White Papers

The following introduction to our ongoing work at Grand Prix Audio begins with an exploration of the basic principles involved. It then introduces examples of mathematical formula used to obtain optimized values for specialized applications.

However, we won't bore you with endless strings of equations for two reasons. Vibration control engineering, while well understood, is a very sophisticated and non-intuitive subject. It requires a high degree of engineering background and specific knowledge to become transparent.

Additionally, we have no intentions of disclosing proprietary test parameters or specific research data that would give our competitors free access to benefit from our proprietary research.

With that said, let's look at some commonly held assumptions as they pertain to resonance control in audio. Many people believe that structural rigidity and high mass are the only elements required to successfully isolate their systems from audible resonances. But can you actually bring enough mass to bear? And -- if you could -- is this truly the most efficient means to obtain maximum sonic improvements?

As you already know from experience, even the massive concrete foundation beneath your home does not prevent floor-borne excitations (generated by your speakers the moment you play your system) from reaching your equipment. Nor does a heavy rigid stand protect your turntable from your very own and gentle footfall if the turntable weren't equipped with some form of suspension and vibration control, either directly or via its supportive structure.

Thus even literal tons -- of foundation and building mass with the damping influence of cubic tons of underlying soil -- prove insufficient to effectively isolate your room from resonances. This is true even when they originate outside your house. You've surely observed how traffic-borne impacts propagate unhindered through black top, dirt, concrete foundations, metal or wood risers and subfloors to be felt in even upper stories of tall buildings.

A heavy equipment machine shop with equipment weighing in at a ton or more each has to use industrial visco-elastic dampers (i.e. suspension) to prevent resonances created by one machine from transmitting to others. Review of equipment mounting in current US submarines shows that virtually all of it is isolated by visco-elastic dampers to make a modern Trident running at full speed quieter than a school of shrimp.

How about the well-known Morse code communication using hammer taps on railroad tracks across long distances, or simply putting your ear to a track to hear the approaching train still miles away? Or the habit of native American Indians and white settlers to put their ear to the ground to hear approaching cavalry that the eye couldn't see yet? Clearly the solidity and rigidity of railroad tracks or miles of soil and rock are far in excess of what could realistically be exploited in a home environment. And even if you could, without damping and freedom of motion, it still wouldn't be very effective as these examples show.

While some attenuation is possible, it remains proportionally insignificant to the effort/mass expended. It's a rather primitive brute force approach that operates at a very low level of efficiency.

How about rigidity?
Did you know that every single computer hard-drive in existence uses compliant suspension and integral damping? They wouldn't work otherwise. Or that all High-End CD/DVD player makers, to isolate their OEM transports from Matsushita, Phillips or Sony for enhanced performance over stock units, incorporate additional damping/suspension? Or that better circuit board standoffs are compliant rather than rigid? That advanced tube amps use compliantly suspended power tube sockets to minimize or eliminate the effects of tube microphony? That transformers are often mounted on viscous substrata? That what separates entry-level from upscale models within a particular turntable line is primarily the sophistication of the suspension?

If rigidity -- i.e. high-torque bolting of metal-to-metal or plastic-to-plastic -- were the solution, wouldn't the corporate giants and high-performance speciality makers use it? Of course they would. But clearly they don't.

Why do all car and motorcycle manufacturers use visco-elastic engine mounts to decouple their motors from the chassis frame? Have you ever driven an old Harley Davidson hard-tail? They tremble so badly that you can't even use the rear-view mirrors. Do we have to mention the intense vibrations transferring from the engine through the handle bars?

To translate this example to audio, think of the road condition as your room's acoustical and spatial properties and how they influence the overall sound. The motorcycle engine is your loudspeakers generating constant vibrations, the engine mounts visco-elastic interfaces between these sources of vibration and the driver = your audio components. Remove the engine mounts (the kind of visco-elastic dampers GPA designs incorporate) and your equipment is taken for a ride on an old hard-tail Harley, with the aural images as blurry as those in the motorcycle's rear-view mirror.

Now envision the horrible ride in a car with its shocks shot. Its springs oscillate out-of-control with every small bump on the road. This same principle of the undamped spring operates in most suspension-based systems as currently employed in audiorelated designs. Air-bladder devices rely on friction shock theory for minimal self-damping. To achieve reasonable results, their spring rate must be matched to within a very narrow range of the weight of the component supported. That is a function of size, number and air pressure of the bladders. They can only work properly with one specific weight - and you won't exactly know what that is. Moreover, to support more than 10 pounds, properly damped, requires multiple bladders and added complexity. Any mismatch between air pressure spring rate and applied load causes oscillations which, due to their haphazard and inconsistent nature, are far more disturbing to the ear than constant non-variable vibrations. That's the reason behind why the steady-state "dither" of an unsuspended turntable's self-vibrations will be sonically less offensive than the variable, inconsistent, haphazard oscillations of an improperly adjusted suspended turntable.

The advantages of compliance (or give) are further illustrated by vibrating bathroom appliances like electrical shavers or motorized tooth brushes. Set atop a hard counter top in the on-position, they not only won't stay put (they move around, their vibration reflected back from the hard surface to translate as motion) but also are quite noisy. Setting those same vibrating tools atop a soft pillow with give and rebound instantly undermines their tendency for self propulsion and significantly reduces their mechanical noise.

Now drop a hard rock and a soft, loosely filled sand bag from the second floor onto blacktop or concrete. The rock will bounce or skip because the hard surface reflects most of its energy. The sand bag won't bounce because its inherent softness absorbs its motional energy. Ditto for a blob of Sorbothane or related visco-elastic materials. They'll land on concrete or asphalt like raw eggs. While the egg breaks to absorb the fall, high-tech visco-elastic materials incorporate fluid-like properties. They absorb and dissipate impacts on a molecular level.

How about bearing-based designs?
The original engineering patents for those date back half a century when they were first used in industrial and architectural protocols, for example under high-rise buildings in the Los Angeles basin. That approach was quickly abandoned for the superior performance of spring/visco-elastic damping technologies that even under such extreme load bearing conditions easily perform measurably superior.

Where does that leave us?
Vibration as generated by earthquakes, automobile engines or computer hard-drives behaves no differently than resonances generated by your audio system. While there are various types of vibration (harmonic, poly-harmonic, random, shock excitations) vibration remains vibration in industry or audio. All vibrations have known characteristics and methods of effective address. Audio applications don't change the fundamental physics of vibrational behavior. Hence, to claim that some unorthodox treatment or misapplied methodology not seen in wide use outside audio generates superior results (as is common with equipment feet in particular) is at best questionable.

To ultimately perform predictably, repeatably and effectively, audio solutions must employ the very same textbook and materials sciences that have been painstakingly developed and documented by industries like NASA, Aerospace, Military, Medical, Automotive and Building/Construction.

The basic principle of effective energy attenuation
The basic and primary principle applied in all industrial energy attenuation protocols is simple. To attenuate vibration (motion) requires a counter-motion (suspension) which, through damping, generates friction which dissipates as heat.

It's common engineering knowledge that such suspension combined with some type of damping is required to achieve significant and effective levels of measurable energy attenuation. As a primary address, non-compliant metal-based bearing solutions, rigid super structures or high-mass loading are simply and measurably inefficient. Suspension and damping are mandatory.

For zero-G applications in space travel such as in the space shuttle, NASA has designed a component rack for scientific monitoring equipment. It employs ultra-sensitive servo motors to physically move the components in response to shock in all three dimensions. This rack must be locked solid until the spacecraft is in orbit and the equipment can be used. Even here, multiple degrees of freedom are incorporated, albeit motor-driven to compensate for the lack of gravity.

Recalling Sir Isaac Newton's maxim that each action always engenders an equal and opposite reaction, to attenuate vibration requires movement (multiple degrees of freedom). Without it, vibration is transmitted, not minimized or cancelled. Remember the railroad track example - a single hammer tap's excitation will travel freely in both directions and for many miles.

Why Grand Prix Audio stands have to move
By now you'll appreciate why our Monaco, as the most extreme iteration of these scientific demands for effective vibration attenuation, has to noticeably move when pushed. Multiple degrees of freedom are an absolute necessity. In addition to the viscous cross-member interfaces, independent shelf suspension of our Sorbothane weight dampers and optional Apex footers of the Monza and Le Mans version, the Monaco adds yet further degrees of motion with the True Vector interface, our adaptation of industry-proven single-ball constant velocity joints.

Real engineering leads to superior performance
Grand Prix Audio is the first company to incorporate structural composites and a comprehensive multiple-degrees-of-freedom approach into an audio/video component vibration isolation system. We didn't invent the fundamental principles or the science involved. Our novel contribution? The adaptation of highly specialized research data for composite materials and race car chassis suspensions that led to our unique composite chassis structures. Those become a significant element of our performance advantage.

Which now begs a question. Why didn't we patent our designs? There are two reasons. In the days of ground-breaking inventions like the light bulb, the radio or the X-ray machine, patents protected their inventors to reap financial rewards without interference from copy cats. In today's market, most patents are not innovations but applications patents. They transfer pre-existing, often already-patented solutions to new application not previously thought of. This never requires independent testing to verify that, besides just being new in this field or for this specific usage, these applied-for applications possess actual virtue. The patent process only involves the verification of the novelty of a claim. Should one be the first to claim that baby diapers make great CD cleaning wipes, one might purchase a patent to extol the unique virtues of such treatment in one's advertising.

One of our personal racing friends is one of the country's preeminent patent attorneys with a prestigious law firm in Los Angeles. When we began to research the patent process, he confirmed that our designs clearly incorporate multiple novel, patentable solutions not previously employed in the audio sector. He also advised that these days, a patent was primarily a marketing tool. It amounts to a licensing fee with the government for a marketing purpose we consider highly questionable. Questionable? Because the absence of a test protocol in the actual patent-granting process renders an affixed patent no more than a claim. It's not proof of virtue or superiority. Obtaining a patent then isn't so different from fancy velvet-lined packaging and glossy leather-bound owner's manuals. While creating an impression of quality and luxury, they do absolutely nothing to improve upon actual performance but spend the consumer's money on throwaway one-time items.

The second reason we decided against using our resources for patent/marketing? Many so-called audio innovations are so basic and simple to manufacture that they would lose their viability without a patent - anyone could duplicate them, or perhaps have them manufactured abroad to take advantage of cheaper labor rates. Conversely, the level of design and manufacturing sophistication necessary to produce Grand Prix Audio products so far exceeds the technical abilities of potential copy cats that, frankly, we are not concerned about the protection patents do afford. Secondarily, we're liberated from having to spend the time and money necessary to enforce patents, which is a requirement to render them effective in the first place.

Concluding this issue, we always and only spend the end-user's money on measurable and audible performance, not claims that disguise as fact by being attached to an apparently impressive "official sanction" in patent form.

Our real challenge? To incorporate the requisite features proven necessary by science into an aesthetically pleasing, functionally elegant and performance-wise uncompromised design. While detractors may grant us a "yes, they do look elegant" comment full of implied dismissal suggesting window-dressing, we've achieved measurable and audible performance far superior to other purportedly world-class approaches.

The hard-data test protocol
Audio is filled with large leaps of faith that connect audible effects to specific causes. Say you placed a ceramic disc underneath a CD player and the treble became more forward. A quick, very unscientific conclusion? Ceramics sound bright. Considering the enormous amount of variables involved (the other components, the room, their interaction etc.), this clearly is a premature assumption. To truly isolate a specific, unassailable cause-effect relationship under laboratory conditions would be exceedingly complicated, long-winded and costly.

When we began our work, we needed to generate ways to document and assess our own progress. We began with the assumption that higher degrees of energy attenuation would be audibly superior. To quantify that assumption, we custom-designed a shaker table to simulate the exposure of audio equipment to environmental vibrations in actual listening rooms. High-sensitivity accelerometers measured and compared the difference between the mechanically induced vibration input and the transmitted output at the component shelf. We knew exactly how much energy we put into the system. What we needed to find out is how much (or little) got through "to the other side". After all, the objective of this exercise was to verify vibration reduction as a function of design efficiency.

We purchased what at the time was the premiere example of a solid steel, hard-welded rigid stand and filled every column including the cross braces with lead shot. Alternately, we added air bladder suspension atop its shelves. We then spent weeks of 10- to 12-hour days compiling, in 5-pound increments from 5 lbs to 150 lbs, the amount of measurable attenuation that occurred at various frequencies and amplitudes under controlled load bearing offsets, between this stand and our own prototype.

We used steady-state tone signals at various frequencies to mimic random vibration, and impulse hammer shock excitations to simulate foot fall, slamming doors and heavy traffic conditions. Until we concluded our data generation, we didn't know whether the elimination or reduction of vibration in specific frequency bands was more or less audible than that in other bands. We didn't know whether there existed a critical threshold of attenuation above which further energy reduction would be inaudible to become a questionable exercise in excess and futility.

Our research thus far? It has shown without question that energy attenuation, over the broadest possible bandwidth, at the highest amplitude attainable, remains the ultimate goal for those committed to ultimate performance. Why? Vibration attenuation is clearly a game of percentages. It's not unlike racing. A famous motto quips "How fast do you want to go? How much money can you spend?".

It epitomizes the realization that every tiny advantage conspires to add up and become important. That's why even our unique 8-stage approach for the top-line Monaco doesn't end there. We've developed (and continue to work on) optional stages like the added inner columns, Apex floor decouplers, Apex component decouplers and Carbon-Kevlar shelf replacements. They add further percentages of energy reduction to afford the end user continuous audible improvements while financially allowing a stageby- stage approach.

The measurements published on our product pages were generated from averaged data, i.e. we added our entire comparative data banks (measurements at different frequencies, amplitudes and loads) to grant the rigid high-mass examples the most conservative and fair position. The fact remains that had we isolated specific A/B comparisons, under specific load-bearing conditions exposed to specific signal inputs, the performance delta between their and our designs exceeded what's published by a factor of 3 to 4.

It's important to remember that we cannot make conclusive cause-and-effect claims. Our empirical knowledge merely states that higher degrees of vibration attenuation are audibly better than lower ones; that certain frequency bands aren't senior in audibility to others; and that there doesn't seem to exist a limit beyond which further reduction of parasitic resonances wouldn't remain audible, hence desirable.

The strange state of affairs in audio
It's a bit troubling that in audio, the honest application of textbook vibration control science should be considered novelty. Where audio equipment stands and accessories are concerned, we're afraid that this, indeed, still continues to be the case. We've spent the time, effort and resources to meticulously compare, measure and document, via custom shaker tables and high-sensitivity accelerometers, the rate of attenuation afforded by various approaches. This included top-line rigid-school examples of hard-welded metal stands filled with lead shot; aluminum-billet rigid structures; wooden structures, and the tested behavior of component support bearings claimed to bestow specific benefits. While all of these approaches did provide vibration reduction, the amount of this attenuation was insignificant when compared to our designs. More importantly, side-by-side listening tests immediately correlated our superior measured performance data with far greater playback performance improvements.

In fact, the degree of attenuation that our top-line Monaco affords is so extreme that the audible benefits to your system often exceed the common improvements of regular component upgrades. We've done extensive supportive experiments. We compared very affordable electronics isolated on our stands to very expensive ones supported on traditional metal and wood supports.

Manufacturers of ultra-expensive components won't like us for making this point. But we cannot lie. You're better served spending a larger-than-intuitive budget percentage on proper (comprehensive and scientific) component isolation than "the next" component or upgrading your speakers. And this isn't just our opinion. Visit our growing review page to see what the experts have to say.

Ongoing myths and misinformation
As our "Research" and "Realization" pages detail, Grand Prix Audio designs employ a unique combination of advanced composite structural elements as well as Sorbothane in two critical junctures. Sorbothane is exceedingly well documented for its superior self-damping properties. They operate over far larger bandwidths, and at far higher rates of effectiveness, than lesser materials. Certain marketing propaganda for less efficient designs would benefit from manipulating your views of Sorbothane as an inferior, ill-suited substance for audio use. That's partially because it has been repeatedly misused and misapplied to create negative impressions.

To operate properly, Sorbothane (just like air bladders) must be compressed at just the right rate to sympathetically match its spring and damping rate to the weight applied. That's because Sorbothane is an integral spring+damper substance. Many audio enthusiasts experimenting with Sorbothane footers have found that after applying mass dampers to their components, the previous dulling or muddying effects of Sorbothane evaporated for truly remarkable improvements. The simple explanation? The mass dampers added the requisite weight to compress the footers at the proper rate. At Grand Prix Audio, this isn't left to casual chance. Each shelf's Sorbothane decouplers are precisely matched to your intended load.

Certain voices in the industry have maligned this material as being merely another rubber or plastic. We have to suspect this either stems from ignorance or is a deliberate effort to discredit the material and its users. Plainly put, Sorbothane has been the visco-elastic damping solution of choice from space shuttles to Trident submarines. If you consider the "golden toilet seat" fiasco, you can rest assured that if something better or more expensive were available, NASA and our Navy would have the classified exclusive on it.

An old proverb goes "Figures don't lie, but liars do figure". Next time you encounter performance claims for certain materials or products, try to unearth corroborative evidence that competes with Sorbothane's 90% effective resonance suppression over a broad frequency spectrum. While we know you won't find them, Sorbothane's specifications aren't secretive or "proprietary" but readily accessible in the public domain. 

Due to the explosive growth of our company and pending product releases for 2003, this White Paper section will remain an ongoing project - there is only so much time we can devote to its development while we're busy filling orders and designing new products. So check back on a regular basis for updates, more treaties on vibration control and further mathematical formulae that explain the science behind it.

What follows for now are the proper scientific definitions for two terms often used in discussions about vibration control, albeit equally often misunderstood or quoted out of context.

Mechanical Impedance is a measure for how a structure "resists" applied forces. A variable force applied to a rigid, unrestrained mass will result in a variable velocity of the mass. The ratio of the average force to the average resulting velocity is defined as the impedance (Zm ) where Zm = F avg / V avg with units of (Lbs- sec) / Ft (mechanical ohms). A very high mechanical impedance implies that when an average force is applied to such a structure, it results in a very small average velocity of that structure.

Acoustic Impedance ( Za ) is defined as the ratio of average sound pressure over a surface to the "volume velocity" through the surface where Za = P avg / U avg with units of (Lbs- sec) / Ft^5 (acoustical ohms). A very high acoustic impedance implies that the applied sound pressure on one side of a surface results in a very small "volume velocity" of the air on the opposite side. This means that a surface with high acoustic impedance will transmit only a small amount of the applied sound pressure to the opposite side, which also implies that the surface itself has a small average velocity.where U avg = (Ft^2 x Ft/sec) = Ft^3/sec. (volume / time = volume velocity) and (Lb/Ft^2) / (Ft^3/Sec) = (Lbs-Sec) / Ft^5.

Lastly, a few documents property of the Sorbothane Corporation to point at the amount of research data and special applications flexibility inherent in Sorbothane (1 / 2 / 3) as a very high-tech engineered material.

For some fun pix from our racing past, continue on to our Racing Past.