Also the picture on page 7
Appears to show when elliptical is set at 2, spherical is 2.5

https://www.audioasylum.com/images/Skating-force-Misunderstanding-and-misinformation-about-it.pdf

 

Sorry
Misunderstood

 

One point I think someone else made in a linked thread and with which I'll agree: anti-skating becomes an issue at end-of-side for me.

Likely because a whole lot of other things are happening here. The speed of the vinyl is decreasing, the tracking error is increasing, and the orchestra is about to crescendo.

So I concentrate all my efforts at making certain my stars align at the end of the side.

 

Just when I thought you two couldn't get further in the weeds...

 

Okay I've found a copy of the paper by Pardee, and interestingly the concentration is on friction before and after cleaning with detergents (@pacvr I imagine you've seen this?), as well as the ability of lubricants to reduce this friction (Pardee worked @ Ball corporation, apparently a maker of lubricants for vinyl records).

The stylus shape used is a Shibata (not sure of exact version) @ 1.5g.

And the skating force found (via an interesting method) seems to average approx. .23g per g of VTF. This is 1.27x the typical amount of skating force applied via the dial on a Technics 1200.

This is all moot for most everyone.

I do have some unique records, however, where the amplitude is high enough to cause mistracking without sufficient VTF and ideal anti-skating.

I've found optimizing my setup for these extreme records doesn't prevent my setup from playing mainstream albums perfectly fine. Perhaps I'm wearing my stylus unevenly but the effects will take a long time to materialize and I'd sacrifice my stylus than risk vinyl damage due to mistracking.

 

Thanks for all that, I think. While I don't have Ph.Ds in math or science or physics, I know a little.

It seems to me that the coefficient of friction at a fixed downward tracking force would be exactly the same whether the stylus is a conical or MicroLine, or a .7 cube stylus. A MicroLine spreads out the friction in the groove making any contact point have less friction, but the total friction of any stylus type would be the same. Thus so far as the friction has anything at all to with anti-skate, it is the least worrisome of problems.

It seems to me that the skating force could be exactly known at every point across a disc side, and that could be exactly counteracted. It seems to me no turntable maker has ever done it. Such things as a "Bio-Tracer" arm did things but not from a known fixed "lookup table" of "skating" force across every point of the disc side.

 

Ball Corporation, mostly known for their canning jars and lids (of lowest imaginable tech), somehow and with vague hints it was related to some space age work they did or researched for NASA, came up with the product Sound Guard, said to reduce friction in the groove, and said to bind itself to the groove. I bought that at the time, one package, and used it, and used it up, and it seemed to work, I guess. It was said to last a lifetime on the disc, which I didn't understand then or now. As an extreme example, a heavy tracking conical would have to scrape it right off the groove at the contact points of such a stylus.

The package came with a nice scrubber brush pad to first clean the disc with their special cleaner included in the package, then scrub the real Sound Guard stuff onto a disc, and a there was a nice extra-cost accessory mat to place the disc and perform the scrubbing. The Sound Guard scrubber brush/pad was nearly identical to the cheapest record cleaning brush/pad thing that china makes now. The mat is still useful.

I think, and others suspected, that Sound Guard was basically a coating of silicone in the groove, perhaps the best grade or formulation for use on vinyl. I think the mat also was silicone+plastic much like you can buy a pot holder or other similar things made of silicone+plastic now.

They only sold Sound Guard for a few years, then it disappeared.

I think they took advantage of an assumption that anyone fool enough to buy the stuff would have a Shibata or Stereohedron (I did). The most of the advantage was giving a record a good cleaning and playing with my Stereohedron.

 

Oh wow I didn't make the connection to the maker of canning products, thanks.

 

u is independent of area, true
Pressure = F/A

imo friction is the ONLY variable.
TF and offset angle are constants.

It looks like u changes with stylus shape

 

When I measured my SL vs setting I got 0.25 at 1 gm (red dots on my graph).
2 gm ~ 0.38
2.5 gm ~0.44
It follows the AS curves vs TF

so if the ML needs more than Shibata, and 2 gm = 0.46 AS the setting >2.5

I have a test lp coming, I'll play with it.
I just looked at stylus deflection and 'jump' and it seems best at 1.5 (0.3 AS) but so hard to judge even with a magnifying glass.

 

I have one of the original Sound Guard kits from way back. I now only use the mat and that's on rare occasion.

 

Yeah, it wouldn't be hard to spend a few hours driving oneself around the bend trying to get the drop stationary. Plus, the further into the disc one gets, the further away one gets from the stylus, which complicates things.

Also a factor - I can't make much of a claim that the actual AS force at any given setting is in spec on my table. The springs do eventually wear out, so the 2.5 I'm at might be well out from what 2.5 would be on a new/properly calibrated table. Or not - I've got no good way to tell.

 

My knowledge of the Ball Corporation "Sound Guard" vinyl treatment is here - Sound Guard - NASA Technical Reports Server (NTRS). The Ball Corp "Sound Guard" product as stated is from their "Vac Kote" deep vacuum lubricant line which by this document - a113766.pdf (dtic.mil) "...produced by Ball Aerospace Systems Division and is commonly called Vac Kote (BBRC 36233). The oil's basestock is Apiezon C, a low vapor pressure hydrocarbon oil used in vapor diffusion vacuum pumps. The oil contains five percent lead naphthenate concentrate as an antiwear agent. The concentrate contains approximately 88 percent lead naphthenates and 12 percent of a lower boiling hydrocarbon diluent.".

 

The overall Sound Guard trademark from Ball was filed in 1976 and abandoned in 1997. Odd. It takes very little effort to keep a trademark even if something is out of production at the time of renewal.
SOUND GUARD Trademark of Ball Corporation Serial Number: 73077596 :: Trademarkia Trademarks

A specific trademark for the version sold for record use was probably this, filed in 1978 and abandoned 1985.
SOUND GUARD Trademark of Ball Corporation Serial Number: 73182631 :: Trademarkia Trademarks

 

For skating forces its good to read the original "Kogen" articles in these two Audio magazines - Audio-1967-10.pdf (worldradiohistory.com) and Audio-1967-11.pdf (worldradiohistory.com). Few topics generate more debate, how to set and probably more confusion. You want to avoid anti-skate - use a tangential arm. Otherwise, there is no perfect setting - only the best compromise, and some anti-skate can help to obtain equal wear on the stylus. But, to completely confound the issue - some will say no anti-skate.

I have two VPI tonearms and together with another VPI Forum member developed a pretty ugly spread-sheet to calculate the anti-skate from the VPI device http://www.vpiforum.com/download/file.php?id=5995 , but to summarize for those who have VPI tonearms with the anti-skate device three factors contribute to the amount of anti-skate force:

1) The lower the fishing line is attached to the cam post, the less leverage, therefore, the more force is required.
Lower = more anti-skate, Higher = Less anti-skate

2) As you put more rubber rings on the bottom cam post, the greater the mass, therefore, the greater the force required to move the mass.
More rubber rings = More anti-skate, Less rubber rings = Less anti-skate

3) the location of the rubber donuts on the bottom cam shaft, the closer to the end of the shaft, the more force is required.
Closer to the cam = Less ant-skate, Closer to the end of the post = More anti-skate