Audio Physic Caldera Loudspeakers

Audio Physic Caldera Loudspeakers

Grant Samuelsen

13 February 2002


Dimensions: 44″ H × 9.9″ W × 20″ D
Weight: 119 lb each
Power rating: 250 watts
Impedance: 4 ohms
Frequency Range: 32Hz-22KHz (-3db)
Sensitivity: 91 dB /1 watt 1 meter
Price: $15,995 in supplied Mahogany finish

US Distributor:
1717 A Fourth Street
Berkeley, CA 94710
Phone: 510.559.2050
Fax: 510.559.1855

(Editors Note: This review was originally written by Grant Samuelsen and submitted to Ultimate Audio.)

Hello Stereo Times readers. This review was written for the summer 2001 issue of Ultimate Audio, but as there have been no subsequent issues, Clement Perry has graciously agreed to publish the work here. I will not be writing reviews from this point forward because I am now affiliated with an industry company, Shunyata Research. There were no existing conflicts or industry affiliations at the time this review was written and submitted for publication.

Grant Samuelsen

About the only relevant question I could muster when presented with the opportunity to review the $15,995 Audio Physic Calderas, along with comparisons to the $16,995 OLS Kharma’s Ceramique 1.0’s and $16,000 Talon’s Khorus X was, “How long will it take ’em to get here?” Predictably, the preoccupation with my good fortune made the logistical and physical challenges involved in such a venture seem trivial — until they were upon me. Indeed, a heady combination of missing lift gates, gashes, splinters and six spine-warping trips down stairs almost derailed the review before it began. Thankfully, with a few visits to the chiropractor, some intensive spousal counseling, and a few bandages had me back to almost as good as new. The musical experience provided by these varied speaker designs made the journey worthwhile. However, if there is a big-speaker swapping session in your future, plan ahead, enlist plenty of help, and find out if your chiropractor makes house calls.

Technical Highlights

The Calderas engineering concepts and construction place emphasis on preserving and refining the internal signal path and perfecting the infinite baffle approach to the outward wave front. Even to the casual observer, the Calderas exterior shows the extreme attention to detail that designer Joachim Gerhard paid to vibration isolation and realistic sound dispersion. The woodwork involved in the construction of the Calderas alone must be estimable in cost and is a testament to the skilled craftsmanship of their maker.

Beginning at the top, the sleek, asymmetrical treble housing not only cancels unwanted resonance and mitigates sound diffraction; its deep chassis extends the bandwidth of the heavily customized 28mm SEAS tweeter. Both the dual 7″ midrange drivers and 8 ½”, push-push, side firing woofers began life at the ScanSpeak factory, but have been heavily doped with carbon fiber to lower resonance, and further modified to Audio Physic’s exact specifications. Scan Speak’s patented SD-1 magnet system confers low distortion and excellent power handling to all of the drivers. The midrange drivers are mounted one in front and one to the inside of the Calderas heavily cross-braced central cabinet. Not only does this inner-mount driver increase the systems power handling, but when coupled to the virtually edgeless cabinet design, allows the outbound wave-front to virtually surround the speaker.

The Calderas woofer section is comprised of eleven internal chambers and is heavily cross-braced in the interests of minimizing the vibration inside the cabinet, especially near the crossover. The dual woofers work in a push-push configuration that equals the out put of one twelve inch unit, yet preserves the articulation and touch that smaller sized drivers are capable of. The Calderas crossover network and internal wiring are kept simple and direct, favoring a minimalist approach, and avoiding the complexity and steep slopes of many competing designs. The treble and mid-range crossovers are first order, using the highest quality film capacitors and minor impedance shaping components. Once the mid-range crosses over to the bass, the crossover advances to third order and increases slightly in complexity. All crossover elements are housed inside resonant resistant sections of each driver section.

Though the Calderas rated sensitivity is 91dB, their 4-ohm impedance infers that an amp of reasonable power should be used to drive them. Audio Physic recommends a minimum of fifty watts.

Getting underway

The Calderas are a beautifully finished five driver, three-way dynamic loudspeaker system comprised of three individual cabinets per side. Each segment has it’s own driver compliment and set of WBT binding posts. The enclosures are de-coupled from one another via non-slip polymer mats placed between each bass and midrange cabinet, and polymer pucks inset under the treble housings. Only two slender coupling grooves per channel hint at the Caldera’s vibration isolated driver systems. Everything about the build of these speakers exudes quality and elegant craftsmanship. For believers in design stereotypes, ‘precision German Engineering‘ matches the Caldera’s elegant, form, fit and finish to a T.

Right out of the box (sorry), the Calderas have an advantage over most speaker systems due to the interchangeable way in which they can load a room with bass energy. The heavily cross braced woofer cabinets can be inverted, bringing the back to back, dual bass drivers up from their standard floor boundary position, to just beneath the midrange enclosure. Threaded spike sleeves are inset on both the top and bottom of each bass module, allowing the speakers to be spiked to the floor in either configuration. In most rooms, the standard floor coupled position offers slightly deeper bass. For problematic rooms, the woofer cabinets can be inverted, and switched from left to right, eliminating floor-coupled reinforcement of room induced bass gremlins.

Three sets of binding posts at the back of the Calderas confer a variety of connection options, from tri-wiring to tri-amping and anything in between. Audio Physic recommends the use of the ‘star grounded’ connection method, necessitating the use of a bi-wire jumper harness to connect the woofer module to both treble and midrange posts. A few casual trials proved the supplied jumpers to be superior to either a tri, or bi-wire set up with more exotic cables. Yes, contrary to popular opinion, it can occasionally pay to follow a manufacturer’s advice.

The reversible woofer modules made it easy to achieve a stable low frequency performance virtually anywhere in the room, but after experimenting with the near-field set up suggested by the US distributor, Immedia, the choice of final placement was easy. The Calderas ended up just shy of eight feet out into the room and were spread nine feet apart along the room’s 19-foot dimension. These sleek fraulines realized their most natural tonal balance and image focus with their tweeters aimed just outside of my pointy, eager ears.

Symmetry in Sound

The Calderas proved within the first few minutes of listening that they are much more than just a space-filler in the Audio Physic line. Though they were possessed of prodigious resolving power and other worldly soundstaging, it was the Calderas endless palette of tonal shades that had this listener flipping discs into the wee hours. While listening to Bill Evans Trio’s Sunday At The Village Vanguard [JVCXR-0051-2], I was immediately struck by a symmetry of color and vibrancy that brought new energy to familiar recordings. On “Alice in Wonderland”, the Calderas framed the deeply hewn shades of Bill Evans key-strokes within the silver-gold shimmer of Paul Moitan’s deft cymbal work, bringing a new appreciation for the artistic interplay between these jazz stalwarts. This startling sense of realism and tonal verity brought a multi-sensory connection with music that captured and held my attention.

The Calderas tonal grandeur is owed, at least in part, to their silent progression through the leading edge of a transient. They moved so adroitly through a note’s inception that the character and texture of each note and instrument was completely exposed. Music became saturated with a sinuous continuity reminiscent of the finest electro-stats, yet retained the authority and dimension inherent in the Calderas dynamic driver construction. Their noiseless transient flow was particularly evident on loud music such as Los Lobos’ Colossal Head. The bombshell track “Mas y Mas” is a favorite of mine, not only because it gives the neighbors dog fits, but also because it challenges any speaker system with its incendiary transient attacks. Though this music has been disappointing on many big-ticket speakers, ‘Mas opened into a layered panorama of instrumentation through the Calderas, highlighting their linear note progression. Lobos front man David Hidalgo’s searing guitar lead emerged with an incisiveness and staccato pitch that had me, and the pooch next door, rediscovering the intensity of his performance.

Though the Calderas exhibit excellent low frequency extension, weight and power, it’s clear that their design favors quality over sheer quantity through the lower octaves. There is a lithe touch and flawless articulation apparent in their presentation that will engage rather than throttle a listener with sound pressure. The Calderas belong to a very short list of speakers that can not only render theimage of a bass instrument in the soundstage, but can also recapture the essentials of touch, timing and pitch through the mid-bass. However, for those that like to be bounced off the couch with low frequency energy, or are looking for speakers that double asearth-movers, the Calderas specified 32Hz will not excavate the lowest octave.

Throughout the midrange, the Calderas presented music with a natural expression and purity that seemed unerringly consonant with live instruments and voice. They struck a musically neutral balance of clarity allied to warmth that never sounded contrived, colored or analytical. The subtlety with which the Calderas retrieved micro detail, tonal nuance and texture was particularly evident when listening to both male and female vocals, and piano works. From Sarah McClaughlin to Eddie Vedder, the Calderas captured the character and unique sonority of instruments and voice with ease. And that, friends, is a rare quality in any audio product.

As is the case with many speakers, the Caldera’s treble balance was the last thing to fall into place during break in, finding its voice after 150 hours. Once again, the Caldera’s full spectrum of light and color in the treble range stands out from the norm, at any price. When listening to demanding orchestral works such as Hayden’sSymphonies, Volume 13 [Naxos 8.550770], or crashing high hats, like those on the track “Tomorrow Afternoon”, from Tony WilliamsLifeTime, [Blue Note 7243 499004 2 4], the Calderas showcased an ability to combine high frequency definition, delicacy and extension within a natural, even languid overall balance. On axis response was extremely linear, tight and defined with bloom and air to spare, but lost a shade of refinement and ease when listening off axis. As always in this price range, time and attention paid to set up will make a big difference in achieved performance.

Audio Physic speaker’s soundstaging qualities have been highlighted in reviews and by consumers many times and for good reason. The entire line has a striking ability to unravel complex images within a sound stage and preserve the original acoustic of a recorded venue. However, as good as the less expensive AP models are, they merelyhint at the Calderas ability to mimic a recording’s environment and the characters within it. When toed in to a near field position, the Calderas layered a sound stage so rich in detail and ambience that it brought the virtual reality of a musical event into my listening room. Anyone who believes that a three dimensional soundstage is an afterthought to believable music reproduction has never heard the Audio Physic Calderas.

Khorus Komparison

The Talon Audio Khorus X is a relative newcomer to the high performance speaker arena but has wasted little time in shaking up the status quo. They share several performance attributes with the Calderas, but ultimately approach music reproduction in ways that are all their own. The Khorus X is room friendly, but again, my listening preference brought them out seven feet from the front wall with well over eight feet of space between them — I guess there’s no sense in trying to hide my near-field predilection. Toe in was generous, similar to the Calderas.

The Khorus X tonal presentation is unlike that of any speaker I’ve experienced, which, depending on one’s point of reference, or preference, could elicit a variety of reactions to their overall balance. The Khorus X, like the Calderas, transition from a note’s leading edge into its fundamental and decay with such alacrity, that no hint of artifice or etch is evident anywhere in the frequency spectrum.

The X’s tonal palette has an added resonance, density and weight, especially down low, that was very different from the Calderas lighter, more sanguine shading. Overtones, especially when listening to orchestral works, had more body, richness and impact with the Khorus, lending a more physical presence to music’s scale and weight. However, upper mid-range and lower treble characters have a more reserved tonal presence through the Khorus that was very different from the vibrancy and finesse of the Calderas. This difference was especially noticeable on brass instruments, such as Lee Morgan’s trumpet on the track “Expoobident” off the re-issue of the same name, [Vee Jay VJ-008]. The Calderas presented Morgan’s trumpet with a shade more light and varied coloring, bringing the instrument forward in the mix, while the Khorus shaded the trumpet two steps back, behind their authentic rendering of bass and kick drum.

The top octaves in both the Calderas and Khorus were extended and resolved. Each system reproduced the treble range’s signatures and timing cues with ease, but the Calderas captured a bit more of a note’s trailing edge and surrounding hall ambient, increasing separation between instruments and offering a better aural view of music’s micro detail and subtlety up top. The Khorus X meanwhile, was less directional with treble energy, and carved out a wider sweet spot, allowing some advantages in seating and set up.

Instrumental and vocal characters had a timbral density and masswhen played through the X’s that redefines this area of reproduction. While the Calderas paint the outlines of images with feather — like delicacy and refinement — the Khorus X’s fill in those holograms with broad strokes of texture and palpable mass, surprisingly, without slowing down or disrupting music’s rhythm and flow.

Though the Khorus were champions of loud, the Calderas resolution of fine detail and tonal contrast infused smaller scale recordings with more light and energy. Both were convincing in each domain, but had unique talents that defined their overall balance.

The German and the Flying Dutchman

The Charles Van Oostrum designed Kharma Ceramique 1.0’s, like the Calderas, are one of the most finely crafted loudspeaker systems on the market. Their contoured exterior, exquisite finish and sonic aptitude exude sophistication and beauty, providing the perfect foil for any loudspeaker system with ambitions to grandeur.

The Ceramiques were not as pleased with the near field set up as either the Khorus or Calderas. They were most comfortable set three to four feet out from the front wall, facing straight ahead, with only 6 to seven feet of space separating them. I assumed that this difference alone would take some getting used to, but assimilation with the Ceramique’s placement and sonic was not only quick and painless, but proved to be a pleasure.

The Kharmas expressed music with a single driver coherence and authority that eclipsed the superb driver integration of both the Talons and Calderas. Music flowed from their drivers with such uniformity and casual beauty that it took me a long time to break through my musical reverie and settle into a pick every nit, reviewer mode.

The Ceramiques rated 25 Hz bass response propelled music with a rhythmic intensity and full body that either had me lost in the poly-rhythms of complex drum music, or tapping out solo notes on my air bass along with Dean Peer. The Calderas performed convincingly on this music as well, but in direct comparison, missed a fraction of the low-end body and extension that the Khorus and Kharmas had to spare.

The Ceramic driver midrange of the Kharmas should come labeled with a WOW-factor warning label. Throughout the midrange, the Ceramiques had a crystalline transparency and energy I had previously associated only with ribbon drivers. Terms like incisive, open and lightning quick came immediately to mind. While the Calderas could not equal the immediacy of the Ceramiques midrange, I found them to sound truer to the natural timbres of instruments and voice. Woodwinds, brass and piano had more individualized tonal signatures when played through the Calderas. Also, the upper midrange of the Kharmas could harden a bit when played above 90 db, giving me slight pause when I had the urge to shake the rafters.

The treble range of the Calderas was more varied and complete than that of the Kharmas, cueing more readily into ambience, color and expressive detail. The 1.0’s had a silky smooth lower treble that, on its own, sounded extremely detailed and beguiling, but when compared, had a noticeably darker overall balance, growing more shaded as they approached the top octave. I would stop short of labeling the Ceramiques “dark,” but I perceived them as more charming than detailed in the top octave compared to the openness and brilliance of the Calderas.

Imaging and soundstaging characteristics of the Ceramiques were superlative, but very different from their German counterparts. Rather than engulfing a listener in near field imagery and layered depth, the 1.0’s unraveled sound images in front and to the sides of each gleaming speaker. Images began at the front plane of the speakers and moved forward and out, giving the listener a more wall-to-wall perspective on sound. Beautiful as the Ceramiques are, they were very visible within the sound plane, and as such, were a more obvious source of music and sound than the Calderas, who’s wide placement and slender presence made them virtually disappear from this listener’s consciousness.


The Calderas possess an array of musical and engineering attributes that are simply beyond the grasp of most speakers in their price range. This system’s true to life spectral balance, low-level resolving power and harmonic integrity inspired hour after hour of listening enjoyment. As well, their ability to disappear as a source of sound in the listening room and layer front to back sound portraits is nothing short of stunning. The Calderas elegantly crafted cabinetry and segmented construction offer a rare combination of beauty and flexibility, making them an easy fit in virtually any décor or reasonably sized listening space.

Quibbles with the sound of the Calderas had to be dissected and were apparent only in direct comparison to their competition. The Talons and Ceramique 1.0’s reproduced music’s overtones and timbral signatures with palpable mass, and had slight advantages in the rhythm and scale departments. But these were notable only as parts of the whole, as the Calderas were capable of conveying the essence of music’s message in all dimensions.

Other than a few physical scars and an aversion to heavy boxes, what I’ve taken away from this experience is the unwavering truth that loudspeakers are still the number one sound shaper in a music system, and provide the life giving umbilical to musical involvement. In terms of completing this listener’s immersion into the heart and soul of music, I can’t recommend the Audio Physic Calderas highly enough.

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