Vibration Air & Roller Bearings - Thanks to Barry & Warren

[jabbr]

20 minutes ago, Audiophile Neuroscience said:

 

Well some compromises need to be made. I also gave up on wearing those full body contamination suits as it went against the audiophile's creed that one must sit naked while listening to music.. The bass waves resonate certain jiggly bits of anatomy and improve SQ !

 

Heigthening the importance of vibration isolation so that when you, err, dance, the standing waves don't damage your DAC ?

[Audiophile Neuroscience]

26 minutes ago, Ralf11 said:

http://newatlas.com/subpac-m2-wearable-audio/39920/

 

 

Just ordered mine. Best results are obtained sitting on it (naked of course).

[AnotherSpin]

3 hours ago, Audiophile Neuroscience said:

 

My intuition and limited experience is that this whole approach most likely works best for smaller, lower mass/weight equipment, especially in relation to air bearings.

 

I would compare my practical experience with your intuition. In my system best effect was achieved by using bearings under heaviest components (speakers). Bearings under light items also made good impact but not so much "hearable".

[fas42]

Local audio friend also did the roller bearings under speaker thing - it didn't do it for me. Something was lost, a "tightness" to the sound went missing - good test material is Boney M, there's a gutwrenching wallop to the bass line which mega speakers get completely wrong - and his did too on these.

 

My approach is to effectively "concrete" the speakers to the ground, for best results.

[rando]

Glad I dug into the previous thread more readily tonight.  Pages 11-25 had a lot more interesting developments.  Hopefully AnotherSpin and jabbr will still be hanging around in here when I finally finish compiling my thoughts on two separate college dissertations and a growing pile of papers.       

[Audiophile Neuroscience]

2 hours ago, AnotherSpin said:

In my system best effect was achieved by using bearings under heaviest components (speakers).

 

What size were your roller bearings and cups?

[AnotherSpin]

2 hours ago, Audiophile Neuroscience said:

 

What size were your roller bearings and cups?

 

Did I post the pictures in old thread? 

 

I do not use cups/bearings anymore, but should have it somewhere. Cups were about 5 cm outer diameter, I guess.

[Audiophile Neuroscience]

Just some additional thoughts about damping,isolation, and resonance.

 

These are tricky concepts (for me) to truly understand and their inter-relationship. I may have used "damping" in a way that suggested it was desirable, basically meaning any sort of thing that reduces the effect of vibration.

 

Damping and isolation can both be used to manage vibration but they have different meanings and in the context we are talking about, damping is not desirable.

 

As Barry puts it "It is not desirable for an isolator to provide damping too.

To be clear, there is an inverse relationship between the degree of damping and the degree of isolation.  That is, the greater the damping on isolator motion, the *less* steep the rolloff (i.e. the less isolation) above the isolator’s resonance.  In the case of a roller bearing like a Hip Joint, we want the ball to roll as slowly as possible (lowest resonance frequency) and to continue to roll for as long as possible (*least* amount of damping for steepest rolloff above resonance).  Similarly with an air bearing, the more supple the material, the less damping on the bearings’ isolation."

 

To quote another engineer

Isolation is a reduction in the ability of a system to react to an excitation. This is achieved by the use of a flexible decoupling element between the equipment and mounting surface. It allows the inertia of the isolated component to oppose and thereby reduce the vibratory motion transmitted to the support.

 

Damping removes energy from a system by converting kinetic energy into heat energy (in the case of conventional shock absorbers, for example)

 

Every isolator has a peak resonant frequency below which transmissibility is almost unity and above which attenuation occurs. However, should the natural frequency of an isolated system coincide with the forcing frequency then resonance will occur i.e. amplification of vibrations. In this case, damping is required to reduce the amplitude of the resonant response by removing energy from the system.

 

The ideal isolator would have as little damping as possible in its isolation region and as much as possible at the systems natural frequency to reduce amplification at resonance – this is clearly not possible with standard damping systems.
If there is no resonance present in the important operating frequencies of a system then damping can actually make things worse as it leads to a loss of isolation efficiency. The damper will act somewhat like a strut and vibrations are then transmitted to the isolated element. For example rubber is not an ideal isolator as it not only has isolation properties but also some damping properties inherent to the material. This can increase the transmission of non-resonant vibrations.

 

 

[rando]

I'm amazed at all the crazy ideas people have tried to better what BD settled on over a decade ago.  Too bad nobody else has ever used his full Enjoyyourshelf© rack to compare it with their own system.

 

 

[JohnSwenson]

I recently moved into a new house and JUST got the system up and running in the listening room. (no acoustic tweaking yet, but I HAD to have some music after 6 months without any). A major part of this was to use roller bearings on almost everything.

 

I tried some DIY versions many years ago and eventually stopped using them because of inconvenience, cables would pull things around etc.

 

The new system does it a bit differently which makes a big difference. I bought two sets of level two blocks from Ingress Engineering, these are designed to be used with blocks on top and bottom, but I much prefer to use them block on the bottom and flat surface on the top. My original approach was to put each component on its own set of bearings, but this time I did it differently, I put 1/2" thick aluminum slabs on top of the bearings. On the bottom of the slabs I glued stainless steel "camping" mirrors. These are small rectangles of metal that are highly polished (to make a mirror), they are great as a rolling surface for the bearings. (the ones I like best are from Hobby Tool Supply, model 220R7, I bought mine on Amazon)

 

The components sit on top of the aluminum plate using their normal "feet". The aluminum is special for this purpose, I found it is much better than anything else I tried. It actually has a fair amount of internal damping, which prevents internal acoustic wave from forming. And it is very stiff, which prevents bending from forming acoustic resonances. This leaves surface acoustic waves, which are a big problem. A slab of this stuff will ring like a bell from standing waves forming on the surface. Fortunately it is very easy to disrupt these waves. Just placing the slab on the bearings disturbs the standing waves enough that they do not form, so the bottom doesn't ring, placing any object on the top does does the same thing as well. The result is a very simple non-resonant platform. You can take a metal rod and hit the plate, you just get a soft "tink" out of it, much lower resonance than any other platform I tried. The aluminum is also a very effective electric AND magnetic shield.

 

The big heavy platform completely changes things, it still has a very low resonant frequency, but cables don't seem to make any difference any more. Turning knobs have barely any difference in feel from normal operation.

 

Now this does NOT have any vertical isolation, it is just horizontal. I don't like the inner tube approach so I have been trying to come up with a good solution for about a decade. The requirements are interesting: a low spring constant to produce a low frequency resonance, but this means that the weight would just flatten the springs. A spring with a high enough spring constant to support the weight has way too high a resonance. You want something that is stiff at DC (to support the weight) and soft as you go up (up being 1Hz and up). Viscoelestic is the opposite, soft at DC and gets stiff as frequency goes up.

 

As has been mentioned Euler springs do exactly this (look it up if you want to know how they work) but are very "fidly". I tried building a system with them and it was a pain in the neck getting them to work right. I gave up after working a couple years with them.

 

I have come up with what I THINK will work well, the DC offset part is handled by constant force springs. This is a coil of flat metal strip which takes a constant force to unroll it. This scheme is used in the common metal "tape measure". These springs can be made as very precision devices available in a very wide variety of forces.

 

The idea is to have a platform suspended from constant force springs at the corners, with the rating of the four springs set to just a little less than the total weight of platform and what is on it. As is this would just unroll the springs until platform hit the bottom. To fix this you add some normal compression springs under the platform, but these have very low spring constant, they just have to support the "left over" weight. The result is a very low resonance frequency, just what we want.

 

Unfortunately this produces a platform that doesn't just go up and down, it wobbles all over the place. To fix that you need to constrain the platform. I haven't tried this, but it seems to me the best way to do this is have vertical polished steel shafts at the corners, with good quality linear bearings on the shafts. The platform is suspended from the linear bearings. The constant force springs are suspended from the top of the shafts down to the platform. Regular springs sit under the platform. This should give a constrained motion, just up and down, with very low friction.

 

For example lets say your platform and components weigh 50 pounds, you use four 12 pound constant force springs which support 48 pounds of the load. The compression  springs just have to support two pounds, so they are "wimpy" springs which have a low resonant frequency.

 

On top of THIS platform you add the roller bearing and platform as described above, and there you have it, an isolation solution that works extremely well, is not particularly "floppy", you don't have to use extremely flexible cables etc.

 

Unfortunately I can't build this right now, all my construction tools are in storage until I get a new shop building built at the new place. It is probably going to be next summer before that happens.

 

So, anybody want to try this?

 

John S.

 

 

[jabbr]

30 minutes ago, JohnSwenson said:

So, anybody want to try this?

 

Hi John, interesting approach. Do you think the steel wire based isolator might have a non-linear/Euler like effect if the steel wires were sufficiently narrow & loaded?

[rando]

Nothing is beyond the realm of possibility however I'm having a slightly hard time picturing your idea John.  I do have to ask if you have done the scribbling surface treatment suggested in the former thread to the top of your aluminum shelf to eliminate ringing?

 

I came across this company's flagship rack under review today along the announcement of their partnership with TAD to design and supply custom racks and speaker stands for the company itself, their dealers, and their customers.  Some interesting stuff going on in the Trio/BBS rack

 

[Ralf11]

for less than 3,800 euros you can find actual low vibration stands made for lab use

[Audiophile Neuroscience]

20 minutes ago, rando said:

Some interesting stuff going on in the Trio/BBS rack

 

from their website, " spike point support (contact area has been minimized and kinetic energy turns into heat) have been combined with the effects of deadening vibrations owing to to sliding friction and rolling resistance. "

Resistance and friction doesn't sound right to me as achieving isolation but I could be wrong!

[fas42]

Man, this is all too hard, - truly effective isolation is so, so much harder to get right than taming the impact of vibrational energy where it actually does the damage ... ultimately, there is some part or parts of the system which are too sensitive to vibration - the further away from the sensitive souls you are when trying to appease them, the harder it's gonna be ...

[Audiophile Neuroscience]

32 minutes ago, rando said:

I'm having a slightly hard time picturing your idea John.

 

As am I. In my case, it's a 'it's me not you' kinda problem.

 

To be honest I also stared at the descriptions on Ingress engineering and for the life of me I do not get what "blocks" are and what goes on *top* of a device. The "footers" appear to be just the 'cup' part of a roller bearing. Most pictures seem to show 'cups' and ball bearings .

[rando]

Ralf, I neglected to import their pricing scheme so we could focus on how they implemented the isolation.  The idea of using self lubricating polymer caps on cones with carbon fiber shafts as bearings in particular.  The curvature of their metal dishes look quite steep  as well.  Actually it uses a few ideas I was kicking around to simplify the amount of pieces and microscopic wear.

 

AN, John's idea could be executed a few ways.  I was asking for clarification of how he theoretically saw this going together.  There are at least a few clever mechanical advantages that could be harnessed if they failed to disrupt the primary purpose.

[JohnSwenson]

42 minutes ago, rando said:

Nothing is beyond the realm of possibility however I'm having a slightly hard time picturing your idea John.  I do have to ask if you have done the scribbling surface treatment suggested in the former thread to the top of your aluminum shelf to eliminate ringing?

 

I came across this company's flagship rack under review today along the announcement of their partnership with TAD to design and supply custom racks and speaker stands for the company itself, their dealers, and their customers.  Some interesting stuff going on in the Trio/BBS rack

 

It turns out the scribing stuff is unnecessary, just having the balls touch the bottom of the slab, and the components touch the top is enough the disrupt the standing wave. They don't "damp" them, they just disrupt the travel enough that there is not enough energy traveling in the proper direction to sustain a standing wave. Kind of like a laser if the mirrors are not exactly aligned properly.

 

Those racks are another form of damping vibrations. They can be effective for some ranges of vibrations and not for others. As has been talked about previously the way to isolate one system from another is to have a system resonance significantly below the frequency of vibrations. This is hard to do, so many other forms of damping systems have been tried. Frequently designers get these concepts confused and don't really implement them correctly resulting in isolation that is not as good as it could be.

 

All this roller bearing stuff is aimed at providing isolation down to very low frequencies, in the single digit Hz range. Systems like this rack are useless for this sort of thing. They may be effective for preventing stuff hundreds or thousands of Hz range being generated by one component from getting to another.

 

John S.

[asdf1000]

1 minute ago, JohnSwenson said:

All this roller bearing stuff is aimed at providing isolation down to very low frequencies, in the single digit Hz range. Systems like this rack are useless for this sort of thing. They may be effective for preventing stuff hundreds or thousands of Hz range being generated by one component from getting to another.

 

Hi John, I'm going to get laughed at for this question, but are even 10mm thick sortbothane sheets  ineffective compared to this roller bearing stuff?

 

[JohnSwenson]

31 minutes ago, Audiophile Neuroscience said:

 

As am I. In my case, it's a 'it's me not you' kinda problem.

 

To be honest I also stared at the descriptions on Ingress engineering and for the life of me I do not get what "blocks" are and what goes on *top* of a device. The "footers" appear to be just the 'cup' part of a roller bearing. Most pictures seem to show 'cups' and ball bearings .

The level 2 system consists of two "blocks" per support location. Each block has a highly polished spherical depression. You put a ball in the depression, and put another block upside down on top. The level 2 ones take a 3/8" ball. The top one just flops around on top of the ball until you put something on top of a set of three. The top block then "levels out" on the under side surface of the supported device. As the blocks move relative to each other the ball is rolling between the the two curved surfaces.

 

This particular system has a very small amount of play, so as you turn knobs, push buttons etc, it can't move very far which doesn't feel too wobbly. The isolation is still effective because the actual displacement for real seismic noise is VERY small.

 

I prefer to use them with a flat plate on the top, this halves the resonant frequency, which is good for isolation, but it allows for more motion when your hand is moving things.

 

A set of level 2 supports contains 6 blocks, using two for each support location (assumed to be a triangle), with a single ball for each set of two.

 

When I got mine they did not come with balls, I ordered some from McMaster Carr. I got both 1/4" and 3/8" chrome steel balls, for the two block approach it has to be the 3/8, for the flat top approach either works but I preferred the 1/4".

 

When going with the flat top you only need one block per location so you can do two platforms for the price of one!

 

John S.

[JohnSwenson]

14 minutes ago, Em2016 said:

 

Hi John, I'm going to get laughed at for this question, but are even 10mm thick sortbothane sheets  ineffective compared to this roller bearing stuff?

 

Sorbothane has exactly the wrong properties for this. It is designed to be squishy at low frequencies and stiff at high frequencies, which might be appropriate for some applications, but is useless for this.

 

John S.

[JohnSwenson]

1 hour ago, jabbr said:

 

Hi John, interesting approach. Do you think the steel wire based isolator might have a non-linear/Euler like effect if the steel wires were sufficiently narrow & loaded?

I looked at the wire devices a couple years ago, as far as I remember they are in the damper category, as the top plate moves is causes the wires to twist, causing strand to strand movement dissipating movement as heat.

 

John S.

[asdf1000]

4 minutes ago, JohnSwenson said:

Sorbothane has exactly the wrong properties for this.

Ha thanks. Time for me to start over and go through all of your posts on the topic.

[Ralf11]

There are dat a sheets for Sorbothane posted somewhere on the internet

 

 

What I am looking for is some cheap, easy to obtain smooth cups...

[jabbr]

11 minutes ago, JohnSwenson said:

I looked at the wire devices a couple years ago, as far as I remember they are in the damper category, as the top plate moves is causes the wires to twist, causing strand to strand movement dissipating movement as heat.

 

John S.

 

Yeah the military/aircraft ones are very stiff.  The video I referenced above looks less stiff. I was considering drilling some holes into a block and inserting narrow carbon fiber tubes into a similar arrangement. If the tubes are bent to a "C" shape they should be in the nonlinear region?