Spindle oil

What oil are people using to lubricate their spindle bearing?
Mine is from the manufacturer -- it costs a mint (even my dealer has a hard time getting it). I look forward to hearing from others to see if a more attainable solution is out there.
Grade 30 motor oil, as per manufacturers recommendation.
personally i use snake oil. ;)
For my TNT 5, Vpi tech department recommended, Lithium Grease. $6. for a large tube at Home Depot. Works just great.
The type of lubricant depends on the type of bearing. I would stick with what the manufacturer uses.
Have been using 3-in-One oil on my Oracle MKII. Been doing it for 20 yrs. with no problems.
I use what Rega recommends,80w/90 Gear Oil(2 drops only).
Along with about a half dozen other projects i have going right now, i'm in the process of slowly setting up two different tables. While they don't mention the suitability of this product for use in turntable's, i'm probably going to try using TufOil in one of them. Since it is the most slippery substance known to man, i can't see anything doing a better job of lubricating the bearing / reducing drag on the motor. Sean
I use maiden oil. They ought to sell this stuff in a health food store. It's sure good for what ails you. It even whitens your teeth.

Slappy, you really need to quit milking those snakes. They'll bite you some day.

Seriously, I use the manufacturers oil and I don't know why. The proper weight motor oil should work fine. Hell, even an improper weight oil would probably work great.
I had a Rega P3 for 17 years and never lubricated it with anything and never had a problem or never became aware of something different; I have had my P9 for 2 or so years, how do you know they need re-lubrication?
I use sewing machine oil. It is available at,
well, a sewing machine store. There is natural and
man-made stuff. I use the man-made stuff.

I use Redline D4 which is an ATF designed for transmission use...manual transmissions that is. It is capable of providing metal protection , friction reduction, and able to operate in a moist environment. This oil is overkill, but cheaper than a bearing. It is light, about equal to a 30w engine oil. It is a synthetic and I change it every year or two. Cost is about 9.00 per qt. All you need is a few drops. It is also recommended for BMW manual transmissions where the engine is putting out 250-300bhp. This should be good enough for a turntable spindle. The problem I have with grease only or a 80/90 gear oil is that I want oil to be between the metal surfaces and if it is too thick it wont be where it should be. Jallen
slappy where do you purchase or obtain this "snake oil" I'm always seeing it referred to around here but nobody explains where to buy it? maybe there is a huge read insanely profitable market for this special magical substance?
I used to use the sewing machine oil. Now I use a teflon "oil" for bicycle components. It's as fine as the sewing machine oil and seems to last forever.
As Rives audio pointed out, the best thin oil money can buy is from bicycle source. Tri-flow, Superlube, and others are the best thin oil money can buy. If you need grease, white lithium grease from bicycle store is also the best source.

If you need in betwee, any synthetic motor oil should do a fine job.
SAE 80W90 is recommended by Rega. It's available at the hardware store (gear lubricant at ACE) 2 drops into the spindle. First, clean spindle and bearing with alcohol and dry with soft cotton rag.
xiekitchen- yes, your rega needs a lube job periodically. My P2 made a popping sound eventually. Rega told me to relube it with 2 drops of gear oil. The old oil had turned into black, dirty sludge. Poor lubrication stresses the belt and motor.
Don't use motor oil. Motor oil is too thick. It's designed to work inside a pressurized system.

Snake oil is actually not something you can buy, however, you CAN harvest it.

All you need are a few snakes, a grill, and a sunny sundar afternoon with some beers.

It is pretty simple, first you want to kill the snake. To make this task easier, i would reccommend against using rattlesnakes, black mambas, pit vipers, asps, or anything else that can kill you in one strike. Personally i preffer a large burmese python. (the bigger the snake the more the oil)
Next, slice the snake right down the middle and open it up. Fire up the grill, and get it to around 550-600 degrees. Then put the snake on the grill, with the opened belly facing down.

Grill the snake like that untill the meat has turned a dull grey-brown. Make sure you occasionally press down on the snake with the spatchula, this will get its fats to drain down.

Now, you also wanty to be sure you have a very clean grill, because you need the juices that flow from the snake and dont want it mixed with other types of animal fats. One method is to create a funnle out of aluminum foil that will drain the fats to the grease catcher.

When the snake is no longer dripping, take it off the grill and remove the meat and put it on a plate with fresh chopped greens beneath. I reccommend a good cherry ramalaude glaze to be brushed on, it really brings out the flavor, another good way to enjoy the snake is with some tartar sauce.

After yer done eating, you gotta go back to the grill and remove the grease trap with all of the snake fats in it. Scrape all the grease out of the trap and put it in a small pan with some water. Bring the water to a simmer and let it simmer for about 35 minuits, then remove it from heat and let it cool down a bit. There will be a layer of oil across the surface of the water now, this is snake oil. I reccommend usnig an eye dropper to get the oil off the surface of the water without getting too much water.

Now this is why you want to use a big snake, because you can get i mililiter of snake oil per 3oz of snake. So using a 20lb burmese python obviously yields more oil than a 1/4lb garden snake.

Voila, you have snake oil and a full stomache from a fine meal. Feel free to sell to audiophiles for $200.00 per gram. Or, use it on the spindle, it drastically reduces friction over other conventional oils.

There ya go! Snake Oil! :)
ATF- automatic transmission fluid.
Slappy, you win this thread! ROTFL.
I'll put my vote in for lithium grease. VPI Scout
RE Snake Oil Tom Fletcher of Nottingham Analogue sells a spindle oil for his TTs that he calls "Snake Oil". I've tried it with my Hyperspace and it is actually quite good.
I use lithium grease for my HR-X. Works wonderfully well.
Snake Oil can be obtained at home by taking an interconnect cable, holding it vertically, and with your free hand, squeeze it from top to bottom over an open container. The more expensive the cable, the better the results.

K-Y Jelly is also well-known to solve hi-friction spindle problems...

On a lighter note, VPI has bounced around between an amber colored oil that I'd guestimate at 15W. They currently use a white grease. I use bicycle lube; Pedro's Syn-Lube. Thinking about it, it might be interesting to try my auto lube: AmsOil 30W. Further thinking suggests that liquids (oils) are *not good on inverted bearings, since gravity will want to take the oil away from the bearing. TT's don't have oil pumps and pressurized circulation systems.
(Political aside: Synthetic motor oil usage is a tiny step taken to wean off the petrochemical teat of crude oil suppliers.)
NO ATF or MOTOR OIL! They are designed for pressurized systems, and WILL RESULT IN BEARING WEAR. Lithium grease is a good alternative. The Gear oil worked for 20 years before my bearing seized, and there are other Rega owners in this thread who exclaimed "you have re-lube it?" so I know gear oil (80W90) works.
ATF is one of the finest lubricants known to mankind. Your warning is nonsense.
If it is simply a matter of lubrication, there's no contest. I've already posted a link to what is the most slippery substance known to man. Since the whole idea of lubricating a bearing is to reduce drag on the motor and increase the longevity of the bearing itself, using the product that reduces friction to the lowest possible levels and has the highest lubrication factor should obviously work best. The fact that this is a thicker substance would also allow it to cling to the bearing rather than just run off of it.

If you want to see what i'm talking about, take a look at this comparison of various lubricants and oil additives. Look at how long Tufoil lasted compared to the 22 other lubricants. While the average failure time for these 22 other formulas was appr 7 minutes, Tufoil lasted 16 DAYS under the same test conditions !!! While the average failure temperature for these 22 other formulas was appr 79 degrees, Tufoil failed at 60 degrees. That is an appr reduction in operating temperature of 25%. Since friction and heat are what cause bearing failure and metal fatigue, it should be common sense that reducing the friction and lowering the operating temperature would produce the longest lifespan for all the materials involved. Sean
Those of you who recommend a particular lubricant as ideal for all spindles are simply wrong. Look at your car. Why do we use one thing in the motor, something different in the transmission, something different on the wheel bearings, and so forth.

Sean, the link you posted above even points out that the type of test used was applicable to engines but not to other situations.

The type of materials at the pressure point, the shape of this point, the amount of pressure on it, the tolerance of the machining, whether or not it is inverted, and many other factors all play a role in what constitutes the ideal lubricant for a spindle.

The bottom line is that this is NOT a one size fits all situation. Deviate from the manufacturers recommendations at your own peril.
Herman: Those are all good points but you're making it far more complex than it really is. The reason that we have different fluids in a car has to do with the materials and applications being used. ATF is different from motor oil because ATF is used as a hydraulic fluid with detergents and lubricants added. It is not exposed to gasoline, anti-freeze, carbon, etc... and the clutch materials inside the transmission are of a different compound than any of the materials used inside of a motor.

The fact of the matter is that it would be hard to improve upon a situation requiring lubrication when you're already using the slipperiest substance known to man. So long as one did not exceed its' thermal limitations, which would be hard to do because of the reduction of heat involved, how could you reduce drag & friction any lower? If this lubricant won't work here, what is it that would allow other lubricants to work better? Neither would be under any pressure other than the weight of the platter on the bearing. On top of that, there's no circulation system involved, so flow time isn't a concern. You basically have a bearing sitting captively in a machined area that needs lubrication. There's nothing high tech or diverse about this application what so ever. Sean
Sean, I believe it is a bit more complex than just choosing a lubricant based on how slippery it is.

From the Teres website: "The bearing is designed with large amount of surface area to maximize viscous damping. The oil in the bearing exerts a smooth, constant resistance as the platter rotates adding to speed stability." Evidently they want a certain amount of drag. Don't you think the amount of viscous damping is dependent on the type of oil used, and that they chose one to achieve the desired result? If the wonder oil you tout reduces drag to too low a level then the bearing would not be doing what it is intended to do.

Why does VPI recommend lithium grease? Perhaps for the same reason. In any case, it is inconceivable to me that a company such as VPI would recommend lithium grease if a lighter weight oil would be better. Surely they have looked into this a little deeper than your average audiophile and come up with what they feel is the best lubricant for their turntables.

The "slipperiest substance known to man" is not always the best stuff for a particular application.
Herman: Tufoil is basically a combo of specially formulated thicker oil mixed with moly grease that has microscopic particles of PTFE imbedded in it. It is neither as thin as oil nor as thick as grease i.e. it is somewhere in the middle.

As far as counting on the lubricant used to stabilize the speed of the platter and reduce pulsing of the motor by creating drag, that is a piss-poor design. Not only do all lubricants break down over time, but their viscosity varies with both ambient and internal temperatures. As such, i can see the need to use a specific type of lower grade lubricant as a "band aid" IF the product was poorly machined and / or lacking in design integrity ( poor speed regulation / stability ). If a product is truly well designed and well machined, the name of the game for any bearing type device would be the lowest friction possible. Sean
KY reduces friction wonderfully. ;)

I think that you missed the point about viscous damping. The intent is to compensate for stylus drag. The drag from a stylus is highly variable exerting a very small but non-uniform braking force. The theory behind viscous damping is that applying a highly uniform braking force that is many times greater than stlyus drag will swamp out the effect of the stylus. I can't prove the validity of this theory, but there seems to be a great deal of supporting evidence. The primary evidence is that the vast majority of high-end turntables have bearings with a lot of vicous damping and are decidedly not optimized for low friction.

Variance in viscosity is not an issue for two reasons. 1) Temperatures in a turntable bearing will not change enough to be meaningful. There simply is not enough energy present to affect more than a one or possibly two degree temperature change. 2) The magnitude of drag is relatively unimportant. Any change in drag from temperature will be slow and gradual enough to be irrelevant.

Back to the original thread, my experience is that bearing oil viscosity does make a small difference in sound. My unproven theory is that oil with the higest viscosity that produces laminar (non-turbulent) flow in the bearing will be optimal. Turbulent flow will produce less uniform drag. So the objective is to maximize drag without turbulence. Radial bearing clearance and bearing design both effect flow so the best viscosity will be different for each bearing design.

Beyond viscosity it is difficult to imagine that additives or expensive formulations would be relevant. When it comes to lubrication a turntable bearing is a cake walk. Low temp, low speed, low pressure and clean.
Teres: If your stylus is centered in the groove, there's minimal drag. The only "friction" that the stylus should encounter would be converted as motion in the cantilever, which energizes the cartridge and is converted to electrical impulses known as music. If the stylus is exerting massive amounts of drag i.e. enough to cause the platter to destabilize rotational speed and effect the stability of the motor / speed regulation system, you're vinyl system is in really bad shape.

Then again, i keep forgetting some very important facts here. Most of you folks are using pivoted arms that are only in the center of the groove at two points per record side. I guess that if i were dragging my stylus sideways through all of grooves except for a very few, i'd be more concerned about this. Then again, one would think that they would be more concerned with the damage being done to their irreplaceable vinly recordings than to how much speed variation such an arrangement was causing.

Outside of all of this, i guess that one should contact the manufacturer of their table. They should know how well their products are designed and whether or not they need some type of "band aid" to work properly. Sean
Sean, I'm suprised to see this side of you. Now that you have been proven wrong, you've decided to go on the attack labeling designs that deviate from what you consider to be proper as "piss-poor?"

If the platter rotates at a constant speed and continues to do so for a long period of time then it is a good design, case closed. It doesn't make one bit of difference how the final result is achieved.

So I'll go back to the original question and try to make my point once again. The folks at VPI, Teres, Linn, Basis, etc. have dedicated countless hours to optimize every aspect of the performance of their tables. I believe it to be highly unlikely that you can improve that performance by using a lubricant other than the one they recommend.

What causes variation in stylus drag is groove modulation. Loud passages create more drag. This will be the case regardless of how well the stylus is centered.

Viscous damping is a successful, widely used technique, not a Band aid".
Herman: If a diamond can cut through hardened glass, what kind of "drag" could there be slicing through pre-cut grooves of soft vinyl? If there's enough "drag" there to cause speed irregularities, there's something wrong with the design of playback device.

Not only should there be enough inertia built up in the platter to more than compensate for any type of variance in drag caused by the stylus, the motor and speed regulation system should detect these variances as fast as they occur. The only reason that the motor / speed regulation circuitry couldn't correct quick enough is if it was of a poorer design with slow circuitry and / or there was too much drag on the bearing from using a heavy, motionally stable platter and too weak of a motor. As such, reducing the drag on the bearing would be beneficial in terms of both bearing and motor life and should contribute to faster response times from the speed correction circuitry as ANY drag would be noticed faster.

Like i've said before, what passes for "high end" typically only means "high price". You can throw money at a product but that doesn't make it well designed. Friction is the enemy of any well designed product that requires motion. After all, friction generates more heat, causes more wear, requires more force and is nothing more than lost energy. Sean
Sean, while I respect your opinion on most matters, after looking into this a little more deeply, just about everything you said turns out to be wrong.

Your diamond cutting glass analogy makes no sense. The stylus isn't "slicing" through the vinyl, it rides along the surface following the modulations already cut into it, and just because the stylus is harder than the vinyl doesn't mean there isn't any friction. It is well documented that the stylus temperature can easily reach in excess of 100 degrees celsius. Where do you think that heat comes from? I'm guessing friction, and the drag caused by that friction must be dealt with.

You are also confused about the differences in viscous damping and friction. "Friction is the enemy of any well designed product that requires motion. After all, friction generates more heat, causes more wear, requires more force and is nothing more than lost energy." Viscous damping is not causing the bearing to wear away.

Your idea about instantaneous speed correction is completely incorrect. The motor doesn't and can't correct for every tiny variation in speed that would be caused by the stylus and there isn't a turntable in the world that uses the motor controller to do this.

It won't work for the same reason that motor driven, servo controlled linear tracking tonearms won't work. With the tonearm you are constantly trying to correct for something that has already happened so the arm is always out of postion. Same thing with the system you advocate. Even if you could build a controller fast enough to keep up, in order for it to compensate for the variations in stylus drag it would have to be able to predict when they will occur, and that's not going to happen.

So how can you overcome these variations in drag caused by the stylus when you can't predict when they will occur? One way is to introduce another source of drag into the system (such as viscous damping) that is far greater than the stylus drag, and while the motor is working to overcome this induced steady state drag it will in effect ignore the tiny variations caused by the stylus. To use an electronic term you may be familiar with, they are swamped out.

This is not poor engineering. It is a brilliant, simple, elegant solution to the problem.
100 deg C/212F on a stylus tip?? Yow, can you find a thermocouple small enough to fit on a cantilever? Can you get a handheld infrared gun with a small enough beam pattern? Can you measure this with an infrared thermography device??

Back to lubes; the more I think about it, I wonder how many square inches of contact area are on the tip of the spindle bearing and it's contact plate. Mighty small... Seems to me like this is going to have to be a regular maintenance item - lubing the spindle bearing.
Herman: If the stylus wasn't "scraping" its' way through the vinyl troughs, it wouldn't be generating heat at the tip. That heat is wasted energy due to unnecessary friction. It's pretty simple when you break it down.

Amplitude modulations in the vinyl surface should simply produce vertical displacement of the cantilever. This vertical displacement is the result of energy transfer, which produces voltage from the cartridge and the accompanying music from your phono stage. There is some horizontal deflection also as there are various amplitude passages that occur in one channel that don't occur simultaneously in the other channel. This is what gives us output in the individual right / left channels.

As such, the "friction" between the stylus and the vinyl groove comes from the fact that the stylus is NOT centered in the mass majority of grooves. As a result, the cantilever is constantly being twisted rather than being pushed up and down on loud to quiet passages or side to side during left to right / right to left signal changes. This is how records get "worn out" due to the "cutting action" of the diamond "dragging" across the sides of the grooves, not through the center of the grooves.

If you can align the stylus in a fashion that it stays relatively centered in the grooves, you'll find that surface noise is drastically reduced and stylus' will last a LONG time. Then again, you can't ever hope to achieve this type of performance from a pivoted arm due to the very nature of the design.

As to your comments about servo's, they can be made quite fast and quite good. Compared to a pivoted arm that can only be correct in two places ( at best ) along the entire side of an LP, i'll take a well designed servo controlled linear tracker any day of the week. I would rather have something that was "very close" most of the time as compared to something that was "rarely correct" at best due to the law of averages.

As far as introducing more drag to compensate for other drag, that sounds like complimentary colourations to me. Neither is "right", but you end up with something that is bearable. It's not necessarily "good", but it works. Like i said, you can throw money at a design, but that doesn't make it good. It might be better than others of similar design, but that doesn't make it good. It just makes it slightly better than "poor" because it isn't quite as obvious due to the blatant errors being covered up. Sean
Sean, your seeming inability to even hint at the possibility that you might be wrong makes it impossible to discuss this in a logical manner. I'm leaving the topic after this.

First you claimed that the stylus was "slicing" through the vinyl like a diamond cutter through glass. When I point out you are wrong because it is "riding along the surface" you change to "scraping," which is in effect exactly the same thing I just said, and make a condescending remark like I don't get it. You should go into politics.

The heat isn't generated simply because the stylus isn't centered. It comes from the stylus tracking the modulations. Heavily modulated grooves produce more heat than lightly modulated ones no matter how well centered the stylus is. Centering has nothing to do with it.

This is a well proven fact, not an opinion. You are wrong. No matter how many times you put forth the centering argument, you will still be wrong.

Also, there isn't a manufacturer in the world that uses a servo motor controller to compensate for instantaneous stylus drag. Why? It won't work. No matter how fast, servos will always be reacting to something that happened in the past. Again, not an opinion. It is a fact that you are unwilling to acknowledge.

All servo controlled linear arms to date have been inferior to other designs for the same reasons. This is also a fact. I do believe given the advances in servo motors since the attempts in the early 80's, and the speed of todays microprocessors, that it should be possible to build one that will work well. Perhaps combining the tracking capabilities of the newer laser tonearms as the feedback to the controller along with high speed processors might work. The laser tracker could be positioned ahead of the stylus, in effect predicting where it needs to be instead of reacting to it being where it shouldn't be. Feel free to use and develop that idea.
Herman...There are servos, and there are servos. The faults you cite can be avoided. The microprocessor controlled linear tracking arm on my Sony PS X-800 TT maintains tracking angle within 0.05 degree across the entire disc, even when the groove spacing is variable. No pivoting arm can do this.

By the way, like all linear tracking arms, many other problems such as skating force are eliminated entirely.

But this was supposed to be about spindle oil. Damping, viscous or otherwise, can stabilize a servo that tends to oscillate. Consider the shocks on your car...without them you would bounce a lot. Speed regulation in the presence of variable friction is the job of the platter inertia, at least at a frequency higher than what can be followed by the speed control servo of a direct drive table. If there is no speed control servo, there will be some slowing down.
However, the stylus drag variation is so small, and turntable motors so powerful, relative to the drag they overcome, that I doubt any noticable slowdown actually occurs.
El: Speaking of shock's and servo's, one might find this servo-related suspension system designed by Bose to be of interest. I would suggest looking at the whole article and then watching the videos at the end. Quite impressive if actually performed / tested in an even-handed manner.

Herman: My specific choice of wording may have been poor and lacking in continuity, but i meant the same thing. When a diamond is "scraping" or "dragging" across the side-walls of the vinyl, it IS "carving" through the vinyl. This is what causes sonic degradation, groove distortion, stylus wear and heat.

As far as stylus temperature goes, the cantilever will act as a heatsink for what would be "normal" drag. That is, the type of material that the cantilever is made of will depend on how efficiently it absorbs and radiates heat. After all, there IS going to be a certain amount of drag / heat as the diamond and the vinyl are in direct contact ( hopefully ) and the vinyl is in motion. More modulation "should" simply cause more vertical deflection, which "should" be transmitted strictly as mechanized energy. This generates electricity in the motor structure of the phono pick-up, not heat at the tip from "scrubbing" due to mis-alignment. How efficiently this mechanized energy is converted to electricity without loss will depend on the rigidity of the cantilever, the tracking ability of the cartridge, how "correctly" the cartridge / arm interphase is set up, etc...

YES, there IS going to be drag in a vinyl system. The key here is to minimize it and have a system that maintains proper operating speed with high stability. If properly designed, the platter will have enough inertial mass and be balanced well enough to maintain a steady speed even with varying levels of groove modulation. The motor should have enough torque to "muscle" the mass of the platter as needed and the system monitoring the speed should check and update often enough to make the proper adjustments without the speed varying too far out of tolerance.

Reducing the friction at the bearing simply means less energy lost i.e. closer to perpetual motion of the platter due to less "rolling resistance". Once this has been addressed in the bearing / platter support structure by using proper machine tolerances and the proper lubrication, the platter spins freely, both more consistently and longer due to less drag. If the machining was well performed and the lubrication itself doesn't introduce drag inconsistincies due to surface tension ( how "slippery it is" ), the result is a reduction in frictional losses. With less frictional losses, we need less error correction from the speed monitoring device to come into play. This in turn reduces the vibration from the motor as it isn't lurching or clutching due to the reduction in speed adjustment needed.

The only drag involved in such a system would be that of the centered stylus in the groove, which inertia from the weighted platter should pretty much take care of most of the time. Since we haven't been able to design a "lossless" mechanical system, the motor and speed correction devices are still needed though. That's because the tracking force of the stylus is introducing loss into the system along with the minimal amount of drag that we can't get rid of in the bearing. Obviously, the less friction in the bearing, the less drag / vibration in the whole turntable due to the domino effect of losses & correction involved. Sean
El, I'm not familiar with your table but once had a Technics linear table with direct drive and a motor driven linear arm. They were all the rage back in the early eighties but fell out of favor with the high end crowd after proponents of belt drive platters and conventional pivoted arms convinced us that the former were inferior because the direct drive motor was always searching for the proper speed and the arm was crab walking across the record. Maybe it's true and maybe not, but as far as I know they did disappear from the market.

I do believe the best linear arms are capable of better peformance than the best pivoted arms. If they could just get the cost down to where I could afford one. In my price range I think the pivoted arms are superior but I'm not sure what all is out there in the linear world. Everything I see is in the $10,000 plus range.
"On top of that, there's no circulation system involved, so flow time isn't a concern." Not so for all TTs. Sean, you haven't considered the bearing design used by Tom Fletcher in his Nott. TTs. This design does 'pump' oil around the bearing sleeve.
John: Thanks for making me aware of that fact as i was not aware of it.

Herman: High quality linear tracking arms aren't that expensive. That is if you don't mind buying used, can shop around on the net and move fast once you find one. Sean
Herman..."Crab walking"? I'm not sure what you mean. The Sony PS X-800 arm actually does have a pivot. However, the arm angle is constantly measured, (Hall effect sensors) and the pivot point is moved as necessary to keep this angle tiny. The pivot movement is biased to match the nominal LP groove spacing. Only if the groove spacing changes from nominal does an arm angle develop, and the pivot movement speed varied so as to get the arm angle back to zero (plus or minus 0.05 degrees). At all times the arm is free to pivot, so the servo activity is not seen by the pickup.

Bottom line is that it works flawlessly, and the biotracer vertical servo (not on all Sony linear tracking TT) will handle warped records that would be unplayable on most systems. Another nice feature of the biotracer arm is that the VTF is applied as a bias to the servo, and can be adjusted WHILE a record is playing, so that sonic effects of VTF can be evaluated.
El: I think that Herman meant that the servo controlled linear arm would be cogging side to side ( crab-walking ) trying to constantly correct for the center of the groove. Sean