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In the Forum: Analog Playback
In the Thread: Dynamic viscose stabilization of turntable’s platter.
Post Subject: Will not workPosted by N-set on: 1/22/2017
For some reason I've remembered this old idea of Romy and decided to check it
from the physics point of view. Unfortunately it seems it will not work:
the momet of intertia of a fluid in a vessel is with a resonable accuracy zero with
respect to the fluids center of mass. So rotating the fluid, one wouldnt feel much its presence.
This is in contrast to moving its center of mass (like in Romy's example of a train with oil), when
the intertia will manifest itself. Here is a nice explanation with a good example
(the 1st answer):

https://www.researchgate.net/post/Can_we_use_the_term_rotational_inertia_for_the_fluids

Cheers,
Jarek



 Romy the Cat wrote:
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Ok, it is bogus but no more bogus than anything else in “Ultimate Turntable” thread. Still, I like the notion, even though I have no idea if it might have any sonic consequences. I do not see the concept was used in turntable; perhaps the people who make turntables would give some thinking to this idea.

Among many professions I had in my youth one of them was a locomotive engineer. So, when I was driving trains I remember that under the same conditions to stop a 6.000 tones train with coal took much shorter distance then 5.000 tones  train with oil.  It is obvious that the inertia of oil displacement propelled the train forward creating extra moment.

Why do not use the same idea in a TT’s platter.

Pretend that we have a good mass platter and this platter in addition it it’s mass has a large circular chamber near the outside skirt. The chamber or the channel is 50% filled with some kind of heavy liquid. When the platter start to spin and reach it’s stable cruse speed then in a few moment the liquid synchronies with platter, becoming dynamically in uni-speed with platter. Now when the platter has mine fluctuation in speed then the liquid try to maintain it’s gyroscope moment and by tension with the chamber’s wall it would damp the speed fluctuations. It sounds very reasonable to me.

This idea has even some very good marketing possibility as the outer wall of the chamber might be made transparent and a user will be actually seeing the liquid. Now, pit on the wall of the chamber some verticals screen and insert into the liquid some floating markings and you have a perfect natural indicator of platter’s stability.

I can see the Stereophile advertises the tunable with “Heavy Water” platters…. Sounds catchy.

The Cat

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