Bourne-Jones
More entertainment...
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More entertainment...
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The claim of Mr. Schröder that his construction is free of skating force and tracking error is simply unfounded. On figure 1 of the patent description (see post 571 of this thread) the friction pull of the tonearm exerts a torque on lever 21. What prevents this lever from turning clockwise all the way? Since it is coupled to the tonearm through magnetic forces, the force exerted by the inner wall of the groove on the needle prevents the lever from turning. So there is a skating force.
The magnetic servo has a much greater steady error than an electronic servo would have, so the tracking error is not zero either.
It is an intelligent design, but does not solve entirely the two biggest problems of conventional pivoting arms, e.g. skating force and tracking error, just diminishes them.
The magnetic servo has a much greater steady error than an electronic servo would have, so the tracking error is not zero either.
It is an intelligent design, but does not solve entirely the two biggest problems of conventional pivoting arms, e.g. skating force and tracking error, just diminishes them.
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A bit off topic, but interesting anough. Completely different approach. Seems to be achieved the ideal linear tracking.
Poliak Juraj, fibre optique, lock-in-amplifier, appareil de mesure, virtuel, ens
Optical Fibre Turntable for Archives Records - YouTube
Poliak Juraj, fibre optique, lock-in-amplifier, appareil de mesure, virtuel, ens
Optical Fibre Turntable for Archives Records - YouTube
Hi alighiszem,
I've demoed, cartridge on blank disc(test record issued by VEB Deutsche Schallplatten: "LB27 Prüfplatte Driftkompensation") that there is no movement when properly adjusted and it doesn't change when VTF is changed(which is what is inescapable if your claim was correct). Why are there some people who seem to have a better understanding of this design than me? Particularly when they have not even been present during such a demo...
And even if I were to put such a demo on youtube, there'd still be doubting Thomases, so why bother.
Yes, I can set it up, so that there is skating, but I can and it should be set up so that there is no skating occurring. Easy as that.
When you don't level an airbearing arm or the wiring exerts a force, skating is present too. Does that mean, this is the norm? No...
"The magnetic servo has a much greater steady error than an electronic servo would have".
Now where did you get that conclusion from? All forces involved are taking into account in this arm, incl. the varying "stiffness" of the magnetic linkage over its operating range.
Hope I made my point, - and forgive me for sounding a little stressed. I've heard or seen the "this can't work" - comments too often. Build your own version if you don't want to buy the real thing, then check with me if you don't get it to work(I will help you), THEN report your findings on the internet.
Have a relaxed sunday,
Frank
I've demoed, cartridge on blank disc(test record issued by VEB Deutsche Schallplatten: "LB27 Prüfplatte Driftkompensation") that there is no movement when properly adjusted and it doesn't change when VTF is changed(which is what is inescapable if your claim was correct). Why are there some people who seem to have a better understanding of this design than me? Particularly when they have not even been present during such a demo...
And even if I were to put such a demo on youtube, there'd still be doubting Thomases, so why bother.
Yes, I can set it up, so that there is skating, but I can and it should be set up so that there is no skating occurring. Easy as that.
When you don't level an airbearing arm or the wiring exerts a force, skating is present too. Does that mean, this is the norm? No...
"The magnetic servo has a much greater steady error than an electronic servo would have".
Now where did you get that conclusion from? All forces involved are taking into account in this arm, incl. the varying "stiffness" of the magnetic linkage over its operating range.
Hope I made my point, - and forgive me for sounding a little stressed. I've heard or seen the "this can't work" - comments too often. Build your own version if you don't want to buy the real thing, then check with me if you don't get it to work(I will help you), THEN report your findings on the internet.
Have a relaxed sunday,
Frank
Frank
I'd love to see that demo, especially if it included a change in VTF and a demonstration that it will hold position in several places on a blank disc. Bit far for me to travel to see it in person.
When I first started on my LT design I tried a magnetic track arrangement not dissimilar to yours but I couldn't get rid of the residual torque around the main pivot, so I abandonned that and moved to a different arrangement which is all mechanical.
Your elegant solution to the problem is, in my opinion, the most interesting aspect of your design.
All the best
Mark
JVC Nivico Perfect Tracking
This extremely rare turntable showed up on an online auction recently so I can't help to post some pictures here.
One forum member posted his personal unit on this thread before. Later, I reposted his pictures in higher rez. I also found one selling in Malaysia and I posted pictures of that one too.
This one, however, is broken. Notice the base area is damaged with pivot housing disassembled out of the base and wires all over the place (see picture#3). Such a shame! This appears to be JVC's answer to the Garrard Zero 100 with perhaps better build quality and the guiding rod is on the left side. Check it out.
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This extremely rare turntable showed up on an online auction recently so I can't help to post some pictures here.
One forum member posted his personal unit on this thread before. Later, I reposted his pictures in higher rez. I also found one selling in Malaysia and I posted pictures of that one too.
This one, however, is broken. Notice the base area is damaged with pivot housing disassembled out of the base and wires all over the place (see picture#3). Such a shame! This appears to be JVC's answer to the Garrard Zero 100 with perhaps better build quality and the guiding rod is on the left side. Check it out.
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Sorry for being able to read technical drawings. In your design the actual position of the needle on the record is a function of the angle between the lever and the tonearm and the momentary pulling force on the tonearm (resulting from friction and modulation). So there is always an error which can't be compensated.
"sorry for being..."
So the inevitable forum snarkiness has landed here. Shame; maybe it's over, since the OP is reposting interesting pieces from the early days. Oh well. I've thoroughly enjoyed this one, and am still inspired to cobble together my own unoriginal copycat version of the BJ/Garrard/JVC. Thanks Directdriver!
So the inevitable forum snarkiness has landed here. Shame; maybe it's over, since the OP is reposting interesting pieces from the early days. Oh well. I've thoroughly enjoyed this one, and am still inspired to cobble together my own unoriginal copycat version of the BJ/Garrard/JVC. Thanks Directdriver!
I too have enjoyed this thread from the beginning, but I dont think anyone has been out of order so far. Even with the piqtures, I myself have trouble to conceive the concept of how the arm function in real life, but I love the enginuity Frank has shown. My own take on that 90 degree angling is far less spectacular
Steen
The JVC Nivico pictures are not a repost. They are recent pictures. At least it's a different turntable!
Don't worry about "snarkiness," just enjoy what fits your interest. People just have to remember this is still a hobby.
Despite I'm mostly ignored here, just hard to stay silent. According to many posts by Berlinta here, in different threads, he is not a person that would mislead, or make false statements. His design is not just a theoretical one. I'm pretty sure, that a lot of practical measurements were done with ready made arms, including supposed skating force and angular mistake. So it is better to keep sarcastic skepticism for designs such as 47LABS RS-1.
So the Schröder LT has a horizontal effective mass that varies with tonearm position and is always more than the vertical? Also, the tangency force varies with groove modulation? Hmm...
I think I would like to see some proper independent measurements of its behaviour, static and dynamic....
I think I would like to see some proper independent measurements of its behaviour, static and dynamic....
As you can see on the photos, the Schroeder arm does not differ from conventional pivoting arms in respect of the effective mass.
Concerning the skating force the following equation applies:
L1 x Ffr = L2 x -Fsk
Where Ffr is the friction force pulling the tonearm, and Fsk is the skating force.
L1 and L2 are on the drawing (the original was taken from the patent application).
When the lever and the tonearm are not perpendicular (as in reality), then the equation is more complicated, with some trigonometry.
Concerning the skating force the following equation applies:
L1 x Ffr = L2 x -Fsk
Where Ffr is the friction force pulling the tonearm, and Fsk is the skating force.
L1 and L2 are on the drawing (the original was taken from the patent application).
When the lever and the tonearm are not perpendicular (as in reality), then the equation is more complicated, with some trigonometry.
Attachments
Hi,
Only some unipivot arms come close to equal eff. mass lateral plane vs. the vertical plane.
Even cardanic bearing(i.e. Triplanar, Alphason, Dual ULM, etc...) arms display a (minute and inconsequential) difference in this department.
"I think I would like to see some proper independent measurements of its behaviour, static and dynamic.... "
And why is that?
If you meant, "skating force varies with groove modulation"... this would be correct.
@ alighiszem: the drawing above just shows the elements from above. You must draw the previously voiced conclusions, I understand. But the drawing leaves out other factors(not elements)...
If I find the time(after x-mas), I will fabricate a little video and you can then tell me how it's done.
Btw, this isn't about teasing or playing hide and seek, but about keeping commercial copycats from exploiting the principle.
Cheers,
Frank
Only some unipivot arms come close to equal eff. mass lateral plane vs. the vertical plane.
Even cardanic bearing(i.e. Triplanar, Alphason, Dual ULM, etc...) arms display a (minute and inconsequential) difference in this department.
"I think I would like to see some proper independent measurements of its behaviour, static and dynamic.... "
And why is that?
If you meant, "skating force varies with groove modulation"... this would be correct.
@ alighiszem: the drawing above just shows the elements from above. You must draw the previously voiced conclusions, I understand. But the drawing leaves out other factors(not elements)...
If I find the time(after x-mas), I will fabricate a little video and you can then tell me how it's done.
Btw, this isn't about teasing or playing hide and seek, but about keeping commercial copycats from exploiting the principle.
Cheers,
Frank
Hi Again,
I'm finally ready to begin a clone of this amazing design,Contrats Frank on your patent approval, it is this idea below that I am currently struggling with.
So there is a varying stiffness with respect to the magnetic force applied over the arms movement? Hmmm. Guess I'll have to experiment. Does it get weaker or stronger?
MC
I'm finally ready to begin a clone of this amazing design,Contrats Frank on your patent approval, it is this idea below that I am currently struggling with.
So there is a varying stiffness with respect to the magnetic force applied over the arms movement? Hmmm. Guess I'll have to experiment. Does it get weaker or stronger?
MC