What is vibration isolation for?

Good tip Piezo, right on! Pbb, here's a thought experiment, that might help understand the possible means by which vibrations can effect the sound of a component.

Firstly, let's consider sound waves, and the energy contained by them. Think about a system running at a "good" listening level, say 90db peaks at 10ft. What does that mean? If your ears are 10' away from the speaker, then some amount of sound energy defined as 90db is hitting your eardrum. Now, just how big is an eardrum? compare that to the surface area of a rectangular box. Then place that rectangular box not 10' away, but between or perhaps right next to one of the speakers. Clearly, the box is receiving many hundreds of times the energy, than the ears are.

Secondly, consider vibrations transmitted from speaker to component through floor, rack, etc. Almost all systems share the same "mechanical ground", and it is usually not a very good one at all - the floor of the listening room - which for most people is a skin of thin layers of wood attached at various points to a lattice of wooden beams. One can imagine that this floor resonates in various manners at various frequencies at various locations.

Clearly, vibrations EXIST. Now, the three more arguable questions: 1) How do the vibrations effect the sound? 2) How can tweaks stop/reduce/change those vibrations? and 3) even if the first two are possible, how could it be audible?

Let's consider how vibrations can effect the sound, in a solid state phono stage for example. A device of this nature is a set of electronic components (transistors, capacitors, etc), SWIMMING in an electro-magnetic field of complex structure. The power supply components, the copper foils conducting current, and the transistors themselves, are bathing each other is em energy. Sure, designers work to reduce the thickness of this soup, but in reality, the "sound" of the phono stage is derived with the effect of this soup already considered. Now comes the imprtant part - MOVE that transistor, within that EM field it is sitting in. High school physics tells us that the very movement will create a current. Thus, if the box is vibrated/resonated in some manner, one can clearly conclude that the electrical signal is being effected to some extent. Next, consider the fact that the vibration is RELATED and caused by the VERY SIGNAL that passed through that transistor some milliseconds ago. The vibration's amplititude and frequency are thus harmonically related to the very signal the transistor is currently trying to pass. Thus, it seems quite clear that "vibrations" can effect the "sound" of a component, and the harmonic relationship may multiply the effect by several factors. So far, we have no conclusion as to whether the "change" is audible or not, but clearly we can conclude that the type of statement "vibrations can not change the sound" is false. Further, I think it is almost impossible to see how these vibrations can FAIL to change the sound.

The physics behind tweaks of this nature are pretty clear. Some of them convert vibrational energy into heat, thereby attenuating the vibration. Others transmit vibrations very effectively, and in theory "remove" vibrations from within a box, and prevent them from "returning" to the box. If a 20lb metal box is well coupled to an 80lb rack, then it will vibrate with less amplitude, and resonate at different frequencies. I can't say much about the removing and preventing return part, but clearly, COUPLING or ISOLATING components will CHANGE the nature of the vibrational problem.

So far then, we have the conclusions that vibrations CAN effect the sound, and that various tweaks CAN change the nature/magnitude of that effect. I would go so far as to change the CAN to WILL.

In terms of actually perceiving the effect, we are back to square zero. I hear it, others don't, and some don't even try, yet proclaim it can't happen. Nothing new there.

Nothing new in this statement by Pbb either: " I find it another thing to assert, based solely on one's personal uncontrolled observations, that HUGE improvements occur for no logical reason. "

The last phrase is clearly false, yet it is thrown around like some ultimate postulate of the universe. The logical reasons clearly exist, and even if we are not currently aware of them, that does not mean they do not exist. (the reasons, not the sounds or perceptions).

"huge" is clearly a relative term. If one has never gotten to know "excellent" wine (like me), the difference between two bottles of similar wines would escape me, let alone the difference after one glass has sat on the table for a few minutes. Yet, a wine connissuer would go on and on about the "huge" differences between those same two bottles of wine, and how one of them needs to decant a little longer. After a little learning and some experience, I would also notice at least some of those differences in the boquet and the body of those wines.

What is getting REALLY old and boring is the attitude "ho hum, you fools are enjoying your circle of mutual masturbation, and who am I to stop your fun. But here I am anyway, with this pamphlet I have about blindness."

beautifully explained Audiophile9: but somehow I also get the feeling that some others will never hear you - not because they cannot, but rather because they choose not to...

Isolation in the purist term does not exsist, so why waste your time. Speaking of time,everything moves and vibrates. These artificially induced motions create their own current of noise which are regurgitated, and again misproduced by your equipment, over and over again. Look to the Coloumb law of physics. Yes you can damp it down and move it around and change its sound, but it never left town.{ Damn I couldn"t resist the rhyme.} Its still trapped and reaping havoc on your system. If you want to give it a ticket to ride, check out the Sistrum platforms. They work. I have been using them for three years now. And all is better.

Audiofile9, you are making this up as you go, no? Your techno babble sounds almost convincing. The problem is you have nothing quantified. Just because something is a theoretical possibility does not mean that it has any practical implications. As an analogy (for what it's worth) the world is chockfull of bacteria and viruses. Their mere presence does not signify that the carrier is diseased. My point is, and always has been, whatever turns you on. I draw the line when leaps of faith brings one to conclude that HUGE benefits can be heard from any kind of change anywhere down the line, only if one is gifted with golden ears. To my mind, assuming that there is such a gift as better quality ears allied with a superior brain capacity to resolve musical detail,it is not much of a gift since it seems to induce way more neurotic anxiety about physics and things than true musical enjoyment. I have never seen a hobby that provokes such needlesss discussion as audio. It's about enjoying music, not fretting over imagined problems and so-called solutions. I will trot out the usual question-to-end-it-all (and will probably get the usual stock answer): why would the manufacturers of ultra-high-end transistor amps sold for kilo bucks not build the best isolated chassis possible if this is such a concern? Again to get back to the original question, yes there are vibrations, yes they travel through the air and through whatever materials are in and around the room. No, I don't think we should worry ourselves sick over it. Like all issues concerning audio blowing things out of all proportion gives one a feeling of importance, of being in- the-know. There is no percentage in doing otherwise. The "if a little is good then a lot has to be better" attitude (read disproportioned power supplies, power cables, high current power amps etc.) has taken over some time ago and is seen as being the future of audio by high-enders. I just think that this escalation is making audio what it is now: a very marginal proposition at best, with very few new devotees. A sense of proportion is sorely lacking. When does attention to detail, to minutiae becomes more of a hindrance than a source of advancement? I truly wonder.

While your post is not aimed at me specifically, I am going to take it on. Your comments are copied and pasted below.

"I will trot out the usual question-to-end-it-all (and will probably get the usual stock answer): why would the manufacturers of ultra-high-end transistor amps sold for kilo bucks not build the best isolated chassis possible if this is such a concern?

My response:

First, your question begs the same answer as the previous posts that question why high end manufacturers do not include audiophile power cords with their products. I will answer BOTH of these issues, because they can both be answered by the same response.

First, there ARE manufacturers that in order to keep the performance to price ratio in line for their place in the market, choose NOT to include these additional cost items.

However, there ARE manufacturers that charge enough for their superior performing products THAT DO include these.

Examples are manufacturers such as Walker Audio, who include two very high end aftermarket power cords with his best turntable. One goes from the wall outlet to the motor controller and one from the motor controller to the turntable motor. This is an example of two power cords improving a rotating motor, turning a belt, driving a 70 pound platter. Not only is it audible, it is necessary to the performance of the product.

Second, there are manufacturers that DO use special damping, copper cladding and / or high grade machined chassis's to improve isolation.

A quick look on the internet will allow you to view examples from Pioneer who use honeycomb embossed low resonance chassis for their high end products, many of which are clad in copper.

Machined aluminum billet construction is employed by Rowland for their transistor amps. By CTC in their Blow Torch transistor preamp, and Rockport in their isolated transistor motor drive for their turntable. These are a fraction of the companies that believe in this technology and use it in their production.

Third, there ARE companies that manufacture their products with SPECIAL ISOLATION FEET as part of normal product production. Prime examples are the Number Cruncher D to A manufactured by Entec which is equipped with the Vibrapod aftermarket isolation foot as standard issue.

McCormack Audio supplied Soft Shoes (Trade Mark) as an OEM part. They were sold by the thousands and installed as the standard issue isolation foot on many audio products.

This is not alchemy or fiction, many of these product's were inspired from Military and or NASA space research programs.

Audio products benefit from trickle down technology from better funded sources that are working to solve isolation and vibration problems. These are real problems and the solutions wind up helping those of us that care about making things the best they can be.

Audiogon is a site that is frequented by audiophiles who concern themselves with the passion for music and the tools necessary to make it the best it can possibly be.

There are visitors who are content with bedside radio, and those who will pay any amount to retrieve the last bit of realism from their music systems.

No crazier than musicians who seek vintage Genelex KT88 tubes in order to achieve vintage sound from their electric guitars.

The passion for "getting it right" is not new, even if in conflict with your idea as to what constitutes good value.

You may dismiss these advancements, call them frivolous and doubt those who seek to make the experience better, but until you become open minded enough to listen to these products work their magic in a direct listening session, you will never understand.