Good work! It looks nice too. No sliding risk ?
No, as with my design, the movement of the balls is constrained: in this case because the angle at the edge of the cup is quite steep.
With my design the black plastic piece is held in place in the recess in the brass cup and the inner diameter of the plastic prevents the ball from moving completely out of the depression in the middle.
It takes negligible force to move the glass / box a couple of mm which is all I think is necessary. The cup is made with a 20mm diameter cutter so twice that of the ball thus free to move but well restrained from sliding.
I was referring to Bill system, which is different from yours if I am not wrong. You use little nitride balls inserted in holes ?
Bill responded in that time.
The two are much closer than you assume.
With my system the silicon nitride ball sits in a shallow spherical depression in the brass. The plastic with the ‘hole’ is just there to restrict the movement of the ball so that it can’t be rolled too far and get out of the depression in the brass. in normal use with everything ‘at rest’, the plastic doesn’t actually touch the silicon nitride ball (only the brass cup).
Hei Dan, good question.
You prompted me thinking that the Naim veneered boards could be used as templates to make new shelves from Corian. As Corian would come in many different colours, this could look extremely sophisticated/cool depending on ones interior.
The Naim shelves are 19mm thick, but I dont think it would be prudent to go less than than 19mm even in Corian and it would depend on the limitations of the producer of the Corian, but I leave others to comment on the appropriate thickness for strength and stability and resonance control.
I am thinking that a kitchen worktop manufacturer would be the producer.
Corian data sheet…if not too off topic. 
A hifi friend and I discussed corian for shelves. He felt the Corian was superior to glass. I haven’t tried it. However I have worked with it. It cuts nicely with wood working tools.
I have used brass in turntable vibration abatement, it works well.
Liking the use of cap head bolt heads there, neat bit of repurposing.
Is it possible to give a star ? Consider a star awarded!
I don’t know if it is superior in terms of resonance control, others can comment on that. But yes definitely better to work with than glass and the colour/texture pattern could look very good compared to glass.
Glass can also come in different colours or simply sandblasted though.
I guess if you are going to use another company to manufacture the shelves, workability will not come into it, except then for labour costs.
Well, a penny dropped last night.
The self-created problem I just got rid of started 10 days ago (see post 221 for photo) when I installed 3 silicon nitride balls under a sheet of 10mm toughened glass under my 272 in my oak-shelved Quadraspire rack.
I was aware that one of the 3 steel nuts I used from my box full of random hardware bits was smaller in width and length than the other 2, but it seemed to be the same thickness by eye and when I ran my finger across the 3 of them. I don’t have a micrometer, so cannot check it.
And it didn’t matter that much anyway as it was never anything but a temporary arrangement and a test en route to proper shelf isolation.
It made an improvement in SQ, but also there were a couple of quite nasty rattles when playing loud - but these rattles happened at first then disappeared. But although the SQ was clearer, there was also something bugging me about the hifi since then.
A week ago I order 5 brass nuts from t’Bay for £2 to compare them to the steel nuts.
They arrived and I swapped them in last night.
Bang! A major improvement in SQ. All the benefits of the shelf isolation, but the overall sense that something was wrong with the system vanished entirely.
It seems that the stray steel nut was probably a fraction of a mm thinner after all.
And the brass is probably much better as a support for the ball because it’s softer.
I’m looking forward to getting the more sophisticated isolation system working.
I need to make a decision on what to put under my speakers before I can take the 2 glass shelves out from under them.
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From a theoretical perspective, the vibration isolation (by reflection, not absorption incidentally) comes from layering materials of different sound velocity (proportional to hardness / density) with very small contact patches. Hence a hard material against a softer material maximises the reflection.
(If you want vibration absorption btw, very little beats Sorbothane.)
Does this apply to all mechanical vibrations/kinetic energy in the system?
Vibrations come from:
- the various parts of the isolated component vibrating one another;
- movement of attached cables;
- vibration of other components on the rack;
- air movement;
- vibrations from the floor into the rack.
So cup, ball and glass plate carry (reflect?) vibrations away from the component more efficiently than a standard rack shelf alone.
But they also reduce vibrations of the rack entering the component too.
It applies to all essentially elastic interfaces (i.e. where the elastic modulus of both components substantially exceeds the loss modulus of either component).
This does not apply to air movement (or pressure - which you forgot about and is usually more significant than the movement!) or to cables where the flexible insulation has significant loss modulus).
The cup, ball and glass don’t actually carry the vibrations away from a component, they actually reflect it back toward the component and reflect external vibration back into the rack; however the individual components are designed to deal with their own vibrations. The important thing is that they greatly reduce the extraneous vibration coming from the environment (including other components in the system with differing vibrational harmonics) traveling through the rack into the more sensitive components. Setting things like power supplies and power amps on the same isolating components reduces the more aggressive vibrations from these heavier components from entering the rack - connecting these to the rack via a unidirectional vibration path conducting vibration away from components into the rack is exactly what you don’t want!
Incidentally the concept of a unidirectional vibration path (i.e. a mechanical diode) is misinformation promulgated by the marketing department of the various manufacturers of the stainless steel cup and ball type of isolators - these marketing people clearly just don’t understand vibration control!
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I moved my 555DR onto my second rack.
Not sure whether to move the NAP 150X across too?
But then everything will change when I get them isolated.
Anyway, the whole system sounds lovely at the moment.
I’ve been so happy since I put those brass nuts in to replace the steel ones.
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Well hopefully today or tomorrow you’ll be able to compare that arrangement to single point contact with the brass with the glass held on a ‘floating’ bearing.
Yes, so that should sound even better because:
The contact between glass and ball and brass is minimised to just 2 small points.
The contrast between the hardness of the silicon nitride and the softness of the brass is much greater than in most comparable systems.
The ball is free to move - this means it is automatically stabilised by gravity within the dent, plus the weight of the glass and component pressing down on it.
Will the movements of the ball on the brass over time create a dent within the main dent?
Will this smaller dent still help to fix the ball in place even more?
Will the smaller dent tend to have a slightly more flared concave shape than the ball itself?
Also, it will be more stable on the shelf because the brass cup has a much larger and rougher surface than the tiny brass nut I’m using at the moment.
One of the reasons for pressure forming of the dent in the brass cup is to locally work harden the surface of the dent. this way the surface of the dent is preserved even against the pressure produced by a 555PS sitting on 10mm glass; on (unhardened) soft yellow brass, this pressure is sufficient to mark the surface.
The lack of surface marking ensures as small a contact areas as can be achieved and ensures smooth movement of the ball in response to external force.
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