Grand Prix Audio Monaco Modular Component Isolation System Michael Fremer July 2001
When I think of Shaker furniture, I usually think of simple, elegant wood designs originally made by religious fundamentalists. Grand Prix Audio designer Alvin Lloyd uses a very different kind of shaker table in the development and design of his carbon-fiber composite-based audio racks and amplifier stands. His shaker tables actually do shake. They're laboratory instruments, not furniture, and with their help he has developed racks and amp stands which, his measurements indicate, isolate components from vibrations and resonances even better than air-suspension systems do.
Grand Prix Audio is more than just a dramatic-sounding company name. Lloyd has spent more than 20 years in professional auto racing, as a driver, mechanic, and crew chief. Most recently he served as VP of operations for racecar builders Swift Engineering. Most important for the purposes of this discussion, Lloyd is a longtime audiophile. Aided by two Swift Engineering co-workers (one of whom collaborated on the first American-made Indy car to win a race in 14 years), he's designed these aerospace-quality racks and amplifier stands to provide seven stages of isolation. First time through, I kept waiting for a list of seven items.
The heart of the amp stand I auditioned is an ultra-lightweight, ultra-rigid A-frame of carbon-fiber composite supported by three large-diameter, heavy-walled support columns of aircraft-grade "304" stainless steel, which contact the floor via large-diameter 304 stainless-steel spikes. A coating reduces the transmission of vibrations. I'll spare you the details of the thinking and technology that went into the column caps, the material interface between the caps and the columns, and a few other intricacies.
The columns are not attached directly to the A-frame. A layer of Sorbothane under pressure acts as a transmission barrier that, according to Lloyd, operates "in the 90th percentile from below 1Hz to 15kHz," though not in a linear fashion, and with limited effect at 20Hz. There is still some transmission of ground- and airborne vibrations, Lloyd told me, but the key to the Sorbothane's effectiveness is that it's under pressure, when it begins to act as a liquid. Sorbothane not under pressure, he insisted, is nothing but a spring (which is why a Sorbothane record mat is a terrible idea). Sorbothane's behavior is critically dependent on the amount of compression it's subjected to, which is why the stands have to be assembled at the factory and individually calibrated.
The next step in the system is the interface of the acrylic stand and the A-frame. Again, Sorbothane is used, but the end user is supplied with a variety of thicknesses and diameters specifically matched to component weight. You determine the weight of your amplifier, choose the correct damper, apply it to recesses in the carbon-fiber frame adjacent to the supports, and then lower the shelf on to the dampers, being sure not to let it contact the columns. When the component is placed on the shelf, the pressure will be sufficient to "liquefy" the Sorbothane to the point where it will behave as desired.
As for the choice of acrylic for the shelves, Lloyd told me the material can have favorable damping properties, but only in specific ways. A "yield curve" depends on a component's thickness and weight. For most amplifiers, ¾" acrylic is ideal, but Grand Prix can supply ½" for lighter loads. Too thick and the acrylic will transmit more energy. Thicker is not better.
The amp stands cost $999 each and come with three sets of dampers; if the end user knows the weight of the specific amplifier to be used, Grand Prix will supply the correct dampers.
Why go to the trouble to damp vibrations from a piece of electronics? What difference can it make? If you've experimented with various tuning feet and cones, you don't need an answer. Manufacturers like Naim have found out for themselves and isolate their electronics with elastomer suspensions. Capacitors, cables, circuit boards—and, obviously, vacuum tubes—do not like to be vibrated.
I used the Monaco amp stands with the two-piece Nu-Vista 300 power amplifier, the Chord CPM 3300 integrated amplifier, and (when I reviewed the Red Rose Music R3 speakers for the May issue) with a vintage Dynaco Stereo 70. I paid the greatest attention to sonic differences during the Chord review by auditioning the amp on the Grand Prix Audio stand, on a piece of wood on my carpeted floor, and on my usual amp stand—a hollow- and tubular-legged metal stand from Target, fitted with a Symposium Acoustics isolation stand resting on spikes in the Target stand. To keep from going crazy from too many variables, I omitted the usual Walker Audio Valid Points.
I didn't have to pay much attention to hear the difference between the Stereo 70 on the Grand Prix Audio Stand and the floor: it sounded much cleaner and more focused on the stand, especially the bass.
The difference between the sound of the Chord on the wood and the Chord on the Grand Prix Audio stand was absolutely easy to hear. The overall focus, image definition, clarity, and blackness between the notes were clearly better on the composite stand (located between the speakers and directly in front of the Audio Physic Rhea subwoofer), as was retrieval of low-level detail. The rhythmic organization of complex music seemed to improve, and there was a greater sensation of listener relaxation (though that could have been psychological—the Grand Prix stands are dramatically good-looking!).
There was less of a difference between the Grand Prix stands and the Symposium Acoustics isolation shelves set into the Target stands, and I wouldn't bet the farm on a blind listening test—though I'd comfortably bet an acre or two on the differences between the wooden board and the Grand Prix!
Of course, with eyes open, there was no contest: the stainless-steel, composite, and acrylic Grand Prix Monaco stand has high-tech good looks that most of us would welcome seeing between our speakers.—Michael Fremer