Understanding Vibration control

The following is the result of decades of research, testing, questioning, and listening. This is based on actual hands-on (and ears-on) experience and results.

Cable elevators have been around for a very long time now. There are a lot of different versions from many manufacturers, not to mention all the DIY versions people are using. No wonder, they really do work. The question is, Why?

That is indeed the question. One perfectly reasonable answer is, Who cares? As long as it works, do it, and let others puzzle why. One problem with this is, there are a lot of different products out there, and yet damn few comparative reviews. In the absence of listening evaluations all we have to go by is design. With no idea what is going on? Might as well throw a dart.

So it is that for 30 years, at least, Millercarbon has been wondering, tinkering, and testing. This section of the site is devoted to understanding high end audio. Let’s get to it!

There are in this universe of ours four forces that act at a distance: strong nuclear, weak nuclear, gravity, and electromagnetism. The strong and weak nuclear forces are incredibly powerful but act on such a small scale they are only a factor within the atomic nucleus. Gravity is so weak it is a factor only with massive bodies, like millions of times the mass of a speaker cable.

This leaves electromagnetism. The reason it is all one word, electromagnetism, is because they go together. Run a current through a wire, generate a magnetic field. Cross a wire with a magnetic field, generate a current in the wire. Everything from transformers to generators and motors, phono cartridges (both MM and MC) and more, all rely on this same property of electromagnetism. We could be onto something here.

Even within electromagnetism however there’s still a number of different things it could be. The two most often thrown out there are static charges, and dielectric discharge. 

Static charges do indeed mess with the audio signal. This is easily demonstrated by spraying a little Static Guard over cables. This neutralizes static charges and does indeed improve clarity. How much of course will vary depending on your system’s resolution, listening skills, and of course how bad a problem you have with static in the first place. Regardless, the effect is there and must be considered.

If cable elevators work by minimizing static charges then there should be little to no improvement compared with eliminating static charges with Static Guard. This is demonstrably not the case. Scratch static off the list.

Dielectric discharge then? Dielectric is a fancy word for insulator. No insulator is perfect. They all absorb a little bit of the magnetic field energy, and then bleed this back into the signal again. This is why different insulators sound different, they absorb and bleed at different rates. This is a factor in the time it takes for cables to burn in. As time goes by the insulator saturates and desaturates until reaching a state of equilibrium. 

Okay, so if this is it, then what? Well then the idea is nylon carpet is a lousy insulator, it bleeds and smears a lot, and so getting cables up off the floor and away from all that is why cable elevators work. 

Only problem, they work pretty much the same regardless of what type of floor, carpet, wood, tile, all pretty much the same.

All the really good candidates are shot through with holes. In order to be sure however we had to test a lot of these to see if what we hear agrees with what we think might be going on. So far, in every case, it does not. Are we beginning to understand why figuring this out took us so long?

There’s one more we haven’t discussed, because no one else ever talks about it, even though it seems to work with everything else: vibration.

But first, more electromagnetism! With electricity we like to use the metaphor of current being like water in a hose. Works for a lot of things, but not this one. Mainly because while we call it a current, the thing that flows is not so much a particle as a charge.

Electrons carry negative charge. Current propagates much the way “the wave” propagates around a stadium. We’ve all seen it. The people don’t actually run around the stadium. When the people on one side stand up then you do too, and sit down. This way the people standing up runs around the stadium. When electrons at one end of a wire "see" the ones next to em standing up then they stand up too. Only electrons are way faster than us. They do this so fast electricity seems to flow at near the speed of light. Even though, again, hardly any electrons go anywhere. Mostly they just transfer charge, one to the next. 

Are you with me? Okay, hang in there, because from here on in things get real interesting real fast.

The difference between electrons and people is while we see and move, they actually push against each other. The “push” is electromagnetism. Remember: the physical force that acts at a distance. Which wouldn’t mean much, electrons are super low mass. But they are strongly attracted to the protons at the center of the atom, and protons are bound to neutrons (the weak and strong nuclear forces, remember?) and THEY are super massive! The nucleus is where the mass is. Yet puny electrons are so powerful they are what determines where atoms go. The tail wags the dog. Go figure.

Anyway, bottom line, the very same electricity that we think of as ephemeral, without mass or form, in a way has a lot of both. Jostle electrons, you jostle the whole atom. It is all one inextricably bound thing. (Atom by the way is a combination of “a” not, and “tomos” cut. Cannot be cut. Smallest thing there is that retains the properties of the thing. Atom.)

All well and good. But here in Millercarbon land we don’t like to take anyone’s word for anything. We like to test, to verify.

Simple enough. Play some music with powerful bass, feel your speaker cables. Our experience is this varies a lot depending on the type of cable and other factors. Not the point. All we need is one positive example to validate. It was shocking how much our Synergistic Element CTS cables vibrated in this test! So much so the reasoning goes, if you don’t feel it doesn’t mean it isn’t happening, but rather more likely just below the level you can feel. Think about it. You wouldn’t think there’d be any. To even feel it at all there must be quite a lot.

Okay so now we have signal causing speaker cables to vibrate. This puts them in the same category as amps, CDP, DACs and more, all of which are markedly improved by vibration control. This puts cable elevators in the category of vibration control devices.

Having eliminated all the contenders what we are left with must, however unlikely, be the one. Speaker elevators work by means of vibration control. Raising cables off the floor greatly reduces the surface area of the cable interacting with the floor. That simple.

Only one problem: none of the cable elevators currently on the market are designed with vibration control in mind. They are all based on the mistaken assumption it must be height above the floor, when really getting them off the floor is only one very small part of the problem.

As unlikely as it might seem, experience shows a significant amount of vibration comes from the component itself. Yes even with something as seemingly inert as cables. Testing proves it.

Over the years- decades, really- all kinds of vibration control methods have been tried. Heavy, dead mass loading, sharp pointy spiky things, globs of goo, constrained layer laminates, composites, on and on. All of these affect the sound in various ways. A lot of crazy theories have been advanced to sell them, like the idea of a spike acting like a diode that like a diode passes vibration one way and not the other. As if.

Back to physics. Vibration is a wave. Waves move through different materials at different speeds. When a wave reaches a break in the material- could be where the stuff ends, or where it connects to something different- then that wave is reflected back where it came from, refracted off in another direction, or diffracted (ie reflected off in different directions), or absorbed and dissipated as heat energy. 

This is pretty much what happens with all waves, be they vibrations in materials or air. Happens with electrical vibrations too- the music signal in the wire. Happens with sound in the room. Same general idea, all of it.

Knowing this then it should be clear all the different cones and stiff or squishy things are merely channeling or tuning the resonance of all these different vibrations. Something soft like an Owens Corning 703 fiberglass panel (used in many acoustic panels) will affect sound waves by absorbing, converting acoustic energy to heat. This only works at certain frequencies however. This is why bass panels must be so large. Bass waves are low frequency and very long wavelength. They can only be absorbed by proportionately  large panels. 

Another thing to keep in mind, different materials behave differently at different frequencies. Put your hand in water, it feels very soft. Jump off a bridge into water, die from the sudden impact. The typical rubber turntable belt feels very soft and pliable. Mark Baker of Origin Live has done testing that shows that at 5 kHz these same belts are not compliant at all. They react to vibrations at 5kHz quite differently than at 60 Hz. 

When the vibrational damping or compliance changes with frequency this has the effect of tuning or channeling sound from one band to another. This emphasis/de-emphasis more than any other single factor accounts for the differences we hear between different vibration control devices.

This is why there are so many different approaches. This is also why a lot of them combine different methods. Roller balls combined with different materials, each one skewed one way or another, with the hope that all together will balance out. We could name names. But we won’t.

A spring on the other hand, assuming the stiffness of the spring is tuned to the mass of the component, then what happens is the vibrational energy is dissipated flexing the spring. It never really reaches the other end, and so there is no reflection. 

This is far from perfect. Vibrations aren’t actively stopped. They are however allowed to dissipate as fast as possible. This in itself is a huge advantage over all the other methods.

Even with springs there remains one more thing that needs to be done. Springs bounce. This bouncing is resonant behavior. If the spring is stiff it will bounce fast. If soft it will bounce slow. Either way it will bounce, and this resonant frequency will be imparted, even if only in part, to a sonic signature imposed on our music.

This is another one that can easily be tested and confirmed. Nobsound springs are designed to use up to 7 small springs per footer. They are cheap, effective, and easy to use and experiment with. 

Changing the number of springs per footer is easily heard to change the sound. Too many springs, they are too stiff, and the sound is fast and extended, but light in the bottom end. Too few, the footer is too compressed and the sound is rolled off and bloated. Somewhere in between is just right, and the sound is balanced and greatly improved compared to just about anything else.

Anything other than properly damped springs, that is. Townshend Audio perfected this with their ingenious bellows air damping system they call Seismic Load Cells used in their Pods and Podiums. These are optimally damped to eliminate resonant coloration while still allowing vibrations to be effectively dissipated by the springs.  

This is the highest level of isolation currently available, without going to extreme (read, tremendously expensive) lengths. 

Millercarbon developed Cable Isolators to apply all the advantages of properly damped springs to cable isolation. To do so properly the isolator must be designed to allow the cable to move freely in all planes, with just a small amount of damping to control resonance. This proved to be nowhere near so easy as with other components!

Normal cable elevators are able to achieve a degree of isolation only because the cable is held up off the floor. This reduces ringing.  When on the floor any cable (or floor) vibration is transmitted one to the other and back again. This results in ringing- cable vibrates floor, floor in turn reflects back to cable, and back and forth the cycle goes until the energy is slowly dissipated from the system.

A video of ringing recorded on a iPad seismograph can be seen here: 

https://youtu.be/dW9-r83IvhI?t=34

This video is demonstrating speakers on Podiums, but the concept is exactly the same for speaker cables. In both cases the spring isolates, breaking the cycle of ringing. This ringing is very clear to see on the seismograph trace. Same exact thing happens with speaker cables!

The trick is to design a spring isolation system that will suspend speaker cables while at the same time allowing full freedom of movement in all axes and planes and with just the right small amount of damping to prevent resonance from coloring the sound.

The ingenious design shown to the right does exactly this. The cable is free to move and dissipate vibration equally in all planes. Constrained layer construction combined with elastomer achieves optimal damping for a smooth uniform response across the frequency range. The result is impressive and easy to hear. 

What is High End Audio, anyway? Is it expensive? Is it exclusivity? The truth is there are as many opinions as there are audiophiles.

The surest definition is the difference between high end audio and any other stereo has to do with the focus of the system being on playing music capable of capturing your full attention and carrying you away, lost in your music. By this definition it is possible to have a true high end system that costs peanuts, and also equally possible to spend thousands and have little more than a big loud stereo. And yet, if that is what carries you away lost in your music then even this is high end, for you. 

Which in the end is all that counts. Unless that is you are doing this to attract a paying audience, or have a significant other to please. For most of us however few things will help more than to know there really is only one who ever gets to decide what is high end, and pleasing, and that is you.

Even so, this still leaves a lot of challenges. The classic one being, what about these speakers? A huge part of being carried away is being able to recreate a believable sound stage. This is all but impossible to do without the freedom to place the speakers where they need to go. A luxury few of us possess. Inevitably then a high end system will almost always involve compromise. Lots and lots of compromise.

The key to high end audio is when push comes to shove the designer leans music and sound quality and not features and cosmetics. In the same way the high end audiophile strives wherever possible to side with sound quality and musical satisfaction over convenience.

A dark subject, needlessly complicated.

Speaker placement is one of the easiest ways to get a big improvement with only a little time and without spending any money. The key is in understanding a few simple concepts. This is made even more important by the fact most all of us have some sort of limitations on where the speakers can go- and equally important, where we can sit when we listen! Our goal here is to learn enough so anyone can get the most from their own particular situation, whatever that may be.

Before we begin, and as always, it will help to keep in mind the words of the great audio philosopher Harry Callahan, “A man’s got to know his limitations.”

Nothing ever is perfect, nor will it be, especially not in our case where the physics of sound and room impose a lot of not so easily overcome limitations. To see what I mean, and for extra credit, study this paper http://www.gedlee.com/Papers/multiple%20subs.pdf  You don’t have to read far to find: "All rooms of equivalent volume, regardless of shape will have the exact same first mode.”

To fully explore and understand this one simple statement is beyond the scope of this freshman level introductory course. Patience. We will get there. What it means for now is, relax. Your room is not all that unusual. They are in certain regards all pretty much the same, and so you might as well relax and learn to distinguish what you can easily do from the near impossible, and content yourself, at least for now, with the low hanging fruit.

Are you with me? Okay. Here we go.

There are three main factors that have a huge impact on what you hear from your speakers: wall reinforcement, symmetry, and early reflections.

These same three factors are equally as important with respect to where you sit to listen!

So if, for example, you are sitting on a sofa right up against a wall where there is a lot of bass reinforcement, don’t get upset when no amount of speaker moving changes this. Instead, to the extent you can, change where you sit. Where you sit and where your speakers go are two sides of the same coin.

The next thing to keep in mind is wall reinforcement is not just walls but any large flat surface. Something easily demonstrated, probably right now while reading this. Play some music on your laptop sitting on the desk or table. Now raise the laptop up. Notice how the sound changed? Even a few inches has a big effect. Same with your speakers. A big bookshelf or wide flat rack of gear is functionally, as far as sound waves are concerned, a wall.

And now, here is how to use the main characteristics of speaker/room interactions to methodically work through and arrive at an optimal solution for speaker/listener placement. The process involves working through three main phases to optimize in turn tone, image focus, and soundstage width and depth.

Tone, or frequency response, is a function of where the speakers, as well as listening position, are in respect to the walls. Begin by moving speakers closer to, or farther away from, the front and side walls. Listen for tone and clarity. Don’t be overly concerned with imaging or anything else at this point. Just listen for the way the sound becomes thick and boomy too close to a wall, more present and clear farther away.

Each time the speakers are moved try doing the same with your listening position. This is worth doing even if you are severely restricted into only a small range of choices, as people are often surprised how much difference even a few inches one way or the other can make.

The goal here in this first phase is simply to find your best tradeoff between a good balanced sound and speaker/chair positions you can live with. Depending on your room and degrees of freedom this can be the longest/hardest phase, or short and sweet. Sometimes we just don’t have all that many options. Accept your limitations, and move on.

Next phase, imaging with symmetry, is really rather cut and dried. Use a tape measure to position the speakers precisely equidistant and symmetrical with respect to your sweet spot. 

The method that works great in all kinds of crazy rooms calls for a tape measure and framing square. Measure from outside corner to outside corner of your speakers, leaving the tape measure laying on the floor. Use the tape to find the exact center, and place the framing square there. Anywhere along this line is equidistant and will have terrific imaging. Now simply tweak one speaker or the other closer or farther away until this line points precisely at the sweet spot.

At this point you should be hearing improved tonal balance and imaging. In the final phase we will fine tune this to find your own personal preferred balance between soundstage width and depth, and image focus.

Is that three phases, or only two? In all the excitement I kind of forgot.

In the first phase symmetry hardly mattered. In the second phase symmetry was the goal, and so important we used a tape measure. In this third phase precision placement is even more important. No more listening for generalities. Our goal in this final phase is to find a magic balance between image focus, soundstage width, and soundstage depth. In this there is no right or wrong. Some people want as wide a presentation as they can get. Others want razor sharp image focus. Still others love it when the stage extends back beyond the front wall. Whatever it is that you like, this is the way that will give you your best chances of getting there.

Start with speakers toed in whatever amount you think is about right. Whatever this is, is not important. What matters is that it be precise. Absolutely precise. Use your tape measure to make sure the speakers are toed in exactly the same amount on each side. Often times we find adjustments as small as one degree can make all the difference. Because we are listening for image focus, if your speakers are asymmetrical by even a small amount this can throw it off enough to create a false impression. 

An arduous process, to be sure. But the payoff is in achieving a balance very likely better than you have ever heard before. Maybe not what anyone else thinks it should be, but unless you’re doing it for them that’s their problem, not yours!

From here on in it is fine-tuning. The closer you get, the smaller your adjustments, and the more important precision becomes. Take your time. When setting up my Moabs this phase went on for about a month. During that whole time they were moved only about one degree in or out, and they were moved only two or three times. In between I was thoroughly enjoying them, listening to a lot of records, only gradually over time forming a clear preference for one over another. Fine tuning.

There are a lot of different speakers with a wide range of characteristics. Generally speaking however what happens is image focus and sound stage depth improves as they are pointed more and more directly at you. One tradeoff here is you really only hear this phenomenal imaging from right on that line of equidistance. Spaciousness and stage width improves as they are pointed more straight ahead, but you lose image focus. The tradeoff here is imaging is not as precise, but you get pretty much the same sound from a wider range of locations. 

As always there is no one right or wrong, but only what works best for you and in your situation.