Equipment isolation and vibration damping.

[YashN]

I think the cup and bearing materials are less about ringing, and more about surface hardness:rolling friction, stick-slip, deformation ect.

 

Yes, but if we want freer oscillation, doesn't friction damp it? So I was looking for a way to reduce that, but still keep the hardness aspect.

 

After reading on industrial seismic isolations of the ball and cup type, I saw at least one manufacturer mentioning Teflon.

[YashN]

How about polished steel, as in those camping mirrors that John S. recommended ?

 

I will ask about them when I go to the nearby sports/equipment shop.

 

There is something about a Teflon coating that just doesn't sit right with me for this application, but I can't put my finger on a rational explanation.

 

Can a Teflon-coated surface be made very smooth? I don't know. What if we coat both steel ball and steel plate with Teflon?

[YashN]

Because the rolling friction is too high using teflon.

 

Ah, interesting. Now, why is that, just the normal way it works with two different materials in friction? What if it's Teflon over Teflon?

[kenreau]

I really dig all the ideas and reported benefits. My hang up is, how effective can these really be with the appliance plugged into, at a minimum, a power cable and a data cable. These are not isolated and free standing devices without "tethers" anchoring to something.

 

Most audiophile cables are thick and stiff and, in my mind, probably act much like a ball and chain hanging off the back of the appliance negating a significant amount of the isolation benefits. Yes, no?

 

Kenreau

[YashN]

In my listening room my speakers are isolated (in the horizontal plane) by suspending them from the ceiling by bowstrings.

 

Thought I saw that in the article over at Audiostream

 

Must have read that article about 6 times already because it's packed with great info!

[YashN]

I really dig all the ideas and reported benefits. My hang up is, how effective can these really be with the appliance plugged into, at a minimum, a power cable and a data cable. These are not isolated and free standing devices without "tethers" anchoring to something.

 

Most audiophile cables are thick and stiff and, in my mind, probably act much like a ball and chain hanging off the back of the appliance negating a significant amount of the isolation benefits. Yes, no?

 

Those are good points that John Swenson already touched upon in a previous post in the thread.

 

So these isolations force you to consider your cables in two ways really:

 

First is the mention by Barry that in one instance, he found the isolation not to be effective if the cables aren't well-dressed, i.e., ensure you're not running your interconnects close and parallel to AC power cords.

 

Second is the mechanical pull/push of cables as mentioned by John.

 

So, we definitely need a way to structurally support the cables. Judicious placement of cable elevators and holders could do the trick, together with using light and flexible cables I guess.

 

Haven't yet tried cable elevators myself.

[YashN]

Mind you, these are very expensive. Some folks on WBF are bent on testing them out, even saw reports of them having a large effect on the Trinity DAC...

 

Accurion, Herzan

 

The discussion on active isolation going down to 1Hz came up, and the conclusion from the Spiers people was that 1Hz frequencies are generated by sub sub sub bass phenomena maybe many blocks/miles away like wind turbulence, roads and bridges flexing, underground structures resonating, earth movements etc.

 

Discovery 2 :

 

- The benefit of Accurion & Herzan is universal, i.e. improvement present for all types of components (LP turntables/CDP/SACD/DAC/phonoamp/preamp/PSU...).

- Even hiend hifi racks have been used, there was still significant benefit.

- The degree of benefit was quite unpredictable. We thought turntable & CD transport should be benefited most but it turned out that the Trinity DAC exhibited the biggest benefit, second only to a AW Accustic turntable. Many possible factors : built of the components, rack quality, apartment location & baseline vibration ... etc.

 

The lesson learned is that since the benefit is universal but variable for individual components, it's best to have home-trial before buying.

If home-trial is not available from the dealer, buy just one and test it on each of the components before making the decision of buying more.

 

These devices' use of active isolation make them work down to very low frequency isolation where it's needed for the kind of earth-borne waves isolation, and where passive means like what we are doing may not be as effective.

[YashN]

Also at WBF:

 

Isolation devices under speakers

Coupling, de-coupling loudspeakers

 

Puget found the Wave Kinetics isolators the best he tried in one of those threads or a related one.

The A10-U8 is designed to provide a stable structure while still allowing for damping and vibration control. When the system is at rest, the A10-U8 behaves as a solid slug with thin compliant top and bottom caps. The weight of the component applies force to the top of the A10-U8 which then compresses a spherical bearing array. The bearings align into a hexagonal packed structure held in place by the compliant walls of the container. The walls of the container are soft and thin providing virtually no solid path for vibration to travel from stand to component. At rest, it is as if the component is sitting on a narrow stack of very dense metal bearings with a thin compliant surface on top and bottom. There is no rigid path for vibration transfer, yet the component sits on a stable surface!

[YashN]

A good page comparing various isolation methods on the Wave Kinetics page, The Truth:

 

Wave Kinetics

A10-U8 Component Control System:

 

• Rapid settling time – at least as fast as active systems.
  
• Does not over-damp
  
• Impedance mismatch prevents flow from structure to component
  
• Damping at component side dissipates machine generated vibration and air-born vibration transmitted to case.
  
• Quiescent state is very rigid due to hexagonal close pack of spherical bearing array
  
• 
  

[Daudio]

A good page comparing various isolation methods on the Wave Kinetics page, The Truth:

 

And a not-so-good part of that page:

 

"There are many products designed around very hard ball bearing interfaces where the theory is that the single point of contact on the bearing provides an efficient path to allow vibration to flow out of a component or speaker into the supporting structure or floor. If the impedance from the component to footer is mismatched and there is no damping in the system then vibration is reflected back into the component and can cause sonic coloration. If there is an impedance mismatch but there is damping at work, then the vibration energy can be dissipated due to the damping. Hard bearing systems attempt to match the impedances sufficiently to allow vibration to move relatively freely both from the component to the platform and from the platform to the component."

 

It gets worse in the Pro's and Con's...

[YashN]

Understanding the phenomena, mechanisms and pros and cons of each can help in designing and implementing new ways of isolation for audio.

 

Additionally, I don't think the cup-and-ball + air-cushion is ideal, but as an affordable, potential DIY solution which provides results even in its most simple form, it is very interesting.

 

Tried my idea for making a circular notch in wood in the garden today: test run wasn't convincing at all.

 

Requisitioned my gf's pancake pan while she was not looking, rested 3 good-sounding marbles on it and balanced a bamboo plate on it: now, THAT'S free motion!

[Daudio]

Understanding the phenomena, mechanisms and pros and cons of each can help in designing and implementing new ways of isolation for audio.

 

Additionally, I don't think the cup-and-ball + air-cushion is ideal, ...

 

Yes, but, misunderstanding the phenomena is not very helpful

 

 

Yash, you remind me of one of those firework pinwheels, showing sparks in all directions ! I can't keep up with all the different stuff you're coming up with. Wheeeuh !

 

I'm more interested in looking at what is, or can be, available in the here and now, and can be used to the benefit of many audio systems, modest or expensive. So, I'm going to try and focus on that goal and leave the invention of the Absolute Best Isolation Mechanism to others for the time being

 

Not that I've lost interest in which parameters in the ball and cup system seem to be more significant then others !

[4est]

I imagine the balls and cups are larger for a building sized set, as are the forces. The compression of the teflon coating would matter much less.

Yes, but if we want freer oscillation, doesn't friction damp it? So I was looking for a way to reduce that, but still keep the hardness aspect.

 

After reading on industrial seismic isolations of the ball and cup type, I saw at least one manufacturer mentioning Teflon.

[AnotherSpin]

Can you give us an idea

Why did you ask?

[jabbr]

I'm playing around with sandwiching: Look at this on eBay:

 

http://pages.ebay.com/link/?nav=item.view&alt=web&id=400809737864&globalID=EBAY-US

 

Self Adhesive Silicone Gel

 

In between an aluminum disc and double concave lens as base for a 1/2" ball bearing ... The other option is moon gel but they aren't exactly the right shape.

[YashN]

Yes, but, misunderstanding the phenomena is not very helpful

 

Which is why understanding is important, including the theory, different approaches, their implementation details. Misunderstanding is only part of the process of learning, and transforms into understanding with time.

 

I can't keep up with all the different stuff you're coming up with. Wheeeuh !

 

This path is fraught with frustration: don't even try to keep up with me. If I told you what I was thinking of yesterday on top of all this, you'd probably go insane.

 

 

So, I'm going to try and focus on that goal and leave the invention of the Absolute Best Isolation Mechanism to others for the time being

 

This, on the other hand is a misunderstanding: I'm not trying to come up with the absolute best. I am trying to come up with a deep understanding so that I can build the best I can do myself with limited means.

 

This is why the air-cushion and cup-and-ball arrangement as implemented by Barry and others is very interesting: it is really easy to start with sub-optimal materials just to test for audible effects and improve on that.

 

The deep understanding funnels effort and time into what should work better. If one day, time and budget allows, then perhaps I can do more sophisticated stuff.

 

The understanding is valuable even if I can't implement things in an ideal manner (I could write a book about that).

[YashN]

I imagine the balls and cups are larger for a building sized set, as are the forces. The compression of the teflon coating would matter much less.

 

They're much, much larger: about 70 sq. inches or so for the diameter of the sphere or similar object, judging approximately from a photograph.

[YashN]

I'm playing around with sandwiching: Look at this on eBay:

 

http://pages.ebay.com/link/?nav=item.view&alt=web&id=400809737864&globalID=EBAY-US

 

Self Adhesive Silicone Gel

 

In between an aluminum disc and double concave lens as base for a 1/2" ball bearing ... The other option is moon gel but they aren't exactly the right shape.

 

Very interesting idea about sandwiching the elastic material between two concave surfaces.

 

Silicone gel does great vibration isolation. I was thinking of using the silicone covers for iPads and iPhones, cutting them into shape and experimenting with those.

[kenreau]

Tossing out Herbie's Audio Lab products for cost effective consideration.

 

 

Per website info;

...They provide superb isolation and decoupling...Iso-Cups maintain a linear frequency response with full-bodied dynamics and texture, punctual bass, intricate highs, smooth dynamics with plenty of punch and detail. Isolates amplifier-borne vibrations from penetrating the audio rack to contaminate the sonic integrity of other components, and vice-versa.

Iso-Cup: Firm yet compliant silicone-based formulation holds 1" ball firmly in place; ball will not roll.

SuperSonic Hardball: Compressed composite of metallic powders, carbon microfibers and polymers, this proprietary 1" ball is formulated to achieve the most sonically neutral and linear results possible. With no discernible coloration or "character," SuperSonic Hardball, together with Iso-Cup base, is sonically more natural and lifelike than any of the hundreds of materials we've tested, including exotic ceramics and metal alloys, gemstones, polymers, high-performance plastics, and hardwoods. Provides fast, punctual dynamics with unsurpassed musicality and tonal realism.

 

Kenreau

[AnotherSpin]

Theories may sound nothing less than mind-blowing. Any comparison between practical solutions? Please no plastic egg-holders with wooden balls. Teflon? Until we are going to fry our brains.

[Daudio]

The string is about 6 feet long, this gives a very low frequency resonance which is very effective at isolating the speakers from everything else.

 

John,

 

What does it sound like when you pluck one of them ?

 

Both when quiet and music playing ?

 

[JohnSwenson]

John,

 

What does it sound like when you pluck one of them ?

 

Both when quiet and music playing ?

 

 

The strings are long without much tension on them so they resonate at a very low frequency. When not playing music it's very difficult to hear them, I have to put my ear right next to the string to hear it at all. When playing music they are completely masked by the music. Also I'm not in the habit of plucking the strings while listening to music. Although Alex kept on running into them when he was here. When the music has a really good string bass line I'm kind of tempted to get up and "play the strings" along with it, but have resisted the temptation so far.

 

John S.

[JohnSwenson]

As to Teflon, it has a fairly low friction when mated with some materials, and very low "sticktion" with others. In all cases the friction is orders of magnitude more resistance than what you get from a hard ball rolling on a hard surface. A ball rolling on Teflon will have much more resistance than when rolling on a hard surface.

 

John S.

[JohnSwenson]

Now on to the promised tome on vertical isolation.

 

Horizontal isolation is fairly easy to achieve, a pendulum or good implementation of the ball between hard surface does a good job of isolation down to low single digit Hz range.

 

But how do you do something equivalent in the vertical direction? There is this massive DC bias (weight due to gravity) that you have to somehow overcome. This is not easy.

 

Several years ago I was trying figure what a vertical isolator would do, ignoring for a moment any practical implementation details. What I came up with is a system that is stiff at DC but highly flexible at AC. This is exactly opposite to things like Sorbothane which are stiff at AC but soft at DC. All the "vibration damping" systems I could find had it all backwards.

 

So I asked this question on an internet forum, what material has a high spring constant at DC, but a low spring constant at AC? I was given the answer of a Euler spring (pronounced "Oiler"). This is not a material but a way of using common materials in an unusual way. It turns out it doesn't distinguish between DC and AC per se, but is a HIGHLY non-linear spring. As you increase the force on it the spring constant is extremely high, until you get to a specific threshold, then it transitions into a very low spring constant. This is EXACTLY what we want for vertical isolation. The system is set so the weight of what is being isolated just puts the Euler spring over the threshold into the very low spring constant range. Once you achieve this a very small force causes a large displacement, exactly the same thing as happens in the horizontal mode with the ball and shallow bowl.

 

So what IS a Euler spring? It is a rod or bar of material with the load applied right down the axis. It can be made out of many different materials, steel, brass, carbon fiber, all kinds of stuff. The trick is to arrange things so all the load is perfectly in line with the main axis, ie there is no "bending" force. In the literature this is commonly referred to as the "column". As the force on the column increases nothing happens at first, the material is basically incompressible. BUT at some point something gives, the column "buckles", it bends even though there is no "bending force" applied. This is the special zone. Now a small change in force causes a large increase in the buckling, causing a large displacement.

 

Most people will immediately think of several things wrong with this. First is "that has got to take a LOT of force to cause that to happen" maybe thousands of pounds. For a thick column, quite true. But it doesn't have to thick, take a very thin bar or rod and the buckling can start at very low forces. Then the next thought is, well it will just fall over! Yep, in order for this to work properly the column has to be constrained so the force is always applied completely axially to the column. Making a supporting structure that doesn't interfere with the basic operating principles has been one of the tough challenges with using Euler springs in actual useful situations.

 

The traditional implementation has been a pair of thin bars of metal (say an inch wide and very thin) constrained in such a way that when they start buckling they bulge out away from each other. This helps a lot with the stability, but is still pretty unstable and requires considerably more support structure. A common support is the top of each bar is connected to a long horizontal arm with a hinge at the other end. This keeps things in place and doesn't interfere too much with the operation of the spring. But it is large and cumbersome, not something you would want in your stereo system.

 

Recently (in the last couple years) a new configuration of a Euler spring has been invented which I personally think is going to revolutionize the whole concept of Euler springs and make them applicable to a much wider range of uses. This is the tetrahedral Euler spring. If you are not familiar with a tetrahedron it is essentially a three sided pyramid. The tetrahedron has four sides (a cube has 6), one as the base and three that make up the "sides" of the pyramid.

 

Think of a tetrahedron made out of very thin carbon fiber rods. Take such a structure and place one side on the ground, pointing up is a "point" of the tetrahedron. Now take three of these and place a platform on top of the three "points". It is a nice stable platform. Now start putting weight on the platform. At first nothing happens, but then as you reach the "critical force" the rods in the tetrahedrons start to buckle and the whole platform moves down an inch or so. Now a very small force applied to the platform causes it to move down. Because of the tetrahedral configuration the platform is stable, it doesn't "fall over" or wander all over the place, it just moves up and down. If you get the length and thickness of the rods right you can make the resonant frequency of the system quite low (sub hertz).

 

Now on top of the platform put the shallow bowl and ball bearing we have been talking about and you have a VERRY effective isolation system that works down to the low single digit Hertz range.

 

This generally tends to work better with longer rods, so I came up with a rack with six foot high tetrahedrons, from which are suspended strings holding up a shelf, so the system uses Euler springs for vertical and pendulum for horizontal. It would certainly be a conversation piece in your listening room! You could use these for speakers as well as equipment.

 

Note I have not built a tetrahedral Euler spring yet, my clients keep me too busy designing stuff for them.

 

I have done the traditional "leaf spring" version. These are really weird feeling things, you press down hard then it reaches the threshold and all of the sudden it is "squishy", it is a very bizarre feeling, there is nothing else in your experience that feels this way.

 

BTW the person that invented the tetrahedral Euler spring used them as a protection system for drones. A far cry from stereo systems.

 

John S.

[Jabs1542]

John - The tetrahedral Euler springs you talk about here are mostly for impact resistance., not steady state It will be interesting to see if you can harness one in its deformed state (low Hz) without getting into the plasticity limit of the material. The euler spring essentially takes the material past its elastic limit, the key is to keep it in that narrow range between the elastic limit and the plastic limit. And then there's plasticity creep.

 

Carbon fiber might be your material of choice, but it will depend on the laminates that make up the fiber mesh.

 

It would be very interesting to see what someone can come up with. If I get a little time this weekend I might do some FEA modeling using the tetrahedron.