I see a new match coming. This thread will be hot very soon.
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These theorists 
.
@Xanthe,.This seems interesting,.my only question to you is.
And that’s the only important question for me.!!
How do you think these work practically,.to contribute to better soundquality in your music-system.?
This is,.as usual,the only thing that matters…
/Peder🙂
And so it begins, cables will be a walk in the park…
The new mania thread is born: ceramic or not ceramic?
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This sounds like discussions from years ago when the use of plano concave lenses and balls were being used with varying degrees of success.
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Well…
1 it works
2 the percentages aren’t just picked out of the air; they are from proper calculation of the energy distributions involved.
Those on here who know me know that I explore research and design things meticulously and also that I have a good grounding in physics and engineering. I’ve done the calculations; on the other hand you appear to have not done so, merely relying on superficial observations and guess work to jump to conclusions. Just “looking again at it” isn’t sufficient rigour to justify your derogatory remarks.
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I agree. Count.d attacked you but give no reasons or informations to prove you were wrong.
I’m following this with interest Xanthe with a project in mind for the future, I have access to a machine shop & brass, copper, SS etc so disc manufacture is not a problem, question is a curved disc or conical, something to see how you make out.
I’m now thinking about critical frequencies for units such as NDX2 vs 272 or maybe X72 future units. My time frame is apx 2 years out, so cogitation time aplenty.
Indeed the mechanical spectral sensitivity of audio systems is a very interesting question. I’m not sure how to start answering that other than to say that I believe the answer will depend on many factors and is going to be highly variable and individual to the design of each component.
In terms of the effect of vibration induced modulation of signal lines and power rails of analogue circuits, deleterious effect can be induced by almost any frequencies from about 5Hz up to about 500kHz and for some circuits this can extend above 2MHz.
I believe that inductors and capacitors will be the electronic components that are most likely to be significantly affected.
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Following this thread with interest. Several years ago, prompted by forum discussion of what were called “ball nutter” shelves, I made some adaptations to my elderly Sound Factory Tripod stack. It was clear that Fraim balls and cups were considered ideal, however the Tripod didn’t have the vertical clearance to accommodate them. Instead, I used tiny ceramic balls atop matching machine screws to separate the glass from the frame members. I chose ceramic over steel because I assumed that harder was better in terms of vibration isolation. I didn’t do any rigorous testing, however the sound was so improved after the modification that, to this day, it remains the best VFM upgrade I’ve ever made. It removed a rough, fatiguing quality from the sound while improving dynamics and detail. There were no trade-offs that I could discern.
This thread made me curious to know exactly what “ceramic” meant. From the vendor’s website, I see that the balls are listed as “Si3N4,” which I assumed was an internal reference. But a quick search shows that that’s the chemical formula for silicon nitride (properly rendered as Si3N4).
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Naim apparently chose mild steel in preference to stainless steel balls for Fraim, so perhaps hardness alone is not their priority. Maybe this depends on the relative hardness of other materials, as Xanthe mentions above, but I’m just speculating here.
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Yes, I was aware of that. Back in the 80s and 90s, every support worth its salt was spiked, and every nut and bolt was tightened to within a hair of stripping the threads, so I had always assumed that the smaller the contact area, the better. My thinking was that a small, hard ball would work better than a larger, softer one, but clearly there’s more to it that that. Now it seems that there are all sorts of ways of dealing with vibration – not just balls instead of spikes, but compliant interfaces – and it seems every fixing has an optimal (and usually moderate) torque.
@ChrisSU
Yes the relative hardness is important, but not directly, rather it’s an indicator of compression rigidity (in fact hardness is often measured and expressed as compression rigidity).
@Corry
The higher hardness of the silicon nitride ball reduces the contact area, but only so far. The contact area (at a given force) is related to the compression rigidity of both materials. Since silicon nitride has higher rigidity than the glass, the contact area is primarily determined by the elastic deformation of the glass.
Another effect of the rigidity comes when it is considered in context of the density of the material, together these combine to determine the velocity of sound within the material. This is important because this represents the impedance presented to a sound wave travelling through the material. When waved encounter a sharp change of impedance they are subject to reflection at the interface, hence with silicon nitride having a higher sound velocity than glass, reflection occurs at the interface. The lower contact area does also help to reduce the total energy that can be transmitted, but remember this is limited by the glass not the ceramic ball!
So, looking at the Naim Fraim. Austenitic stainless steels have higher rigidity than mild steels. Stainless steels have slightly higher rigidity glass, mild steels have lower rigidity glass, but both have higher density than glass. This means that the sound velocity in stainless steels is similar to that in glass, whereas for mild steels it is significantly lower than glass; hence against glass, mild steels give better reflection and hence better isolation of vibration than do stainless steels.
Silicon nitride is more rigid than glass and has about the same density, so you get the smaller contact area and the better reflection at the interface.
A further point for consideration is the potential for energy storage in the component. Simple harmonic motion is the repeated cyclic interchange of kinetic and potential energy, so analysing either the kinetic or the potential component gives the same result: the amount of energy that can be stored is proportional to mass. So for the same size of component, silicon nitride can only store half as much energy as can be stored by a similar component made of steel.
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Hi Xanthe, very interesting - what effects do you feel, a denser grade 10 Tungsten Carbide bearing would bring in your system?
It depends entirely on the grade/type of stainless and the grade/treatment of ferritic steels in question. Are naim mild steel balls purely mild steel and not case hardened or heat treated in any way, just normalised or annealed?
True, and martensitic 400 grade steels are different again!
However most austenitic steels are, in effect, very similar as they can’t be hardened by heat treating, although they do work harden (as does brass).
My understanding is that the Fraim balls aren’t heat treated but are chrome plated (I assume chromium over nickle over copper, or one of the deposition techniques).
I was trying to keep things simple and not get diverted into a discussion about the allotropes of iron!
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Tungsten carbide is more rigid than glass, but also denser by a fairly similar ratio, hence the sound velocity is quite similar to that of glass. Unfortunately this will reduce the back reflection at the interface so reducing the degree of isolation obtained. With both tungsten carbide and silicon nitride, the contact area is mostly controlled by the rigidity of the glass so, in both cases it will be very similar. The much greater density of tungsten carbide will give greater mass and so permit greater energy storage within the ball, and this is potentially detrimental to the system.
Use of tungsten carbide is not indicated for this application.
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So ideally you want a light ball with a hard surface. chromium plate aluminium alloys?..
It’s even better if it’s light and hard throughout so it doesn’t deform under the contact pressure - e.g. silicon nitride or silicon carbide!
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