Anthony Gallo has always been an iconoclastic loudspeaker designer, and thus his speakers neither look nor sound like the majority of their competitors. Nowhere is this more apparent than in Gallo’s otherworldly but now-discontinued flagship model, the Reference Nucleus 3.5 floorstander (reviewed by Neil Gader in Issue 209)—a product that despite its unorthodox appearance won considerable critical acclaim. Yet the size, look, and current unavailability of the Nucleus 3.5 raises a question: What solution is available to listeners who appreciate the sound of the Nucleus 3.5, but want something smaller, more manageable, and less visually imposing? The answer, as it turns out, comes from the newest member of the Gallo Reference-series family: the Reference Strada 2 monitors ($1998/pair) and their companion TR-3d subwoofer ($984). Veteran audiophiles might at first mistake this sat/sub system for a mere “lifestyle” or “home-theater” product, but in performance the Reference Strada 2 package packs serious audiophile-caliber credentials.
To come to grips with the Reference Strada 2, it is helpful to understand some of the engineering principles that inspired its unorthodox design. From the outset, Mr. Gallo has sought to produce speakers with high-rigidity, low-diffraction enclosures. With this end in view, Gallo’s “think-outside-the-box” solution has been to use semi-spherical enclosures made of spun stainless steel, with openings on one side for the drive units. Each Reference Strada 2 uses two such spherical enclosures housing wideband carbon-fiber mid/ bass drivers, with the spheres attached at opposite ends of a die-cast metal backbone/frame and Gallo’s signature, cylindrically shaped CDT3 tweeter in-between. The whole assembly resembles a space age “barbell” finished in silver and black (though an all-black option is also available).
The Strada 2 is astonishingly rigid and robust (try the time-honored knuckle-rap test and you’ll get, well, bruised knuckles), and it offers virtually no sharp edges to cause diffraction. In the interest of enhancing enclosure rigidity, Gallo mounts his mid/bass drivers from inside their spherical housings, using sturdy compression rods to press the drivers against the mouths of the enclosures. An advantage of this approach is that not even the driver frames protrude from the enclosures, again eliminating possible sources of diffraction.
A thorough discussion of Gallo’s CDT (cylindrical diaphragm tweeter) driver could fill an entire white paper, so a brief description must suffice. In simple terms, the CDT is a semi-cylindrical tweeter whose diaphragm is made of a film-like piezoelectric material called Kynar. As audio signals pulse back and forth, the thin-film material expands and contracts, generating nearly textbook-perfect semicylindrical wavefronts with an extraordinary 180o of horizontal dispersion. Because the Kynar film is low in mass and does not need to travel far in order to produce adequate output, transient speed is excellent and distortion is low. One further benefit is that the Kynar diaphragm acts as a high-pass filter, meaning that the tweeter literally serves as its own crossover network (though a transformer is used to match the tweeter’s output level with that of the mid/bass drivers).
Further reasoning that the best-sounding crossover network is no crossover at all, Gallo has configured the Reference Strada 2 so that its two mid/bass drivers are allowed to run full-range, using natural roll-offs at the high-and low-frequency extremes to limit their operating band. In turn, the CDT3 tweeter, serving as its own crossover network, takes up where the mid/bass drivers leave off, handling upper-midrange and treble frequencies with speed and finesse. In short, the Reference Strada 2 is for all intents and purposes a completely crossover-less, wide-bandwidth compact monitor.
The innovations don’t end there, though, because Mr. Gallo—much like his counterparts at KEF—has done considerable research into the feasibility of giving compact speaker enclosures the physical characteristics of much larger enclosures. KEF’s solution was the firm’s ACE (acoustic compliance enhancement) technology, while Gallo’s ingenious answer involved the creation of a proprietary enclosure damping material called S2. (Our understanding is that S2 is a type of shredded polyolefin film, though Gallo does not generally discuss the material’s exact formulation.) Either way, the result, as Gallo says, is that the “Stradas perform as though the speaker enclosure is significantly larger than it actually is.” Finally, the Reference Strada 2 uses Gallo’s Optimized Pulse Technology (OPT), which is described as “an impulse correction and synchronization system designed to integrate the low, middle, and high frequencies into one unified sound source.”
The TR-3d subwoofer (the higher output of the two cylindrical subs offered by Gallo) applies many of the same design precepts of the Strada 2. Thus, the TR-3d eschews traditional box-type cabinetry in favor of an all-metal, cylindrically shaped enclosure with the woofer fitted in one end of the cylinder and the subwoofer amplifier and controls in the other. Designed to rest on its side, the TR-3d looks more than a little like the depth charges seen on WWII-era destroyers, and some quip that, if turned up too loudly, the TR-3d can sound like a depth charge, too. The sub uses essentially the same ceramic-coated aluminium woofer originally used in the Nucleus 3.5, backed by a rock-solid 300-watt amplifier equipped with line-level and speaker-level inputs and a useful set of controls, including a bass trim switch with settings for 0, +3, or +6dB of boost centered at 30Hz.