Rockport Technologies Antares loudspeaker
By Michael Fremer   •   August, 2002 Antares is a giant red star in the constellation Scorpio. According to Rockport Technologies' Andy Payor, the $41,500/pair Antares loudspeaker is the "ultimate" reasonably sized, full-range loudspeaker, and is built to a standard "unequaled in the industry." Rockport's $73,750 System III Sirius turntable came with equally boastful claims that turned out to be anything but hyperbole. Has Rockport done it again with the Antares?

That's what I asked myself as Payor's brother-in-law, Mike, and I uncrated each gleaming black 400-lb monolith in my driveway, under Payor's supervision. According to him, it takes 40 skilled man-hours just to finish the clear-coat cabinet—a job also accomplished by bro'-in-law Mike, who didn't need to be told to remove his ring and wristwatch before maneuvering the curvaceous, black, high-gloss speakers onto the dolly.

Sideways on the dolly (the only way those 400 lbs can be practically maneuvered), the deep cabinet barely made it through the doorway from the garage into my listening room. Only when the Cardas rhodium-plated hex nuts were removed from the binding posts could the speakers pass—and then just barely. This is not a speaker you'd want to try to move down or up a narrow flight of stairs.

Yet the Antares is, as advertised, a "reasonably sized" loudspeaker. Viewed from the front, it's nothing out of the ordinary: about 4' tall with a 17"-wide base. The side view is something else: at 28", this tapered speaker's base is deep. The idea is that the 100-liter volume of the rear-ported enclosure will help provide deep bass. For your $41,500, Rockport says you'll get an in-room response down to 25Hz.

It Doesn't Hurt to Be Inert
There's nothing particularly unusual or innovative about the Antares' design. It's a three-way vented box featuring a 1" silk-dome, ferrofluid-cooled tweeter, a 6"-cone midbass unit, and a 13" cone woofer, stacked one atop the other. What you get for your $41,500 is fanatical execution, particularly in the cabinetry but everyplace else as well. In an ideal speaker, the enclosure would be inert. In the real world, cabinets have resonances that ring at particular frequencies, which causes problems in the frequency and time domains. You can brace and damp cabinets and perform all kind of other tricks to reduce resonances, but almost all still resonate.

The Antares' enclosure is said to be "essentially...an inertial reference, subsequently, there is virtually no tendency for it to vibrate." I believe Rockport's claim. The Antares' physical presence was unique in my experience: more like two energy- and light-sucking black holes of inertness than a pair of glowing red suns. Infesting and surrounding them were zones of stillness that went beyond the stone-monument variety. "Rock-solid" doesn't begin to describe the vibe of having two Antares in my room, hugging the floor like abstract Easter Island heads. I could have put spikes under them, but that seemed pure superstition. Four hundred pounds couples to your floor. Your listening room's in the attic of an old frame farmhouse? Forget it.

At 50 hours to build and 40 more to finish, the Antares' cabinet is unlike any other, as far as I could tell. Here's a simplified version of the building process: A female mold is sprayed with an industrial-strength version of Pam (the actual chemical bears no resemblance to aerosol vegetable oil, but serves the same purpose), to keep the cast from sticking, then layers of resin reinforced with glass fiber are laid up, much like a Corvette body. Each layer is allowed to harden before the next is applied, until there is a 12mm-thick shell of "high tensile strength." (Payor loves to lard his descriptions with sexy tech terms.) When finally pulled from the mold, the seamless, five-sided shell weighs around 100 lbs.

The same glass-fiber-reinforced resin process is applied in reverse to a smaller, male mold. When that 60-lb shell has hardened, it is pulled off the mold and inserted into the larger shell. Then, 240 lbs of high-density, high-hysteresis-loss, mineral-filled epoxy goo specially developed for Rockport is poured in between the two, to form a 30mm-thick core that bonds the two skins together.

The result is a five-sided monocoque cabinet with internal braces built into the molds, and separate sealed chambers for the tweeter, midrange, and bass units. The latter two chambers include integral molded rear portholes (the ports themselves are machined from thick aluminum) that are part of the separately laid-up cabinet rear, which is eventually mated to the five-sided monocoque and then sealed. There is only one seam in the entire structure.

Rockport claims that the core material is three times as dense as typical MDF, while the outer skins are three times as stiff and dense as MDF of the same thickness. The composite "cannot be matched by single material construction," according to Rockport, because no single material, whether MDF or acrylic resins such as Corian or Fountainhead, has sufficiently high mass, high stiffness, and high damping.

The cabinet's unique shape, nearly impossible to fabricate with traditional woodworking methods, is optimized for correct driver placement, reduction of internal standing waves, and diffraction and reflection attenuation. If you look closely at the tapered cabinet, you'll see that there are no straight dimensions or parallel side walls. What appear to be straight lines are actually slightly curved.