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I. Design and Performance:
A vibration isolation platform is the next most important sonic upgrade after you've mounted your equipment on well-designed conepoints. Massive platforms made of granite, marble, corian (or more exotic plastic composites), graphite, plywood, medium density fiberboard, or glass can all work quite well. In our experiments the actual platform material makes more difference than the mass. (This is not surprising, if you view the platform as the sink or ground for the vibrational energy being drained out of the equipment by the conepoints). A heavy slab of maple or maple butcherblock (2" thick or more) sounds better then any of the above materials—and sounds better than cherry, oak, walnut, poplar or mahogany.
Whether you already have an isolation platform or are making a new one out of a maple slab, you need to mount it on a good-sounding isolation suspension. The suspension needs to have correctly tuned infra=bass resonant frequencies (vertical and torsional and horizontal resonances count) and clean, non-distorting attenuation of the midrange frequencies. The proper balance of these characteristics is far too complex to settle with instruments, so we have done all of our experiments by ear. We have tested high damping, rubber-like materials (Sorbathane, Navcom, Vibrapods, Iso-Bearings, Sorbo-Gel, Blu-Tak, etc.), sand mountings, and air suspensions (air cylinders, inner tubes, balloons). Our results show that the rubber-like materials, though often improving some part of the frequency spectrum, generally lead to soft, woolly bass. The best of the air suspensions sometimes give solid bass, but typically have some deficiencies in midrange clarity (not that the air suspensions don't effectively isolate mid and high frequency energy).
In the studio, I've been mounting all our equipment (tape recorders, microphones, preamps and the whole playback chain) on 2" to 4" thick maple platforms. At first, I mounted each of these maple platforms on four Vibrapods; these gave excellent sonic results. However, in the course of testing other promising materials, I came up with rubber-cork-rubber laminate of the IsoBlocks. In our very first prototype test, the laminate immediately sounded significantly better than the Vibrapods, which had been our preferred mounting. Subsequent design refinements (carefully tuned block sizes, double layer laminated, etc.) have widened that gap.
Thus, any audiophile that wants to take the trouble can, with $50 worth of thick maple and $24 worth of IsoBlocks, come up with a state-of-the-art vibration isolation platform that equals or outperforms the $2000+ air suspensions. And, by the way, the maple blocks can be made to look very handsome with chamfered edges and a rubbed oil finish.
II. Installation Tips:
- Place IsoBlocks under the four corners of the supporting platform or wood slab. Arrange in diamond orientation, not with sides parallel to the sides of the platform. For platform plus equipment weight totals up to 99 pounds, use our smaller IsoBlocks; for heavier weights, use the larger IsoBlocks.
- Make sure each IsoBlock carries roughly equal weight (if the surface under the platform is slightly warped, one of the blocks will feel loose). Take the loose block and add cardboard or hardwood veneer shims under it until it’s about as tight as the others are. If you’d rather avoid the shimming, you can use a three-IsoBlock suspension with only a very small loss in sound quality. If you’re using three, always put two at heavy end and one at the lighter end.
- The maple slab/IsoBlock isolation platform will work well placed on audiophile racks, on ordinary shelves and furniture, or on the floor (wood, tile or concrete). For mounting a maple slab on carpet we recommend our brass conepoints rater than IsoBlocks.
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