Floor Loudspeaker Reviews

A specially designed Vibration Control Terminal, floating on a Neoprene frame, contains a single pair of WBT five-way binding posts. Like all of Audio Physic's floorstanding models, the Caldera sits on two heavy, smoothly machined cross-pieces of aluminum screwed into the cabinet bottom. Set into circular endcaps are the floor spikes, which are conveniently adjustable from above. A top plate covers each spike to give the footing a neatly finished appearance that goes with the handsome overall design.

Setup
Careful placement is key to achieving sonic satisfaction with any high-resolution, high-performance loudspeaker, and I spent a lot of time and effort maximizing the Calderas' sound. Predictably, they performed best when placed very close to where the Avanti IIIs had sat, which is close to where every speaker seems to sound best in my room: fairly close to the front wall and about 9' apart. Speakers with side-firing woofers, such as the Calderas, need to be placed farther out into the room so that the centers of the woofer cones coincide with the line where front-baffle–mounted woofer speakers tend to go. The speakers sounded best when toed slightly outward so that the tweeter axes crossed just behind my head.

Into the cauldron
The word caldera is Spanish for cauldron. How hot is Audio Physics' new cauldron? It didn't take long to figure out that the Caldera was a better loudspeaker than the Avanti III, which you'd expect for the price. It went much lower, was more dynamic at both ends of the scale, played louder without strain, resolved more information, produced a more expansive soundfield, and overall sounded more transparent and, especially, less congested. Most important, with one curious exception, it bore a familial similarity to the speakers above and below it in the Audio Physic line, a consistency critical for a speaker manufacturer's credibility.

Maybe it was because my Kronos was an early sample, but the Caldera struck me as a better-sounding loudspeaker overall for less than half the price. The Caldera consistently produced a far more coherent and believable soundstage, with none of the effect of sound emanating from an upper-story window that the Kronos had offered with many recordings. As John Atkinson's measurements of the Kronos showed, the combination of the side-firing midbass drivers (250–500Hz) between the powered woofers and the front-mounted coaxial midrange/tweeter created a midrange suckout that I heard but misinterpreted as being an elevated presence region, and as a design choice that deliberately "sacrificed midband lushness and texture in favor of an almost acidic transient snappiness."

The Caldera didn't go nearly as low as the Kronos, and couldn't compete with its powered subwoofer's control, authority, and setup flexibility, but the Caldera did go satisfyingly low—subjectively to below 30Hz in my room. Any speaker costing $30,000/pair had better deliver deep, supple, pitch-defined bass, and the Caldera did, with impressive weight and without thickening the midbass and lower midrange. Was its bottom end as good as the Wilson MAXX2's? No. The $45,000/pair MAXX2 went even deeper and delivered tighter, more clearly defined lows with greater wallop. The Caldera was sprung somewhat more loosely and was unable to match the Wilson's extraordinary start/stop speed and control—but then, nothing I've heard in my room has matched the MAXX2's bass performance.

Most important, the Caldera delivered low frequencies as well-textured music, not as "bass." For instance, I preferred its bass performance to that of the far more expensive Mårten Design Coltrane (reviewed in the February 2005 Stereophile). Over time I did detect what sounded like either a slight midbass bump caused by the additive effects of the two front-mounted drivers operating in tandem to 500Hz, or a midrange dip that accentuated the midbass. This could also be a room-coupling issue. In any case, while it did impart a slight, subtle bit of warmth in my room, it was minor and easily ignored and forgotten, though some listeners will prefer "tighter" bass. Few, though, will complain about the Caldera's bass extension and weight or its ability to deliver believable acoustic bass.

With the coaxial driver operating from 150Hz to 40kHz as a quasi–point-source, I'd have expected the Caldera to produce an exceptionally coherent, focused, and smooth overall sound. Given the Scan-Speak tweeter's performance in the Kronos, which I described as "satisfyingly sweet, airy, smooth, crystal-clear, ultra-extended, and capable of creating an enormous sonic picture, free of hot spots, etch, obvious peakiness, or other mechanical glitches," my expectations were high as I sat down for the first time to do some serious listening—especially given the smooth, coherent picture I'd heard at January's CES from a pair of prototype Calderas.

The message I got from the Caldera in that first home listening session was as coherent and focused as I'd expected, with extraordinarily convincing and seamless reproduction of male and female voices. But instead of smooth, I got "bright." Was it a break-in issue? I let the speakers break in for another three weeks of more casual listening. I pummeled them all day, every day, with all varieties of music at high SPLs as I worked in an adjacent room—but all of that had little effect on the Caldera's most noticeable and curious "sizzly" coloration, which had not abated even after two months. There was a peak at around 6kHz that I found impossible to ignore. It accentuated tape hiss, record surface noise, cymbals, hand-claps, bows drawn across strings, and especially human vocal cords. Drum-kit mixes seemed out of whack, annoyingly emphasizing the cymbals.

Familiar records made this sizzly character all too obvious. Female voices became reedy and thin when pushed to within the peak's range. Pianos sounded glorious in the lower registers, but as the notes ascended toward the peak the sound grew glassy, the image popping noticeably forward in the mix.

The brass section on Belafonte at Carnegie Hall (45rpm LPs, RCA Living Stereo/Analogue Productions) was edgy, almost jumping out of the picture. Belafonte's voice had an unusually thin, sandpapery quality that was all sibilants (not smeared) and transients with very little body. Handclaps sounded like rain on a tin roof. All of the familiar information was still in the picture, but suppressed relative to this laser-pointer peak. Contrast that with what I wrote about the Kronos' rendering of this recording: "The Kronos produced an ideal overall balance...which may have been the highlight of the month's audition."

Records I'd thought were quiet now sounded noisy, as the peak was located where both tape hiss and surface noise reside. Familiar CDs fared somewhat better, especially because there was no surface noise to be excited, but even as I appreciated the snap and crispness of such well-recorded discs as Arturo O'Farrill's Live in Brooklyn (CD, Zoho ZM200507), a stunning jazz set, the cymbal sizzle and hyperpercussive piano were all too obvious.

But it would be a mistake to call the Caldera a "bright" speaker—the very top was smooth, not tilted-up, edgy, harsh, or smeared. Instead, there appeared to be a narrow peak, which makes all the more confounding my comment about the Kronos: "If anything, it was slightly on the mellow side right at the top, but only slightly." The Kronos measurements and everything I've read about this Scan-Speak ring-radiator tweeter (some posts on DIY speaker sites disparage it as "sizzly") suggest that its off-axis response is somewhat uneven and rolled off, which should give it a slightly mellow sound in my well-treated room.