WHAT HAS WORKED FOR YOU? ISOLATION PLATFORMS, FOOTERS, ETC. for a DAC?

Actually the 6 degrees of freedom is a misnomer since it’s obvious that for the horizontal plane there are an infinite number of directions, not just the two X and Z directions. Which explains why roller bearings are so effective for the horizontal and why isolation devices with multiple lateral springs like my olde Nimbus unipivot and whatever iso pod that has a bunch of lateral springs radiating outward from the center. You will also get better rotational isolation with a single spring or air spring than with multiple ones. It’s too bad you can’t get away with using a single roller bearing assembly.

And is why roller bearings are best positioned as an equilateral triangle.

That would be true if the mass distribution of the component is uniform. But since mass is often not uniform - such as when a large transformer is located on one side of an amplifier or a motor is located on the side of a turntable - the mass should be distributed equally among the bearings to ensure the component can move freely in all directions. Obviously cords and cables must be squared away so they don’t apply forces, including rotational forces, to the delicate set up. If mass is not distributed equally more force will be applied to one or more bearings than the other one or two. So, the best arrangement for the bearings is often a non equilateral triangle. It’s whatever gives the best "action" when you touch the component. When pushed slightly the component should return to its original equilibrium position. When the mass and forces are all balanced out, including friction, the system is in equilibrium. It’s the same for springs, the mass should be distributed equally among the springs, so the forces are balanced out, assuring uniform mass-on-spring performance as well as perfect level of the component.

@geoffkait  and others, 

Is there a simple or somewhat simple way to figure out mass distribution of a component, other than eyeballing transformer postion(s) and weightier sections and going by felt weight?

 
david_ten OP
352 posts
07-29-2017 9:28am
@geoffkait and others,

Is there a simple or somewhat simple way to figure out mass distribution of a component, other than eyeballing transformer postion(s) and weightier sections and going by felt weight?

Springs you can measure with a bubble level, when the top of the component is level the mass will be distributed. The only exception is a CD the top of the chassis may or may not be the exact same level as the CD transport. Obviously, or perhaps not obviously, the CD should be absolutely level during play. For roller bearings you have to determine level some other way, for example the surface on which the roller bearing sit. But the only way to determine when the system is balanced is by moving one or more bearing a little at a time until all three bearings are centered in their cups and the component doesn't get hung up in one cup when the mass off balance forces it over to one side. The component should always come back to the equilibrium position where all bearings are in the center of their cups. If the system isn't perfectly balanced the bearings cannot move freely up the shallow angle of the cups, hurting rotational isolation. But this all isn't as hard as it sounds. Once you see the bearings in action you'll understand.