Equipment isolation and vibration damping.

[sdolezalek]

Although this has been a fascinating thread, I wonder whether, like it seems most things in audio, we don't fully understand the physics we are dealing with. For that reason, I do support Barry's notion of "try it and if you like it keep it..."

 

But I also ask myself whether (with rollerblocks for example) the earth-borne vibration that we are trying to keep away from those speakers is a tiny fraction of the vibration that each sound puts into the frame of the same speaker? Just how much does a 30Hz bass note move that speaker on those bearings compared to an imperceptible shaking of the earth underneath them? And if the speaker moves on the bearings in response to the bass note, how much does that discolor the sound when it then has to return to its starting point? Is there such as thing as roller-bearing post ringing?

 

Further, since the speaker diaphrams move forward and backward, should we be coupling in the horizontal (to effect bracing/rigidity) but springing in the vertical? Which way do the waves of the tiny earthquakes move?

 

And as to box speakers, if you are trying to couple them to a heavy bass to lessen the ringing of the boxes themselves, how does that affect the sound compared to just internally bracing those speaker walls? Or packing them in a blanket, etc.? Is it like puttting your finger on a vibrating guitar string -- the vibration goes away but you have also changed the sound and not for the good?

 

Obviously, the fact that we are dealing with a "live" system in which the music being played constantly creates a new series of vibrations of different frequencies, it is much harder to tell what are beneficial and what are harmful effects (as compared with that box just standing still).

 

Please don't stop with the helpful and interesting posts, I just wish I (we) understood better both what we are really trying to accomplish and whether these tools actually do that.

[sdolezalek]

Hi sdolezalek,

 

With regard to driver motion from a speaker or sub on roller bearings, my experience has been that with a properly designed roller bearing (resonance in the very low single digits), the bearing does not "see" the speaker or sub. In other words, the expected Newtonian reaction to the driver motion does not happen -- or if it does, it is of such small magnitude as to be audibly insignificant. There is no cancellation of driver motion and no Doppler effect -- not of any significance as far as I can tell. What there *is* is an apparent complete freeing of the speaker (or sub or whatever the component) to perform its best, with the isolated device exhibiting clear, immediate, and obvious improvements in every area of audio (or video) that I know how to describe.

 

Thanks Barry. Yes, I remember seeing this somewhere in your writings and it was a concept that was both very interesting and made some sense. As I would interpret it, a roller bearing would have a frequency range at which its elasticity is maximal and there would be other ranges at which it would function with rigidity, with the idea being that the vibrations we are trying to keep out of the equipment are all at the subsonic (less than 10Hz) level. That, in turn raises two new questions:

 

1. Do we have any frequency plots or similar information for different roller bearings as to what frequencies they actually isolate?

 

2. Everyone seems very focused on creating a very smooth and hard surface for both the bearing and the cup, but what about the contact with the equipment -- does that also need to permit free movement of the ball bearing to be effective?

[sdolezalek]

Humor me, because I am in no way a DIYer, but is there a reason why something like the drawing below couldn't work (using magnetic levitation but without the stabilizer bars that Barry correctly describes as carrying the vibration up the platform)? The idea is that by tilting up an edge around the perimeter of the platform you create both a centering as well as a lifting magnetc force, thereby theoretically giving more than just horizontal or vertical isolation.

 

I can think of two issues: (i) is the magnetic disturbance caused by this worse than the vibration cured; and (ii) would these have to be electromagnets so that the device wouldn't fade over time (which I assume is a problem for the design shown in the video)? Lastly, Barry: I'll need to do more reading on Earnshaw's levitation work to see whether, if using electromagnets, this would run afoul of his work.

 

Anyway, more food for thought.

[sdolezalek]

https://en.wikipedia.org/wiki/Earnshaw%27s_theorem

 

Earnshaw's theorem proves that using only paramagnetic materials (such as ferromagnetic iron) it is impossible for a static system to stably levitate against gravity.

 

For example, the simplest example of lift with two simple dipole magnets repelling is highly unstable, since the top magnet can slide sideways, or flip over, and it turns out that no configuration of magnets can produce stability.

 

However, servomechanisms, the use of diamagnetic materials, superconduction, or systems involving eddy currents allow stability to be achieved.

 

In some cases the lifting force is provided by magnetic levitation, but stability is provided by a mechanical support bearing little load. This is termed pseudo-levitation.

 

Pseudo levitation is what the video up thread shows and is why the two little posts are needed to keep things in place. I wouldn't be worried by those little posts as they can be made to not corrupt the action much. I still would worry about the magnetic fields myself.

 

This is why it is good that we have really smart people on this site! ;-)) I assumed that with regular magnets the platter would just spin rotationally until it was no longer "levitating" but thought that maybe there might be a fix with electromagnets. Fully agree about the magnetic field concern.

 

Oh well, back to bowls and balls it is...

[sdolezalek]

To the extent that any of these must bear a certain amount of weight over a given surface area size, isn't the "resonant frequency" ultimately determined by the weight of the device plus the platform? In other words, a lighter weight can use a less inflated tube, therefore a springier, lower resonance. A heavier weight object will put more pressure on the tube, thereby raising the effective air pressure and the resonant frequency. Obviously you can increase the size of the tube only so much...

 

Am I missing something?

[sdolezalek]

This topic just seems to be begging for a viable $100-$150/component type of solution. But all of the commercial solutions are priced more like high-end cables and seem even less able to justify exactly what drives those product costs. Of course there are also literally a dozen or more pages of isolation feet offered on eBay (mostly made in China and at a broad range of prices, with the "mag-lev isolators being particularly popular). See the picture below for some of what is on offer:

 

 

That being said, the individual parts list shouldn't be that expensive: a) very high quality bearings, b) high polish machined cups, and 3) something to contain the cups and bearings. Per Barry Diament's designs you probably want to complement that with some up and down vibration attenuation (like his innertubes).

 

When I look at pictures such as those Theophile posted, the combination of high cost (for the large quantity of ClearAudio feet for one turntable alone) plus the DIY look of the rest of it, I know we can do better.

 

Maybe Barry D will offer us a "productized" and affordable version of his design that enough of us will buy in volume to be producible at an attractive cost?

[sdolezalek]

It would be great if this thread could actually clarify what exactly we are trying to accomplish with isolation and damping:

a) keeping environmental resonances from reaching our equipment (if so what frequencies are we trying to keep out?)

b) draining vibrations and resonances existing in our equipment out of the equipment (same question re relevant frequencies)

c) isolation in all directions or coupling in vertical and isolation in horizontal?

d) what are the actual resonant frequencies of the materials/equipment we are trying to use for this (for example what frequencies are drained by sorbothane, versus an airtube, versus stillpoints footers, for example?)

 

There are lots of interesting approaches and even more manufactuer/user comments about how great this or that solution is, but very little in the way of science that links the problem (what resonances are we trying to kill) to the solution (what resonances does your device actually absorb, drain, isolate from).

 

I have read Barry Diament's good posts on this, as well as those from a dozen or more manufacturers, but even the best are short on identifying specific resonances and none I have seen dared to show a before and after measurement that actually reflected real isolation.

[sdolezalek]

Well, not really. There is one manufacturer that shows actual measurements. Solid Tech Tech Talk | Solid Tech

See the PDF dokument in the bottom of the page. [/url]

 

Thank you. I had not seen these before. The measurements shown do suggest these are having an isolation effect at 50Hz and 70Hz but I have to admit that I'm at a loss to understand how fairly heavy looking metal springs can provide isolation at frequencies that would seem to be far below the resonance frequency of those springs. None of the reviews I found on-line provided any further enlightenment.

[sdolezalek]

Every few months this topic appears here and on *every* other audio forum. And a misunderstanding of kinematics is the root of it, as well as a vast waste of money and effort. I'm no genius with physics, for example I struggle to describe *exactly* what squishy materials like sorbothane do. Barry Diament, John Swenson, and some others have a solid grasp of the problem. But many vendors spew nonsense in the guise of some esoteric action.

 

Sam: Thank you for the extremely detailed and well explained posts. The one part you didn't address, but that Barry frequently mentions, is isolating your speakers and other components from environmental oscillations and vibrations. In fact, I think Barry suggests that it is these, rather than vibrations produced by the equipment itself, that need to be controlled. If that is true, then presumably those environmental vibrations must be large enough to move the whole house, floor, cabinet, etc. no matter how massive or heavy it is. His roller bearing approach would seem to provide effective isolation at least in the horizontal direction to such vibrations and I suppose the frequency of those vibrations would determine the extent to which inner tubes solve that problem in the vertical direction. Do you have a view on the degree to which the problem that really needs to be solved is equipment based versus environment based?

[sdolezalek]

Thanks.

BnW had their famous matrix design of a heavily braced cabinet.

It's a pity we can't compare measurements and listening impressions of the same design with different cabinet construction...

 

I still think Magico is king when it comes to over-the-top cabinet bracing...

 

 

Of course it begs the question of whether the resulting box then needs to be equally rigidly tied to the room or "floated" in space...

[sdolezalek]

The spiking will transmit seismic vibrations to the speakers though.

 

So living a few hundred yards from the San Andreas fault line, I'm pretty sure my listening pleasure will be adversely affected when "the big" one strikes; but, exactly what seismic frequences and of what magnitide are we actually trying to protect speakers and equipment from on an everyday basis?

[sdolezalek]

sdol,

The stylus tip traces the musical signal inscribed in the record groove, which can contain modulations as small as a millionth of an inch.

 

At these tiny dimensional figures even very tiny vibrations become antagonistic to retrieval of the full measure of what is in the groove. Here is a primer on how these tiny vibrations interfere with retrieval of minutely dimensioned information in the Scientific realm.

 

Although I use a digital rather than phonograph-based front-end for my system, your example is still quite useful because I assume that at the exact opposite end of the musical chain (the loudspeaker), the amount of physical space that a tweeter moves is equally microscopic and certainly smaller than the degree of seismic movement felt in most buildings. Given that in most speakers that movement is in the horizontal (front-to-back) direction, I wonder whether that also is the reason why the cup and ball and similar systems that couple vertically but are highly compliant at relevant frequencies in the horizontal direction, produce better results than soft footers which are vertically compliant but can never stop horizontal vibrations of the type that could counteract the movement of a speaker cone?