Pantograph
Has the Pantograph principle ever been used for LT tonearms? I mean moving along a linear guiding rail copied to the radial travel of the stylus.
Has the Pantograph principle ever been used for LT tonearms? I mean moving along a linear guiding rail copied to the radial travel of the stylus.
Interesting idea Icsaszar - but have you ever used one?
My 2 cents: the parallelogram copies, in small or large, what you draw with the pencil, the lines on which the tracking force is applied (multiplied or demultiplied according to the magnification ratio).
Here the force is exerted by the stylus, so - frictions apart - you may just have a small or large copy of his path: if instead you want that the stylus follows a line, the force must be applied on the guide line = that means to use a servo. And feedback?
carlo
My 2 cents: the parallelogram copies, in small or large, what you draw with the pencil, the lines on which the tracking force is applied (multiplied or demultiplied according to the magnification ratio).
Here the force is exerted by the stylus, so - frictions apart - you may just have a small or large copy of his path: if instead you want that the stylus follows a line, the force must be applied on the guide line = that means to use a servo. And feedback?
carlo
More than a problem of bearings, imho it's a problem of vectors: the stylus drag is orthogonal to the guide and therefore completely unusable - the side force breaks down according to the angles of the levers, so on guide point is available only a fraction.
But the idea merits to be further investigated
c
I meant a common drawing pantograph: the effort to make it work in magnification is so great that is normally used simply by reporting reference points
But the idea merits to be further investigated
c
I meant a common drawing pantograph: the effort to make it work in magnification is so great that is normally used simply by reporting reference points
Klaudio tonearm FreeCAD model
For those interested in the Klaudio tonearm, I have created in FreeCAD 0.18 a functional model (attached). In order to see it at work, you must copy/paste the contents of the attached Kla_python.txt in FreeCAD's Python console.
Besides the ruby jewel bearings, the toughest challenge for a normal DIYer is machining the Gaussian bell shaped guide
But where there's a will, there's a way...
For those interested in the Klaudio tonearm, I have created in FreeCAD 0.18 a functional model (attached). In order to see it at work, you must copy/paste the contents of the attached Kla_python.txt in FreeCAD's Python console.
Besides the ruby jewel bearings, the toughest challenge for a normal DIYer is machining the Gaussian bell shaped guide
But where there's a will, there's a way...
Attachments
Last edited:
Dear directdriver, IMHO I can't see the tonearm skating. In fact I see it... anti-skating
I mean its slight tendency to move from the label to the middle of the record, tamed after a proper setup of the parallelism of the two arms using that Allen key.Since no Klaudio video shows us the needle running on a rotating grooveless record face, we cannot say whether this geometry exhibits skating or not.
Last edited:
Since the arm is floating with zero tracking force, isn't that similar to playing it on a blank groove record? And if it's skating free, why would it drifts in the first place? Will this pass Ray's string test?
The fact that it has a tendency to drift without fine tuning, which seems to be a form of anti-skating or anti-anti-skating adjustment, suggests, at least to me, skating force exists. Maybe the drifting is caused by bearing friction or uneven tensioning of the dual pivots? The fact that it rests in the middle reminds me of the Thales Easy arm that the single tangential point is set in the middle groove so the arm gets to overhang on the outside groove and underhang on the inside groove.
I'll let the more perceptive members here to settle this one.
Last edited:
Absolutely not. A tonearm balanced at zero VTF with zero anti-skating setting (if this setting exists in the makeup of the tonearm) should stay exactly where it's placed by hand, no matter if that place is near the record rim, the middle or at the runout groove.
The inward skating force appears as a result of the friction between the stylus and the surface it is running on, be it a record groove or a flat surface of a one sided record. That's why some purists in terms of anti-skating adjusting say that the flat record face test is not relevant enough due to the higher skating forces implied by the much higher friction faced by the stylus plowing the grooves. So, no needle contact = no skating
That drift appears when the arm is floating, meaning no contact between stylus and groove.
Absolutely correct. According to my understanding, that drift was just a result of an improper parallelism between the two arms. In fact that was exactly the purpose of that movie. To show us how this drift can be eliminated by a proper setup. The general idea emanating from the movie is that the drift is by no means intended by design as an anti-skating mechanism, but some unwanted "bug" of the design that can be eliminated (or at least minimized) with a proper setup. That's why they even admit that a certain drift is acceptable
Now, returning to the "string test", I must admit I can't say if this tonearm will pass it or not. Of course it will pass it in the middle position, but due to its intricate geometry, I can't say what will happen when you pull the cartridge along the cantilever. And this is simply because the direction of the friction force is exactly the opposite of the direction the arms base moves in order to move the cartridge to the middle position!
In fact, while writing these lines, a crazy idea came to my mind: what would happen if we take this Klaudio tonearm perfectly balanced for zero VTF and turn it 90 degrees to a vertical position of the arms with the cartridge dangling below? In this position the gravity would replace the "string"
Would the position of the arms be indifferent? <<< The ideal case
Or would the arm either tend to stay vertical or fly to one of the sides?
Food for thought...
Last edited:
Sorry to tell you but ALL pivoted arms regardless of whether they are traditional fixed geometry or tangential will exhibit skating. The vector of the stylus drag can only be aligned directly through the lateral pivot axis at one point and only when it is aligned is skating zero. At all other locations there will be a skating force induced. With most designs the vector of the stylus drag is never perfectly aligned through the pivot axis so skating force exists across the entire playing surface of the record. The only type of arm that does not exhibit skating is the linear tracker.
You can actually use a blank record to set skating. Adjust skating bias so that the arm is stationary with the stylus on the rotating blank disk. Now increase the bias by about 60%. Skating bias should now be set approximately right for a modulated groove. It is important to remember that it is impossible to set bias absolutely perfectly as stylus drag, and thus skating force, will be changing constantly with varying groove modulation. What you are aiming for is the minimum average error. In fact you want to set bias slightly higher than this for the following reason. A groove cut with lower than average modulation will have lower than average skating and a groove cut with higher than average modulation will have higher than average skating. As the higher level groove is louder any distortion caused by skating errors will also be louder and thus more audible. At the other extreme 100% distortion or a zero amplitude signal is still zero distortion. As distortion is more audible with greater modulation it is preferable to set bias for slightly higher than average modulation.
Niffy
You can actually use a blank record to set skating. Adjust skating bias so that the arm is stationary with the stylus on the rotating blank disk. Now increase the bias by about 60%. Skating bias should now be set approximately right for a modulated groove. It is important to remember that it is impossible to set bias absolutely perfectly as stylus drag, and thus skating force, will be changing constantly with varying groove modulation. What you are aiming for is the minimum average error. In fact you want to set bias slightly higher than this for the following reason. A groove cut with lower than average modulation will have lower than average skating and a groove cut with higher than average modulation will have higher than average skating. As the higher level groove is louder any distortion caused by skating errors will also be louder and thus more audible. At the other extreme 100% distortion or a zero amplitude signal is still zero distortion. As distortion is more audible with greater modulation it is preferable to set bias for slightly higher than average modulation.
Niffy
Of all the aspects that can negatively effect the sound quality of an arm skating has to be one of the more benign. A 9" conventional arm, with a well set up bias system, will have an average tracking error due to skating of 0.15-0.25° (depending on compliance and tracking force) . To those of you who are chasing tracking errors in arc-seconds this may seem a lot but it really really isn't. With an arm with the geometry of the KL the average offset is probably only a tenth that of the 9" arm so the tracking errors due to skating are going to be much less. The bias system for the KL will be a bit more complicated as it has to vary from outwards to inwards as it travels across the record.
Niffy
Niffy
Agree but with some modifications. For a regular pivot arm with an offset angle, skating exists even at null points. In the early part of this thread, I did an analysis of the skating force. Here I repeat it again.
Please see the diagram. In this diagram, the arm has no offset angle. If the arm has an offset angle, skating exists everywhere. When I say an offset angle, I refer to the cantilever is NOT overlapping with the straight line, AB.
So, as long as it meets two conditions, there is no skating. Otherwise, skating always exists. The two conditions are:
The cantilever is tangential to groove and is overlapping the centerline of the arm wand.
Attachments
Last edited:
Hello Niffy,
Those two sentences may have been true before October 2018, when I introduced the world's first pivoting, tangentially tracking tone arm with an offset head-shell, where the stylus sees NO inside force and therefore cannot skate!
In addition, my tone arm tracks perpendicular to the LP's radius without error, no plus or minus tolerance!
Sincerely,
Ralf
Hello super10018,
The cantilever is NEVER tangential to the groove. The groove is a spiral and always intersects the radius of the LP at an angle. The greater the groove pitch, the greater the angle! The cantilever should always be perpendicular to the radius of the LP. If you want to use the word "tangential" it should be stated in reference to a circle with its center at the center of the platter.
Sincerely,
Ralf
Member
Joined 2019
Hi. I feel here some misuse of definitions. The skating force is the one directed to the groove movement. It always exists. The lateral component of the skating force is what we try to compensate, as it creates a dis-balance of the stylus pressure on the two sides of the groove and a lower trackability of the channel with decreased pressure.
The "anti-skating mechanism" does not compensate skating!
The principal question in ANY type of pivoted tonearm, regardless of the type of pivoting, is whether it exists a lateral skating force component. The stylus holder may be always parallel to the groove direction and still exhibit a lateral component of skating force. This will occure if the current effective (momentary) axis of tonearm rotation does not coincide with the direction of the skating force.
The "anti-skating mechanism" does not compensate skating!
The principal question in ANY type of pivoted tonearm, regardless of the type of pivoting, is whether it exists a lateral skating force component. The stylus holder may be always parallel to the groove direction and still exhibit a lateral component of skating force. This will occure if the current effective (momentary) axis of tonearm rotation does not coincide with the direction of the skating force.
Last edited:
Ralf
I understand what you are saying perfectly. If you want to dig deep, you didn’t go far enough. In fact, the groove is not a simple curve, it is a complicated waveform. Therefore, saying the cantilever is perpendicular to the radius of the LP doesn’t mean anything either because skating force still exists caused by the waveforms and the spiral. So is your arm and so are all the linear tracking arms and pivot arms.
If my assumption is not reasonable for analysis of skating, the assumption for the classic calculations of Loefgren and Baerwald is not reasonable either. The two null points are not null points anymore because there are tracking error at these two null points. Since everyone accept Loefgren and Baerwald’s assumption, I don’t see why my assumption is not acceptable.
Jim
Last edited: