DALI Rubicon 6 C Wireless Integrated System

REVIEW
by Andrew Quint
Jun 07, 2021

The next time that audiophile catalog lands in your mailbox—you know, the one that’s been coming every month or so ever since you bought a gallon of record cleaning fluid sometime during the second Clinton administration—take a close look at the photos used to show off the equipment to its best advantage. A Spartan turntable sits on a tastefully distressed wood-plank table with three potted cacti looking on admiringly. A top-quality surround-sound system is displayed in a living room on a well-maintained oak floor with glimpses of an expensive-looking Persian rug and a contemporary Italian glass coffee table in the frame. A sleek equipment rack holding thousands of dollars worth of gear sits beneath an abstract watercolor. The presentation is intended to communicate that owning good audio gear demonstrates an appreciation for the finer things in life. But do the hypothetical inhabitants of these refined spaces only look and not listen? I ask because there’s not a cable in sight.

The idea of a wireless audio system has a lot of appeal, and not just because of aesthetic considerations. There’s the chance for a designer to optimally match amplification to a loudspeaker’s drivers and enclosure. There’s all the assets and angst spared by not having to deal with interconnects and speaker cables. Although most active loudspeakers are smaller models intended for desktop or studio use, the product class has been burgeoning lately, and there have been some recent high-profile successes with full-range models aimed at the audiophile market. Bruno Putzeys’ Kii Three, the Gayle Sanders’ Eikon, and several others have joined offerings from trailblazer Meridian Audio. In the loudspeaker game since 1983, Denmark’s Dali—that’s Danish Audiophile Loudspeaker Industries—has decided to commit resources to this approach, as well.

Dali introduced two powered loudspeakers in 2017, the Callisto 2 and Callisto 6. The bookshelf Rubicon 2 C and the Rubicon 6 C floorstander considered here are the first instances of DALI taking an existing product (the Rubicon 6, at $5499 per pair, debuted in 2014) and building in the wireless technology of the Callistos. The Rubicon 6 C, with the DALI Sound Hub that serves as a streaming preamplifier connecting wirelessly to the loudspeakers, retails for a smidge under $8800.

The DALI Rubicon 6 C loudspeakers are handsome, if conventional-appearing rectangular boxes measuring 7.9″ (W) x 39.1″ (H) x 15.0″ (D). Each speaker weighs in at 45.8 pounds. The 6 C is a 2½-way bass-reflex system, with both its hybrid tweeter and two 6.5″ mid/bass drivers built by DALI in Denmark using European-manufactured parts. The high-frequency unit combines a 1″ soft dome, featuring a copper-clad aluminum voice coil, and a wide-dispersion magnetostatic ribbon. The complete tweeter assembly functions from about 2500Hz to beyond 30kHz. The mid/woofer has a wood-fiber diaphragm that’s both light and rigid, possessing an uneven surface that assures more ideal pistonic movement of the membrane. Perhaps the driver’s most significant design element is the Soft Magnetic Compound (SMC) used to replace a key iron part of the magnet structure. As explained to me by DALI CEO Lars Worre, SMC is “a pulverized material consisting of very small iron particles, which are individually coated so that when you press them together into a form, none of the particles will—electrically—be in contact. Consequentially, there will be no electrical conductivity: SMC is around ten thousand times less electrically conductive than iron but has the same excellent abilities to conduct magnetism.” DALI manufactures its mid/bass driver’s pole piece entirely from SMC, enclosing it in a slitted copper cap. A measurable consequence of this design is the virtual elimination of hysteresis, a phenomenon resulting from the asymmetry of the magnetization/demagnetization process that introduces distortion-causing resistance to the voice coil. Despite that, by necessity the SMC pole piece is located close to the magnet gap. Worre said, “We don’t lose energy to the surrounding iron materials, and the result is a dramatic reduction in distortion, particularly with odd-order harmonics.”

The Rubicon’s enclosure is fabricated from MDF, with the drivers attached directly to a one-inch-thick front baffle. Strategic internal bracing is used to reduce standing waves and resonances. There are three available finishes, all priced the same—black and white gloss lacquer and walnut veneer. The mid/bass drivers are situated in two equal-sized internal compartments, each with its own rear-firing port tuned to 36.5Hz. The 6 C employs two identical, 250W, self-oscillating, “Eigentakt” Class D amplifiers; one powers the tweeter unit and the other the two mid/bass drivers. The crossover is a hybrid of active DSP filtering and passive analog topology with hand-off frequencies of 800Hz (bottom to top midrange/bass driver), 2.6kHz (top mid/bass to dome tweeter) and 14kHz (dome to ribbon.) The system’s DAC lives in the loudspeaker, a Burr-Brown 1796 chipset. This is a PCM-only device, so those devoted to native DSD may be disappointed. Lars Worre wasn’t exactly sympathetic. “From a radio transmission point of view, we could have quite easily decided to transfer a DSD stream with oversampling corresponding to the commonly used 2.8MHz version,” he told me. “But it would have called for another platform for D-to-A conversion in the speaker. We decided to stay with the rather good-sounding 24-bit/96kHz basic format, as the use of true DSD sources is so commercially marginalized that we believe it will never, in reality, be an issue for actual customers.”

On the rear of each Rubicon 6 C, where you’d expect to find the binding posts, are an AC connector for the supplied power cord, a rocker-type power switch, a USB service port, and an RCA input to allow the loudspeaker to get line-level input from an external preamp or processor instead of DALI’s wireless Sound Hub. Above these connections is a small screen that illuminates to guide the wireless pairing process, and above that is the critical Link/Connect button. Each 6 C is provided with two metal bars that fit neatly into recesses on the speaker’s bottom to create a stabilizing outrigger structure. Four supplied spikes can be threaded into the bars; rubber bumpers are an alternative. A single grille attaches with plastic pins to cover all the drivers. Like most loudspeaker grilles, it’s not completely transparent sonically, and should be removed for critical listening—though the same party who OK’d the speakers’ admission to a shared living space because of the absence of cables may balk at the prospect of exposed drivers. So, it goes.

DALI’s Sound Hub is the brains of the operation, a diminutive, shiny black box measuring 11.8″ (W) x 3″ (H) x 8.4″ (D). On the front panel are three small buttons (power, mute, and source select) and a rotary volume knob that also indicates the status of the speaker-pairing process, when that’s happening. On the back, in addition to the Link/Connect button (identical to the one on the rear of each loudspeaker), there’s a receptacle for the plug from the decidedly non-audiophile wall-wart power supply. Also on the rear panel are inputs for analog stereo (a pair of RCAs and a 3.5 mm mini-jack), as well as digital connections (a single coaxial SPDIF and two optical inputs—one for a music source and one for a TV.) There’s a line-level stereo output, responsive to the Hub’s volume control, and a subwoofer output. The input selector on the front panel (and the compact but easy-to-use remote control) lets the user choose among the hard-wired source options, plus a Bluetooth input that supports AAC, aptX, and aptX HD. Other Sound Hub functions that are easily activated and/or adjusted include auto-sensing/auto-power on, display and LED dimming, individual speaker volume adjustment (i.e., balance), and several Bluetooth settings.

Also accessible from the back of the Sound Hub is a modular expansion port that allows for customization and, to some degree, future-proofs the DALI system. As far as I could determine, the only “extra” function included in the review sample was BluOS connectivity, which allows for the Hub to connect with other devices that are so enabled. The BluOS NPM-1 plug-in module is MQA certified, so users streaming Tidal can listen to Masters files fully “unfolded.”

The Hub utilizes either a 2.4GHz or 5.8GHz band to establish the wireless connection to the Rubicon loudspeakers, sending an I²S 24-bit/96kHz audio signal via a proprietary 30-bit transfer protocol. (The extra bits are used for volume adjustment, channel identification, error correction, and other control data.) The latency is low, less than 25 milliseconds, so synchronization between video and audio isn’t problematic if you’re watching a movie or television with the Rubicon system providing the sound. The “high-bandwidth, low-latency protocol” also facilitates the connection of multiple speakers to the same stereo data signal. I tried this out with the BluOS-enabled, Paul Barton-designed Bluesound Pulse Mini 2i active loudspeaker; the Hub connected to both the Bluesound and DALI devices simultaneously without a hitch.

This review didn’t require much in the way of “associated equipment”—I guess that’s kind of the whole idea—just two boxes and a cable. An Oppo BDP-103 served as a disc transport and music files were played with my Baetis Reference media computer. I actually used two of the same Apogee Wyde Eye 75-ohm coaxial cables to make life simpler, one connected to the disc player and one to the server; when I changed sources, it was only necessary to switch the cables at the Hub. I understand that many users will be connecting all sources wirelessly (and I did play music off my phone into the Hub to confirm how easy it is to do.) But I do wish there was another RCA digital input—do any audiophiles use TosLink nowadays?—and feel that a Type B USB interface ought to be standard with any device that does D-to-A conversion. In my 15′ x 15′ room, the two speakers and the prime listening position formed an equilateral triangle measuring about 8′ 6″ per side. The DALI’s were positioned about 21″ from the wall behind them and were toed-in toward the sweet spot.

Getting the DALI Rubicon 6 C’s wireless connection up and running isn’t at all challenging, thanks to its user-friendly design and an eight-page “Quick Set-Up Guide” included in the box with the Sound Hub. (If you’d prefer a few words of explanation in addition to the IKEA-esque how-to diagrams, a more complete owner’s manual is available online.) Basically, you press the Link/Connect button on the back of the Hub—a schematic of the speaker configuration lights up beneath the glass top surface—and then, in turn, activate the identical button on the back of each speaker. The 6 C emits a musical tone when it’s ready to be paired and you identify each speaker as the right or left channel. Link/Connect is then pressed again on the Hub and the pairing is complete. This procedure doesn’t need to be repeated each time the Rubicon is turned on, by the way—the wireless connection happens automatically.

Naturally, I wanted to know that it worked. The Baetis server was connected to the Hub’s coaxial input and I planted myself on the sofa and started up the music I’d been listening to the previous evening with my usual loudspeakers and amplification. That was Suzanne Vega’s 1992 gem, 99.9Fº, specifically the third song, “In Liverpool.” Sound, indeed, came out of the 6 Cs—and did it ever. Vega’s voice, suspended in the air between the two speakers, was effortlessly immediate and definitively her. Bass was articulate, there was abundant detail, and the spatial presentation was gratifyingly open. I didn’t budge for 34 minutes, listening all the way through to the end, and then to the first two songs I’d missed. This was an auspicious beginning.

I decided to depart from my usual modus operandi, which is to systematically listen to recordings chosen to test a given sonic parameter—bass dynamics, midrange purity, treble extension, soundstage reproduction, image specificity, and so on. Instead, I determined to ramble from genre to genre to see if there was some sort of music that would trip up the Rubicon 6 Cs in a potentially disqualifying way. Spoiler alert: There wasn’t. Here are some highlights from that exercise.

•Symphonic music and opera. With well-recorded classical “power music,” the Rubicon 6 Cs manifested surprisingly good dynamic headroom for what isn’t a large loudspeaker. The finale of Mahler’s Symphony No. 6 (Tilson Thomas/San Francisco) may have been less apocalyptic than with my reference Magico M2s, but the two infamous “hammer” strokes that punctuate the movement’s dramatic trajectory were plenty potent. On this recording and with other large-scale orchestral material, the soundstage was expansive and continuous, with good layered-depth and image localization. The last half-hour of Wagner’s Lohengrin (Janowski) features a rousing extended orchestral interlude, a celebratory chorus, and solo turns by most of the opera’s principals, notably “In ferner Land,” memorably sung by Klaus Florian Vogt in the title role. Through the DALIs, the build in theatrical excitement was palpable, as the spatial and distanced effects created by PentaTone’s engineers registered tellingly.

•Pop and rock. Power pop classics from the 1980s, such as “She’s a Beauty” by The Tubes or Madonna’s “Cherish,” were played by the Rubicon 6 C’s with all the buoyant energy and good spirits that explain their anthemic stature. Well-engineered bass and kick drum locked in with satisfying impact. Music that was a bit edgier, songs like “Dancing in the Dark” (Springsteen) or “Heavy Fuel” (Dire Straits), and—just to name a few from bands whose principals aren’t AARP members just yet—”Hot Thoughts” (Spoon) and “Basket Case” (Green Day) came through with their drive and dynamic life intact.

•Chamber music and small group jazz. With both genres, the DALIs were a window into the sort of musical groupthink achieved with the most successful small group collaborations. This was the case with well-recorded jazz that’s a bit on the “lite” side (“Three Cowboy Songs” from Dave Grusin’s Discovered Again), as well as with all those records-for-the-ages recorded by a NJ optometrist in his mother’s living room (e.g., “Locomotion” from John Coltrane’s Blue Train). When the Emerson String Quartet decided to cover all eight parts of Schubert’s Octet for Strings, they went to a lot of trouble to assure that the final product didn’t sound like obvious overdubbing. The four players frequently changed seats and used different instruments for the “second pass.” The revealing nature of the Rubicon 6 Cs made all the production summersaults worth the effort.

•Vocals and choral music. Favorite singers—Linda Ronstadt (“When You Wish Upon A Star”), Dietrich Fischer-Dieskau (Schubert’s “Die Heimweh”), Cécile McLorin Salvant (“Growlin’ Dan”), Aaron Neville (“Tell It Like It Is”)—sounded utterly like themselves, communicating a song’s meaning as if the electromechanical interface had disappeared. Good choral recordings of both early repertoire (Stile Antico singing “Never weather-beaten sail”) and contemporary music (Kile Smith’s Grammy-nominated The Arc in the Sky from The Crossing Choir) demonstrated both the beauty of individual voices and the revelatory blend and balances achieved by the best ensembles.

•Plucked instruments. There’s no better demo recording for this kind of musical material than Tone Poems, a collection of 17 duets from Tony Rice and David Grisman, who play a different guitar and mandolin on each selection. The initial attack of a note is convincingly attached to the subsequent body of the tone and subtle differences in the size and sonority of the vintage instruments are beautifully delineated. The Stockholm Guitar Quartet’s arrangement of the opening Allegro from J. S. Bach’s Brandenburg Concerto No. 3, on the Opus 3 label, is similarly successful, thanks to the speed of the Rubicon’s hybrid tweeter and its smooth transition to the speaker’s upper midrange/bass driver.

•Piano and organ music. For a smallish loudspeaker, the DALI Rubicon 6 Cs did well by the King of Instruments, providing information about the physical scale of the organ being recorded as well as the space it calls home. On Volume 9 of David Goode’s complete traversal of Bach’s organ works, the presence of “mutation” stops that speak at an interval other than the unison or octave was apparent in the richly textured full organ sonorities rendered by the DALI’s. Piano recordings were believable, whether the ambience was “wet” (Shen Lu’s recording of Ravel’s Miroirs on the Steinway & Sons label), “dry” (anything from Glenn Gould), or somewhere in between (Matti Raekallio’s Prokofiev Sonata series from Ondine.) The DALI speakers strongly supported the contention that all three approaches can eventuate in believable piano sound.

•Big Band. On high-octane charts— “High Maintenance” from the Big Phat Band’s XXL album is a good example—the DALIs kept their composure until I reached a playback level that was probably ill-advised, given that the president of the condo association lives two doors down. Count Basie’s densely-scored “Lil’ Darling,” as heard on either Bob Mintzer’s Basie tribute album for DMP or one of several versions from the Count himself, demonstrated why this sensual slow burn is a perennial favorite.

With the varieties of music I listen to a lot (and a few that I don’t but tried out anyway) the DALI Rubicon 6 Cs did justice to just about everything. This loudspeaker is obviously a good bet for music lovers with eclectic tastes, though I suspect it will also deliver long-term satisfaction to those with more circumscribed interests—if all you care about is Baroque opera, experimental jazz, British Invasion bands from 1964 to1966… whatever.

The whole question of what constitutes “good value” in high-end audio is a vexed proposition. Take a look at the list of the “50 Greatest Bargains in High-End Audio” on the last page of the 2021 TAS Buyers Guide. Though every product listed there can certainly be viewed as a wise purchase, when the price tag gets into five-figure territory, I begin to get a little uncomfortable. Is a $28,000/pair of loudspeakers really a “bargain” just because they perform as well as someone else’s $60,000 model? I owned the speakers in question and certainly felt that way—but I can see that someone else might see it differently. I’m pretty certain that, at $8798 for a product that can go toe-to-toe with an assiduously assembled system of amplification, speakers, and cabling that costs far more, the DALI Rubicon 6 C really is an exceptionally good deal. If you’re starting from scratch with a second system or even with a first, consider very seriously this wireless wonder.

Specs & Pricing

Type: Two-and-a-half-way, ported, active loudspeaker
Driver complement: Hybrid tweeter unit: one 1″ soft-dome tweeter and one 0.67″ x 1.77″ magnetostatic ribbon; two 6½” wood-fiber midrange/bass drivers
Frequency response: 37Hz–30kHz
Impedance: 5000 ohms
Amplifier power: 250W x 2 (per speaker)
Dimensions: 7.9″ x 39.1″ x 15″
Weight: 45.8 lbs
Price: $8798 (includes DALI Sound Hub streaming preamplifier)