NSGarch:With all cartridges except those with the stiffest suspensions, as long as you can see the cantilever from the front of the cartridge, it's quite easy to set AS force visually. I always did it that way with my MM Shure cartridges. You just lower the stylus into the groove while watching the cantilever from the front. If it deflects to the right (relative to the cartridge body) you need to add AS force. If it deflects to the left, AS needs to be reduced. No deflection of the cantilever when the stylus hits the groove means the skating force is balanced out. It could also mean that the skating force (even without AS applied) is not enough to alter the relationships in the cartridge's generator (usually because the suspension is stiff enough to resist the skating forces) and so you would HEAR no difference with or without AS applied. Nevertheless, with no AS applied, the inner groove wall of the record would wear faster than the outer groove wall Although I don't profess to have anywhere near the expertise in these matters of several of the protagonists in this thread, Neil's statement above seems to me to be the common sense bottom line, regardless of the fact that any anti-skating setting will be a compromise to a degree that will vary with position across the record. NSGarch: The Grace 707 is a vintage tonearm calibrated for MM cartridges, not MC which require far less AS. The rule of thumb in the MM days was that the AS should equal the VTF, and even at that, how much sideways AS force (in grams) was applied was definitely NOT the same as the actual weight on the string. FWIW, I have over the years used several MM/MI cartridges on multiple turntables and arms (mainly a Grace F9E Ruby and a high output Grado Reference Sonata on a SOTA Sapphire with Magnepan Unitrac tonearm), and using the visual alignment method I've consistently found that the optimal setting was about 2/3 of the setting recommended by the tonearm manufacturer for the particular vtf. Regards, -- Al |
HP speaks on Oct. 3, 2009: A lot of systems don't sound like music," said Harry. "They sound like hi-fi. When I go to Carnegie Hall, I sometimes close my eyes and try to pretend I'm listening to a hi-fi system, so I can see what I'm missing." Some of the great designers continued to issue great gear even as their hearing declined with age, because they were designing to what they heard in the concert hall. Hence the importance of a life reference, the experience of acoustic music performed in an excellent acoustic.
Harry also reminded us that his magazine was the first to hire women reviewers, and that women's hearing is superior in the crucial 48 kHz range. One of the very few women present (were there more than two?) then spoke, noting that she had to flee a number of rooms at RMAF because the sound was too bright. I wonder if she saw me asking people to either turn the music down because it was too piercing, or following in her footsteps and making a quick exit It is always the same: When you don't understand what you hear...but even HP can't change it anymore. |
Newton would smile.....
Again Nsgrach - your simplified model does not meet reality.
It is obvious and a simple fact that the skating is altering - ever seen any skating in the zero point ?
The offset is changing - and so is the amount of skating force.
You are calling for simplicity - this is a very simple fact.
Where is your problem ? |
Dertonarm, my explanations are based on the Laws of Mechanics introduced by Sir Isaac Newton July 5, 1687, and which remain true and in use to this day. You can point to all the little nuances which you assert would have an effect on the basic design, but they are so small as to be irrelevant. You seem to want to make things as complex as possible, which makes any useful solution impossible of course. Nonsense!
As I said before, I have no problem with your expressing your ideas, but remember, without any scientific proof or technical underpinnings, that's all they are: thoughts, and whimsy ;-)
Anti skating in it's basic form is a very useful concept, if only to prevent uneven record wear and reduce surface noise in the left channel. To those who think anti-skating is of no value, or just TOO COMPLICATED to implement (dear, dear!), I say, "don't worry, be happy" or better yet, get a 16" tonearm with no offset ;-) |
Nsgarch explanations are based on the original patent description of skating force and the anti-skating applied. And its too is not a matter of MM-cartridges vs MC-cartridges. Their different basic mechanical characters do contribute some details to the behavior, but not essentially so.
This general patent description from over 60 years back - while not entirely incorrect - is an incomplete model and is simplifying a quite complex issue. All anti-skating devices designed for tonearms are based on this patent description and a simplified model which gives the impression that skating is a constant force which can be nulled with a correct applied counterforce.
Well - it is a neither constant nor linear force and it is depending on tonearm length (with the resulting offset being more or less depending on effective length), stylus shape, size (especially so by older elliptical/conical styli, which do create a "double-side-contact" towards the inner grooves! )and alignment, groove cut, VTF, groove-compliant VTA and tonearm geometry aligned for (2nd zero close to inner grooves give another benefit here... see our sadly deleted tonearm geometry thread from early summer...... if you saved it in time).
As I said before - this is NOT a simple model.
I still believe that it is rather smart not trying to counter a highly variable force with a constant applied anti-force. It is obvious, that there are only very few seconds of the 20-35 minutes of a record side in which the counter-force is really correct and nulling the skating force of the moment. During the rest of the time the anti-skating applies a more or less unwanted side force of its own - just going in the opposite direction.
With the standard "skating vs. anti-skating"- model we have a model which is incomplete and the consequences drawn from it were wrong.
We would need a variable anti-skating force based on the tangential curve of the given tonearm. This antiskating force would then be inverse to the tangential curve and would indeed null the skating force if properly aligned.
Several questions in tonearm geometry today are long set aside as "complete", but are based on models which were simplified and as a result of this simplification did not give the correct results.
But so far we are living with these - less than optimal - results.
Partly due to laziness, lack of knowledge, partly ignorance (this is not meant to offend anyone !!), partly ease of use. |
Stanwal, first of all the Grace 707 is a vintage tonearm calibrated for MM cartridges, not MC which require far less AS. The rule of thumb in the MM days was that the AS should equal the VTF, and even at that, how much sideways AS force (in grams) was applied was definitely NOT the same as the actual weight on the string. Skating force is expressed as torque (foot-pounds, or centimeter-grams in the case of tonearms) and is the product of friction (in grams of drag) TIMES the (virtual) lever arm created by the tonearm offset, in centimeters; and is easily calculated if you know the amount of drag of the stylus in the groove (admittedly hard to determine without proper instruments ;-) The lever arm length is a result of the tonearm dimensions and offset angle. Those two factors don't change, regardless of where the tonearm is positioned. To be fair, the amount of groove friction actually CAN change (but only very slightly) between the beginning and end of the record as a result of the slignt difference in linear velocity (the speed of the groove under the stylus) between the outside and inside grooves of the record -- not enough to make a significant difference in AS force required. I suppose if one wanted to get REALLY nit-picky, one could also mention that louder passages produce more friction than softer passages. But that's pretty much it in terms of the causes of skating force (torque.).
With all cartridges except those with the stiffest suspensions, as long as you can see the cantilever from the front of the cartridge, it's quite easy to set AS force visually. I always did it that way with my MM Shure cartridges. You just lower the stylus into the groove while watching the cantilever from the front. If it deflects to the right (relative to the cartridge body) you need to add AS force. If it deflects to the left, AS needs to be reduced. No deflection of the cantilever when the stylus hits the groove means the skating force is balanced out. It could also mean that the skating force (even without AS applied) is not enough to alter the relationships in the cartridge's generator (usually because the suspension is stiff enough to resist the skating forces) and so you would HEAR no difference with or without AS applied. Nevertheless, with no AS applied, the inner groove wall of the record would wear faster than the outer groove wall ;-)
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Dertonarm has stated the facts as I have always heard them. If it was that easy to apply the correct force then why, for example. did the Grace 707 bias control give twice the necessary force? It was a well designed arm. I have never heard that a given amount of bias compensation would be correct all across the record, the setting is always a compromise. That said, the compromise I chose is not to use any. |
Thanks for that Tom............ |
Hi Wes,
When I set VTA, i did it by ear only. Didn't even look to see if it was parallel. It's pretty easy to hear when you've got it right. The sound kind of pops into focus. Bass and treble become balanced. Bass is taut, not sloppy. Treble is clean, not strident. When you're off, either bass (too low at the tonearm base) or treble (too high) will dominate and exhibit the sloppy/strident characteristic.
Later on, I saw a post here recommending the 3 x 5 card method (Thanks, Stan). I tried it and found that my arm was exactly parallel to the record surface.
I haven't done it in a while, but I thought that turning the VTA wheel clockwise raises the arm at the pivot point.
Cheers. |
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Indeed - God bless america.
Especially so in our troubled times.
Thanks to him, that not all americans always go for the most simple model in everything......
In this sense - good luck to Nsgarch too. |
God bless America. Dertonarm has a right to express whatever ideas he feels are true ;-) and on any subject. Besides, they say laughter is the best medicine. So I say 'Good luck' to him! |
Skating force is a result of the offset of the polished area of the stylus in perspective of the groove wall. During the journey of the tonearm cross the record side this offset becomes zero 2 times - the zero tracking error point - and is depending on the tangential error angle (which changes all the time - becoming more and less again during the journey from and towards a zero error point).
Less derivation from tangential zero error = less skating force.
Skating force too is influenced by misalignment of the stylus in the groove and - to a VERY high degree - by the total contact area. Larger contact area (= modern line contact) is far less force on the groove wall with a given VTF as the skating is a by-result of VTF divided through contact area.
In summary:
- less derivation - offset - from tangential zero = less skating force.
- super precise vertical alignment of stylus in groove = lower skating force.
- larger contact area of stylus = lower skating force.
- old - conical or elliptical - stylus = higher skating force compared to line contact or similar.
MOST IMPORTANT: skating is NOT linear, but a force which gets higher, lower, zero and higher again.
Trying to compensate such a force with a linear anti-force is......... well....... no good idea.
"Correctly applied" anti-skating would fix the problem in 2 short moments of the record side and produce a new problem for most (98%...) of the rest.
Then there still is the (objective and empirical by observation ...) "fact" that most tonearm/cartridge- combo featuring very high VTF (2.5 grams +) do indeed produce LESS skating force .........
Thats why Ortofon did not care for antiskating at all in its 12" tonearms w/SPU cartridges and why my FR-66s runs smoothly w/ FR-7fspec. without any anti-skating....... |
Thanks again for all of the comments.......much appreciated.
Tom,
When you set the vta was it done by sight i.e. with the lined card as suggested by vpi, or by ear after this and If you turn the vta wheel clockwise does this lower the arm? I am currently on my second Mint...the first one cracked as I was taking it off the platter spindle. |
Skating force is a 'twisting torque'. It occurs only in tonearms that have an angular offset built into them to help minimize tracking error - making it zero at two points across the record instead of one point (which would result if there were no offset.) The amount of the skating force is the result of the friction force (or drag) of the stylus in the groove times a lever arm. The length of this lever arm is the length of a line drawn from the stylus, pependicular to the axis of the cartridge, to the point where it intersects at 90 degrees with a line drawn through the pivot of the tonearm. Since this relationship remains constant, regardless of the stylus' position on the record, the skating force remains essentially constant across the record. I say 'essentially' because there is some very minor variation in the force-of-friction as the velocity of the stylus-in-the-groove slows down toward the center of the record. ANTI skating force, when applied with a spring, can be made to compensate for this (VERY slight) variation, as in SME arms. However, the weight-on-a string method or the twisted-cartridge-leads method will work just fine. Whether AS has an effect (or not) depends on the design of the cartridge. Stiffer suspension material and/or lower VTF reduce the need for AS. Further, the larger the size and strength of the magnetic field in which the coil is immersed, the less AS will make a difference/improvement.
Increasing the VTF will ALWAYS increase the skating force/torque because increasing the VTF increases the friction of the stylus in the groove. The fact that line contact styli produce so much less friction (compared to conical and elliptcal styli) is why moving coil cartridge makers (using line-contact styli) are able to use higher VTF's and stiffer suspensions necessary for the generally superior performance of MC cartridges.
With MM cartridges the situation is reversed. True they customarily track at 1/2 the VTF of MC cartidges, and many of them now employ line contact styli. However, because of their extremely compliant suspensions, it's easy for just a little skating force/torque to pull their tiny magnets out of alignment with the field coils.
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Hi,
The lemo connector has a small amount of anti-skate bias, even when not twisted. Twisting it (counter-clockwise, I think?) will increase the anti-skate force.
I experimented with the anti-skate on this arm, both via the lemo connector and the anti-skate assembly. The difference I heard was minimal. I only heard a noticeable difference when way too much anti-skate was applied. The soundstage moved off-center and the sound became smeared.
I currently use the optional anti-skate with no weights on it. It makes no difference that I've ever been able to hear consistently, but it tracks the test record better and so I would assume it's probably better in terms of groove wear.
The great improvements I've made with this arm were the result of a) dialing in VTF/VTA, and b) nailing the alignment with a Mint LP protractor.
I've never tried using the damping fluid. Just seems too messy.
Regarding Srwooten's post, if you don't have a syringe handy, a Q-tip works too.
Cheers.
Tom |
When you lift your arm off the well you should see a string of oil coming off the tonearm base. That is if you want damping. I would suggest using the damping oil that came with your Scout. Again if you want damping. Use a syringe to suck out any extra.
Anti-skate is arm/cart dependent- try it with your set up to see what is best. With my VPI 9 arm twisting the wire was perfect, with the VPI 9 Mem arm it is not. |
Agree with all the above.
With regard to your question, on most unipivots that offer fluid damping in the bearing well, the fluid must actually touch the upper (movable) portion of the bearing to have much audible effect. Just damping the well isn't going to do much. I haven't played with the damping on a JMW, but if your well is tall enough to allow it, that's the right idea.
That said, I'd heed Nsgarch's sage analysis regarding damping with this particular cartridge/arm combo. Your bass and dynamics response are borderline now. Even a little damping might impair them noticeably.
Of course you could try it and hear for yourself. Just remember, once you've added enough fluid to touch the upper (free) part of the bearing, adjust in TINY amounts. Dertonarm's suggestion to use thinner fluid than what's considered normal makes excellent sense (again, because of your arm/cart combo).
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Great posts that are spot on! |
In general - "skating force" is not linear. It is general with modern styli much less than it used to be in the 1970ies. Several respected tonearm designers (Pierre Lurne, Mortensen, ...) do recommend not using anti-skating at all and for good reason - applying a steady and linear "anti-force" upon a non-linear force is not a good idea at all......
Dampening - if you REALLY need it, the cartridge/tonearm match is less than optimal in terms of its mechanical parameters.
In general - less is more with both issues.
If you apply any dampening fluid, do use as little as possible and do use fluid which is NOT like honey but more like water......
If you apply antiskating at all, do set it as little force as possible - 1/2 of what is recommended by the manual will be enough and more than that.
The higher the VTF - the lower the antiskating ! |
Thanks to all for the advice.............I have read that the damping fluid is ineffective unless it is actually in contact with the internal part of the tonearm that sits on the pivot point is this correct? Thinking about it...........this does sound logical, However, it contradicts most of the other comments I have read about damping fluid. |
IMHO the wire on the Signature arm is to stiff for the twisting method to work. I use the VPI anti-skating gizmo with just a bit of anti skate applied and no twist of the wire either way. |
I actually do not use any with my 12.7 or JMW 9" arms. The amount suggested is often wrong and it is impossible to apply the correct amount all across the record. When I do use it I try to use as little as possible. Use Denon 304 on the 12 and 103 and AT OC9 on the 9". |
This is a great resource for figuring out stuff like this: http://www.cartridgedb.com but this time I'll save you the trouble. Your cartridge has a pretty low compliance, even for a moving coil (10, compared to say Transfigurations at 15, or vdH at 30) and weighs 9.8gm. Your Sig TA has an effective mass of 9.5gm, which is borderline-low for such a stiff cartridge suspension. Here is the compatibility chart for your TA and cart: http://www.cartridgedb.com/resonance_from_arm.asp?adesc=VPI%20JMW%209%20Signature&amass=9.5If you read down the left side until you come to 10, the compliance of the te Kaitora, and then read across to the cart weight + mounting hardware column (figure 9.8 gm + 1.5+ gm for mounting bolts and nuts, total = 11.5 -12 gm) you will find yourself (barely!) in the 'green' zone at 11Hz, which is the natural resonance of your arm/cartridge combo. Lower (like 8Hz) would be better but you're SAFE for all but the wildest, loud, low-frequency tracking conditions! With a cartridge with as stiff a suspension as yours, you probably should not need any fluid damping at all. Even a slight amount could slow down bass transients. As for AS, line contact styli (like yours) develop very little friction in the groove because of their shape, and therefore the arm tends not to "skate" toward the spindle with any significant force. If you feel more comfortable, twist the wire until the floating arm just barely creeps toward the outside of the record and that will be plenty ;-) |
