High End Isolation - HRS, SRA, Active platforms

Our Nimbus and Promethean isolation stands incorporate "selective frequency damping" and viscoelastic damping to "quiet" the top plate and other critical parts.

Our damping techniques address airborne and component generated vibration as well as residual structureborne vibration.

Nimbus is a 6 degree of freedom design with resonant freq. as low as 0.5 Hz.

NB - We design isolation and resonance control products.

I have no doubt on the ability of cones/spikes, elastic interfaces, and shelves of varying density to affect oscillations and change the sound for the better. I have tried some varieties of all of these things.

However, it seems the passive approach is limited by (1) the efficiency of bringing the object to rest, and (2) the selection of frequencies which are a function of the material being used.

I would think that an active system would isolate a component by damping the oscillations. Just as a swinging pendulum is brought to a stop by using your finger as a counter-force, so will an active system bring an oscillating platform to a rest by applying appropriate counter-forces. An active system would also have an advantage of operating over a wide frequency range.

It seems that the other problem with a passive approach, is that they could potentially induce their own oscillations. Placing a component on a displacable material will enhance it's ability to move at certain frequencies. Also, footers are a 2-way street, are not truly fixed, and probably resonate at their own frequencies.

Of course, nothing is perfect. I am also thinking that the only way to truly shield a component from air-borne vibrations is to literally place it in an insulated box.

It is too bad that manufacturers of racks do not routinely provide real data to aid in their design and help consumers make informed choices. Also, our rooms have very individualized frequencies being transmitted through the building structure. Hence, I agree with Jeff above that there is no one-size-fits-all. What may work well in one person's room may not work in someone else's room.

Finally, the huge advantage of passive isolation is obviously cost. Therefore, it remains a useful approach as we are all seeking to obtain the best value for our sound.

I disagree that a rack is designed only to isolate components from vibration coming from the floor. Most rack/shelves are also designed to dissipate vibration coming from the component itself (e.g., the vibration of power transformers). Couplers are used to transfer the vibration to the shelf and the shelves are designed to convert the vibrational energy into heat. Tap the case of a component coupled properly to a well designed shelf and one just sitting on rubber feet on an ordinary rack and you can hear a big difference in how quickly the vibrations are deadened with a good shelf/rack.

Any passive design will have a resonant frequency, below which it will not isolate. In fact, around resonance it will amplify the vibration. Although some passive systems are designed to be tuned to the specific weight they will support, many designs are not and hence, their properties will vary with the supported mass.

Therein lies the beauty of active isolation.

Rob RTML,
I see in your posted system here on these pages that you employ the use of at least four Sistrum SP 101 platforms.
These platforms are designed to be reactive to their environment. Their reaction is induced by the in room air pressure generated by your speakers as well as their cabinet resonances. External modulated vibration as well as self induced vibrations in and around your electronics are then also collected given direction and then mechanically grounded to earth.

I also see in the photos that your system has great horizontal sight lines. If your were to lower each shelf that supports your independent amps to midway of the three support/grounding rods you would reduce the inertia and increase the resonance transmission speed of the platform/amp combo.

Likewise if you were to move your Wadia player to the midway point within your rack you would increase the stability of the transport itself, reducing the amount of timing error correction and shortening the pathway to ground provided by the particular rack in use.

Sistrum does in no way try to isolate. In fact Sistrum does provide a pathway for energy to collect and then transfer to a higher mass/ground. Reducing the amount of time, energy is stored in a component, system or rack is much the same as reducing the time smear self induced by the constructive materials of a capacitor.

I first started as a user of audiopoints many years ago.[1993] I have since 2002, been a dealer of products designed and sold by Starsound. Tom