by Wim van der Maarl
As long as equipment is connected to the ground, its enclosure might be set into vibration because the base at which it stands is vibrating. Shock impulses from walking around the stereo-chair also will be transfered to the enclosure. But do these vibrations or shock impulses have any detoriating influence to the sound reproduction? Some technical principles are involved to answer this question.
First, speaking of a mechanical active system like a CD or DVD player, any mechanical vibration at a specific frequency and amplitude near or at the laser/fotodiode system will cause the feedback control system to be more busy than without. In the worst case scenario instability of the power supply will be the result thereby causing interferences in all electronic circuits. Because the trackingservo does have to follow an always eccentric track up to 10 times a second, there might be some real power needed. At that moment there will be a kind of chain reaction where other functions will be disturbed. And because a digital signal does have a high frequency (in the order of some MegaHertz), any power supply instability will cause the system to have a phase shift. And here we are coming to a familiar aspect of digital audio: time-shifting problems like jitter which is easily heard.
The obvious conclusion is this: a well-designed audioproduct with assumed high-end quality deserves anti-vibration packages to assure a minimum amount of vibration energy enters the critical parts of the system.
Passive systems like amplifiers, especially tube amplifiers, are influenced by mechanical vibration in a way of vibrating PCB's and grids in the tubes which cause capacitance variations. The disturbance although is with a 0 dB reference in the -60 to -80 dB region so the question is if there is a problem which can be heard. If we are talking about a well-done recording, the room acoustics are recorded in a proper way. But when playing that record the fine definitions of the room acoustics are in the -60 to -80 dB region! You now can imagine that the elimination of vibrations will be a major subject if you are concerned about maximum defined sound reproduction.
A question of concern is then: how should the system be eliminated from its surroundings? Well, if it could be possible to disconnect the player from the ground and let it fly in the air, a minimum of contact vibration energy will be transferred to the system. As far as I know, a technical solution providing an in the air flying object in such a way, is not yet available and practically implemented. Another type of elimination of the vibration energy is to isolate the system with springs which are tuned at a very low frequency. But then still some energy will be transferred into the system. This energy should be converted into warmth. This can be done with the use of damping material.
The strange thing about the usual available products is, that many solutions provide extreme stiffness and mass, wherein damping (converting the vibration energy into warmth) is neglected. Research and experiments have shown that damping is one of the main principles which will stabilize the construction in the time-domain. In contrary, high stiffness and weight provide minimum deflection, but no time-stabilization at all.
The outcome of the research and development is a sandwich plate, made out of PVC-plastic (which itself is damping material!) with a damping layer within. The Constrained Layer Damping technique is more and more widely used in any vibration critical design.
To decouple the construction from its surroundings, soft butyl rubber feet are used, which are strategically placed at minimum deflection points.
A double-blind listening test has shown that there is a remarkable increase of sound definition and liveliness. To obtain this quite revolutionary product, you should contact Hawk Audio which is gladly willing to demonstrate the superb sound innovation which is achieved with this product. This product has a very versatile application and can be used with all kinds of CD-players be it a DVD and/or SuperAudio player, but will also provide benefits with amplifiers and DAC's.
