Ingress Audio Engineering

The physics of roller bearings, pt 2.

If the base of the roller bearing assembly is flat there can be only rotational isolation in the twist direction. 🕺🏻 Plus isolation in the horizontal x-z plane. You lose the isolation in the roll and rock directions. It is the rotational seismic forces that try to rotate the building and everything inside. If the base is concave the component is isolated in those two rotational directions. The smoother and harder the surfaces of the bass and base the easier the component will move when acted on by any external forces. Which means the whole roller bearing set up can easily get “stuck” when the balls roll to the edge of the base if the set up is not perfectly level and balanced. That condition limits the iso device’s isolation, since it cannot move further in that direction. Isolation effectiveness in a given direction is proportional to how easily the component can move in that direction.

Another advantage of a concave surface for the base is that when the component rotates slightly due to rotational forces, there is some degree of vertical isolation since the component moves up and down vertically 🔝 as it rocks and rolls, no? Up and down as it rotates around its centerline axis. Recall wave passing under boat analogy.

You can buy miniature 2” shallow ceramic bowls on line that might work very well and a glass marble of the appropriate size, one bowl on top and one on the bottom. Total cost for set of three roller bearing assemblies $30.

I's still waiting for the same responses I got when I brought up Ingress Audio on another thread some time ago. A couple of posters claimed whatever sat on the bearings would roll right off and couldn't believe it would work.

I believe I was one of those posters Nonoise.
But it was not that I claimed they would roll right off , more I was having trouble in my mind seeing just what there was that would STOP the amp rolling right off very easily.

But at $70 I was willing to give it a try and nope it did not move a mm once sat down on top of all three so mind put at rest.

You do not know what you do not know......

I too was part the earlier Barry discussions (on CA) on his hipjoints and had many offline conversations with. He is without a doubt one of the most gracious and pleasant individuals I have come across and has shared a wealth of info. Being relatively new to this hobby, this topic goes back even earlier on other forums and I think he bowed out as some indiv have an axe to grind with everything.

I purchased a set of ingress V1 when he first started out, and they were quality made, but the design didn’t follow the cup profile needed, so I outsourced a local shop to have them made (prob 25-30 qty) based on the larger 1" profile cut/6061. I put them under everything using the .5" marble slab for the smooth surface. Even speakers (at the time). I also use inner tube for the vertical, so its rack > inner tube > MDF > cup/bearings > marble > component. Works like a charm! Although with heavy speakers now, I opt’d for the GAIA’s

However, the inner tube does present some challenges one of which is maintaining their pressure. So I used a tube inlet extender which then gives you the ability to inflate/deflate without having to remove the components. I researched a ton on bladders (square ones like acoustic revive $$) and small inner tubes that are used on those small IC cars/toys etc.. but time is always a challenge and never took it farther then the bike inner tube..
These look to be great idea, but as usual in this hobby, ridiculous cost
http://pneuance.com/.
I would like to made two adjustments to my platforms:
1. Being the other challenge with inner tubes are getting the correct psi based on the component weight, its basically a guess (by eye) and putting just enough air that the tube isn’t grounding out on the platform. To that end I would like to try some wave washer/comp springs instead of inner tubes and just started looking/researching. Since you can then design around the max load per spring, it should be easier..
2. Replacing the marble with say a .25" plate of alum and then maybe some cork or wood on top. The marble works but the heavier components give me pause and would feel better with a more structurally sound formula.  Something like the symposium segue platforms come to mind, but not sure if that would be too compliant and would need about 5 so that is costly

It’s probably not that obvious but worth pointing out since inner tubes were just mentioned. The smoother and harder the surfaces are made for the roller bearing assemblies the more critical balance and level become, even if cups are used top and bottom, as I pointed out a couple posts down. Therefore, I humbly submit inner tubes are not (rpt not) a good choice for vertical isolation with roller bearings, or even used alone. Steel springs like you know who’s are a much better choice, not only because of the leakage issue but because inner tubes have a very non-ideal geometry for pneumatic isolation - the ideal geometry being tall and slender. I.e., large volume of air v per surface area in2. As I also just got through mentioning, there is some degree of vertical isolation with ONLY roller bearings and cups. Which reminds me, the reason some components can be mounted directly on bearings with no cups is probably because the hard roller bearings make slight depressions in the metal of the chassis base.