I am in recent possession of a Grace 704 uni-pivot tonearm, which has no anti-skate adjustment. This is not optimal IMO, but should I really be worried?
The one way to be sure is by listening for mistracking. Specifically, mistracking much more often in one channel than another. Occasional mistracking in one channel or the other you can disregard, at least as far as anti-skate is concerned. But the purpose of anti-skate is to equalize stylus force side to side.
Anti-skate pulls the arm to the outside, away from the spindle. The side of the record groove closest to the spindle carries the left channel. If you’re hearing much more mistracking in the left channel then it means you have too much anti-skate. If you hear mistracking more in the right channel then stylus isn’t pressing against the outside enough and you need more anti-skate.
That’s how you tell. And contrary to what you will probably hear there is no one right level of anti-skating to set. That is because the force anti-skating is intended to counteract varies across the record, and varies by how modulated the grooves are (loud passages) and varies by tracking force.
Even if you do hear a little breakup in one channel that is still not decisive, for all the above factors. You need to pay attention and determine if there’s a consistent pattern.
Anti-skate is like most things analog imperfect and a matter of trade-offs. Some we get to make. Some the designer. You see which way the designer of your arm went. Are you sure you want to be second-guessing him? Based on Audiogoners advice?
I wouldn’t. I would listen to my rig. Let my own ears decide.
Anti-skate is reqired to counter the effect of the "drag" the stylus/cartridge exerts on the arm while playing a track. - Things can change if the cartridge, or even stylus-type is changed.
Even which track is selected sometimes has an impact, but with a mono recording this is rarely the case
Other impacts are - the amount of friction the arm pivot bearing produces - how good the actual anti-skate device on the arm is designed and operates.
Well designed/built arms tend to have very effective Anti-skate designs and their low friction pivot bearings tend to make them much more sensitive to anti-skate adjustment, in which case it is best to get it right.
I’ve had arms where anti-skate made little to no difference - but my Audomods arm/Cartridge combo is very sensitive and has an excellent anti-skate device that even counters the changes in drag that occur as the cartridge approaches the center of the album.
The easiest method to test ant-skate is to play an album that has been recorded in Mono. - You should hear a centralized image, which may move left and right as you adjust the anti-skate.
You can also go "high-tech" with test records and a meter to measure output voltage of each channel
Personally - i trust my ears and use the mono-recording method - if the image is "relatively" central you probably have little to worry about.
Full (if late) disclosure, most of what I wrote above is straight from Michael Fremer. One of his several hour plus talks on turntable setup. Forget which one. Anyone wants to really understand the subject could do worse than to watch them all. Unfortunately you really do need to watch them all, at least if you’re new, because while he’s a great talker he does have the somewhat detracting habit of meandering and jumping and looping back and putting a somewhat different perspective on things depending on which video you see. But again, you could do worse than watch them all.
Anti-skate is reqired to counter the effect of the "drag" the stylus/cartridge exerts on the arm while playing a track.
That is mistaken. Anti-skate is used to compensate for a force that an offset pickup arm exerts that gives it a tendency to "skate" towards the spindle. That’s why true linear tracking arms don’t include anti-skate adjustment.
Some manufacturers discourage the use of anti-skating force, including some who include antiskate adjustments on their arms. VPI is one such example.
Opinions by audiophiles about the necessity of using anti-skate are divided. Surprise! The best approach is to decide for yourself. My preference is to use anti-skate, but in an amount much less than is typically indicated on a pickup arm.
Thanks for all the input. It sounds perfectly fine to me...no mistracking, no imbalance in the channels, no distortion that I've noticed. But I should do some comparison listening tests in highly-modulated tracks using one of my other turntables, and see if I notice distortion in the left channel.
The Grace 704/714 tonearms did not come with anti-skate, so no parts are missing. They are low-mass arms (6g from what I've researched), and stock pictures of them had F9s mounted, so I really think they are meant for high-compliance cartridges. @viridian Where did you see that they were designed for low-compliance?
@cleeds I saw as well how older VPI arms did not have anti-skate, and were also uni-pivots. But Lederman notes in his anti-skate article (on SoundSmith's website) that VPI eventually added AS adjustment, probably at the behest of users.
Cleeds, Stringreen has made no mistake. Unipivots are generally designed to be as stable as that configuration permits. This means that ”lowering the tail end” increases downforce not decreases it as you have suggested.
That is mistaken. Anti-skate is used to compensate for a force that an offset pickup arm exerts that gives it a tendency to "skate" towards the spindle.
Thanks for the correction - That was what I was attempting to say in my rather "clumsy" manner.
I also forgot to include the important aspect of Anti Skate, which is
"
that gives it a tendency to "skate" towards the spindle"
Unipivots are generally designed to be as stable as that configuration permits. This means that ”lowering the tail end” increases downforce not decreases it as you have suggested.
It isn’t clear what you mean here when you use the word "downforce." If you lower any statically balanced pivoted arm - regardless of bearing type - you will decrease VTF, all other things being equal. That’s just simple physics, and what I was trying to clarify.
VTF is maximized when the stylus/record interface and tonearm bearing are horizontally inline with one another. Any deviation from this reference will reduce VTF. Although the VTA will affect VTF, it is not used to set VTF, that's the job of the counter weight.
VTF is maximized when the stylus/record interface and tonearm bearing are horizontally inline with one another. Any deviation from this reference will reduce VTF.
Sorry, but this is mistaken and makes no sense.
VTF stands for "Vertical Tracking Force." By definition, it is measured at the stylus. As you raise the arm - all other things being equal - you will increase VTF. This is simple physics. Consider two people carrying a heavy item up a stairs. Who has the heavier load: The guy at the bottom of the stairs, or the guy standing a few stairsteps higher?
You can measure VTF using a proper gauge and see for yourself the change as you raise and lower the arm.
I do agree that keeping the stylus and the pickup arm bearing on the same plane improves tracking as opposed to designs that place them on different planes (again, all other things being equal). But that really has nothing at all to do with VTF. Perhaps that is what is causing your confusion.
Cleeds is correct. VTF goes down if the pivot point is moved down. Also, The skating force is due to the friction of the stylus in the groove. Therefore the magnitude of the skating force will vary based on the stylus shape, the degree of tracking angle error, the headshell offset angle, and the modulations in the groove wall. This is why no one value of anti-skate force will be absolutely correct across the surface of any LP. It’s a moving target.
Any tonearm which is designed to be mounted so that the stylus tip overhangs the spindle will develop a skating force at all points across the surface of the LP. There are no exceptions. Therefore to say that some tone arms do not need anti-skate is to me a bit of self deception. If you cannot hear the effect of the absence of anti-skate, nevertheless there is a skating force. And that force can result in aberrant wear on the stylus.
... the magnitude of the skating force will vary based on the
stylus shape, the degree of tracking angle error, the headshell offset
angle, and the modulations in the groove wall. This is why no one value
of anti-skate force will be absolutely correct across the surface of any
LP. It’s a moving target.
I agree. The best one can achieve with anti-skate is a compromise, a happy medium.
Any tonearm which is designed to be mounted so that the stylus tip
overhangs the spindle will develop a skating force at all points across
the surface of the LP. There are no exceptions. Therefore to say that
some tone arms do not need anti-skate is to me a bit of self deception.
If you cannot hear the effect of the absence of anti-skate, nevertheless
there is a skating force.
Agreed! That's why I prefer to use anti-skate, even if there is no one, single perfect setting. There is no reason to allow perfect to be the enemy of the good.
Moonglum, are you going to take your marbles and go home? I am very interested in your hypothesis. Please explain in more words. I am willing to be convinced. First of all, I want to be sure what you are saying. Are you saying that there will be no effect on vertical tracking force if you lower the pivot point of the tonearm? Or are you saying that vertical tracking force will go up? Also, if you can explain more thoroughly what you mean by a “restorative force” that would help.
I remember when Thomas Schick's tonearm was designed without antiskating, it was about 5-7 years ago when i bought my Schick "12. At that time the designer said antiskating is not needed for such a long tonearm.
But now i can see on his website that
All his tonearms are equipped with an Antiskating mechanism
! His distributor also have all his arms with antiskating now.
Seems like Thomas learned a bit about proper tonearm design over the years :)
Lew, Pleased to oblige. Consider an old-fashioned set of weighing scales. - The pivot point is high - The CofG is below the pivot - the scales are stable, balanced
Now if one of the pans is manually raised upwards then released, there will exist a restorative force. A downward force. So to summarise, raised stylus = extra downward force. Rasied stylus could be due to warp or change in VTA. Both apply. Have a good day.
Maybe Schick was thinking about the fact that for longer tonearms, the tracking angle error due to non-tangency of the cantilever to the groove is less on average than for a "shorter" tonearm, all other things being equal. But you still have headshell offset angle, and as we know, any error in setting up a long tonearm is magnified such that the resulting increase in tracking angle error can be worse than that of a "short" (9-inch) tonearm. (We're all tilting at windmills in my opinion, because it is rare indeed to have any tonearm that is "perfectly" set up.)
Moonglum, In your model using a balance scale, the restorative force is gravity, acting to restore equilibrium once you remove the upgoing force you applied in order to raise the pan on one side. At the starting point, where the two pans are level with each other in the same plane, gravity exerts an equal force on both pans, because they are equal in weight or mass. So equilibrium is reached when the pans are level with each other. Your upgoing force is tantamount to reducing the mass on the side that it is applied. It is a momentary force opposing gravity. A tonearm is not entirely analogous to a balance scale, because it is supported at TWO points, at the pivot and at the stylus. The stylus exerts an upward force on the tonearm equal to VTF. When you mess around with the vertical position of the pivot point and change nothing else, there has to be a shift in the fraction of the mass that is supported by the stylus (=VTF), vs that which is counterbalanced by the counter-weight, which can only exert a fixed downward force equal to the effect of gravity upon it. The change in VTF is usually small, I admit, for the usual very small changes in VTA that one is trying to achieve.
The balance scale model is flawed as a model for a tonearm.
Lew, While I do not deny what you’ve said, remove the other supporting point, zero VTF so that it is balanced and floating freely, then the tonearm becomes analogous to the scale i.e. a stable balanced tonearm will behave in the same way.
Your beliefs are contrary to those who have measured the force at the elevated stylus point and compared with “horizontal” arm measurements for VTF.
Have you performed such measurement to confirm your belief?
Your beliefs are contrary to those who have measured the force at the elevated stylus point and compared with “horizontal” arm measurements for VTF.
Have you performed such measurement to confirm your belief?
It isn’t clear what you’re asking here.
I can tell you that - all other things being equal - if you increase the height of a statically balanced pickup arm, you will also increase VTF, however slightly. Similarly, if you decrease the height of a statically balanced pickup arm, you will decrease VTF, however slightly. You can easily measure this with a proper VTF gauge.
I’m really surprised that there is any debate about this. It’s pretty basic geometry and physics, and easily measured.
When you change the vertical position of a pivot, you are in
effect changing the horizontal distance between the stylus/record and pivot point
of a fixed length tonearm, which in turn changes the balance. As we reduce the distance between stylus/record
and pivot, the measured force at the stylus tip will be reduced. Any adjustment to the vertical position of the
pivot that results in the pivot interface and the stylus/record not being inline
will result in a lowered measured force.
This can be easily demonstrated. Hold a 5lb weight 45 degrees away from your
body (the weight will be farthest from you body). Do the same at 23 and 67 degrees. Tell me which one feels heavier when the only thing that has change is the distance between you (pivot) and the weight.
Moonglum, Just to clear up a basic point in our discussion, I think/thought that originally you were claiming that LOWERING the pivot point would.... etc. But in your last post, you are talking about RAISING the pivot point. In the latter case, the set VTF will go up, because your shoving more of the total mass onto the cantilever/stylus which must support it. So, to summarize my position, move pivot point down in the vertical direction and the set VTF goes down. Move pivot point up in the vertical, and the set VTF goes up. And this is for a static balanced tonearm. For a dynamically balanced tonearm, one with springs, etc, to set VTF, the effect is largely obviated.
A very simple analogy is to think of two guys carrying a sofa up a staircase. Which guy is bearing most of the weight? The guy on the bottom.
Testpilot, You wrote, "Any adjustment to the vertical position of the pivot that results in the pivot interface and the stylus/record not being inline will result in a lowered measured force." I don't know what the phrase "pivot inteface and the stylus/record not being in line" means, but I do believe that moving the pivot down vs up does not have the same effect on VTF. Maybe if I better understood your lingo, I would agree.
So, to summarize my position, move pivot point down in the vertical direction and the set VTF goes down. Move pivot point up in the vertical, and the set VTF goes up.
Not so - it depends where you start. If the arm is level, then moving the pivot point up or down moves the counterweight closer to the pivot and increases vtf in BOTH instances. In your example you would have to start with the arm up at the back for your statement to be true.
@hdm
Effects of tonearm geometry and mass distribution on the measurement of VTF :
If you calculate the change in overhang from moving the arm up or down 5mm then there is more distortion caused by this than the increased tracking force.
Not a big deal with many tone arms. But a very big deal with arms unipivots with under slung counterweights.
Only if you play lots of warped records.
The reason the counterweight is often placed lower on the unipivot is to stabilise the unipivot bearing by lowering the centre of gravity below the bearing point. This lowering of the centre of gravity also has a mechanical benefit of damping stylus motion.
Lowering of the centre of gravity has little, if any, benefit on a conventional arm with captured bearings. In fact if you read up on Pierre Lurnes design of the Romeo unipivot he presents an argument for having the centre of gravity slightly forward and only slightly below the pivot point to reduce the pendulum effect of a lowered counterweight which is not desirable on warped records.
At the end of the day the designer has to balance the pros and cons of each design facet and choice.
My reference to it being "a big deal" with unipivots was really with respect to the importance of measuring VTF directly at record height with that type of arm.
Very easy to be out/light .2 to .3 grams if measuring above record height with unipivots. With other arms, not so much of an issue.
I wasn't suggesting in the least that records would be played at that level due to warps or any other reason (ie. installing an aftermarket mat without adjusting for SRA/VTA) that would result in the overhang being off.
@hdm Yes I agree - I always measure and set vtf with arm dead level and more importantly do the alignment with the arm level as well first. If the vta needs significant adjustment I recheck the alignment before doing dialing in VTF by ear. Its an iterative process.
If the arm is level, then moving the pivot point up or down moves the counterweight closer to the pivot ...
It isn’t clear what you’re claiming here. It doesn’t make sense if what you mean is that raising the arm brings the counterweight closer to the pivot. The distance between pivot and counterweight will remain the same if all you do is raise the arm.
You can use a VTF scale to confirm that if you raise a statically balanced arm, you’ll increase VTF and if you lower the arm, you’ll decrease VTF. That’s easy to measure.
To be fair, the VTF doesn't really change much, based on my measurements.
I have not used anti-skate since I got my vpi classic 2 with the JWM-10.5. I did use it on pro-ject table with a 9 inch tonearm. If you need it, use it.
@lewm @cleeds If you put your thumb on the cartridge end of the tonearm and move the back of the arm up and down ( like VTA adjustment ), the counterweight tracks an ARC realtive to your thumb. The point I made was that If the arm starts at level then the centre of mass is the furtherest from your thumb. Moving the back of the arm up and down at the back will move the centre of mass forward towards the mounting position because the counterwieght moves in an ARC. Therefore IF you start with a level arm, the VTF will increase with either up or down motion because the centre of mass moves towards the cartridge in both instances. If you cant follow this then I cant help you any further, sorry.
Dear HDM, Brilliant post! I didn’t even know this one existed! I know Werner from PFM and he is a very good guy. His knowledge of electronics, digital & analogue, is even more impressive.
What is interesting about his measurements is that that the “underslung” COG examples all show the VTF increase, which is basically what we’ve been arguing about. Cheers!
Cleeds, It is not quite clear what you are saying here... You are the only person so far who claims to have measured it and obtained the result you describe.
Was this a recent measurement i.e. did this phenomenon happen on your current system? If so, please supply details e.g. stylus gauge model, expected VTF, actual VTF, tonearm pivot displacement below normal (rough estimate is fine), tonearm/cartridge used etc.
If you can’t clearly remember don’t worry, just guess. No stress. Kind regards,
... if the arm starts at level then ... Moving the back of the arm up and down at the back will move the centre of mass forward towards the mounting position ...Therefore IF you start with a level arm, the VTF will increase with either up or down motion because the centre of mass moves towards the cartridge in both instances ...
That’s a fanciful theory. Why don’t you try and actually perform this test and measure the result? If you do, you’ll find your theory is mistaken. It’s as simple as that.
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