Peter, That contraption looks even worse "in person." I walked by an UO store in my neighborhood and saw it in the window. I thought for sure it was a window prop. Sadly, it was not, and someone is tearing their records to shreds listening through "built-in dynamic full range stereo speakers" as we write. They will then tell their friends vinyl does not at all sound any better than their IPod... |
There is the Kronos and then there is this. Everyone is now trying to cash in on the resurgence of vinyl. I cringe thinking what it would do to a record. |
In an ideal universe there would be no bearing friction. Admittedly, this never happens. But in such a closed system, a force equal in magnitude and opposite in direction, i.e., counter-clockwise in this case, would be exerted on everything that is not part of the platter, when the motor is in action. In the real world, gravity pulls the assembly down on its base, and the friction between the footers and the shelf normally prevents the counter-rotation of the assembly. But the contrary force is present, nonetheless. (This is a problem with spring suspended turntables.) By having the counter-rotating platter of equal composition and mass borne on the same assembly as the functional platter, that force is nullified. Think about it; in outer space, in a manned space capsule, one could not play a record unless one bolted down the whole turntable to the mass of the ship itself. Otherwise, the platter and the rest of the turntable would both rotate but in opposite directions due to the rotational force put into them by the motor. (Of course, setting VTF would be a bitch as well.) |
Lewm, I'm trying to understand your point. In a conventional turntable design where the one platter is rotating clockwise, that is the "action". What is the "equal and opposite" reaction? The Kronos designer told me that the platter rotating tends to make the supporting plinth rotate also, I guess in the SAME direction due to bearing friction, ie. clockwise. But if the friction is low, then how much of an issue is this really for all other conventional turntables? Now apply this principle to the lower platter on the Kronos. That platter is rotating in the opposite direction making that second, lower plinth rotate slightly in that direction, ie. counter-clockwise. It seems that the platters cancel each other, but the two plinths which are floating due to the SME like four leg towers, are rotating in opposite directions and they meet at the four corners. Those forces are acting on the four legs in opposite directions. So it seems to me that the forces are not cancelled by the rotating platters but by sheer force at the corner leg supports. I did not think to ask the designer to clarify this for me, so perhaps I am completely misunderstanding the point. This may be the wrong thread to discuss the technical design of the Kronos, so I apologize to the OP. |
Peter, I may be wrong, but I think the counter-rotating platters would have a nice stabilizing effect, rather like a gyroscope, but not actually gyroscopic. I am gratified to see that the quote from the designer, "counter-rotating platters cancel the tendency for the plinth to rotate in the horizontal plane around the axis of the bearing", is another way of saying what I wrote above. It's the Law. However, the execution of the idea is what would determine whether the results are worth the added complexity. Which is why I'd love to hear one of these tables. Would be cool to do a direct drive with counter-rotating platters. DD would be better suited to this concept than belt-drive, IMO. (This is not to take a shot at BD; it's just that BD requires those two external motors and the associated drive belts, which might serve to reduce the possible advantages of this particular idea.) |
Love the exposure. That's an SME V-12 arm (non detachable headshell). I spoke to the designer about this at the NYC show a couple of weeks ago. He used the V-12 two years ago and the 12" Grahm this year. He told me that the counter-rotating platters cancel the tendency for the plinth to rotate in the horizontal plane around the axis of the bearing. Bearings aren't frictionless, but if they have very very little friction, I wonder how much this force really matters. I also think that two motors with two rotating platters may introduce more vibrations into a system than having only one of each. I wonder what kind of set up service and ongoing service HS will give to its customers. It is great to see this on the cover, though. |
"KronosÂ’ variation on the theme is to rotate their second, identical, 30-pound platter in the opposite direction of the main platter spinning the record. In essence, it completely cancels any vibration induced by the first." I took this quote from one of the reviews cited by Raul. I believe it is incorrect. I don't see how the equal and opposite rotation of the bottom platter could "cancel any vibration". It might cancel some vibration (and it might introduce new sources of vibration), but what it could cancel is the effect dictated by Newton's Third Law of Motion: For every action, there is an equal and opposite reaction. Forces exerted on the motor and plinth opposite in direction to those exerted on the platter by the motor could/would be counter-balanced. This would obviate the need for a massive plinth structure and could be a "good thing", but it does not cancel all vibration per se. I would be very curious to hear it. |
Dear Hiendmuse: A lovely and very good looking TT that against what are on the market seems to me like this Canadian design could be a " bargain " at those 28K dollars. The idea is not a new one, was implemented in Japan before for 47Labs and Sansui. The main subject here could be how well is the whole implementation design. Reading over reviews seems the design is successful: http://www.kronosaudio.com/Reviews/Tone%20Audio%20Review.pdf http://www.kronosaudio.com/Reviews/Audio%20Beat%20Review2.pdf Ok, now I have to think where I can find out 28K!!!! Regards and enjoy the music, R. |
