Review: Opera Callas Loudspeakers

wo grill

by Brian Hunter

At first look, the Callas bookshelf-style speakers ($5,000/pair) by Italian-based Opera Loudspeakers should grab your attention. Grill on or off, black leather can be seen covering the front faceplate and a fine execution of wood and finish gently caresses the remaining visible back and sides. Upon even closer inspection one may notice the sizeable collection of tweeters the Callas represents. Two vertically aligned 1” Sonotex dome tweeters surround the 5” forward-facing cone woofer and surprisingly, three rear-firing tweeters can be found mounted to the back of the loudspeaker.

Build and Construction

Overall the cosmetics on the Callas fall perfectly in line with what you might expect from loudspeaker that sets you back 5 large. Picking up the almost 30 lb. speaker drops a not-so-subtle hint at its interior makeup. The wood finish exhibited a very pleasing deep gloss look that complemented the choice of wood very nicely. Every texture and choice of material bled out the attention to detail that helps define a quality high-end product against the masses of assembly line wares. While some may find the leather finish of the front panel polarizing, most visitors who gazed upon the design of the review pair that inhabited my listening room agreed that the look was appealing. The solid copper phase plug and white woofer give the Callas a surprisingly classy look in an endless sea of right-angle boxes and black-paper cones. A quick rundown of the specs from the Opera site claims a sensitivity of 86 dB and a nominal impedance of 4 ohms. The 15 x 9 x 13 inch cabinet isn’t exactly conducive to the desktop (or even really a bookshelf, for that matter), but if you are in the market for a speaker in this price range chances are you already know better. The crossover point is set slightly higher for the rear radiating tweeters than the front (2k vs. 1.5k Hz).

About those Tweeters…

A double dose of high frequency drivers in the front and three in the back pushes the Callas design out from the rest of the market, especially for a bookshelf. Marc Phillipps from Opera shed some more light on their design:

The Callas and Grand Callas have been around since the ’90s … the cabinets and drivers have been updated periodically in the last twenty years, but the basic design has been the same. The rear tweeters are not true arrays; that would imply that all the tweeters have the same output levels. In this arrangement, which Opera calls a “triplet,” each tweeter has a different value/output. These values were arrived at through plenty of experimentation … Unison and Opera has their own research lab and can test designs whenever they want. The Callas line was developed through years of this type of testing.

One might assume that all this extra energy would lead to a top-heavy signature, but in the case of the Callas, it does not. In fact, when compared to the full range Zu Soul Mk.2 loudspeaker, the Opera delivered a slightly less treble-leaning presentation. The upper octives here feel like they follow a straight line up from the mids, if not perhaps just a little more subtle than flat that at times. Listening to a variety of tracks from rock to jazz, the Callas offered up a little less high frequency sizzle and bite, which was more often than not a good thing, especially on digital tracks from questionable origins.

The (sound)stage is set

The Callas has a very natural demeanor to its sonics, complemented exponentially by its luxurious soundstage. Vocal-centric albums like Diana Krall’s Glad Rag Doll were perfectly hung within the stereo field. With the right setup, a female vocal lead can seem to emanate from some unseen phantom third speaker set perfectly in the middle the two bookshelves. I think it’s safe to say Opera’s loudspeakers were in some part inspired by the acoustic experience that bears their namesake. This notion seems subtly evident in the overall presentation of vocals. The big, rich sound field just begs for an equally large voice to fill it, even if its overall resolution can be finicky at times. Fans of opera and orchestral music should be right at home with the wide natural throw of the 2-way, 6 driver design. The Callas is successful in its endeavors in creating an illusion of a larger speaker source; the stage it sets certainly feels huge for a driver roughly the size of a human palm. Opera is clear to point out the Callas needs plenty of room behind them to sound their best. Their website recommends at least 1.6 feet of space between them and any wall. Any less and the rear reflection might start to play havoc with the balance of sound  headlining the show. Giving the tri-tweeter rear radiators additional breathing room beyond this recommendation improved their performance significantly. So in this situation, the designated loudspeaker size “bookshelf” really doesn’t fit the bill. Close proximity to a rear wall can really start to negatively impact low frequencies as well (especially ones with a rear-ported design), so in the case of Callas vs. “The Wall”, please steer clear.

The “bookshelf” paradox

Bass from the Callas is extremely impressive, the one area where no bookshelf can claim to be king. The Opera websites states the pair travel down to a mighty 32 Hz, just 12 shy from the human range of hearing goalpost. One could say that they sound similar to a floor-standing loudspeaker, except that you could find more than one product in that full size category that actually sounds a bit thinner than the Callas in the southern regions. The extension really catches enough to remain informative, and is delightfully tight and responsive. It is quite balanced and by no means bloated. Listening to “Do I Wanna Know?” off the Arctic Monkeys latest release provided an enticing and unfettered romp between bass guitar and drum. Clear, concise delineation between these instrumental High Kings of the Low-End leaves a very pleasing taste on the acoustic palate. The guitar tone here is textured and deep, ever so slightly processed and eloquently spiced. As the bass breaks through the mix at the halfway mark, the Callas kicked in with the flush tone, missing only but the very lowest “thumpage” (that’s a technical term). You can feel it in your chest with the volume up, no doubt about it … but there still is really no substitute for a full size subwoofer when it comes to music you can feel through your toes. R&B and dance listeners may want to add a dash of rumble; all others should be satisfied with the balance — and your neighbors will thank you. While the market for $5k speakers might be slightly smaller than the potential for a Beats headphone, the bookshelf size makes this niche within a niche an even smaller target to hit. But for those who just checked off every box on a list of requirements, these Operas offer a great vantage point from which to view your options. Those with more modest budgets may want to check out the company’s KEF LS50-style (in size and price) Mezza bookshelf. Operation Opera Callas is a success by many measures. This small-speaker collection of drivers stands a few steps apart from the rest of the crowd in more ways than one. First and foremost the soundstage is unique for this style of loudspeaker and the tri-tweeter treatment does not undermine the listening experience in the least. Bookshelves can be a real blessing to those who have tighter space and/or volume restrictions but still want good sound. The Callas is proof that small(-er) speakers don’t have to sound closed in, threadbare or tinny. As always with loudspeakers, placement and room acoustics play a big part what you get out of your gear. Get it right with the Callas and they will reward you tenfold. In addition to this expansive reach, there is a solid richness to the tonal structure across the bandwidth that pushes the delicate seesaw down to a natural configuration and away from the pushy and over processed. Then there is the bass. The Opera gets high marks for its presentation and extension, balance and posture. Herein lies the real challenge for speakers of similar stature. Stringent depth requirements for bass vary from person to person, but after an audition with these tiny dancers you may even find yourself redefining what your needs are. Bass expectations for this class of speaker are definitely attained — with flying colors. Overall, the build, fit and finish all feel like the real deal — a solid demonstration from a solid loudspeaker. I highly recommend an audition of the Callas if you have the means, its sonic demeanor will entertain and surprise you.

W Grill


Phase plug


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Associated Equipment

  • Macbook Air running Audirvana Plus
  • PC running Foobar 2000
  • Zu Soul Mk.II Loudspeaker
  • Auralic VEGA DAC
  • Benchmark DAC2 D
  • The Calyx Integrated
  • Calyx Femti 125 Amplifier
  • Zu Mission RCA Mk.2-b Interconnects

About the Author

Brian Hunter is a recovering musician turned audio reviewer. He currently manages and writes reviews for his own head-fi site and freelances with several other publications, including Computer Audiophile. He loves tech and the tools of music, especially the ones involved in reproduction. After he finished his undergrad degree in business, he went to the local community college and got one in photography, which was way more fun. He likes it when people have unbridled enthusiasm for something and has the utmost respect for individuals who try to create, and even more for those who are good at it.


  1. I regret missing these gems at 2013 Rocky Mountain Audio Fest. The more press devoted to this particular loudspeaker, the better for audiophiles and music lovers.

    Unlike most audiophiles and speaker junkies, experience tells me the last frontier in loudspeakers has nothing to do with drivers, enclosures, diaphragm materials…and everything to do with radiation patterns and modified reverberant field output. Dr. Amar Bose did not get it exactly right in his Model 9, but there is good reason why musicians/audiophiles like my friend placed them atop his wish list many decades ago. The classic and ubiquitous mono pole radiation pattern fails miserably in recreating live music cues compared to other more advanced patterns (no, I’m not a fan of omni-pole radiation patterns).

    I’m pleased to see this Italian company break new ground in this area, especially in a package so enticing and easy on the eyes. How could one ever tire of admiring these beauties?

    In his Stereophile review of the Opera Callas, John Marks found similarities to his beloved discontinued French ASA (Atelier de Synergie Acoustique, Workshop of Acoustic Synergy) Pro Monitor, circa $5500/pr, not to be confused with the lesser Baby nor Standard Monitor. I owned and loved the Pro Monitor, and still own six improved clones of that gorgeous speaker. That is high praise, and good reason to audition Callas if it’s within one’s budget. I recommend you audition Callas, even if your list comprises floor standing speakers only.

    In the elevator at RMAF I briefly spoke with Ms. Cardas, the USA distributor for Opera. Her company seems like one well worth supporting.

    • Wow, James, thanks for all the kind words! Colleen and I were pretty smitten with the Callas’ performance at RMAF…we constantly had people entering the room and thinking that the Trenner & Friedl Pharaohs were actually subwoofers for the Callas. It’s a fascinating design–these little speakers go really deep in the bass and all those tweeters create a spaciousness in the treble that creates an amazingly large soundstage. We hope to see you at future audio shows, just introduce yourself to either Colleen or me.

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