Bad Vibes! Page 11

Though some of these reactive spring-based systems have resonant frequencies that low, I feel that they simply are not as efficient as a good pneumatic system, and the stability of some is questionable. When properly implemented, air-based isolators attenuate much lower amplitudes of very-low-frequency vibrations than even the best spring designs (with the exception of the new NSM system offered by Newport, which is a little too expensive for home audio in its present configuration).

Take Andy Payor's Rockport Cappella and Sirius II turntables, for example. Each of these 'tables contain a fully developed pneumatic suspension with a vertical and horizontal frequency of ca 2Hz or less. Compared with most spring or elastomer suspensions, even those which claim similar resonant frequencies, these pneumatic systems are at least 40dB better in the ultimate isolation of very-low-frequency, micro-inch levels of displacement.

The Vibraplane, reviewed elsewhere in this issue, is very close to the Rockport suspension in isolation performance, though these cost-no-object turntables have several other key features that contribute to their outstanding sound quality---and high cost. In addition to isolating very-low-frequency vibrations in both planes, the Vibraplane also contains the real-time damping characteristics shared by the Rockport as well as other pneumatic systems like Newport's "BenchTop" or "Noise Block" (the latter is an audiophile version built for Immedia by Newport). (Footnote 4)

Wrapping It Up
The particulars of pneumatic isolation and its sonic contributions are covered in my reviews of the Seismic Sink and Vibraplane. In summing up this evaluation of practical vibration control, it's important to realize that, although the isolation effectiveness of these pneumatic systems surpasses that of traditional suspensions, the complexities of vibration in the audio environment are such that subjective differences are perceptible even between competing pneumatic designs. These differences arise primarily from the relative effectiveness of the various isolated platforms and the coupling methods used to connect equipment to them---particularly how well they damp component-sourced vibrations.

Subjectively, this is the tuning effect we've discussed, and it's perceived as subtle tonal variations, focus, and changes in soundstage perspective. It won't take long, however, before you'll be able to easily distinguish these spectral variations---no matter how pleasing---from the concurrent, across-the-board improvements in system resolution, spatial definition, and greater emotional connection to the music that result from pneumatically isolating your favorite source components.

Though turntables clearly demonstrate the most dramatic improvement from proper isolation with a Vibraplane, digital gear isn't far behind. (This is still the biggest surprise for me.) Even preamps and amplifiers, particularly those containing tubes, show a real enhancement in sound quality with the more affordable Seismic Sink, and there is a definite synergistic effect from floating the entire system. Pneumatic isolation should never be considered just a tweak. When done right, the impact can be more musically significant than changing certain amplifiers or preamps, not to mention many other accessories. This does not mean that gross sonic changes are necessarily greater than that experienced from most component upgrades, but simply that it can be more relevant in conveying the nuances and dynamics that give music so much vitality and presence.

However, the bottom line is that truly effective vibration control in audio systems requires a measured, comprehensive approach utilizing rigid, well-damped stands and platforms, careful selection and placement of coupling devices, and isolation of key components---using air-based suspensions wherever possible.

All of our references up to now have concerned typical home audio systems, yet it is my fervent hope that the pro-audio world takes notice of the influence vibration has on fidelity. Eliminating the rickety rack systems common in studios around the world, then properly supporting and isolating A/D converters, microphones, preamps, tape drives, and cutting lathes could have a major impact on our treasured source material. Knowing what I now know about the impact of mechanical resonances, I get the willies when I go into a studio, see an A/D converter barely hanging off the edge of a console, and realize that vibration-induced grunge is being encoded into our source material. In some studios you can look through the inspection microscope attached to a cutting lathe during the cutting of a lacquer and actually see the light shimmering off the grooves as a truck rumbles past!

While it may seem that I've been a bit hard on tuning products when used as the only means for dealing with vibration, my intentions were simply to contrast their effects---which are familiar to most audiophiles---with those attainable from a well-rounded program that addresses each element of the equation, including tuning. Isolation and tuning should not be seen as competitive alternatives, but as complementary and essential partners in the fight against bad vibes.

As lengthy as this report has been, I've only outlined this pervasive subject in broad strokes. As you explore the commercially available resonance-control products, you'll discover numerous shades and variations of these principles, some which work very well. In any event, the purpose of this article will have been served if many of you now feel better equipped to sort through the maze of possibilities, and, above all, have fun in implementing your own vibe-reduction plan. Now take a breather, listen to some tunes, and---when you're ready---take a look at how best to use the Townshend Seismic Sink and the Vibraplane.

Footnote 4: Noise-Block Isolation Base, $2300 including air tank and regulator valve. Dimensions: 20" W by 16" D by 2" H. Weight: 22 lbs. Contact Immedia, 2629 Mabel St., Berkeley, CA 90701. Tel: (510) 654-9035.
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