The anti-skid system of my tone arm (Micro Seiki MA 707) is actuated by a spring that is inside its structure (see attached brochure) and has a knob with preset adjustments according to the working pressure of the pick.
If I make the adjustment as marked on the knob, choosing the type of needle (spherical or elliptical) and the work force, when I try to start playback by bringing the arm manually to the beginning of the vinyl (Long play) it moves towards the outside, which prevents me from activating the slow descent (Lift) because the needle would fall out of the plate !
If I adjust the AS with the cut-to-size RX radiograph method, or by using a test disc that has flat surfaces to adjust the AS, either method (they are the same in reality) keeps the arm stable and the arm descends vertically into the groove normally.
Any idea what is going on here? It is evident that the force exerted by the AS does not correspond to the reading determined on the scale.
I have had many turntables, with different anti-skid systems and this has never happened to me.
Micro Seiki MA-707 Dynamic-Balance Gimbal Bearing Tonearm Manual | Vinyl Engine
If I make the adjustment as marked on the knob, choosing the type of needle (spherical or elliptical) and the work force, when I try to start playback by bringing the arm manually to the beginning of the vinyl (Long play) it moves towards the outside, which prevents me from activating the slow descent (Lift) because the needle would fall out of the plate !
If I adjust the AS with the cut-to-size RX radiograph method, or by using a test disc that has flat surfaces to adjust the AS, either method (they are the same in reality) keeps the arm stable and the arm descends vertically into the groove normally.
Any idea what is going on here? It is evident that the force exerted by the AS does not correspond to the reading determined on the scale.
I have had many turntables, with different anti-skid systems and this has never happened to me.
Micro Seiki MA-707 Dynamic-Balance Gimbal Bearing Tonearm Manual | Vinyl Engine
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Pivoting tonearms typically have the set amount of antiskating force applied all of the time, not just went the stylus is in contact with the rotating record. When raised by the tonearm lift, the tendency for the tonearm to swing outwards is overcome by friction between the tonearm and the lift guide plate. The friction usually comes from a rubber strip along the lift guide plate or a rubber bumper under the tonearm.
If there is insufficient friction, the tonearm is likely to swing outwards as it is lowered to the vinyl surface. This is a relatively common problem. The solution is usually to clean the lift table surface that contacts the underside of the tonearm when it is raised. Occasionally I have needed to replace the friction material because it is missing or has deteriorated.
According the the Micro Seiki 707 service manual, the guide plate should have a curved rubber bumper along its surface. I would first try cleaning this bumper with isopropyl alcohol, white spirits or a rubber rejuvenator fluid. If the rubber has deteriorated, evidenced by black smears on the cleaning cloth, the rubber bumper may need to be replaced.
In your case you are reporting a major discrepancy between the antiskating force required to balance the tonearm skating in what I call a static test, i.e. on a blank rotating surface as opposed to a active test in a groove, and the amount applied if you set the scale to match the vertical tracking force.
From your description it seems likely to me that the calibration of the tonearm is incorrect. I think it is safe to assume that is was correct at the time it left Micro Seiki's factory. What has caused the mis-calibration is subject to speculation, but it does happen from time to time.
What I would do is ignore the scale on the tonearm and set the antiskating on test. In some instances I have then been able to remove the scale knob and reposition it to indicate the correct value, which may or not be a valid thing to do. But as the working tracking force for any cartridge is within a very limited range, it's quite accurate for that set-up and seeing the scale in the correct position relative to tracking weight is reassuring to the owner. Obviously I don't do this if the result is not stable and sensible because of a fault in the mechanism, only when it provides true antiskating force from start to finish!
It is usually possible to recalibrate the antiskating mechanism and I do when it is practical to do so. Calibration is a very tedious procedure as it usually requires disassembling and inverting the turntable several times for incremental adjustments until the calibration is spot on.
If there is insufficient friction, the tonearm is likely to swing outwards as it is lowered to the vinyl surface. This is a relatively common problem. The solution is usually to clean the lift table surface that contacts the underside of the tonearm when it is raised. Occasionally I have needed to replace the friction material because it is missing or has deteriorated.
According the the Micro Seiki 707 service manual, the guide plate should have a curved rubber bumper along its surface. I would first try cleaning this bumper with isopropyl alcohol, white spirits or a rubber rejuvenator fluid. If the rubber has deteriorated, evidenced by black smears on the cleaning cloth, the rubber bumper may need to be replaced.
In your case you are reporting a major discrepancy between the antiskating force required to balance the tonearm skating in what I call a static test, i.e. on a blank rotating surface as opposed to a active test in a groove, and the amount applied if you set the scale to match the vertical tracking force.
From your description it seems likely to me that the calibration of the tonearm is incorrect. I think it is safe to assume that is was correct at the time it left Micro Seiki's factory. What has caused the mis-calibration is subject to speculation, but it does happen from time to time.
What I would do is ignore the scale on the tonearm and set the antiskating on test. In some instances I have then been able to remove the scale knob and reposition it to indicate the correct value, which may or not be a valid thing to do. But as the working tracking force for any cartridge is within a very limited range, it's quite accurate for that set-up and seeing the scale in the correct position relative to tracking weight is reassuring to the owner. Obviously I don't do this if the result is not stable and sensible because of a fault in the mechanism, only when it provides true antiskating force from start to finish!
It is usually possible to recalibrate the antiskating mechanism and I do when it is practical to do so. Calibration is a very tedious procedure as it usually requires disassembling and inverting the turntable several times for incremental adjustments until the calibration is spot on.
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Most tone arms with antiskating recommend way too much force. They were often "calibrated"
on a grooveless LP, which of course is completely wrongheaded. Never do this, it is meaningless.
Try much less of the suggested "antiskating" force, in lieu of any better solution at present.
on a grooveless LP, which of course is completely wrongheaded. Never do this, it is meaningless.
Try much less of the suggested "antiskating" force, in lieu of any better solution at present.
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That's a fairly broad-brush claim about turntable manufacturers. In my experience setting up hundreds of turntables the variance between the optimum "in groove" setting is usually pretty close to the grooveless method unless there is another problem with the alignment. Below is a cut and past from a post I made recently in another thread:
If you get the HiFi News test record (HFN 002 Review - HiFi News Test Record | Vinyl Engine) there are twin tone antiskating bands at the outer, middle and inner radii on side 2, so you can check if the antiskating is correct across the record. There is also a blank 'land' sector for a static test of antiskating on side one, plus four tracks of twin tone test track at increasing levels as the last tracks.
If you wear headphones, it is very easy to 'tune' the antiskating force as the buzz sound moves from one side of your head to the other as you move from too much to too little or visa versa; it's tuned when it's in the middle.
If the static test on the 'land' band is radically out after you have tuned the antiskating on the dynamic twin tone test tracks, then I suspect something is wrong with the alignment. Assuming the overhang has been set correctly with a two point protractor the top contenders are stylus azimuth and perpendicularity of the stylus tip.
To adjust the azimuth there is a L+R noise band on the record. If you are able to subtract one channel from the other (I use a KAB Stereo Canceller for this KAB GREAT SOUND ESCORT STEREO CANCELER AT KABUSA.COM) then you can adjust the azimuth for the lowest output, which occurs when the azimuth is correct and the two channels are closely balanced.
If you don't have the ability to subtract one channel from the other, there are two bands that are noise on L, and noise on R channels, respectively. To use these tracks play the left track, but listen to the right channel only, then play the right track and listen to the left channel only. If they sound the same, great; if one is louder than the other, the azimuth is out. Adjust the headshell rotation (looking at the axis from the front) until you are able to get the two channels to sound the same and be at the same (hopefully) very low level. How low is a function of the cartridge's similarity between left and right channel responses.
To check the perpendicularity of the stylus tip you can use a microscope. There are inexpensive USB scopes that are suitable. Alternatively, listening through headphone to the 2-channel noise track, the sound is 'focussed' when the perpendicularity is correct and the two sides of the stylus are contacting the two side of the groove in phase. This track is recorded around the outer tracking null so tracking error doesn't affect the result. To adjust the perpendicularity rotate the cartridge slightly in or out around its vertical axis without changing the overhang until you find the sweet spot. The cartridge may end up not being parallel to the headshell if stylus tip was not perpendicular to the centreline of the cartridge.
I'm not that familer with that brand of turntable, but does the cuing mechanism only raise and lower the tonearm?
OR.... does it also include a clutch or friction type of brake that basically locks the arm in place while it's being lowered?
Machines like the automatics (Dual/Garrard/BSR/etc) use a friction clutch whenever the arm is raised from the record, releasing the arm once it hits the groove.
This prevents any lateral sliding due to the antiskate system.
Any well-designed turntable should have this arrangement.
No way. And the skating force varies substantially across the radius of the LP as well.
And not to mention the variation with groove modulation, etc.
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Which is why properly designed antiskating mechanisms adjust the amount of bias during the playing of a record side to suit the position of the tonearm.
The of skating force at any point of the record is determined by the amount of overhang, the radial distance from the platter axis and the coefficient of friction between the stylus and the vinyl. The friction is a function of the tracking weight, stylus shape and if not a spherical tip the yaw and azimuth of the stylus tip relative to the groove. I think the depth of modulation is only a minor variant in the friction coefficient otherwise test tracks for setting antiskating force would give different results at different recorded levels, but I have not found this to be the case.
As I mentioned in the other thread, by far the best/easiest way to adjust AS is on the fly. Imo a tone arm without that ability is inferior. You will never get any closer than ball park otherwise. Perfect adjustment is possible but only when you're listening for it and it's dependent on correct VTA also which changes with every record. So once you've adjusted VTA(again ideally on the fly for the exact same reason), you now have to again correct the AS. So on the fly is really the only practical way to realize the full potential of the system.
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It does not have that clutch system like the Dual and others, (I know that) in which the arm rises and goes towards the disc.
I'm sorry I have no experience in how to upload videos to YT, and I would waste a lot of time trying to do it now, so you can see how it works on this TT.
But I will try to describe it, I hope it is understood.
It is an almost manual system in its entirety, but it adds the automatic stop at the end of the disc (it does not always do it, due to the issue of the final space of the LP, which is either not standardized by the vinyl manufacturers or it is not fulfilled)
It has a mechanism for raising and lowering the arm, but you must carry it with your hand to the beginning of the vinyl or to the sector you want to play. (Not like the Dual and other TTs that incorporate the start and do it alone, I have one of those CEC brand, but they were manufactured by Micro Seiki)
There you press the "down" button, the "lift" acts and you are on the register.
If you wish, you press the "up" button, the arm rises and you choose another sector of the vinyl or you bring it to its resting position.
The platter keeps turning. You must press "down" again and the arm lowers, the classic thing, only that instead of the classic Lenco actuation lever, Dual, etc., which are mechanical systems, DQ43 incorporates a servo for that function.
When the registration is finished, the servo control receives the order, the arm is raised and remains in that position. The direct drive platter stops. If during the audition, you press "Off", the arm is raised and the plate stops.
The system can be used completely manually, with the arm at rest in its support, press "down", start the engine and lower the "lift" at the same time, and - if you have a good pulse or have been taught the (*) "trick"
- you can take the needle to the vinyl. Simple.(*)The index finger raises the entire arm below the spindle, positions it, and then gently lowers it.
Most people who spoil their needles and vinyls grasp the spindle by squeezing it with their forefinger and thumb.
Adjusting AS and VTA on the fly is reserved for very high priced arms.
I can regulate only the AS on the fly with the MA707. But, it has the advantage that the tracking force system is dynamic, it has a torsion bar, like the suspension of an old Renault 4
, that's useful for warped discs.
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There is an adjustment on the auto-lift control printed circuit board for the point at which the auto-lift function lifts the tonearm. It is most likely that your turntable simply needs adjusting to move the point away from the centre by a millimetre or two. This requires access to the circuitry and digital multimeter, but otherwise is a very simple adjustment.
You would think that if they designed in such a system for cuing, they would also provide the tonearm clutch to prevent antiskating from allowing the arm to wander in med-air from where it's placed.
I call that a design flaw.
A not overhanging pivoted arm also has skating force. This is because the stylus drag force (that is orthogonal to the actual radius and tangential to the actual groove) is at an angle to the stylus-to-pivot line. (Not to be mixed with the tracking angle that could have 0, 1 or 2 zeroes over the recorded radius).
Where does the skating issue originate? I'm not referring to the things that increase or decrease the amount needed. What exactly is causing it at the point of contact on the record and why is it not needed on a linear tracking arm, even an "air bearing" arm? I think it would be useful to clear this up.
Anybody?
Anybody?
Call it what you like best.
I think you have not understood the operation well.
You insist on a clutch system that is actually an unnecessary addition to turntables that claim to be "for audiophiles."
All "entry-level" systems have idiot-proof automated mechanisms, but in the long run they are a problem and do not have the precision that those who want to extract the best sound from a vinyl seek.
I have seen many DIY projects with plints attached to arms from well known brands that trace grooves with excellence.
None of these projects take any part of an automatic Dual TT, but many are based on a fully manual Lenco pulley motor. I have an engine from an old Lenco B-55 waiting to do something similar to this:
Lenco-L75_2017
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Please, I've had enough with the UFOS thread .... you should know that, it's basic.
This is my thread, don't mess it up
Yes, it is what I was afraid of, but it seems that I do not want to accept that I will have to intervene this TT surgically.
I hope there is an adjustment preset or some mechanical part that allows to calibrate ...
I think you're misunderstanding my premise. It's definitely a real thing. But it might be useful to understand where it originates in order to have a conversation pertaining to your actual op. There appears to be quite elaborate apologetic explanations given on the function of a tonearm here already yet no mention of how the skating is initiated/caused as it pertains to the stylus/groove interface. Who knows, you may actually learn something.
There's more to this than meets the eye.
btw, you did participate in that other thread.
Does that tt in the photo have AS?
Skating force comes simply from the fact that the pivoted tonearm is not tangential.
Detailed answer: the stylus has frictional force by the rotating disc. This force is tangential by nature, regardless of the angle of the headshell (or the cantilever) related to the grooves.
This tangential force can be decomposed of two force vectors: one is pointing to the arm pivot point (it pulls the arm agains the pivot), the other vector component is rotating the arm around its pivot (being this motion the only degree of freedom in the horizontal plane). The bigger is the angle between the tangent of the groove and the stylus tip - arm pivot line, the bigger is the skating force.
In simple words: if the arm pivot is located to the left of the groove tangent, there will be an inward skating force. How big is the skating force depends on several factors (one is the arm geometry, call it overhang), as described before.
Detailed answer: the stylus has frictional force by the rotating disc. This force is tangential by nature, regardless of the angle of the headshell (or the cantilever) related to the grooves.
This tangential force can be decomposed of two force vectors: one is pointing to the arm pivot point (it pulls the arm agains the pivot), the other vector component is rotating the arm around its pivot (being this motion the only degree of freedom in the horizontal plane). The bigger is the angle between the tangent of the groove and the stylus tip - arm pivot line, the bigger is the skating force.
In simple words: if the arm pivot is located to the left of the groove tangent, there will be an inward skating force. How big is the skating force depends on several factors (one is the arm geometry, call it overhang), as described before.